Empirical analysis on the connection between power-law distributions and allometries for urban indicators

NASA Astrophysics Data System (ADS)

Alves, L. G. A.; Ribeiro, H. V.; Lenzi, E. K.; Mendes, R. S.

2014-09-01

We report on the existing connection between power-law distributions and allometries. As it was first reported in Gomez-Lievano et al. (2012) for the relationship between homicides and population, when these urban indicators present asymptotic power-law distributions, they can also display specific allometries among themselves. Here, we present an extensive characterization of this connection when considering all possible pairs of relationships from twelve urban indicators of Brazilian cities (such as child labor, illiteracy, income, sanitation and unemployment). Our analysis reveals that all our urban indicators are asymptotically distributed as power laws and that the proposed connection also holds for our data when the allometric relationship displays enough correlations. We have also found that not all allometric relationships are independent and that they can be understood as a consequence of the allometric relationship between the urban indicator and the population size. We further show that the residuals fluctuations surrounding the allometries are characterized by an almost constant variance and log-normal distributions.

Evolution of static allometries: adaptive change in allometric slopes of eye span in stalk-eyed flies.

PubMed

Voje, Kjetil L; Hansen, Thomas F

2013-02-01

Julian Huxley showed that within-species (static) allometric (power-law) relations can arise from proportional growth regulation with the exponent in the power law equaling the factor of proportionality. Allometric exponents may therefore be hard to change and act as constraints on the independent evolution of traits. In apparent contradiction to this, many empirical studies have concluded that static allometries are evolvable. Many of these studies have been based, however, on a broad definition of allometry that includes any monotonic shape change with size, and do not falsify the hypothesis of constrained narrow-sense allometry. Here, we present the first phylogenetic comparative study of narrow-sense allometric exponents based on a reanalysis of data on eye span and body size in stalk-eyed flies (Diopsidae). Consistent with a role in sexual selection, we found strong evidence that male slopes were tracking "optima" based on sexual dimorphism and relative male trait size. This tracking was slow, however, with estimated times of 2-3 million years for adaptation to exceed ancestral influence on the trait. Our results are therefore consistent with adaptive evolution on million-year time scales, but cannot rule out that static allometry may act as a constraint on eye-span adaptation at shorter time scales. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Limb bone allometry during postnatal ontogeny in non-avian dinosaurs

PubMed Central

Kilbourne, Brandon M; Makovicky, Peter J

2010-01-01

Although the interspecific scaling of tetrapods is well understood, remarkably little work has been done on the ontogenetic scaling within tetrapod species, whether fossil or recent. Here the ontogenetic allometry of the femur, humerus, and tibia was determined for 23 species of non-avian dinosaur by regressing log-transformed length against log-transformed circumference for each bone using reduced major axis bivariate regression. The femora of large theropod species became more robust during ontogeny, whereas growth in the femora of sauropodomorphs and most ornithischians was not significantly different from isometry. Hadrosaur hindlimb elements became significantly more gracile during ontogeny. Scaling constants were higher in all theropods than in any non-theropod taxa. Such clear taxonomically correlated divisions were not evident in the ontogenetic allometry of the tibia and hindlimb bones did not scale uniformly within larger taxonomic groups. For taxa in which the ontogenetic allometry of the humerus was studied, only Riojasaurus incertus exhibited a significant departure from isometry. Using independent contrasts, the regression of femoral allometry against the log of adult body mass was found to have a significant negative correlation but such a relationship could not be established for other limb elements or growth parameters, mainly due to the small sample size. The intraspecific scaling patterns observed in dinosaurs and other amniotes do not support earlier hypotheses that intraspecific scaling differs between endothermic and ectothermic taxa. PMID:20557400

Ecological allometries and niche use dynamics across Komodo dragon ontogeny.

PubMed

Purwandana, Deni; Ariefiandy, Achmad; Imansyah, M Jeri; Seno, Aganto; Ciofi, Claudio; Letnic, Mike; Jessop, Tim S

2016-04-01

Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons (Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ∼20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.

Ordinary least squares regression is indicated for studies of allometry.

PubMed

Kilmer, J T; Rodríguez, R L

2017-01-01

When it comes to fitting simple allometric slopes through measurement data, evolutionary biologists have been torn between regression methods. On the one hand, there is the ordinary least squares (OLS) regression, which is commonly used across many disciplines of biology to fit lines through data, but which has a reputation for underestimating slopes when measurement error is present. On the other hand, there is the reduced major axis (RMA) regression, which is often recommended as a substitute for OLS regression in studies of allometry, but which has several weaknesses of its own. Here, we review statistical theory as it applies to evolutionary biology and studies of allometry. We point out that the concerns that arise from measurement error for OLS regression are small and straightforward to deal with, whereas RMA has several key properties that make it unfit for use in the field of allometry. The recommended approach for researchers interested in allometry is to use OLS regression on measurements taken with low (but realistically achievable) measurement error. If measurement error is unavoidable and relatively large, it is preferable to correct for slope attenuation rather than to turn to RMA regression, or to take the expected amount of attenuation into account when interpreting the data. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Ecological allometries and niche use dynamics across Komodo dragon ontogeny

NASA Astrophysics Data System (ADS)

Purwandana, Deni; Ariefiandy, Achmad; Imansyah, M. Jeri; Seno, Aganto; Ciofi, Claudio; Letnic, Mike; Jessop, Tim S.

2016-04-01

Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons ( Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ˜20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.

Controversy in the allometric application of fixed- versus varying-exponent models: a statistical and mathematical perspective.

PubMed

Tang, Huadong; Hussain, Azher; Leal, Mauricio; Fluhler, Eric; Mayersohn, Michael

2011-02-01

This commentary is a reply to a recent article by Mahmood commenting on the authors' article on the use of fixed-exponent allometry in predicting human clearance. The commentary discusses eight issues that are related to criticisms made in Mahmood's article and examines the controversies (fixed-exponent vs. varying-exponent allometry) from the perspective of statistics and mathematics. The key conclusion is that any allometric method, which is to establish a power function based on a limited number of animal species and to extrapolate the resulting power function to human values (varying-exponent allometry), is infused with fundamental statistical errors. Copyright © 2010 Wiley-Liss, Inc.

Dinosaur Metabolism and the Allometry of Maximum Growth Rate

PubMed Central

Myhrvold, Nathan P.

2016-01-01

The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism. Dinosaur growth rates show similar overlap, matching the rates found for mammals, reptiles and fish. The allometric scaling of growth rate with mass is found to have curvature (on a log-log scale) for many groups, contradicting the prevailing view that growth rate allometry follows a simple power law. Reanalysis shows that no correlation between growth rate and basal metabolic rate (BMR) has been demonstrated. These findings drive a conclusion that growth rate allometry studies to date cannot be used to determine dinosaur metabolism as has been previously argued. PMID:27828977

Evolution of brain-body allometry in Lake Tanganyika cichlids.

PubMed

Tsuboi, Masahito; Kotrschal, Alexander; Hayward, Alexander; Buechel, Severine Denise; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

2016-07-01

Brain size is strongly associated with body size in all vertebrates. This relationship has been hypothesized to be an important constraint on adaptive brain size evolution. The essential assumption behind this idea is that static (i.e., within species) brain-body allometry has low ability to evolve. However, recent studies have reported mixed support for this view. Here, we examine brain-body static allometry in Lake Tanganyika cichlids using a phylogenetic comparative framework. We found considerable variation in the static allometric intercept, which explained the majority of variation in absolute and relative brain size. In contrast, the slope of the brain-body static allometry had relatively low variation, which explained less variation in absolute and relative brain size compared to the intercept and body size. Further examination of the tempo and mode of evolution of static allometric parameters confirmed these observations. Moreover, the estimated evolutionary parameters indicate that the limited observed variation in the static allometric slope could be a result of strong stabilizing selection. Overall, our findings suggest that the brain-body static allometric slope may represent an evolutionary constraint in Lake Tanganyika cichlids. © 2016 The Author(s).

Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837) (Rodentia, Sigmodontinae).

PubMed

Maestri, R; Fornel, R; Freitas, T R O; Marinho, J R

2015-05-01

Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal's development. In this study, using Huxley's formula of allometric growth (1932), we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

Dinosaur Metabolism and the Allometry of Maximum Growth Rate.

PubMed

Myhrvold, Nathan P

2016-01-01

The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism. Dinosaur growth rates show similar overlap, matching the rates found for mammals, reptiles and fish. The allometric scaling of growth rate with mass is found to have curvature (on a log-log scale) for many groups, contradicting the prevailing view that growth rate allometry follows a simple power law. Reanalysis shows that no correlation between growth rate and basal metabolic rate (BMR) has been demonstrated. These findings drive a conclusion that growth rate allometry studies to date cannot be used to determine dinosaur metabolism as has been previously argued.

Oak bark allometry and fire survival strategies in the Chihuahuan desert Sky Islands, Texas, USA.

PubMed

Schwilk, Dylan W; Gaetani, Maria S; Poulos, Helen M

2013-01-01

Trees may survive fire through persistence of above or below ground structures. Investment in bark aids in above-ground survival while investment in carbohydrate storage aids in recovery through resprouting and is especially important following above-ground tissue loss. We investigated bark allocation and carbohydrate investment in eight common oak (Quercus) species of Sky Island mountain ranges in west Texas. We hypothesized that relative investment in bark and carbohydrates changes with tree age and with fire regime: We predicted delayed investment in bark (positive allometry) and early investment in carbohydrates (negative allometry) under lower frequency, high severity fire regimes found in wetter microclimates. Common oaks of the Texas Trans-Pecos region (Quercus emoryi, Q. gambelii, Q. gravesii, Q. grisea, Q. hypoleucoides, Q. muehlenbergii, and Q. pungens) were sampled in three mountain ranges with historically mixed fire regimes: the Chisos Mountains, the Davis Mountains and the Guadalupe Mountains. Bark thickness was measured on individuals representing the full span of sizes found. Carbohydrate concentration in taproots was measured after initial leaf flush. Bark thickness was compared to bole diameter and allometries were analyzed using major axis regression on log-transformed measurements. We found that bark allocation strategies varied among species that can co-occur but have different habitat preferences. Investment patterns in bark were related to soil moisture preference and drought tolerance and, by proxy, to expected fire regime. Dry site species had shallower allometries with allometric coefficients ranging from less than one (negative allometry) to near one (isometric investment). Wet site species, on the other hand, had larger allometric coefficients, indicating delayed investment to defense. Contrary to our expectation, root carbohydrate concentrations were similar across all species and sizes, suggesting that any differences in below ground storage are likely to be in total volume of storage tissue rather than in carbohydrate concentration.

Oak Bark Allometry and Fire Survival Strategies in the Chihuahuan Desert Sky Islands, Texas, USA

PubMed Central

Schwilk, Dylan W.; Gaetani, Maria S.; Poulos, Helen M.

2013-01-01

Trees may survive fire through persistence of above or below ground structures. Investment in bark aids in above-ground survival while investment in carbohydrate storage aids in recovery through resprouting and is especially important following above-ground tissue loss. We investigated bark allocation and carbohydrate investment in eight common oak (Quercus) species of Sky Island mountain ranges in west Texas. We hypothesized that relative investment in bark and carbohydrates changes with tree age and with fire regime: We predicted delayed investment in bark (positive allometry) and early investment in carbohydrates (negative allometry) under lower frequency, high severity fire regimes found in wetter microclimates. Common oaks of the Texas Trans-Pecos region (Quercus emoryi, Q. gambelii, Q. gravesii, Q. grisea, Q. hypoleucoides, Q. muehlenbergii, and Q. pungens) were sampled in three mountain ranges with historically mixed fire regimes: the Chisos Mountains, the Davis Mountains and the Guadalupe Mountains. Bark thickness was measured on individuals representing the full span of sizes found. Carbohydrate concentration in taproots was measured after initial leaf flush. Bark thickness was compared to bole diameter and allometries were analyzed using major axis regression on log-transformed measurements. We found that bark allocation strategies varied among species that can co-occur but have different habitat preferences. Investment patterns in bark were related to soil moisture preference and drought tolerance and, by proxy, to expected fire regime. Dry site species had shallower allometries with allometric coefficients ranging from less than one (negative allometry) to near one (isometric investment). Wet site species, on the other hand, had larger allometric coefficients, indicating delayed investment to defense. Contrary to our expectation, root carbohydrate concentrations were similar across all species and sizes, suggesting that any differences in below ground storage are likely to be in total volume of storage tissue rather than in carbohydrate concentration. PMID:24244469

Estimating canopy bulk density and canopy base height for interior western US conifer stands

Treesearch

Seth A. Ex; Frederick W. Smith; Tara L. Keyser; Stephanie A. Rebain

2016-01-01

Crown fire hazard is often quantified using effective canopy bulk density (CBD) and canopy base height (CBH). When CBD and CBH are estimated using nonlocal crown fuel biomass allometries and uniform crown fuel distribution assumptions, as is common practice, values may differ from estimates made using local allometries and nonuniform...

Height-diameter allometry of tropical forest trees

Treesearch

T.R. Feldpausch; L. Banin; O.L. Phillips; T.R. Baker; S.L. Lewis; C.A. Quesada; K. Affum-Baffoe; E.J.M.M. Arets; N.J. Berry; M. Bird; E.S. Brondizio; P de Camargo; J. Chave; G. Djagbletey; T.F. Domingues; M. Drescher; P.M. Fearnside; M.B. Franca; N.M. Fyllas; G. Lopez-Gonzalez; A. Hladik; N. Higuchi; M.O. Hunter; Y. Iida; K.A. Salim; A.R. Kassim; M. Keller; J. Kemp; D.A. King; J.C. Lovett; B.S. Marimon; B.H. Marimon-Junior; E. Lenza; A.R. Marshall; D.J. Metcalfe; E.T.A. Mitchard; E.F. Moran; B.W. Nelson; R. Nilus; E.M. Nogueira; M. Palace; S. Patiño; K.S.-H. Peh; M.T. Raventos; J.M. Reitsma; G. Saiz; F. Schrodt; B. Sonke; H.E. Taedoumg; S. Tan; L. White; H. Woll; J. Lloyd

2011-01-01

Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical...

Scale effects between body size and limb design in quadrupedal mammals.

PubMed

Kilbourne, Brandon M; Hoffman, Louwrens C

2013-01-01

Recently the metabolic cost of swinging the limbs has been found to be much greater than previously thought, raising the possibility that limb rotational inertia influences the energetics of locomotion. Larger mammals have a lower mass-specific cost of transport than smaller mammals. The scaling of the mass-specific cost of transport is partly explained by decreasing stride frequency with increasing body size; however, it is unknown if limb rotational inertia also influences the mass-specific cost of transport. Limb length and inertial properties--limb mass, center of mass (COM) position, moment of inertia, radius of gyration, and natural frequency--were measured in 44 species of terrestrial mammals, spanning eight taxonomic orders. Limb length increases disproportionately with body mass via positive allometry (length ∝ body mass(0.40)); the positive allometry of limb length may help explain the scaling of the metabolic cost of transport. When scaled against body mass, forelimb inertial properties, apart from mass, scale with positive allometry. Fore- and hindlimb mass scale according to geometric similarity (limb mass ∝ body mass(1.0)), as do the remaining hindlimb inertial properties. The positive allometry of limb length is largely the result of absolute differences in limb inertial properties between mammalian subgroups. Though likely detrimental to locomotor costs in large mammals, scale effects in limb inertial properties appear to be concomitant with scale effects in sensorimotor control and locomotor ability in terrestrial mammals. Across mammals, the forelimb's potential for angular acceleration scales according to geometric similarity, whereas the hindlimb's potential for angular acceleration scales with positive allometry.

Scale Effects between Body Size and Limb Design in Quadrupedal Mammals

PubMed Central

Kilbourne, Brandon M.; Hoffman, Louwrens C.

2013-01-01

Recently the metabolic cost of swinging the limbs has been found to be much greater than previously thought, raising the possibility that limb rotational inertia influences the energetics of locomotion. Larger mammals have a lower mass-specific cost of transport than smaller mammals. The scaling of the mass-specific cost of transport is partly explained by decreasing stride frequency with increasing body size; however, it is unknown if limb rotational inertia also influences the mass-specific cost of transport. Limb length and inertial properties – limb mass, center of mass (COM) position, moment of inertia, radius of gyration, and natural frequency – were measured in 44 species of terrestrial mammals, spanning eight taxonomic orders. Limb length increases disproportionately with body mass via positive allometry (length ∝ body mass0.40); the positive allometry of limb length may help explain the scaling of the metabolic cost of transport. When scaled against body mass, forelimb inertial properties, apart from mass, scale with positive allometry. Fore- and hindlimb mass scale according to geometric similarity (limb mass ∝ body mass1.0), as do the remaining hindlimb inertial properties. The positive allometry of limb length is largely the result of absolute differences in limb inertial properties between mammalian subgroups. Though likely detrimental to locomotor costs in large mammals, scale effects in limb inertial properties appear to be concomitant with scale effects in sensorimotor control and locomotor ability in terrestrial mammals. Across mammals, the forelimb's potential for angular acceleration scales according to geometric similarity, whereas the hindlimb's potential for angular acceleration scales with positive allometry. PMID:24260117

Improving LiDAR Biomass Model Uncertainty through Non-Destructive Allometry and Plot-level 3D Reconstruction with Terrestrial Laser Scanning

NASA Astrophysics Data System (ADS)

Stovall, A. E.; Shugart, H. H., Jr.

2017-12-01

Future NASA and ESA satellite missions plan to better quantify global carbon through detailed observations of forest structure, but ultimately rely on uncertain ground measurement approaches for calibration and validation. A significant amount of the uncertainty in estimating plot-level biomass can be attributed to inadequate and unrepresentative allometric relationships used to convert plot-level tree measurements to estimates of aboveground biomass. These allometric equations are known to have high errors and biases, particularly in carbon rich forests because they were calibrated with small and often biased samples of destructively harvested trees. To overcome this issue, a non-destructive methodology for estimating tree and plot-level biomass has been proposed through the use of Terrestrial Laser Scanning (TLS). We investigated the potential for using TLS as a ground validation approach in LiDAR-based biomass mapping though virtual plot-level tree volume reconstruction and biomass estimation. Plot-level biomass estimates were compared on the Virginia-based Smithsonian Conservation Biology Institute's SIGEO forest with full 3D reconstruction, TLS allometry, and Jenkins et al. (2003) allometry. On average, full 3D reconstruction ultimately provided the lowest uncertainty estimate of plot-level biomass (9.6%), followed by TLS allometry (16.9%) and the national equations (20.2%). TLS offered modest improvements to the airborne LiDAR empirical models, reducing RMSE from 16.2% to 14%. Our findings suggest TLS plot acquisitions and non-destructive allometry can play a vital role for reducing uncertainty in calibration and validation data for biomass mapping in the upcoming NASA and ESA missions.

Patterns of threshold evolution in polyphenic insects under different developmental models.

PubMed

Tomkins, Joseph L; Moczek, Armin P

2009-02-01

Two hypotheses address the evolution of polyphenic traits in insects. Under the developmental reprogramming model, individuals exceeding a threshold follow a different developmental pathway from individuals below the threshold. This decoupling is thought to free selection to independently hone alternative morphologies, increasing phenotypic plasticity and morphological diversity. Under the alternative model, extreme positive allometry explains the existence of alternative phenotypes and divergent phenotypes are developmentally coupled by a continuous reaction norm, such that selection on either morph acts on both. We test the hypothesis that continuous reaction norm polyphenisms, evolve through changes in the allometric parameters of even the smallest males with minimal trait expression, whereas threshold polyphenisms evolve independent of the allometric parameters of individuals below the threshold. We compare two polyphenic species; the dung beetle Onthophagus taurus, whose allometry has been modeled both as a threshold polyphenism and a continuous reaction norm and the earwig Forficula auricularia, whose allometry is best modeled with a discontinuous threshold. We find that across populations of both species, variation in forceps or horn allometry in minor males are correlated to the population's threshold. These findings suggest that regardless of developmental mode, alternative morphs do not evolve independently of one another.

Competitive regulation of plant allometry and a generalized model for the plant self-thinning process.

PubMed

Wang, Gang; Yuan, Jianli; Wang, Xizhi; Xiao, Sa; Huang, Wenbing

2004-11-01

Taking into account the individual growth form (allometry) in a plant population and the effects of intraspecific competition on allometry under the population self-thinning condition, and adopting Ogawa's allometric equation 1/y = 1/axb + 1/c as the expression of complex allometry, the generalized model describing the change mode of r (the self-thinning exponential in the self-thinning equation, log M = K + log N, where M is mean plant mass, K is constant, and N is population density) was constructed. Meanwhile, with reference to the changing process of population density to survival curve type B, the exponential, r, was calculated using the software MATHEMATICA 4.0. The results of the numerical simulation show that (1) the value of the self-thinning exponential, r, is mainly determined by allometric parameters; it is most sensitive to change of b of the three allometric parameters, and a and c take second place; (2) the exponential, r, changes continuously from about -3 to the asymptote -1; the slope of -3/2 is a transient value in the population self-thinning process; (3) it is not a 'law' that the slope of the self-thinning trajectory equals or approaches -3/2, and the long-running dispute in ecological research over whether or not the exponential, r, equals -3/2 is meaningless. So future studies on the plant self-thinning process should focus on investigating how plant neighbor competition affects the phenotypic plasticity of plant individuals, what the relationship between the allometry mode and the self-thinning trajectory of plant population is and, in the light of evolution, how plants have adapted to competition pressure by plastic individual growth.

Effects of environmental disturbance on phenotypic variation: an integrated assessment of canalization, developmental stability, modularity, and allometry in lizard head shape.

PubMed

Lazić, Marko M; Carretero, Miguel A; Crnobrnja-Isailović, Jelka; Kaliontzopoulou, Antigoni

2015-01-01

When populations experience suboptimal conditions, the mechanisms involved in the regulation of phenotypic variation can be challenged, resulting in increased phenotypic variance. This kind of disturbance can be diagnosed by using morphometric tools to study morphological patterns at different hierarchical levels and evaluate canalization, developmental stability, integration, modularity, and allometry. We assess the effect of urbanization on phenotypic variation in the common wall lizard (Podarcis muralis) by using geometric morphometrics to assess disturbance to head shape development. The head shapes of urban lizards were more variable and less symmetric, suggesting that urban living is more likely to disturb development. Head shape variation was congruent within and across individuals, which indicated that canalization and developmental stability are two related phenomena in these organisms. Furthermore, urban lizards exhibited smaller mean head sizes, divergent size-shape allometries, and increased deviation from within-group allometric lines. This suggests that mechanisms regulating head shape allometry may also be disrupted. The integrated evaluation of several measures of developmental instability at different hierarchical levels, which provided in this case congruent results, can be a powerful methodological guide for future studies, as it enhances the detection of environmental disturbances on phenotypic variation and aids biological interpretation of the results.

Wind loads and competition for light sculpt trees into self-similar structures.

PubMed

Eloy, Christophe; Fournier, Meriem; Lacointe, André; Moulia, Bruno

2017-10-18

Trees are self-similar structures: their branch lengths and diameters vary allometrically within the tree architecture, with longer and thicker branches near the ground. These tree allometries are often attributed to optimisation of hydraulic sap transport and safety against elastic buckling. Here, we show that these allometries also emerge from a model that includes competition for light, wind biomechanics and no hydraulics. We have developed MECHATREE, a numerical model of trees growing and evolving on a virtual island. With this model, we identify the fittest growth strategy when trees compete for light and allocate their photosynthates to grow seeds, create new branches or reinforce existing ones in response to wind-induced loads. Strikingly, we find that selected trees species are self-similar and follow allometric scalings similar to those observed on dicots and conifers. This result suggests that resistance to wind and competition for light play an essential role in determining tree allometries.

Geometric morphometrics reveals sex-differential shape allometry in a spider.

PubMed

Fernández-Montraveta, Carmen; Marugán-Lobón, Jesús

2017-01-01

Common scientific wisdom assumes that spider sexual dimorphism (SD) mostly results from sexual selection operating on males. However, testing predictions from this hypothesis, particularly male size hyperallometry, has been restricted by methodological constraints. Here, using geometric morphometrics (GMM) we studied for the first time sex-differential shape allometry in a spider ( Donacosa merlini , Araneae: Lycosidae) known to exhibit the reverse pattern (i.e., male-biased) of spider sexual size dimorphism. GMM reveals previously undetected sex-differential shape allometry and sex-related shape differences that are size independent (i.e., associated to the y-intercept, and not to size scaling). Sexual shape dimorphism affects both the relative carapace-to-opisthosoma size and the carapace geometry, arguably resulting from sex differences in both reproductive roles (female egg load and male competition) and life styles (wandering males and burrowing females). Our results demonstrate that body portions may vary modularly in response to different selection pressures, giving rise to sex differences in shape, which reconciles previously considered mutually exclusive interpretations about the origins of spider SD.

The nature of allometry in an exaggerated trait: The postocular flange in Platyneuromus Weele (Insecta: Megaloptera).

PubMed

Ramírez-Ponce, Andrés; Garfias-Lozano, Gabriela; Contreras-Ramos, Atilano

2017-01-01

The origin and function of exaggerated traits exhibited by a great number of species with sexual dimorphism remain largely unexplored. The usual model considered as the evolutionary mechanism for the development of these structures is sexual selection. The nature of growth of the postocular flange (POF) in three species of the dobsonfly genus Platyneuromus (Megaloptera, Corydalidae, Corydalinae) is analyzed to explore sexual size dimorphism and allometric scaling. Results involve positive allometry of POF in males of two species, and negative allometry in males of one species, in general with a female-biased sexual dimorphism. We suggest an ancestral condition of dual incipient ornamentation in Platyneuromus, with a subsequent departure of size and shape of POF in males, triggered by sexual selection. Different sexual selection intensities may explain the parallel or divergent growth of POF within the scheme of dual ornamentation. Empirical behavioral data as well as a phylogenetic framework are necessary to clarify possible causes of phenotypic development, time of origin, and evolution of the POF.

Is complex allometry in field metabolic rates of mammals a statistical artifact?

PubMed

Packard, Gary C

2017-01-01

Recent reports indicate that field metabolic rates (FMRs) of mammals conform to a pattern of complex allometry in which the exponent in a simple, two-parameter power equation increases steadily as a dependent function of body mass. The reports were based, however, on indirect analyses performed on logarithmic transformations of the original data. I re-examined values for FMR and body mass for 114 species of mammal by the conventional approach to allometric analysis (to illustrate why the approach is unreliable) and by linear and nonlinear regression on untransformed variables (to illustrate the power and versatility of newer analytical methods). The best of the regression models fitted directly to untransformed observations is a three-parameter power equation with multiplicative, lognormal, heteroscedastic error and an allometric exponent of 0.82. The mean function is a good fit to data in graphical display. The significant intercept in the model may simply have gone undetected in prior analyses because conventional allometry assumes implicitly that the intercept is zero; or the intercept may be a spurious finding resulting from bias introduced by the haphazard sampling that underlies "exploratory" analyses like the one reported here. The aforementioned issues can be resolved only by gathering new data specifically intended to address the question of scaling of FMR with body mass in mammals. However, there is no support for the concept of complex allometry in the relationship between FMR and body size in mammals. Copyright © 2016 Elsevier Inc. All rights reserved.

Small sample sizes in the study of ontogenetic allometry; implications for palaeobiology

PubMed Central

Vavrek, Matthew J.

2015-01-01

Quantitative morphometric analyses, particularly ontogenetic allometry, are common methods used in quantifying shape, and changes therein, in both extinct and extant organisms. Due to incompleteness and the potential for restricted sample sizes in the fossil record, palaeobiological analyses of allometry may encounter higher rates of error. Differences in sample size between fossil and extant studies and any resulting effects on allometric analyses have not been thoroughly investigated, and a logical lower threshold to sample size is not clear. Here we show that studies based on fossil datasets have smaller sample sizes than those based on extant taxa. A similar pattern between vertebrates and invertebrates indicates this is not a problem unique to either group, but common to both. We investigate the relationship between sample size, ontogenetic allometric relationship and statistical power using an empirical dataset of skull measurements of modern Alligator mississippiensis. Across a variety of subsampling techniques, used to simulate different taphonomic and/or sampling effects, smaller sample sizes gave less reliable and more variable results, often with the result that allometric relationships will go undetected due to Type II error (failure to reject the null hypothesis). This may result in a false impression of fewer instances of positive/negative allometric growth in fossils compared to living organisms. These limitations are not restricted to fossil data and are equally applicable to allometric analyses of rare extant taxa. No mathematically derived minimum sample size for ontogenetic allometric studies is found; rather results of isometry (but not necessarily allometry) should not be viewed with confidence at small sample sizes. PMID:25780770

Dietary Correlates of Primate Masticatory Muscle Fiber Architecture.

PubMed

Hartstone-Rose, Adam; Deutsch, Ashley R; Leischner, Carissa L; Pastor, Francisco

2018-02-01

Analyses of masticatory muscle architecture-specifically fascicle length (FL; a correlate of muscle stretch and contraction speed) and physiological cross-sectional area (PCSA; a correlate of force)-reveal soft-tissue dietary adaptations. For instance, consumers of large, soft foods are expected to have relatively long FL, while consumers of obdurate foods are expected to have relatively high PCSA. Unfortunately, only a few studies have analyzed these variables across large primate samples-an order of particular interest because it is our own. Previous studies found that, in strepsirrhines, force variables (PCSA and muscle masses; MM) scale with isometry or slight positive allometry, while the body size corrected FL residuals correlate with food sizes. However, a study of platyrrhines using different methods (in which the authors physically cut muscles between fascicles) found very different trends: negative allometry for both the stretch and force variables. Here, we apply the methods used in the strepsirrhine study (chemical dissection of fascicles to ensure full length measurements) to reevaluate these trends in platyrrhines and extend this research to include catarrhines. Our results conform to the previous strepsirrhine trends: there is no evidence of negative allometry in platyrrhines. Rather, in primates broadly and catarrhines specifically, MM and PCSA scale with isometry or positive allometry. When examining size-adjusted variables, it is clear that fascicle lengths (especially those of the temporalis muscle) correlate with diet: species that consume soft, larger, foods have longer masticatory fiber lengths which would allow them to open their jaws to wider gape angles. Anat Rec, 301:311-324, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Bite force estimation and the fiber architecture of felid masticatory muscles.

PubMed

Hartstone-Rose, Adam; Perry, Jonathan M G; Morrow, Caroline J

2012-08-01

Increasingly, analyses of craniodental dietary adaptations take into account mechanical properties of foods. However, masticatory muscle fiber architecture has been described for relatively few lineages, even though an understanding of the scaling of this anatomy can yield important information about adaptations for stretch and strength in the masticatory system. Data on the mandibular adductors of 28 specimens from nine species of felids representing nearly the entire body size range of the family allow us to evaluate the influence of body size and diet on the masticatory apparatus within this lineage. Masticatory muscle masses scale isometrically, tending toward positive allometry, with body mass and jaw length. This allometry becomes significant when the independent variable is a geometric mean of cranial variables. For all three body size proxies, the physiological cross-sectional area and predicted bite forces scale with significant positive allometry. Average fiber lengths (FL) tend toward negative allometry though with wide confidence intervals resulting from substantial scatter. We believe that these FL residuals are affected by dietary signals within the sample; though the mechanical properties of felid diets are relatively similar across species, the most durophagous species in our sample (the jaguar) appears to have relatively higher force production capabilities. The more notable dietary trend in our sample is the relationship between FL and relative prey size: felid species that predominantly consume relatively small prey have short masticatory muscle fibers, and species that regularly consume relatively large prey have relatively long fibers. This suggests an adaptive signal related to gape. Copyright © 2012 Wiley Periodicals, Inc.

Genotypic Diversity for Biomass Accumulation and Shoot-Root Allometry in the Grass Brachypodium distachyon

NASA Astrophysics Data System (ADS)

Jansson, C.; Handakumbura, P. P.; Fortin, D.; Stanfill, B.; Rivas-Ubach, A.

2017-12-01

Predicting carbon uptake, assimilation and allocation for current and future biogeographical environments, including climate, is critical for our ability to select and/or design plant genotypes to meet increasing demand for plant biomass going into food, feed and energy production, while at the same time maintain or increase soil organic matter (SOM for soil fertility and carbon storage, and reduce emission of greenhouse gasses. As has been demonstrated for several plant species allometric relationships may differ between plant genotypes. Exploring plant genotypic diversity for biomass accumulation and allometry will potentially enable selection of genotypes with high CO2 assimilation and favorable allocation of recent photosynthate into above-ground and below-ground biomass. We are investigating genotypic diversity for PFTs in natural accessions of the annual C3 grass Brachypodium distachyon under current and future climate scenarios and how genotypic diversity correlates with metabolite profiles in aboveground and below-ground biomass. In the current study, we compare effects from non-stressed and drought conditions on biomass accumulation and shoot-root allometry.

Maintenance cost, toppling risk and size of trees in a self-thinning stand.

PubMed

Larjavaara, Markku

2010-07-07

Wind routinely topples trees during storms, and the likelihood that a tree is toppled depends critically on its allometry. Yet none of the existing theories to explain tree allometry consider wind drag on tree canopies. Since leaf area index in crowded, self-thinning stands is independent of stand density, the drag force per unit land can also be assumed to be independent of stand density, with only canopy height influencing the total toppling moment. Tree stem dimensions and the self-thinning biomass can then be computed by further assuming that the risk of toppling over and stem maintenance per unit land area are independent of stand density, and that stem maintenance cost is a linear function of stem surface area and sapwood volume. These assumptions provide a novel way to understand tree allometry and lead to a self-thinning line relating tree biomass and stand density with a power between -3/2 and -2/3 depending on the ratio of maintenance of sapwood and stem surface. (c) 2010 Elsevier Ltd. All rights reserved.

"allometry" Deterministic Approaches in Cell Size, Cell Number and Crude Fiber Content Related to the Physical Quality of Kangkong (Ipomoea reptans) Grown Under Different Plant Density Pressures

NASA Astrophysics Data System (ADS)

Selamat, A.; Atiman, S. A.; Puteh, A.; Abdullah, N. A. P.; Mohamed, M. T. M.; Zulkeefli, A. A.; Othman, S.

Kangkong, especially the upland type (Ipomoea reptans) is popularly consumed as a vegetable dish in the South East Asian countries for its quality related to Vitamins (A and C) and crude fiber contents. Higher fiber contents would prevent from the occurrence of colon cancer and diverticular disease. With young stem edible portion, its cell number and size contribute to the stem crude fiber content. The mathematical approach of allometry of cell size, number, and fiber content of stem could be used in determining the 'best' plant density pressure in producing the quality young stem to be consumed. Basically, allometry is the ratio of relative increment (growth or change) rates of two parameters, or the change rate associated to the log of measured variables relationship. Kangkog grown equal or lower than 55 plants m-2 produced bigger individual plant and good quality (physical) kangkong leafy vegetable, but with lower total yield per unit area as compared to those grown at higher densities.

The nature of allometry in an exaggerated trait: The postocular flange in Platyneuromus Weele (Insecta: Megaloptera)

PubMed Central

Ramírez-Ponce, Andrés; Garfias-Lozano, Gabriela; Contreras-Ramos, Atilano

2017-01-01

The origin and function of exaggerated traits exhibited by a great number of species with sexual dimorphism remain largely unexplored. The usual model considered as the evolutionary mechanism for the development of these structures is sexual selection. The nature of growth of the postocular flange (POF) in three species of the dobsonfly genus Platyneuromus (Megaloptera, Corydalidae, Corydalinae) is analyzed to explore sexual size dimorphism and allometric scaling. Results involve positive allometry of POF in males of two species, and negative allometry in males of one species, in general with a female-biased sexual dimorphism. We suggest an ancestral condition of dual incipient ornamentation in Platyneuromus, with a subsequent departure of size and shape of POF in males, triggered by sexual selection. Different sexual selection intensities may explain the parallel or divergent growth of POF within the scheme of dual ornamentation. Empirical behavioral data as well as a phylogenetic framework are necessary to clarify possible causes of phenotypic development, time of origin, and evolution of the POF. PMID:28212437

Musculoskeletal determinants of pelvic sucker function in Hawaiian stream gobiid fishes: interspecific comparisons and allometric scaling.

PubMed

Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

2013-07-01

Gobiid fishes possess a distinctive ventral sucker, formed from fusion of the pelvic fins. This sucker is used to adhere to a wide range of substrates including, in some species, the vertical cliffs of waterfalls that are climbed during upstream migrations. Previous studies of waterfall-climbing goby species have found that pressure differentials and adhesive forces generated by the sucker increase with positive allometry as fish grow in size, despite isometry or negative allometry of sucker area. To produce such scaling patterns for pressure differential and adhesive force, waterfall-climbing gobies might exhibit allometry for other muscular or skeletal components of the pelvic sucker that contribute to its adhesive function. In this study, we used anatomical dissections and modeling to evaluate the potential for allometric growth in the cross-sectional area, effective mechanical advantage (EMA), and force generating capacity of major protractor and retractor muscles of the pelvic sucker (m. protractor ischii and m. retractor ischii) that help to expand the sealed volume of the sucker to produce pressure differentials and adhesive force. We compared patterns for three Hawaiian gobiid species: a nonclimber (Stenogobius hawaiiensis), an ontogenetically limited climber (Awaous guamensis), and a proficient climber (Sicyopterus stimpsoni). Scaling patterns were relatively similar for all three species, typically exhibiting isometric or negatively allometric scaling for the muscles and lever systems examined. Although these scaling patterns do not help to explain the positive allometry of pressure differentials and adhesive force as climbing gobies grow, the best climber among the species we compared, S. stimpsoni, does exhibit the highest calculated estimates of EMA, muscular input force, and output force for pelvic sucker retraction at any body size, potentially facilitating its adhesive ability. Copyright © 2013 Wiley Periodicals, Inc.

Evolutionary allometry of the thoracolumbar centra in felids and bovids.

PubMed

Jones, Katrina E

2015-07-01

Mammals have evolved a remarkable range of body sizes, yet their overall body plan remains unaltered. One challenge of evolutionary biology is to understand the mechanisms by which this size diversity is achieved, and how the mechanical challenges associated with changing body size are overcome. Despite the importance of the axial skeleton in body support and locomotion, and much interest in the allometry of the appendicular skeleton, little is known about vertebral allometry outside primates. This study compares evolutionary allometry of the thoracolumbar centra in two families of quadrupedal running mammals: Felidae and Bovidae. I test the hypothesis that, as size increases, the thoracolumbar region will resist increasing loads by becoming a) craniocaudally shorter, and b) larger in cross-sectional area, particularly in the sagittal plane. Length, width, and height of the thoracolumbar centra of 23 felid and 34 bovid species were taken. Thoracic, prediaphragmatic, lumbar, and postdiaphragmatic lengths were calculated, and diameters were compared at three equivalent positions: the midthoracic, the diaphragmatic and the midlumbar vertebra. Allometric slopes were calculated using a reduced major axis regression, on both raw and independent contrasts data. Slopes and elevations were compared using an ANCOVA. As size increases the thoracolumbar centra become more robust, showing preferential reinforcement in the sagittal plane. There was less allometric shortening of the thoracic than the lumbar region, perhaps reflecting constraints due to its connection with the respiratory apparatus. The thoracic region was more robust in bovids than felids, whereas the lumbar region was longer and more robust in felids than bovids. Elongation of lumbar centra increases the outlever of sagittal bending at intervertebral joints, increasing the total pelvic displacement during dorsomobile running. Both locomotor specializations and functional regionalization of the axial skeleton appear to have influenced its response to increasing size. © 2015 Wiley Periodicals, Inc.

BOREAS TE-6 Allometry Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Gower, Stith T.; Vogel, Jason G.

2000-01-01

The BOREAS TE-6 team collected several data sets in support of its efforts to characterize and interpret information on the plant biomass, allometry, biometry, sapwood, leaf area index, net primary production, soil temperature, leaf water potential, soil CO2 flux, and multivegetation imagery of boreal vegetation. This data set includes tree measurements conducted on the above-ground biomass of trees in the BOREAS NSA and SSA during the growing seasons of 1994 and 1995 and the derived allometric relationships/equations. The data are stored in ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

Developmental origin of limb size variation in lizards.

PubMed

Andrews, Robin M; Skewes, Sable A

2017-05-01

In many respects, reptile hatchlings are fully functional, albeit miniature, adults. This means that the adult morphology must emerge during embryonic development. This insight emphasizes the connection between the mechanisms that generate phenotypic variation during embryonic development and the action of selection on post-hatching individuals. To determine when species-specific differences in limb and tail lengths emerge during embryonic development, we compared allometric patterns of early limb growth of four distantly related species of lizards. The major questions addressed were whether early embryonic limb and tail growth is characterized by the gradual (continuous allometry) or by the abrupt emergence (transpositional allometry) of size differences among species. Our observations supported transpositional allometry of both limbs and tails. Species-specific differences in limb and tail length were exhibited when limb and tail buds first protruded from the body wall. Genes known to be associated with early limb development of tetrapods are obvious targets for studies on the genetic mechanisms that determine interspecific differences in relative limb length. Broadly comparative studies of gene regulation would facilitate understanding of the mechanisms underlying adaptive variation in limb size, including limb reduction and loss, of squamate reptiles. © 2017 Wiley Periodicals, Inc.

Positive allometry and the prehistory of sexual selection.

PubMed

Tomkins, Joseph L; LeBas, Natasha R; Witton, Mark P; Martill, David M; Humphries, Stuart

2010-08-01

The function of the exaggerated structures that adorn many fossil vertebrates remains largely unresolved. One recurrent hypothesis is that these elaborated traits had a role in thermoregulation. This orthodoxy persists despite the observation that traits exaggerated to the point of impracticality in extant organisms are almost invariably sexually selected. We use allometric scaling to investigate the role of sexual selection and thermoregulation in the evolution of exaggerated traits of the crested pterosaur Pteranodon longiceps and the sail-backed eupelycosaurs Dimetrodon and Edaphosaurus. The extraordinarily steep positive allometry of the head crest of Pteranodon rules out all of the current hypotheses for this trait's main function other than sexual signaling. We also find interspecific patterns of allometry and sexual dimorphism in the sails of Dimetrodon and patterns of elaboration in Edaphosaurus consistent with a sexually selected function. Furthermore, small ancestral, sail-backed pelycosaurs would have been too small to need adaptations to thermoregulation. Our results question the popular view that the elaborated structures of these fossil species evolved as thermoregulatory organs and provide evidence in support of the hypothesis that Pteranodon crests and eupelycosaur sails are among the earliest and most extreme examples of elaborate sexual signals in the evolution of terrestrial vertebrates.

Pitch (F0) and formant profiles of human vowels and vowel-like baboon grunts: The role of vocalizer body size and voice-acoustic allometry

NASA Astrophysics Data System (ADS)

Rendall, Drew; Kollias, Sophie; Ney, Christina; Lloyd, Peter

2005-02-01

Key voice features-fundamental frequency (F0) and formant frequencies-can vary extensively between individuals. Much of the variation can be traced to differences in the size of the larynx and vocal-tract cavities, but whether these differences in turn simply reflect differences in speaker body size (i.e., neutral vocal allometry) remains unclear. Quantitative analyses were therefore undertaken to test the relationship between speaker body size and voice F0 and formant frequencies for human vowels. To test the taxonomic generality of the relationships, the same analyses were conducted on the vowel-like grunts of baboons, whose phylogenetic proximity to humans and similar vocal production biology and voice acoustic patterns recommend them for such comparative research. For adults of both species, males were larger than females and had lower mean voice F0 and formant frequencies. However, beyond this, F0 variation did not track body-size variation between the sexes in either species, nor within sexes in humans. In humans, formant variation correlated significantly with speaker height but only in males and not in females. Implications for general vocal allometry are discussed as are implications for speech origins theories, and challenges to them, related to laryngeal position and vocal tract length. .

Sexual selection explains sex-specific growth plasticity and positive allometry for sexual size dimorphism in a reef fish

PubMed Central

Walker, Stefan P. W.; McCormick, Mark I.

2009-01-01

In 1950, Rensch noted that in clades where males are the larger sex, sexual size dimorphism (SSD) tends to be more pronounced in larger species. This fundamental allometric relationship is now known as ‘Rensch's rule’. While most researchers attribute Rensch's rule to sexual selection for male size, experimental evidence is lacking. Here, we suggest that ultimate hypotheses for Rensch's rule should also apply to groups of individuals and that individual trait plasticity can be used to test those hypotheses experimentally. Specifically, we show that in the sex-changing fish Parapercis cylindrica, larger males have larger harems with larger females, and that SSD increases with harem size. Thus, sexual selection for male body size is the ultimate cause of sexual size allometry. In addition, we experimentally illustrate a positive relationship between polygyny potential and individual growth rate during sex change from female to male. Thus, sexual selection is the ultimate cause of variation in growth rate, and variation in growth rate is the proximate cause of sexual size allometry. Taken together, our results provide compelling evidence in support of the sexual selection hypothesis for Rensch's rule and highlight the potential importance of individual growth modification in the shaping of morphological patterns in Nature. PMID:19553253

An allometric scaling relation based on logistic growth of cities

NASA Astrophysics Data System (ADS)

Chen, Yanguang

2014-08-01

The relationships between urban area and population size have been empirically demonstrated to follow the scaling law of allometric growth. This allometric scaling is based on exponential growth of city size and can be termed "exponential allometry", which is associated with the concepts of fractals. However, both city population and urban area comply with the course of logistic growth rather than exponential growth. In this paper, I will present a new allometric scaling based on logistic growth to solve the abovementioned problem. The logistic growth is a process of replacement dynamics. Defining a pair of replacement quotients as new measurements, which are functions of urban area and population, we can derive an allometric scaling relation from the logistic processes of urban growth, which can be termed "logistic allometry". The exponential allometric relation between urban area and population is the approximate expression of the logistic allometric equation when the city size is not large enough. The proper range of the allometric scaling exponent value is reconsidered through the logistic process. Then, a medium-sized city of Henan Province, China, is employed as an example to validate the new allometric relation. The logistic allometry is helpful for further understanding the fractal property and self-organized process of urban evolution in the right perspective.

Scaling and functional morphology in strigiform hind limbs

PubMed Central

Madan, Meena A.; Rayfield, Emily J.; Bright, Jen A.

2017-01-01

Strigiformes are an order of raptorial birds consisting exclusively of owls: the Tytonidae (barn owls) and the Strigidae (true owls), united by a suite of adaptations aiding a keen predatory lifestyle, including robust hind limb elements modified for grip strength. To assess variation in hind limb morphology, we analysed how the dimensions of the major hind limb elements in subfossil and modern species scaled with body mass. Comparing hind limb element length, midshaft width, and robusticity index (RI: ratio of midshaft width to maximum length) to body mass revealed that femoral and tibiotarsal width scale with isometry, whilst length scales with negative allometry, and close to elastic similarity in the tibiotarsus. In contrast, tarsometatarsus width shows strong positive allometry with body mass, whilst length shows strong negative allometry. Furthermore, the tarsometatarsi RI scales allometrically to mass0.028, whilst a weak relationship exists in femora (mass0.004) and tibiotarsi (mass0.004). Our results suggest that tarsometatarsi play a more substantial functional role than tibiotarsi and femora. Given the scaling relationship between tarsometatarsal width and robusticity to body mass, it may be possible to infer the body mass of prehistoric owls by analysing tarsometatarsi, an element that is frequently preserved in the fossil record of owls. PMID:28327549

Effect of thermal acclimation on organ mass, tissue respiration, and allometry in Leichhardtian river prawns Macrobrachium tolmerum (Riek, 1951).

PubMed

Crispin, Taryn S; White, Craig R

2013-01-01

Changes to an animal's abiotic environment-and consequent changes in the allometry of metabolic rate in the whole animal and its constituent parts-has considerable potential to reveal important patterns in both intraspecific and interindividual variation of metabolic rates. This study demonstrates that, after 6 wk of thermal acclimation at replicate treatments of 16°, 21°, and 25°C, standard metabolic rate (SMR) scales allometrically in Leichhardtian river prawns Macrobrachium tolmerum ([Formula: see text]) and that the scaling exponent and normalization constant of the relationship between SMR and body mass is not significantly different among acclimation treatments when measured at 21°C. There is, however, significant variation among individuals in whole-animal metabolic rate. We hypothesized that these observations may arise because of changes in the metabolic rate and allometry of metabolic rate or mass of organ tissues within the animal. To investigate this hypothesis, rates of oxygen consumption in a range of tissues (gills, gonads, hepatopancreas, chelae muscle, tail muscle) were measured at 21°C and related to the body mass (M) and whole-animal SMR of individual prawns. We demonstrate that thermal acclimation had no effect on organ and tissue mass, that most organ and tissue (gills, gonads, hepatopancreas) respiration rates do not change with acclimation temperature, and that residual variation in the allometry of M. tolmerum SMR is not explained by differences in organ and tissue mass and respiration rates. These results suggest that body size and ambient temperature may independently affect metabolic rate in this species. Both chelae and tail muscle, however, exhibited a reduction in respiration rate in animals acclimated to 25° relative to those acclimated to 16° and 21°C. This reduction in respiration rates of muscle at higher temperatures is evidence of a tissue-specific acclimation response that was not detectable at the whole-animal level.

Caudal fin allometry in the white shark Carcharodon carcharias: implications for locomotory performance and ecology

NASA Astrophysics Data System (ADS)

Lingham-Soliar, Theagarten

2005-05-01

Allometric scaling analysis was employed to investigate the consequences of size evolution on hydrodynamic performance and ecology in the white shark Carcharodon carcharias. Discriminant analysis using the power equation y=axb was negative for caudal fin span (S) versus fork length (FL) in C. carcharias. In contrast in two delphinid species, Delphinus capensis and Tursiops aduncus, the span of the flukes versus fork length rises in positive allometric fashion, and strong positive allometry of S versus √A (area) was also recorded. The latter reflects a high lift/drag ratio. S versus √A in C. carcharias displays negative allometry and consequently a lower lift/drag ratio. A lower aspect ratio (AR) caudal fin in C. carcharias compared to that of the delphinids (mean 3.33 and 4.1, respectively) and other thunniform swimmers provides the potential for better maneuverability and acceleration. The liver in sharks is frequently associated with a buoyancy function and was found to be positively allometric in C. carcharias. The overall findings suggest that the negatively allometric caudal fin morphometrics in C. carcharias are unlikely to have deleterious evolutionary fitness consequences for predation. On the contrary, when considered in the context of positive liver allometry in C. carcharias it is hereby suggested that buoyancy may play a dominant role in larger white sharks in permitting slow swimming while minimizing energy demands needed to prevent sinking. In contrast hydrodynamic lift is considered more important in smaller white sharks. Larger caudal fin spans and higher lift/drag ratio in smaller C. carcharias indicate greater potential for prolonged, intermediate swimming speeds and for feeding predominantly on fast-moving fish, in contrast to slow-swimming search patterns of larger individuals for predominantly large mammalian prey. Such data may provide some answers to the lifestyle and widespread habitat capabilities of this still largely mysterious animal.

New Insights into Non-Avian Dinosaur Reproduction and Their Evolutionary and Ecological Implications: Linking Fossil Evidence to Allometries of Extant Close Relatives

PubMed Central

Werner, Jan; Griebeler, Eva Maria

2013-01-01

It has been hypothesized that a high reproductive output contributes to the unique gigantism in large dinosaur taxa. In order to infer more information on dinosaur reproduction, we established allometries between body mass and different reproductive traits (egg mass, clutch mass, annual clutch mass) for extant phylogenetic brackets (birds, crocodiles and tortoises) of extinct non-avian dinosaurs. Allometries were applied to nine non-avian dinosaur taxa (theropods, hadrosaurs, and sauropodomorphs) for which fossil estimates on relevant traits are currently available. We found that the reproductive traits of most dinosaurs conformed to similar-sized or scaled-up extant reptiles or birds. The reproductive traits of theropods, which are considered more bird-like, were indeed consistent with birds, while the traits of sauropodomorphs conformed better to reptiles. Reproductive traits of hadrosaurs corresponded to both reptiles and birds. Excluding Massospondylus carinatus , all dinosaurs studied had an intermediary egg to body mass relationship to reptiles and birds. In contrast, dinosaur clutch masses fitted with either the masses predicted from allometries of birds (theropods) or to the masses of reptiles (all other taxa). Theropods studied had probably one clutch per year. For sauropodomorphs and hadrosaurs, more than one clutch per year was predicted. Contrary to current hypotheses, large dinosaurs did not have exceptionally high annual egg numbers (AEN). Independent of the extant model, the estimated dinosaur AEN did not exceed 850 eggs (75,000 kg sauropod) for any of the taxa studied. This estimated maximum is probably an overestimation due to unrealistic assumptions. According to most AEN estimations, the dinosaurs studied laid less than 200 eggs per year. Only some AEN estimates obtained for medium to large sized sauropods were higher (200-400 eggs). Our results provide new (testable) hypotheses, especially for reproductive traits that are insufficiently documented or lacking from the fossil record. This contributes to the understanding of their evolution. PMID:23991160

New insights into non-avian dinosaur reproduction and their evolutionary and ecological implications: linking fossil evidence to allometries of extant close relatives.

PubMed

Werner, Jan; Griebeler, Eva Maria

2013-01-01

It has been hypothesized that a high reproductive output contributes to the unique gigantism in large dinosaur taxa. In order to infer more information on dinosaur reproduction, we established allometries between body mass and different reproductive traits (egg mass, clutch mass, annual clutch mass) for extant phylogenetic brackets (birds, crocodiles and tortoises) of extinct non-avian dinosaurs. Allometries were applied to nine non-avian dinosaur taxa (theropods, hadrosaurs, and sauropodomorphs) for which fossil estimates on relevant traits are currently available. We found that the reproductive traits of most dinosaurs conformed to similar-sized or scaled-up extant reptiles or birds. The reproductive traits of theropods, which are considered more bird-like, were indeed consistent with birds, while the traits of sauropodomorphs conformed better to reptiles. Reproductive traits of hadrosaurs corresponded to both reptiles and birds. Excluding Massospondyluscarinatus, all dinosaurs studied had an intermediary egg to body mass relationship to reptiles and birds. In contrast, dinosaur clutch masses fitted with either the masses predicted from allometries of birds (theropods) or to the masses of reptiles (all other taxa). Theropods studied had probably one clutch per year. For sauropodomorphs and hadrosaurs, more than one clutch per year was predicted. Contrary to current hypotheses, large dinosaurs did not have exceptionally high annual egg numbers (AEN). Independent of the extant model, the estimated dinosaur AEN did not exceed 850 eggs (75,000 kg sauropod) for any of the taxa studied. This estimated maximum is probably an overestimation due to unrealistic assumptions. According to most AEN estimations, the dinosaurs studied laid less than 200 eggs per year. Only some AEN estimates obtained for medium to large sized sauropods were higher (200-400 eggs). Our results provide new (testable) hypotheses, especially for reproductive traits that are insufficiently documented or lacking from the fossil record. This contributes to the understanding of their evolution.

Harvesting tree biomass at the stand level to assess the accuracy of field and airborne biomass estimation in savannas.

PubMed

Colgan, Matthew S; Asner, Gregory P; Swemmer, Tony

2013-07-01

Tree biomass is an integrated measure of net growth and is critical for understanding, monitoring, and modeling ecosystem functions. Despite the importance of accurately measuring tree biomass, several fundamental barriers preclude direct measurement at large spatial scales, including the facts that trees must be felled to be weighed and that even modestly sized trees are challenging to maneuver once felled. Allometric methods allow for estimation of tree mass using structural characteristics, such as trunk diameter. Savanna trees present additional challenges, including limited available allometry and a prevalence of multiple stems per individual. Here we collected airborne lidar data over a semiarid savanna adjacent to the Kruger National Park, South Africa, and then harvested and weighed woody plant biomass at the plot scale to provide a standard against which field and airborne estimation methods could be compared. For an existing airborne lidar method, we found that half of the total error was due to averaging canopy height at the plot scale. This error was eliminated by instead measuring maximum height and crown area of individual trees from lidar data using an object-based method to identify individual tree crowns and estimate their biomass. The best object-based model approached the accuracy of field allometry at both the tree and plot levels, and it more than doubled the accuracy compared to existing airborne methods (17% vs. 44% deviation from harvested biomass). Allometric error accounted for less than one-third of the total residual error in airborne biomass estimates at the plot scale when using allometry with low bias. Airborne methods also gave more accurate predictions at the plot level than did field methods based on diameter-only allometry. These results provide a novel comparison of field and airborne biomass estimates using harvested plots and advance the role of lidar remote sensing in savanna ecosystems.

Interspecific scaling patterns of talar articular surfaces within primates and their closest living relatives

PubMed Central

Yapuncich, Gabriel S; Boyer, Doug M

2014-01-01

The articular facets of interosseous joints must transmit forces while maintaining relatively low stresses. To prevent overloading, joints that transmit higher forces should therefore have larger facet areas. The relative contributions of body mass and muscle-induced forces to joint stress are unclear, but generate opposing hypotheses. If mass-induced forces dominate, facet area should scale with positive allometry to body mass. Alternatively, muscle-induced forces should cause facets to scale isometrically with body mass. Within primates, both scaling patterns have been reported for articular surfaces of the femoral and humeral heads, but more distal elements are less well studied. Additionally, examination of complex articular surfaces has largely been limited to linear measurements, so that ‘true area' remains poorly assessed. To re-assess these scaling relationships, we examine the relationship between body size and articular surface areas of the talus. Area measurements were taken from microCT scan-generated surfaces of all talar facets from a comprehensive sample of extant euarchontan taxa (primates, treeshrews, and colugos). Log-transformed data were regressed on literature-derived log-body mass using reduced major axis and phylogenetic least squares regressions. We examine the scaling patterns of muscle mass and physiological cross-sectional area (PCSA) to body mass, as these relationships may complicate each model. Finally, we examine the scaling pattern of hindlimb muscle PCSA to talar articular surface area, a direct test of the effect of mass-induced forces on joint surfaces. Among most groups, there is an overall trend toward positive allometry for articular surfaces. The ectal (= posterior calcaneal) facet scales with positive allometry among all groups except ‘sundatherians', strepsirrhines, galagids, and lorisids. The medial tibial facet scales isometrically among all groups except lemuroids. Scaling coefficients are not correlated with sample size, clade inclusivity or behavioral diversity of the sample. Muscle mass scales with slight positive allometry to body mass, and PCSA scales at isometry to body mass. PCSA generally scales with negative allometry to articular surface area, which indicates joint surfaces increase faster than muscles' ability to generate force. We suggest a synthetic model to explain the complex patterns observed for talar articular surface area scaling: whether ‘muscles or mass' drive articular facet scaling is probably dependent on the body size range of the sample and the biological role of the facet. The relationship between ‘muscle vs. mass' dominance is likely bone-and facet-specific, meaning that some facets should respond primarily to stresses induced by larger body mass, whereas others primarily reflect muscle forces. PMID:24219027

Germination and allometry of the native palm tree Euterpe edulis compared to the introduced E. oleracea and their hybrids in Atlantic rainforest.

PubMed

Tiberio, F C S; Sampaio-e-Silva, T A; Dodonov, P; Garcia, V A; Silva Matos, D M

2012-11-01

Palms are distinctive plants of tropics and have peculiar allometric relations. Understanding such relations is useful in the case of introduced species because their ability to establish and invade must be clarified in terms of their responses in the new site. Our purpose was to assess the survival and invasive capacity of an introduced palm species in the Atlantic rainforest, Euterpe oleracea Mart., compared to the native Euterpe edulis Mart. and to the hybrids produced between the two species. Considering this, we compared the allometry in different ontogenetic stages, the germination rates, and aspects of the initial development. The ontogenetic stages proposed for both Euterpe illustrated the growth patterns described for palm trees. E. oleracea and hybrids adjusted to the geometric similarity allometric model, while E. edulis presented a slope greater than would be expected considering this model, indicating a greater height for a given diameter. E. oleracea showed the same amount of pulp per fruit as E. edulis and a similar initial development of seedlings. The main differences observed were a lower germination rate and a faster height gain of E. oleracea seedlings. We conclude that E. oleracea, which is similar to E. edulis in aspects of allometry, development, seed and seedling morphology, may be an important competitor of this native palm tree in the Atlantic Forest.

Scaling and Accommodation of Jaw Adductor Muscles in Canidae

PubMed Central

Kemp, Graham J.; Jeffery, Nathan

2016-01-01

ABSTRACT The masticatory apparatus amongst closely related carnivoran species raises intriguing questions about the interplay between allometry, function, and phylogeny in defining interspecific variations of cranial morphology. Here we describe the gross structure of the jaw adductor muscles of several species of canid, and then examine how the muscles are scaled across the range of body sizes, phylogenies, and trophic groups. We also consider how the muscles are accommodated on the skull, and how this is influenced by differences of endocranial size. Data were collected for a suite of morphological metrics, including body mass, endocranial volume, and muscle masses and we used geometric morphometric shape analysis to reveal associated form changes. We find that all jaw adductor muscles scale isometrically against body mass, regardless of phylogeny or trophic group, but that endocranial volume scales with negative allometry against body mass. These findings suggest that head shape is partly influenced by the need to house isometrically scaling muscles on a neurocranium scaling with negative allometry. Principal component analysis suggests that skull shape changes, such as the relatively wide zygomatic arches and large sagittal crests seen in species with higher body masses, allow the skull to accommodate a relative enlargement of the jaw adductors compared with the endocranium. Anat Rec, 299:951–966, 2016. © 2016 The Authors The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology Published by Wiley Periodicals, Inc. PMID:27103346

Ontogenetic changes in size, allometry, and mechanical design of tropical rain forest trees.

PubMed

Sterck, F; Bongers, F

1998-02-01

Size, allometry, and mechanical design were measured for trees of three canopy species in a tropical rain forest in French Guiana. Mechanical design was expressed as the safety factor, using the elastic-stability model, and the wind resistance factor, using the constant-stress model. Changes with ontogeny were described as regressions using stem diameter as the independent variable, and they were compared between species. Height, crown size, and the wind resistance factor increased with ontogeny. The safety factor decreased to a minimum and then increased continuously in thicker trees. The crown width/height ratio did not change with ontogeny. Interspecific differences in allometry and mechanical design were related to the adult stature of the species, and not to shade tolerance. The short stature species (Vouacapoua americana) was less slender (height:DBH [stem diameter at 1.3 m] ratio) and had a higher crown width/height ratio than the tall stature species (Goupia glabra and Dicorynia guianensis). Vouacapoua had a higher safety factor, but a similar wind resistance factor. The safety factors of our study species were lower than those of two temperate tree species because of a higher slenderness. Differences in safety factors between tropical and temperate trees may result from unrealistic assumptions of the elastic-stability model, and may also be related to lower light levels and-or wind rates in the tropics.

How trees allocate carbon for optimal growth: insight from a game-theoretic model.

PubMed

Fu, Liyong; Sun, Lidan; Han, Hao; Jiang, Libo; Zhu, Sheng; Ye, Meixia; Tang, Shouzheng; Huang, Minren; Wu, Rongling

2017-02-01

How trees allocate photosynthetic products to primary height growth and secondary radial growth reflects their capacity to best use environmental resources. Despite substantial efforts to explore tree height-diameter relationship empirically and through theoretical modeling, our understanding of the biological mechanisms that govern this phenomenon is still limited. By thinking of stem woody biomass production as an ecological system of apical and lateral growth components, we implement game theory to model and discern how these two components cooperate symbiotically with each other or compete for resources to determine the size of a tree stem. This resulting allometry game theory is further embedded within a genetic mapping and association paradigm, allowing the genetic loci mediating the carbon allocation of stemwood growth to be characterized and mapped throughout the genome. Allometry game theory was validated by analyzing a mapping data of stem height and diameter growth over perennial seasons in a poplar tree. Several key quantitative trait loci were found to interpret the process and pattern of stemwood growth through regulating the ecological interactions of stem apical and lateral growth. The application of allometry game theory enables the prediction of the situations in which the cooperation, competition or altruism is an optimal decision of a tree to fully use the environmental resources it owns. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Adaptive diversification of growth allometry in the plant Arabidopsis thaliana.

PubMed

Vasseur, François; Exposito-Alonso, Moises; Ayala-Garay, Oscar J; Wang, George; Enquist, Brian J; Vile, Denis; Violle, Cyrille; Weigel, Detlef

2018-03-27

Seed plants vary tremendously in size and morphology; however, variation and covariation in plant traits may be governed, at least in part, by universal biophysical laws and biological constants. Metabolic scaling theory (MST) posits that whole-organismal metabolism and growth rate are under stabilizing selection that minimizes the scaling of hydrodynamic resistance and maximizes the scaling of resource uptake. This constrains variation in physiological traits and in the rate of biomass accumulation, so that they can be expressed as mathematical functions of plant size with near-constant allometric scaling exponents across species. However, the observed variation in scaling exponents calls into question the evolutionary drivers and the universality of allometric equations. We have measured growth scaling and fitness traits of 451 Arabidopsis thaliana accessions with sequenced genomes. Variation among accessions around the scaling exponent predicted by MST was correlated with relative growth rate, seed production, and stress resistance. Genomic analyses indicate that growth allometry is affected by many genes associated with local climate and abiotic stress response. The gene with the strongest effect, PUB4 , has molecular signatures of balancing selection, suggesting that intraspecific variation in growth scaling is maintained by opposing selection on the trade-off between seed production and abiotic stress resistance. Our findings suggest that variation in allometry contributes to local adaptation to contrasting environments. Our results help reconcile past debates on the origin of allometric scaling in biology and begin to link adaptive variation in allometric scaling to specific genes. Copyright © 2018 the Author(s). Published by PNAS.

Adaptive diversification of growth allometry in the plant Arabidopsis thaliana

PubMed Central

Vasseur, François; Ayala-Garay, Oscar J.; Wang, George; Enquist, Brian J.; Vile, Denis; Violle, Cyrille

2018-01-01

Seed plants vary tremendously in size and morphology; however, variation and covariation in plant traits may be governed, at least in part, by universal biophysical laws and biological constants. Metabolic scaling theory (MST) posits that whole-organismal metabolism and growth rate are under stabilizing selection that minimizes the scaling of hydrodynamic resistance and maximizes the scaling of resource uptake. This constrains variation in physiological traits and in the rate of biomass accumulation, so that they can be expressed as mathematical functions of plant size with near-constant allometric scaling exponents across species. However, the observed variation in scaling exponents calls into question the evolutionary drivers and the universality of allometric equations. We have measured growth scaling and fitness traits of 451 Arabidopsis thaliana accessions with sequenced genomes. Variation among accessions around the scaling exponent predicted by MST was correlated with relative growth rate, seed production, and stress resistance. Genomic analyses indicate that growth allometry is affected by many genes associated with local climate and abiotic stress response. The gene with the strongest effect, PUB4, has molecular signatures of balancing selection, suggesting that intraspecific variation in growth scaling is maintained by opposing selection on the trade-off between seed production and abiotic stress resistance. Our findings suggest that variation in allometry contributes to local adaptation to contrasting environments. Our results help reconcile past debates on the origin of allometric scaling in biology and begin to link adaptive variation in allometric scaling to specific genes. PMID:29540570

Ontogenetic and static allometry in the human face: contrasting Khoisan and Inuit.

PubMed

Freidline, Sarah E; Gunz, Philipp; Hublin, Jean-Jacques

2015-09-01

Regional differences in modern human facial features are present at birth, and ontogenetic allometry contributes to variation in adults. However, details regarding differential rates of growth and timing among regional groups are lacking. We explore ontogenetic and static allometry in a cross-sectional sample spanning Africa, Europe and North America, and evaluate tempo and mode in two regional groups with very different adult facial morphology, the Khoisan and Inuit. Semilandmark geometric morphometric methods, multivariate statistics and growth simulations were used to quantify and compare patterns of facial growth and development. Regional-specific facial morphology develops early in ontogeny. The Inuit has the most distinct morphology and exhibits heterochronic differences in development compared to other regional groups. Allometric patterns differ during early postnatal development, when significant increases in size are coupled with large amounts of shape changes. All regional groups share a common adult static allometric trajectory, which can be attributed to sexual dimorphism, and the corresponding allometric shape changes resemble developmental patterns during later ontogeny. The amount and pattern of growth and development may not be shared between regional groups, indicating that a certain degree of flexibility is allowed for in order to achieve adult size. In early postnatal development the face is less constrained compared to other parts of the cranium allowing for greater evolvability. The early development of region-specific facial features combined with heterochronic differences in timing or rate of growth, reflected in differences in facial size, suggest different patterns of postnatal growth. © 2015 Wiley Periodicals, Inc.

Interspecies scaling and prediction of human clearance: comparison of small- and macro-molecule drugs

PubMed Central

Huh, Yeamin; Smith, David E.; Feng, Meihau Rose

2014-01-01

Human clearance prediction for small- and macro-molecule drugs was evaluated and compared using various scaling methods and statistical analysis.Human clearance is generally well predicted using single or multiple species simple allometry for macro- and small-molecule drugs excreted renally.The prediction error is higher for hepatically eliminated small-molecules using single or multiple species simple allometry scaling, and it appears that the prediction error is mainly associated with drugs with low hepatic extraction ratio (Eh). The error in human clearance prediction for hepatically eliminated small-molecules was reduced using scaling methods with a correction of maximum life span (MLP) or brain weight (BRW).Human clearance of both small- and macro-molecule drugs is well predicted using the monkey liver blood flow method. Predictions using liver blood flow from other species did not work as well, especially for the small-molecule drugs. PMID:21892879

In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content.

PubMed

Álvarez, Eva; Nogueira, Enrique; López-Urrutia, Ángel

2017-04-01

In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production. IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution. Copyright © 2017 American Society for Microbiology.

The scaling of tongue projection in the veiled chameleon, Chamaeleo calyptratus.

PubMed

Herrel, Anthony; Redding, Chrystal L; Meyers, J Jay; Nishikawa, Kiisa C

2014-08-01

Within a year of hatching, chameleons can grow by up to two orders of magnitude in body mass. Rapid growth of the feeding mechanism means that bones, muscles, and movements change as chameleons grow while needing to maintain function. A previous morphological study showed that the musculoskeletal components of the feeding apparatus grow with negative allometry relative to snout-vent length (SVL) in chameleons. Here, we investigate the scaling of prey capture kinematics and muscle physiological cross-sectional area in the veiled chameleon, Chamaeleo calyptratus. The chameleons used in this study varied in size from approximately 3 to 18 cm SVL (1-200 g). Feeding sequences of 12 chameleons of different sizes were filmed and the timing of movements and the displacements and velocities of the jaws, tongue, and the hyolingual apparatus were quantified. Our results show that most muscle cross-sectional areas as well as tongue and hyoid mass scaled with isometry relative to mandible length, yet with negative allometry relative to SVL. Durations of movement also scaled with negative allometry relative to SVL and mandible length. Distances and angles generally scaled as predicted under geometric similarity (slopes of 1 and 0, respectively), while velocities generally scaled with slopes greater than 0 relative to SVL and mandible length. These data indicate that the velocity of jaw and tongue movements is generally greater in adults compared to juveniles. The discrepancy between the scaling of cross-sectional areas versus movements suggests changes in the energy storage and release mechanisms implicated in tongue projection. Copyright © 2014 Elsevier GmbH. All rights reserved.

Bud development and shoot morphology in relation to crown location

PubMed Central

Kukk, Maarja; Sõber, Anu

2015-01-01

Plant architecture is shaped by endogenous growth processes interacting with the local environment. The current study investigated crown development in young black alder trees, assessing the effects of local light conditions and branch height on individual bud mass and contents. In addition, we examined the characteristics of parent shoots [the cross-sectional area (CSA) of stem and total leaf area, shoot length, the number of nodes, the number and total mass of buds per shoot] and leaf–stem as well as bud–stem allometry, as several recent studies link bud development to hydraulic architecture. We sampled shoots from top branches and two lower-crown locations: one subjected to deep shade and the other resembling the upper branches in light availability. Sampling was carried out three times between mid-July and late October, spanning from the early stages of bud growth to dormancy. Individual bud mass and shoot characteristics varied in response to light conditions, whereas leaf–stem allometry depended on branch height, most likely compensating for the increasing length of hydraulic pathways. Despite the differences in individual bud mass, the number of preformed leaves varied little across the crown, indicating that the plasticity in shoot characteristics was mainly achieved by neoformation. The relationship between total bud mass and stem CSA scaled similarly across crown locations. However, scaling slopes gradually decreased throughout the sampling period, driven by bud rather than by stem growth. This suggests that the allometry of total bud mass and CSA of stem is regulated locally, instead of resulting from crown-level processes. PMID:26187607

Allometry of root branching and its relationship to root morphological and functional traits in three range grasses.

PubMed

Arredondo, J Tulio; Johnson, Douglas A

2011-11-01

The study of proportional relationships between size, shape, and function of part of or the whole organism is traditionally known as allometry. Examination of correlative changes in the size of interbranch distances (IBDs) at different root orders may help to identify root branching rules. Root morphological and functional characteristics in three range grasses {bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve], crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.×A. cristatum (L.) Gaert.], and cheatgrass (Bromus tectorum L.)} were examined in response to a soil nutrient gradient. Interbranch distances along the main root axis and the first-order laterals as well as other morphological and allocation root traits were determined. A model of nutrient diffusivity parameterized with root length and root diameter for the three grasses was used to estimate root functional properties (exploitation efficiency and exploitation potential). The results showed a significant negative allometric relationship between the main root axis and first-order lateral IBD (P ≤ 0.05), but only for bluebunch wheatgrass. The main root axis IBD was positively related to the number and length of roots, estimated exploitation efficiency of second-order roots, and specific root length, and was negatively related to estimated exploitation potential of first-order roots. Conversely, crested wheatgrass and cheatgrass, which rely mainly on root proliferation responses, exhibited fewer allometric relationships. Thus, the results suggested that species such as bluebunch wheatgrass, which display slow root growth and architectural root plasticity rather than opportunistic root proliferation and rapid growth, exhibit correlative allometry between the main axis IBD and morphological, allocation, and functional traits of roots.

Thin-plate spline analysis of allometry and sexual dimorphism in the human craniofacial complex.

PubMed

Rosas, Antonio; Bastir, Markus

2002-03-01

The relationship between allometry and sexual dimorphism in the human craniofacial complex was analyzed using geometric morphometric methods. Thin-plate splines (TPS) analysis has been applied to investigate the lateral profile of complete adult skulls of known sex. Twenty-nine three-dimensional (3D) craniofacial and mandibular landmark coordinates were recorded from a sample of 52 adult females and 52 adult males of known age and sex. No difference in the influence of size on shape was detected between sexes. Both size and sex had significant influences on shape. As expected, the influence of centroid size on shape (allometry) revealed a shift in the proportions of the neurocranium and the viscerocranium, with a marked allometric variation of the lower face. Adjusted for centroid size, males presented a relatively larger size of the nasopharyngeal space than females. A mean-male TPS transformation revealed a larger piriform aperture, achieved by an increase of the angulation of the nasal bones and a downward rotation of the anterior nasal floor. Male pharynx expansion was also reflected by larger choanae and a more posteriorly inclined basilar part of the occipital clivus. Male muscle attachment sites appeared more pronounced. In contrast, the mean-female TPS transformation was characterized by a relatively small nasal aperture. The occipital clivus inclined anteriorly, and muscle insertion areas became smoothed. Besides these variations, both maxillary and mandibular alveolar regions became prognathic. The sex-specific TPS deformation patterns are hypothesized to be associated with sexual differences in body composition and energetic requirements. Copyright 2002 Wiley-Liss, Inc.

Bite of the cats: relationships between functional integration and mechanical performance as revealed by mandible geometry.

PubMed

Piras, Paolo; Maiorino, Leonardo; Teresi, Luciano; Meloro, Carlo; Lucci, Federico; Kotsakis, Tassos; Raia, Pasquale

2013-11-01

Cat-like carnivorous mammals represent a relatively homogeneous group of species whose morphology appears constrained by exclusive adaptations for meat eating. We present the most comprehensive data set of extant and extinct cat-like species to test for evolutionary transformations in size, shape and mechanical performance, that is, von Mises stress and surface traction, of the mandible. Size and shape were both quantified by means of geometric morphometrics, whereas mechanical performance was assessed applying finite element models to 2D geometry of the mandible. Additionally, we present the first almost complete composite phylogeny of cat-like carnivorans for which well-preserved mandibles are known, including representatives of 35 extant and 59 extinct species of Felidae, Nimravidae, and Barbourofelidae. This phylogeny was used to test morphological differentiation, allometry, and covariation of mandible parts within and among clades. After taking phylogeny into account, we found that both allometry and mechanical variables exhibit a significant impact on mandible shape. We also tested whether mechanical performance was linked to morphological integration. Mechanical stress at the coronoid process is higher in sabertoothed cats than in any other clade. This is strongly related to the high degree of covariation within modules of sabertooths mandibles. We found significant correlation between integration at the clade level and per-clade averaged stress values, on both original data and by partialling out interclade allometry from shapes when calculating integration. This suggests a strong interaction between natural selection and the evolution of developmental and functional modules at the clade level.

In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content

PubMed Central

Nogueira, Enrique; López-Urrutia, Ángel

2017-01-01

ABSTRACT In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production. IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution. PMID:28115378

Intraspecific variation in body size and the rate of reproduction in female insects - adaptive allometry or biophysical constraint?

PubMed

Berger, David; Olofsson, Martin; Friberg, Magne; Karlsson, Bengt; Wiklund, Christer; Gotthard, Karl

2012-11-01

1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative metabolic and developmental constraints. 5. More work is needed to understand how physiology and development together with compensatory behaviours interact in shaping reproductive allometry. Empirical studies should evaluate adaptive hypotheses against proper null hypotheses, including prediction from metabolic theory, preferentially by studying reproductive physiology in combination with behaviour. Conversely, inferences of constraint explanations on reproductive rates must take into consideration that adaptive scenarios may predict similar allometric exponents. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Body size-dependent Cd accumulation in the zebra mussel Dreissena polymorpha from different routes.

PubMed

Tang, Wen-Li; Evans, Douglas; Kraemer, Lisa; Zhong, Huan

2017-02-01

Understanding body size-dependent metal accumulation in aquatic organisms (i.e., metal allometry) is critical in interpreting biomonitoring data. While growth has received the most attention, little is known about controls of metal exposure routes on metal allometry. Here, size-dependent Cd accumulation in zebra mussels (Dreissena polymorpha) from different routes were investigated by exposing mussels to A.( 111 Cd spiked algae+ 113 Cd spiked river water) or B.( 111 Cd spiked sediments+ 113 Cd spiked river water). After exposure, 111 Cd or 113 Cd levels in mussel tissue were found to be negatively correlated with tissue weight, while Cd allometry coefficients (b values) were dependent on Cd exposure routes: -0.664 for algae, -0.241 for sediments and -0.379 for river water, compared to -0.582 in un-exposed mussels. By comparing different Cd exposure routes, we found that size-dependent Cd bioaccumulation from algae or river water could be more responsible for the overall size-dependent Cd accumulation in mussels, and the relative importance of the two sources was dependent on mussel size ranges: Cadmium obtained from algae (algae-Cd) was more important in size-dependent Cd accumulation in smaller mussels (tissue dry weight < 5 mg), while river water-Cd became more important in larger individuals (tissue dry weight > 5 mg). In contrast, sediment-Cd contributed only a small amount to Cd accumulation in zebra mussels and may have little effect on size-dependent Cd bioaccumulation. Our results suggest that size-dependent Cd accumulation in mussels could be largely affected by exposure routes, which should be considered when trying to interpret Cd biomonitoring data of zebra mussels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Height-diameter allometry and above ground biomass in tropical montane forests: Insights from the Albertine Rift in Africa

PubMed Central

Boyemba, Faustin; Lewis, Simon; Nabahungu, Nsharwasi Léon; Calders, Kim; Zapfack, Louis; Riera, Bernard; Balegamire, Clarisse; Cuni-Sanchez, Aida

2017-01-01

Tropical montane forests provide an important natural laboratory to test ecological theory. While it is well-known that some aspects of forest structure change with altitude, little is known on the effects of altitude on above ground biomass (AGB), particularly with regard to changing height-diameter allometry. To address this we investigate (1) the effects of altitude on height-diameter allometry, (2) how different height-diameter allometric models affect above ground biomass estimates; and (3) how other forest structural, taxonomic and environmental attributes affect above ground biomass using 30 permanent sample plots (1-ha; all trees ≥ 10 cm diameter measured) established between 1250 and 2600 m asl in Kahuzi Biega National Park in eastern Democratic Republic of Congo. Forest structure and species composition differed with increasing altitude, with four forest types identified. Different height-diameter allometric models performed better with the different forest types, as trees got smaller with increasing altitude. Above ground biomass ranged from 168 to 290 Mg ha-1, but there were no significant differences in AGB between forests types, as tree size decreased but stem density increased with increasing altitude. Forest structure had greater effects on above ground biomass than forest diversity. Soil attributes (K and acidity, pH) also significantly affected above ground biomass. Results show how forest structural, taxonomic and environmental attributes affect above ground biomass in African tropical montane forests. They particularly highlight that the use of regional height-diameter models introduces significant biases in above ground biomass estimates, and that different height-diameter models might be preferred for different forest types, and these should be considered in future studies. PMID:28617841

Sauropod necks: are they really for heat loss?

PubMed

Henderson, Donald M

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating.

Differentiating causality and correlation in allometric scaling: ant colony size drives metabolic hypometry

PubMed Central

Ochs, Alison; Fewell, Jennifer H.; Harrison, Jon F.

2017-01-01

Metabolic rates of individual animals and social insect colonies generally scale hypometrically, with mass-specific metabolic rates decreasing with increasing size. Although this allometry has wide ranging effects on social behaviour, ecology and evolution, its causes remain controversial. Because it is difficult to experimentally manipulate body size of organisms, most studies of metabolic scaling depend on correlative data, limiting their ability to determine causation. To overcome this limitation, we experimentally reduced the size of harvester ant colonies (Pogonomyrmex californicus) and quantified the consequent increase in mass-specific metabolic rates. Our results clearly demonstrate a causal relationship between colony size and hypometric changes in metabolic rate that could not be explained by changes in physical density. These findings provide evidence against prominent models arguing that the hypometric scaling of metabolic rate is primarily driven by constraints on resource delivery or surface area/volume ratios, because colonies were provided with excess food and colony size does not affect individual oxygen or nutrient transport. We found that larger colonies had lower median walking speeds and relatively more stationary ants and including walking speed as a variable in the mass-scaling allometry greatly reduced the amount of residual variation in the model, reinforcing the role of behaviour in metabolic allometry. Following the experimental size reduction, however, the proportion of stationary ants increased, demonstrating that variation in locomotory activity cannot solely explain hypometric scaling of metabolic rates in these colonies. Based on prior studies of this species, the increase in metabolic rate in size-reduced colonies could be due to increased anabolic processes associated with brood care and colony growth. PMID:28228514

Intra- and Interspecific Interactions as Proximate Determinants of Sexual Dimorphism and Allometric Trajectories in the Bottlenose Dolphin Tursiops truncatus (Cetacea, Odontoceti, Delphinidae)

PubMed Central

2016-01-01

Feeding adaptation, social behaviour, and interspecific interactions related to sexual dimorphism and allometric growth are particularly challenging to be investigated in the high sexual monomorphic Delphinidae. We used geometric morphometrics to extensively explore sexual dimorphism and ontogenetic allometry of different projections of the skull and the mandible of the bottlenose dolphin Tursiops truncatus. Two-dimensional landmarks were recorded on the dorsal, ventral, lateral, and occipital views of the skull, and on the lateral view of the left and the right mandible of 104 specimens from the Mediterranean and the North Seas, differing environmental condition and degree of interspecific associations. Landmark configurations were transformed, standardized and superimposed through a Generalized Procrustes Analysis. Size and shape differences between adult males and females were respectively evaluated through ANOVA on centroid size, Procrustes ANOVA on Procrustes distances, and MANOVA on Procrustes coordinates. Ontogenetic allometry was investigated by multivariate regression of shape coordinates on centroid size in the largest homogenous sample from the North Sea. Results evidenced sexual dimorphic asymmetric traits only detected in the adults of the North Sea bottlenose dolphins living in monospecific associations, with females bearing a marked incision of the cavity hosting the left tympanic bulla. These differences were related to a more refined echolocalization system that likely enhances the exploitation of local resources by philopatric females. Distinct shape in immature versus mature stages and asymmetric changes in postnatal allometry of dorsal and occipital traits, suggest that differences between males and females are established early during growth. Allometric growth trajectories differed between males and females for the ventral view of the skull. Allometric trajectories differed among projections of skull and mandible, and were related to dietary shifts experienced by subadults and adults. PMID:27764133

Allometry of animal-microbe interactions and global census of animal-associated microbes.

PubMed

Kieft, Thomas L; Simmons, Karen A

2015-07-07

Animals live in close association with microorganisms, mostly prokaryotes, living in or on them as commensals, mutualists or parasites, and profoundly affecting host fitness. Most animal-microbe studies focus on microbial community structure; for this project, allometry (scaling of animal attributes with animal size) was applied to animal-microbe relationships across a range of species spanning 12 orders of magnitude in animal mass, from nematodes to whales. Microbial abundances per individual animal were gleaned from published literature and also microscopically counted in three species. Abundance of prokaryotes/individual versus animal mass scales as a nearly linear power function (exponent = 1.07, R(2) = 0.94). Combining this power function with allometry of animal abundance indicates that macrofauna have an outsized share of animal-associated microorganisms. The total number of animal-associated prokaryotes in Earth's land animals was calculated to be 1.3-1.4 × 10(25) cells and the total of marine animal-associated microbes was calculated to be 8.6-9.0 × 10(24) cells. Animal-associated microbes thus total 2.1-2.3 × 10(25) of the approximately 10(30) prokaryotes on the Earth. Microbes associated with humans comprise 3.3-3.5% of Earth's animal-associated microbes, and domestic animals harbour 14-20% of all animal-associated microbes, adding a new dimension to the scale of human impact on the biosphere. This novel allometric power function may reflect underlying mechanisms involving the transfer of energy and materials between microorganisms and their animal hosts. Microbial diversity indices of animal gut communities and gut microbial species richness for 60 mammals did not indicate significant scaling relationships with animal body mass; however, further research in this area is warranted. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Allometry of sexual size dimorphism in turtles: a comparison of mass and length data.

PubMed

Regis, Koy W; Meik, Jesse M

2017-01-01

The macroevolutionary pattern of Rensch's Rule (positive allometry of sexual size dimorphism) has had mixed support in turtles. Using the largest carapace length dataset and only large-scale body mass dataset assembled for this group, we determine (a) whether turtles conform to Rensch's Rule at the order, suborder, and family levels, and (b) whether inferences regarding allometry of sexual size dimorphism differ based on choice of body size metric used for analyses. We compiled databases of mean body mass and carapace length for males and females for as many populations and species of turtles as possible. We then determined scaling relationships between males and females for average body mass and straight carapace length using traditional and phylogenetic comparative methods. We also used regression analyses to evalutate sex-specific differences in the variance explained by carapace length on body mass. Using traditional (non-phylogenetic) analyses, body mass supports Rensch's Rule, whereas straight carapace length supports isometry. Using phylogenetic independent contrasts, both body mass and straight carapace length support Rensch's Rule with strong congruence between metrics. At the family level, support for Rensch's Rule is more frequent when mass is used and in phylogenetic comparative analyses. Turtles do not differ in slopes of sex-specific mass-to-length regressions and more variance in body size within each sex is explained by mass than by carapace length. Turtles display Rensch's Rule overall and within families of Cryptodires, but not within Pleurodire families. Mass and length are strongly congruent with respect to Rensch's Rule across turtles, and discrepancies are observed mostly at the family level (the level where Rensch's Rule is most often evaluated). At macroevolutionary scales, the purported advantages of length measurements over weight are not supported in turtles.

A general model for metabolic scaling in self-similar asymmetric networks

PubMed Central

Savage, Van M.; Enquist, Brian J.

2017-01-01

How a particular attribute of an organism changes or scales with its body size is known as an allometry. Biological allometries, such as metabolic scaling, have been hypothesized to result from selection to maximize how vascular networks fill space yet minimize internal transport distances and resistances. The West, Brown, Enquist (WBE) model argues that these two principles (space-filling and energy minimization) are (i) general principles underlying the evolution of the diversity of biological networks across plants and animals and (ii) can be used to predict how the resulting geometry of biological networks then governs their allometric scaling. Perhaps the most central biological allometry is how metabolic rate scales with body size. A core assumption of the WBE model is that networks are symmetric with respect to their geometric properties. That is, any two given branches within the same generation in the network are assumed to have identical lengths and radii. However, biological networks are rarely if ever symmetric. An open question is: Does incorporating asymmetric branching change or influence the predictions of the WBE model? We derive a general network model that relaxes the symmetric assumption and define two classes of asymmetrically bifurcating networks. We show that asymmetric branching can be incorporated into the WBE model. This asymmetric version of the WBE model results in several theoretical predictions for the structure, physiology, and metabolism of organisms, specifically in the case for the cardiovascular system. We show how network asymmetry can now be incorporated in the many allometric scaling relationships via total network volume. Most importantly, we show that the 3/4 metabolic scaling exponent from Kleiber’s Law can still be attained within many asymmetric networks. PMID:28319153

Height-diameter allometry and above ground biomass in tropical montane forests: Insights from the Albertine Rift in Africa.

PubMed

Imani, Gérard; Boyemba, Faustin; Lewis, Simon; Nabahungu, Nsharwasi Léon; Calders, Kim; Zapfack, Louis; Riera, Bernard; Balegamire, Clarisse; Cuni-Sanchez, Aida

2017-01-01

Tropical montane forests provide an important natural laboratory to test ecological theory. While it is well-known that some aspects of forest structure change with altitude, little is known on the effects of altitude on above ground biomass (AGB), particularly with regard to changing height-diameter allometry. To address this we investigate (1) the effects of altitude on height-diameter allometry, (2) how different height-diameter allometric models affect above ground biomass estimates; and (3) how other forest structural, taxonomic and environmental attributes affect above ground biomass using 30 permanent sample plots (1-ha; all trees ≥ 10 cm diameter measured) established between 1250 and 2600 m asl in Kahuzi Biega National Park in eastern Democratic Republic of Congo. Forest structure and species composition differed with increasing altitude, with four forest types identified. Different height-diameter allometric models performed better with the different forest types, as trees got smaller with increasing altitude. Above ground biomass ranged from 168 to 290 Mg ha-1, but there were no significant differences in AGB between forests types, as tree size decreased but stem density increased with increasing altitude. Forest structure had greater effects on above ground biomass than forest diversity. Soil attributes (K and acidity, pH) also significantly affected above ground biomass. Results show how forest structural, taxonomic and environmental attributes affect above ground biomass in African tropical montane forests. They particularly highlight that the use of regional height-diameter models introduces significant biases in above ground biomass estimates, and that different height-diameter models might be preferred for different forest types, and these should be considered in future studies.

Sauropod Necks: Are They Really for Heat Loss?

PubMed Central

Henderson, Donald M.

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating. PMID:24204747

A general model for metabolic scaling in self-similar asymmetric networks.

PubMed

Brummer, Alexander Byers; Savage, Van M; Enquist, Brian J

2017-03-01

How a particular attribute of an organism changes or scales with its body size is known as an allometry. Biological allometries, such as metabolic scaling, have been hypothesized to result from selection to maximize how vascular networks fill space yet minimize internal transport distances and resistances. The West, Brown, Enquist (WBE) model argues that these two principles (space-filling and energy minimization) are (i) general principles underlying the evolution of the diversity of biological networks across plants and animals and (ii) can be used to predict how the resulting geometry of biological networks then governs their allometric scaling. Perhaps the most central biological allometry is how metabolic rate scales with body size. A core assumption of the WBE model is that networks are symmetric with respect to their geometric properties. That is, any two given branches within the same generation in the network are assumed to have identical lengths and radii. However, biological networks are rarely if ever symmetric. An open question is: Does incorporating asymmetric branching change or influence the predictions of the WBE model? We derive a general network model that relaxes the symmetric assumption and define two classes of asymmetrically bifurcating networks. We show that asymmetric branching can be incorporated into the WBE model. This asymmetric version of the WBE model results in several theoretical predictions for the structure, physiology, and metabolism of organisms, specifically in the case for the cardiovascular system. We show how network asymmetry can now be incorporated in the many allometric scaling relationships via total network volume. Most importantly, we show that the 3/4 metabolic scaling exponent from Kleiber's Law can still be attained within many asymmetric networks.

Patterns of postnatal ontogeny of the skull and lower jaw of snakes as revealed by micro-CT scan data and three-dimensional geometric morphometrics.

PubMed

Palci, Alessandro; Lee, Michael S Y; Hutchinson, Mark N

2016-12-01

We compared the head skeleton (skull and lower jaw) of juvenile and adult specimens of five snake species [Anilios (=Ramphotyphlops) bicolor, Cylindrophis ruffus, Aspidites melanocephalus, Acrochordus arafurae, and Notechis scutatus] and two lizard outgroups (Ctenophorus decresii, Varanus gilleni). All major ontogenetic changes observed were documented both qualitatively and quantitatively. Qualitative comparisons were based on high-resolution micro-CT scanning of the specimens, and detailed quantitative analyses were performed using three-dimensional geometric morphometrics. Two sets of landmarks were used, one for accurate representation of the intraspecific transformations of each skull and jaw configuration, and the other for comparison between taxa. Our results document the ontogenetic elaboration of crests and processes for muscle attachment (especially for cervical and adductor muscles); negative allometry in the braincase of all taxa; approximately isometric growth of the snout of all taxa except Varanus and Anilios (positively allometric); and positive allometry in the quadrates of the macrostomatan snakes Aspidites, Acrochordus and Notechis, but also, surprisingly, in the iguanian lizard Ctenophorus. Ontogenetic trajectories from principal component analysis provide evidence for paedomorphosis in Anilios and peramorphosis in Acrochordus. Some primitive (lizard-like) features are described for the first time in the juvenile Cylindrophis. Two distinct developmental trajectories for the achievement of the macrostomatan (large-gaped) condition in adult snakes are documented, driven either by positive allometry of supratemporal and quadrate (in pythons), or of quadrate alone (in sampled caenophidians); this is consistent with hypothesised homoplasy in this adaptive complex. Certain traits (e.g. shape of coronoid process, marginal tooth counts) are more stable throughout postnatal ontogeny than others (e.g. basisphenoid keel), with implications for their reliability as phylogenetic characters. © 2016 Anatomical Society.

Does encephalization correlate with life history or metabolic rate in Carnivora?

PubMed

Finarelli, John A

2010-06-23

A recent analysis of brain size evolution reconstructed the plesiomorphic brain-body size allometry for the mammalian order Carnivora, providing an important reference frame for comparative analyses of encephalization (brain volume scaled to body mass). I performed phylogenetically corrected regressions to remove the effects of body mass, calculating correlations between residual values of encephalization with basal metabolic rate (BMR) and six life-history variables (gestation time, neonatal mass, weaning time, weaning mass, litter size, litters per year). No significant correlations were recovered between encephalization and any life-history variable or BMR, arguing against hypotheses relating encephalization to maternal energetic investment. However, after correcting for clade-specific adaptations, I recovered significant correlations for several variables, and further analysis revealed a conserved carnivoran reproductive strategy, linking degree of encephalization to the well-documented mammalian life-history trade-off between neonatal mass and litter size. This strategy of fewer, larger offspring correlating with increased encephalization remains intact even after independent changes in encephalization allometries in the evolutionary history of this clade.

Fitness consequences of artificial selection on relative male genital size

PubMed Central

Booksmythe, Isobel; Head, Megan L.; Keogh, J. Scott; Jennions, Michael D.

2016-01-01

Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allometric scaling, which suggests strong selection against genital–body size combinations that deviate from a species' natural line of allometry. We tested this constraint by artificially selecting on the allometric intercept, creating lines of males with relatively longer or shorter gonopodia than occur naturally for a given body size in mosquitofish, Gambusia holbrooki. We show that relative genital length is heritable and diverged 7.6–8.9% between our up-selected and down-selected lines, with correlated changes in body shape. However, deviation from the natural line of allometry does not affect male success in assays of attractiveness, swimming performance and, crucially, reproductive success (paternity). PMID:27188478

Allometry, growth and architecture of two Solidago species in elevated CO{sub 2} environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choung, Yeon-Sook; Bazzaz, F.A.

1995-06-01

We grew the common old-field rhizomatous perennials, Solidago canadensis and S. gigantea, which have compact and relatively spreading clonal structure respectively, in ambient and doubled CO{sub 2} environments to study the influence of elevated CO{sub 2} on the growth, allometry and architecture of these two species. Most growth parameters were enhanced significantly by high CO{sub 2} in both species, but there were no significant differences in the allometric relationships between plant parts except for allocation to rhizomes. Unlike allocation to other plant organs, rhizome growth was directly affected by elevated CO{sub 2}. In a high CO{sub 2}, S. canadensis, whichmore » has short rhizomes, allocated more biomass to new rhizomes, and produced longer new rhizomes, while S. gigantea, which has longer rhizomes, produced shorter and more branched rhizomes, forming a more aggregated clone. If global change will lead to expansion of clonal perennials when trees die, S. canadensis may expand faster than S. gigantea.« less

Does encephalization correlate with life history or metabolic rate in Carnivora?

PubMed Central

Finarelli, John A.

2010-01-01

A recent analysis of brain size evolution reconstructed the plesiomorphic brain–body size allometry for the mammalian order Carnivora, providing an important reference frame for comparative analyses of encephalization (brain volume scaled to body mass). I performed phylogenetically corrected regressions to remove the effects of body mass, calculating correlations between residual values of encephalization with basal metabolic rate (BMR) and six life-history variables (gestation time, neonatal mass, weaning time, weaning mass, litter size, litters per year). No significant correlations were recovered between encephalization and any life-history variable or BMR, arguing against hypotheses relating encephalization to maternal energetic investment. However, after correcting for clade-specific adaptations, I recovered significant correlations for several variables, and further analysis revealed a conserved carnivoran reproductive strategy, linking degree of encephalization to the well-documented mammalian life-history trade-off between neonatal mass and litter size. This strategy of fewer, larger offspring correlating with increased encephalization remains intact even after independent changes in encephalization allometries in the evolutionary history of this clade. PMID:20007169

Allometric shell growth in infaunal burrowing bivalves: examples of the archiheterodonts Claibornicardia paleopatagonica (Ihering, 1903) and Crassatella kokeni Ihering, 1899.

PubMed

Perez, Damián Eduardo; Santelli, María Belén

2018-01-01

We present two cases of study of ontogenetic allometry in outlines of bivalves using longitudinal data, a rarity among fossils, based on the preserved post-larval record of shells. The examples are two infaunal burrowing bivalves of the southern South America, Claibornicardia paleopatagonica (Archiheterodonta: Carditidae) (early Paleocene) and Crassatella kokeni (Archiheterodonta: Crassatellidae) (late Oligocene-late Miocene). Outline analyses were conducted using a geometric morphometric approach (Elliptic Fourier Analysis), obtaining successive outlines from shells' growth lines, which were used to reconstruct ontogenetic trajectories. In both taxa, ontogenetic changes are characterized by the presence of positive allometry in the extension of posterior end, resulting in elongated adult shells. This particular allometric growth is known in others infaunal burrowing bivalves ( Claibornicardia alticostata and some Spissatella species) and the resulting adult morphology is present in representatives of several groups (e.g., Carditidae, Crassatellidae, Veneridae, Trigoniidae). Taxonomic, ecological and evolutionary implications of this allometric growth pattern are discussed.

Colony-Level Differences in the Scaling Rules Governing Wood Ant Compound Eye Structure.

PubMed

Perl, Craig D; Niven, Jeremy E

2016-04-12

Differential organ growth during development is essential for adults to maintain the correct proportions and achieve their characteristic shape. Organs scale with body size, a process known as allometry that has been studied extensively in a range of organisms. Such scaling rules, typically studied from a limited sample, are assumed to apply to all members of a population and/or species. Here we study scaling in the compound eyes of workers of the wood ant, Formica rufa, from different colonies within a single population. Workers' eye area increased with body size in all the colonies showing a negative allometry. However, both the slope and intercept of some allometric scaling relationships differed significantly among colonies. Moreover, though mean facet diameter and facet number increased with body size, some colonies primarily increased facet number whereas others increased facet diameter, showing that the cellular level processes underlying organ scaling differed among colonies. Thus, the rules that govern scaling at the organ and cellular levels can differ even within a single population.

Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina

PubMed Central

Dick, Daniel G.; Maxwell, Erin E.

2015-01-01

We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction. PMID:26579712

Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina.

PubMed

Dick, Daniel G; Maxwell, Erin E

2015-01-01

We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction.

Swimbladder Allometry of Selected Midwater Fish Species

DTIC Science & Technology

1976-01-05

Gibbs, R. II., Jr., 1971. "Notes on Fishes of the Genus Eustomias ( Stomiatoidei , Melanstomiatidae) in Bermuda Waters, With the Description of...N00140-70-C-0307, Smithsonian Institution. Goodyear, R. H. and R. H. Gibbs, Jr., 1970. "Systematics and Zoogeography of Stomiatoid Fishes of the

Body size and scaling of the hands and feet of prosimian primates.

PubMed

Lemelin, Pierre; Jungers, William L

2007-06-01

The hands and feet of primates fulfill a variety of biological roles linked with food acquisition and positional behavior. Current explanations of shape differences in cheiridial morphology among prosimians are closely tied to body size differences. Although numerous studies have examined the relationships between body mass and limb morphology in prosimians, no scaling analysis has specifically considered hand and foot dimensions and intrinsic proportions. In this study, we present such an analysis for a sample of 270 skeletal specimens distributed over eight prosimian families. The degree of association between size and shape was assessed using nonparametric correlational techniques, while the relationship between each ray element length and body mass (from published data and a body mass surrogate) was tested for allometric scaling. Since tarsiers and strepsirrhines encompass many taxa of varying degrees of phylogenetic relatedness, effective degrees of freedom were calculated, and comparisons between families were performed to partially address the problem of statistical nonindependence and "phylogenetic inertia." Correlational analyses indicate negative allometry between relative phalangeal length (as reflected by phalangeal indices) and body mass, except for the pollex and hallux. Thus, as size increases, there is a significant decrease in the relative length of the digits when considering all prosimian taxa sampled. Regression analyses show that while the digital portion of the rays scales isometrically with body mass, the palmar/plantar portion of the rays often scales with positive allometry. Some but not all of these broadly interspecific allometric patterns remain statistically significant when effective degrees of freedom are taken into account. As is often the case in interspecific scaling, comparisons within families show different scaling trends in the cheiridia than those seen across families (i.e., lorisids, indriids, and lemurids exhibit rather different allometries). The interspecific pattern of positive allometry that appears to best characterize the metapodials of prosimians, especially those of the foot, parallels differences found in the morphology of the volar skin. Indeed, relatively longer metapodials appear to covary with flatter and more coalesced volar pads, which in turn slightly improve frictional force for animals that are at a comparative disadvantage while climbing because of their larger mass. Despite the essentially isometric relationship found between digit length and body mass across prosimians, examination of the residual variation reveals that tarsiers and Daubentonia possess, relative to their body sizes, remarkably long fingers. Such marked departures between body size and finger length observed in these particular primates are closely linked with specialized modes of prey acquisition and manipulation involving the hands.

XEROMORPHY INCREASES IN SHOOTS OF PSEUDOTSUGA MENZIESII (MIRB.) FRANCO SEEDLINGS WITH EXPOSURE TO ELEVATED TEMPERATURE BUT NOT ELEVATED CO2

EPA Science Inventory

Seedling structure influences tree structure and function, ultimately determining the potential productivity of trees and their competitiveness for resources. We investigated changes in shoot organ structure, as indicated by biomass allocation, allometry and anatomy in response ...

Stand-level Allometry in Pinus taeda as Affected by Irrigation and Fertilization

Treesearch

J.S. King; T.J. Albaugh; H.L. Allen; L.W. Kress

1999-01-01

Changing environmental conditions have the potential to alter allometric relationships between plant parts, possibly leading to ecosystem-level feedbacks. We quantified allometric shifts in field-grown loblolly pine (Pinus taeda L.) in response to altered resource availability based on data from multiple harvests to correct for size-related changes...

Allometry and biomass of pollarded black locust

Treesearch

David M. Burner; Daniel H. Pote; Adrian Ares

2006-01-01

Climatic constraints can cause forage deficits in the summer in west-central Arkansas, necessitating expensive, supplemental hay feeding. Black locust could be used for summer browse, but the temporal distribution of foliar biomass has not been adequately tested. Our objective was to determine effects of harvest date, fertilization (0 and 600 kg P ha-1...

Minimizing bias in biomass allometry: Model selection and log transformation of data

Treesearch

Joseph Mascaro; undefined undefined; Flint Hughes; Amanda Uowolo; Stefan A. Schnitzer

2011-01-01

Nonlinear regression is increasingly used to develop allometric equations for forest biomass estimation (i.e., as opposed to the raditional approach of log-transformation followed by linear regression). Most statistical software packages, however, assume additive errors by default, violating a key assumption of allometric theory and possibly producing spurious models....

Brain evolution and development: adaptation, allometry and constraint

PubMed Central

Barton, Robert A.

2016-01-01

Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns. PMID:27629025

A validation of 11 body-condition indices in a giant snake species that exhibits positive allometry.

PubMed

Falk, Bryan G; Snow, Ray W; Reed, Robert N

2017-01-01

Body condition is a gauge of the energy stores of an animal, and though it has important implications for fitness, survival, competition, and disease, it is difficult to measure directly. Instead, body condition is frequently estimated as a body condition index (BCI) using length and mass measurements. A desirable BCI should accurately reflect true body condition and be unbiased with respect to size (i.e., mean BCI estimates should not change across different length or mass ranges), and choosing the most-appropriate BCI is not straightforward. We evaluated 11 different BCIs in 248 Burmese pythons (Python bivittatus), organisms that, like other snakes, exhibit simple body plans well characterized by length and mass. We found that the length-mass relationship in Burmese pythons is positively allometric, where mass increases rapidly with respect to length, and this allowed us to explore the effects of allometry on BCI verification. We employed three alternative measures of 'true' body condition: percent fat, scaled fat, and residual fat. The latter two measures mostly accommodated allometry in true body condition, but percent fat did not. Our inferences of the best-performing BCIs depended heavily on our measure of true body condition, with most BCIs falling into one of two groups. The first group contained most BCIs based on ratios, and these were associated with percent fat and body length (i.e., were biased). The second group contained the scaled mass index and most of the BCIs based on linear regressions, and these were associated with both scaled and residual fat but not body length (i.e., were unbiased). Our results show that potential differences in measures of true body condition should be explored in BCI verification studies, particularly in organisms undergoing allometric growth. Furthermore, the caveats of each BCI and similarities to other BCIs are important to consider when determining which BCI is appropriate for any particular taxon.

3D geometric morphometrics of thorax variation and allometry in Hominoidea.

PubMed

Bastir, Markus; García-Martínez, Daniel; Williams, Scott A; Recheis, Wolfgang; Torres-Sánchez, Isabel; García Río, Francisco; Oishi, Motoharu; Ogihara, Naomichi

2017-12-01

Ever since the seminal papers of Keith and Schultz, hominoid primate ribcages have been described as either "funnel-" or "barrel-shaped." Following this dichotomic typology, it is currently held that Homo sapiens and hylobatids (gibbons and siamangs) share a barrel-shaped ribcage and that they are more similar to each other than to the funnel-shaped thoraces of great apes (Gorilla, Pan, and Pongo). Other researchers hypothesized that thoracic width and the invagination of the thoracic spine into the thorax are related to allometry. However, analyses that take into account the complex three-dimensional (3D) shape of the ribcage are lacking. Here, we address hypotheses about thorax shape and evolution using 3D morphometrics of thoraces in anatomical connection obtained by computed tomography scans of 23 hominoid cadavers and 10 humans and examining thorax compartments composed of seven ribs (1-7 thorax) and of 11 ribs (1-11 thorax). In the 1-7 thorax analyses, the human thorax is uniquely flat because of torsion of the upper and central ribs, differing from all non-human hominoids including hylobatids. In the 1-11 thorax analyses, humans are markedly different from African great apes, with hylobatids and orangutans intermediate. In full shape space analyses, affinities between orangutans and humans on the one hand and between hylobatids and African great apes on the other are evident. Therefore, we reject the hypothesis that humans and hylobatids bear any special affinities in overall 3D thorax shape to each other. We find that larger thoraces are wider and flatter, with a more invaginated spine, supporting the allometric hypothesis. Hominoid thorax variation shows complex interactions between allometry, rib curves, torsion, and declination, and the morphology of the costo-vertebral joint and the thoracic vertebral column. When considering functional specializations alongside phylogenetic relationships, an overly simplistic dichotomy between funnel-shaped and barrel-shaped thoraces is not supported. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation.

PubMed

Mielke, Maja; Wölfer, Jan; Arnold, Patrick; van Heteren, Anneke H; Amson, Eli; Nyakatura, John A

2018-01-01

Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime. The present study investigates the effect of body size and lifestyle on trabecular structure in Sciuromorpha. Based upon high-resolution computed tomography scans, the femoral head 3D inner microstructure of 69 sciuromorph species was analyzed. Species were assigned to one of the following lifestyle categories: arboreal, aerial, fossorial and semifossorial. A cubic volume of interest was selected in the center of each femoral head and analyzed by extraction of various parameters that characterize trabecular architecture (degree of anisotropy, bone volume fraction, connectivity density, trabecular thickness, trabecular separation, bone surface density and main trabecular orientation). Our analysis included evaluation of the allometric signals and lifestyle-related adaptation in the trabecular parameters. We show that bone surface density, bone volume fraction, and connectivity density are subject to positive allometry, and degree of anisotropy, trabecular thickness, and trabecular separation to negative allometry. The parameters connectivity density, bone surface density, trabecular thickness, and trabecular separation show functional signals which are related to locomotor behavior. Aerial species are distinguished from fossorial ones by a higher trabecular thickness, lower connectivity density and lower bone surface density. Arboreal species are distinguished from semifossorial ones by a higher trabecular separation. This study on sciuromorph trabeculae supplements the few non-primate studies on lifestyle-related functional adaptation of trabecular bone. We show that the architecture of the femoral head trabeculae in Sciuromorpha correlates with body mass and locomotor habits. Our findings provide a new basis for experimental research focused on functional significance of bone inner microstructure.

A validation of 11 body-condition indices in a giant snake species that exhibits positive allometry

USGS Publications Warehouse

Falk, Bryan; Snow, Ray W.; Reed, Robert N.

2017-01-01

Body condition is a gauge of the energy stores of an animal, and though it has important implications for fitness, survival, competition, and disease, it is difficult to measure directly. Instead, body condition is frequently estimated as a body condition index (BCI) using length and mass measurements. A desirable BCI should accurately reflect true body condition and be unbiased with respect to size (i.e., mean BCI estimates should not change across different length or mass ranges), and choosing the most-appropriate BCI is not straightforward. We evaluated 11 different BCIs in 248 Burmese pythons (Python bivittatus), organisms that, like other snakes, exhibit simple body plans well characterized by length and mass. We found that the length-mass relationship in Burmese pythons is positively allometric, where mass increases rapidly with respect to length, and this allowed us to explore the effects of allometry on BCI verification. We employed three alternative measures of ‘true’ body condition: percent fat, scaled fat, and residual fat. The latter two measures mostly accommodated allometry in true body condition, but percent fat did not. Our inferences of the best-performing BCIs depended heavily on our measure of true body condition, with most BCIs falling into one of two groups. The first group contained most BCIs based on ratios, and these were associated with percent fat and body length (i.e., were biased). The second group contained the scaled mass index and most of the BCIs based on linear regressions, and these were associated with both scaled and residual fat but not body length (i.e., were unbiased). Our results show that potential differences in measures of true body condition should be explored in BCI verification studies, particularly in organisms undergoing allometric growth. Furthermore, the caveats of each BCI and similarities to other BCIs are important to consider when determining which BCI is appropriate for any particular taxon.

Allometric relationship of postmolt net ion uptake, ventilation, and circulation in the freshwater crayfish Procambarus clarkii: intraspecific scaling.

PubMed

Zanotto, F P; Wheatly, M G; Reiber, C L; Gannon, A T; Jalles-Filho, E

2004-01-01

There are few intraspecific studies relating physiological parameters to body mass. This study relates scaling of ionic regulation and respiratory parameters with body mass in crayfish (Procambarus clarkii). These animals were chosen because of their direct development, spanning four orders of magnitude in body mass. Usually, these animals are hyperregulators and must maintain hemolymph electrolyte levels above those in the ambient freshwater. This is especially important in the postmolt, when ion imbalance can occur. Maintaining hemolymph ion levels above ambient involves active processes that are independently related to metabolic rate, ventilation, and circulation. Therefore, this study investigates relationships among size and ionic regulation, heart rate, and ventilation in crayfish, spanning a size range of 0.003-24 g. Postmolt net ion uptake of Ca, titratable base, Na, Cl, and NH4 increase with body mass (positive allometry) with slopes of 0.92, 0.79, 0.90, 0.84, and 0.87, respectively. Between 72% and 97% of variation in ionic regulation was related to body mass. The slopes differed from each other for Ca and titratable base but not for Na, Cl, and NH4. For heart rate and ventilation rate, different relationships were derived for animals smaller and larger than 0.01 g (between first and third instar). Animals larger than 0.01 g show a negative allometric relationship between heart rate and body size ([body mass](0.15)), while smaller animals show positive allometry with body size, but only 29% of variation in heart rate is explained by body size alone. For ventilation rates, the negative allometry with body size for animals larger than 0.01 g is present, but less than 15% of variation in ventilation rate is explained by size, while for smaller animals the size dependency disappears. Based on these results, predictions of physiological parameters such as ionic regulation based on body size are useful in crayfish, but estimates of respiratory parameters and body size should be used with caution.

Allometry, sexual size dimorphism, and niche partitioning in the Mediterranean gecko (Hemidactylus turcicus)

Treesearch

James B. Johnson; Lance D. McBrayer; Daniel Saenz

2005-01-01

Hemidactylus tucrius is a small gekkonid lizard native to the Middle East and Asia that is known to exhibit sexual dimorphism in head size. Several potential explanations exist for the evolution and maintenance of sexual dimorphism in lizards. We tested 2 of these competing hypotheses concerning diet partitioning and differential growth. We found no...

Reproductive allometry in three species of Dusky Salamanders

Treesearch

Richard C. Bruce

2014-01-01

Desmognathus comprises 21 currently recognized species of salamanders in eastern North America. Assemblages of 3–6 species occur in the Appalachian Mountains, wherein the larger species are more aquatic and the smaller more terrestrial. Adaptive divergence along the habitat gradient from stream to forest involves variation in such life-history traits as age and size at...

Development of height-volume relationships in second growth Abies grandis for use with aerial LiDAR

Treesearch

Wade T. Tinkham; Alistair M. S. Smith; David L. R. Affleck; Jarred D. Saralecos; Michael J. Falkowski; Chad M. Hoffman; Andrew T. Hudak; Michael A. Wulder

2016-01-01

Following typical forest inventory protocols, individual tree volume estimates are generally derived via diameter-at-breast-height (DBH)-based allometry. Although effective, measurement of DBH is time consuming and potentially a costly element in forest inventories. The capacity of airborne light detection and ranging (LiDAR) to provide individual tree-level...

Compacting coastal plain soils changes midrotation loblolly pine allometry by reducing root biomass

Treesearch

Kim H. Ludovici

2008-01-01

Factorial combinations of soil compaction and organic matter removal were replicated at the Long Term Site Productivity study in the Croatan National Forest, near New Bern, North Carolina, USA. Ten years after planting, 18 preselected loblolly pine (Pinus taeda L.) trees were destructively harvested to quantify treatment effects on total above- and...

Comment on "Evidence for mesothermy in dinosaurs".

PubMed

Myhrvold, Nathan P

2015-05-29

Grady et al. (Reports, 13 June 2014, p. 1268) studied dinosaur metabolism by comparison of maximum somatic growth rate allometry with groups of known metabolism. They concluded that dinosaurs exhibited mesothermy, a metabolic rate intermediate between endothermy and ectothermy. Multiple statistical and methodological issues call into question the evidence for dinosaur mesothermy. Copyright © 2015, American Association for the Advancement of Science.

Allometry, biomass, and chemical content of novel African Tulip Tree (Spathodea campanulata) forests in Puerto Rico

Treesearch

Ariel E. Lugo; Oscar J. Abelleira; Alexander Collado; Christian A. Viera; Cynthia Santiago; Diego O. Velez; Emilio Soto; Giovanni Amaro; Graciela Charon; Jr. Colon; Jennifer Santana; Jose L. Morales; Katherine Rivera; Luis Ortiz; Luis Rivera; Mianel Maldonado; Natalia Rivera; Norelis J. Vazquez

2011-01-01

The African tulip tree, Spathodea campanulata, the most common tree in Puerto Rico, forms novel forest types with mixtures of native and other introduced tree species. Novel forests increase in area in response to human activity and there is no information about their biomass accumulation and nutrient cycling. We established allometric relationships and chemically...

BAAD: a biomass and allometry database for woody plants

Treesearch

Daniel S. Falster; Remko A. Duursma; Masae I. Ishihara; Diego R. Barneche; Richard G. FitzJohn; Angelica Varhammar; Masahiro Aiba; Makoto Ando; Niels Anten; Michael J. Aspinwall; Jennifer L. Baltzer; Christopher Baraloto; Michael Battaglia; John J. Battles; Ben Bond-Lamberty; Michiel van Breugel; Yves Claveau; Masako Dannoura; Sylvain Delagrange; Jean-Christophe Domec; Farrah Fatemi; Wang Feng; Veronica Gargaglione; Yoshiaki Goto; Akio Hagihara; Jefferson S. Hall; Steve Hamilton; Degi Harja; Tsutom Hiura; Robert Holdaway; Lindsay S. Hutley; Tomoaki Ichie; Eric J. Jokela; Anu Kantola; Jeff W. G. Kelly; Tanaka Kenzo; David King; Brian D. Kloeppel; Takashi Kohyama; Akira Komiyama; Jean-Paul Laclau; Christopher H. Lusk; Douglas A. Maguire; Guerric Le Maire; Ammikki Makela; Lars Markesteijn; John Marshall; Katherine McCulloh; Itsuo Miyata; Karel Mokany; Shugeta Mori; Randall W. Myster; Masahiro Nagano; Shawna L. Naidu; Yann Nouvellon; Anthony P. O' Grady; Kevin L. O' Hara; Toshiyuki Ohtsuka; Noriyuki Osada; Olusegun O. Osunkoya; Pablo Luis Peri; Any Mary Petritan; Lourens Poorter; Angelika Portsmuth; Catherine Potvin; Johannes Ransijn; Douglas Reid; Sabina C. Ribeiro; Scott D. Roberts; Rolando Rodriguez; Angela Saldana-Acosta; Ignacio Santa-Regina; Kaichiro Sasa; N. Galia Selaya; Stephen C. Sillett; Frank Sterck; Kentaro Takagi; Takeshi Tange; Hiroyuki Tanouchi; David Tissue; Toru Umehara; Matthew A. Vadeboncoeur; Fernando Valladares; Petteri Vanninen; Jian R. Wang; Elizabeth Wenk; Richard Williams; Fabiano de Aquino Ximenes; Atsushi Yamaba; Toshihiro Yamada; Takuo Yamakura; Ruth D. Yanai; Robert A. York

2015-01-01

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to...

Diel trends in stomatal response to ozone and water deficit: a unique relationship of midday values to growth and allometry in Pima cotton?

Treesearch

D. A. Grantz; R. Paudel; H.-B. Vu; A. Shrestha; Nancy Grulke; L. J. De Kok

2015-01-01

Plant responses to ozone (O3) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux...

The quarter-power scaling model does not imply size-invariant hydraulic resistance in plants

Treesearch

Annikki Makela; Harry T. Valentine

2006-01-01

West, Brown, and Enquist (1997, 1999) propose an integrated model of the structure and allometry of plant vascular systems, which has come to be known as the 'WBE model' (Enquist, 2002). The WBE model weaves together area-preserving branching (Leonardo da Vinci), elastic similarity (Greenhill, 1881), the constant ratio of foliage mass to sapwood area (...

Critical wind speed at which trees break

NASA Astrophysics Data System (ADS)

Virot, E.; Ponomarenko, A.; Dehandschoewercker, É.; Quéré, D.; Clanet, C.

2016-02-01

Data from storms suggest that the critical wind speed at which trees break is constant (≃42 m /s ), regardless of tree characteristics. We question the physical origin of this observation both experimentally and theoretically. By combining Hooke's law, Griffith's criterion, and tree allometry, we show that the critical wind speed indeed hardly depends on the height, diameter, and elastic properties of trees.

Critical wind speed at which trees break.

PubMed

Virot, E; Ponomarenko, A; Dehandschoewercker, É; Quéré, D; Clanet, C

2016-02-01

Data from storms suggest that the critical wind speed at which trees break is constant (≃42m/s), regardless of tree characteristics. We question the physical origin of this observation both experimentally and theoretically. By combining Hooke's law, Griffith's criterion, and tree allometry, we show that the critical wind speed indeed hardly depends on the height, diameter, and elastic properties of trees.

Allometry of visceral organs in living amniotes and its implications for sauropod dinosaurs

PubMed Central

Franz, Ragna; Hummel, Jürgen; Kienzle, Ellen; Kölle, Petra; Gunga, Hanns-Christian; Clauss, Marcus

2009-01-01

Allometric equations are often used to extrapolate traits in animals for which only body mass estimates are known, such as dinosaurs. One important decision can be whether these equations should be based on mammal, bird or reptile data. To address whether this choice will have a relevant influence on reconstructions, we compared allometric equations for birds and mammals from the literature to those for reptiles derived from both published and hitherto unpublished data. Organs studied included the heart, kidneys, liver and gut, as well as gut contents. While the available data indicate that gut content mass does not differ between the clades, the organ masses for reptiles are generally lower than those for mammals and birds. In particular, gut tissue mass is significantly lower in reptiles. When applying the results in the reconstruction of a sauropod dinosaur, the estimated volume of the coelomic cavity greatly exceeds the estimated volume of the combined organ masses, irrespective of the allometric equation used. Therefore, substantial deviation of sauropod organ allometry from that of the extant vertebrates can be allowed conceptually. Extrapolations of retention times from estimated gut contents mass and food intake do not suggest digestive constraints on sauropod dinosaur body size. PMID:19324837

Multi-scaling allometric analysis for urban and regional development

NASA Astrophysics Data System (ADS)

Chen, Yanguang

2017-01-01

The concept of allometric growth is based on scaling relations, and it has been applied to urban and regional analysis for a long time. However, most allometric analyses were devoted to the single proportional relation between two elements of a geographical system. Few researches focus on the allometric scaling of multielements. In this paper, a process of multiscaling allometric analysis is developed for the studies on spatio-temporal evolution of complex systems. By means of linear algebra, general system theory, and by analogy with the analytical hierarchy process, the concepts of allometric growth can be integrated with the ideas from fractal dimension. Thus a new methodology of geo-spatial analysis and the related theoretical models emerge. Based on the least squares regression and matrix operations, a simple algorithm is proposed to solve the multiscaling allometric equation. Applying the analytical method of multielement allometry to Chinese cities and regions yields satisfying results. A conclusion is reached that the multiscaling allometric analysis can be employed to make a comprehensive evaluation for the relative levels of urban and regional development, and explain spatial heterogeneity. The notion of multiscaling allometry may enrich the current theory and methodology of spatial analyses of urban and regional evolution.

Allometry, nitrogen status, and carbon stable isotope composition of Pinus ponderosa seedlings in two growing media with contrasting nursery irrigation regimes

Treesearch

R. Kasten Dumroese; Deborah S. Page-Dumroese; Robert E. Brown

2011-01-01

Nursery irrigation regimes that recharged container capacity when target volumetric water content reached 72%, 58%, and 44% (by volume) influenced Pinus ponderosa Douglas ex Lawson & C. Lawson growth more than either a 1:1 (by volume) Sphagnum peat - vermiculite (PV) or a 7:3 (by volume) Sphagnum peat - sawdust (PS) medium. Exponential fertilization avoided...

Efficacy of generic allometric equations for estimating biomass: a test in Japanese natural forests.

PubMed

Ishihara, Masae I; Utsugi, Hajime; Tanouchi, Hiroyuki; Aiba, Masahiro; Kurokawa, Hiroko; Onoda, Yusuke; Nagano, Masahiro; Umehara, Toru; Ando, Makoto; Miyata, Rie; Hiura, Tsutom

2015-07-01

Accurate estimation of tree and forest biomass is key to evaluating forest ecosystem functions and the global carbon cycle. Allometric equations that estimate tree biomass from a set of predictors, such as stem diameter and tree height, are commonly used. Most allometric equations are site specific, usually developed from a small number of trees harvested in a small area, and are either species specific or ignore interspecific differences in allometry. Due to lack of site-specific allometries, local equations are often applied to sites for which they were not originally developed (foreign sites), sometimes leading to large errors in biomass estimates. In this study, we developed generic allometric equations for aboveground biomass and component (stem, branch, leaf, and root) biomass using large, compiled data sets of 1203 harvested trees belonging to 102 species (60 deciduous angiosperm, 32 evergreen angiosperm, and 10 evergreen gymnosperm species) from 70 boreal, temperate, and subtropical natural forests in Japan. The best generic equations provided better biomass estimates than did local equations that were applied to foreign sites. The best generic equations included explanatory variables that represent interspecific differences in allometry in addition to stem diameter, reducing error by 4-12% compared to the generic equations that did not include the interspecific difference. Different explanatory variables were selected for different components. For aboveground and stem biomass, the best generic equations had species-specific wood specific gravity as an explanatory variable. For branch, leaf, and root biomass, the best equations had functional types (deciduous angiosperm, evergreen angiosperm, and evergreen gymnosperm) instead of functional traits (wood specific gravity or leaf mass per area), suggesting importance of other traits in addition to these traits, such as canopy and root architecture. Inclusion of tree height in addition to stem diameter improved the performance of the generic equation only for stem biomass and had no apparent effect on aboveground, branch, leaf, and root biomass at the site level. The development of a generic allometric equation taking account of interspecific differences is an effective approach for accurately estimating aboveground and component biomass in boreal, temperate, and subtropical natural forests.

Comparative morphology of the prothoracic leg in heliconian butterflies: Tracing size allometry, podite fusions and losses in ontogeny and phylogeny.

PubMed

Moreira, Gilson R P; Silva, Denis S; Gonçalves, Gislene L

2017-07-01

Prothoracic legs of heliconian butterflies (Nymphalidae, Heliconiinae, Heliconiini) are reduced in size compared to mesothoracic and metathoracic legs. They have no apparent function in males, but are used by females for drumming on host plants, a behavior related to oviposition site selection. Here, taking into account all recognized lineages of heliconian butterflies, we described their tarsi using optical and scanning electron microscopy and searched for podite fusions and losses, and analyzed allometry at the static, ontogenetic and phylogenetic levels. Female tarsi were similar, club-shaped, showing from four to five tarsomeres, each bearing sensilla chaetica and trichodea. Male tarsi were cylindrical, formed from five (early diverging lineages) to one (descendant lineages) either partially or totally fused tarsomeres, all deprived of sensilla. Pretarsi were reduced in both sexes, in some species being either vestigial or absent. Tarsal lengths were smaller for males in almost all species. An abrupt decrease in size was detected for the prothoracic legs during molting to the last larval instar at both histological and morphometric levels. In both sexes, most allometric coefficients found at the population level for the prothoracic legs were negative compared to the mesothoracic leg and also to wings. Prothoracic tarsi decreased proportionally in size over evolutionary time; the largest and smallest values being found for nodes of the oldest and youngest lineages, respectively. Our results demonstrate that evolution of the prothoracic leg in heliconian butterflies has been based on losses and fusions of podites, in association with negative size allometry at static, ontogenetic and phylogenetic levels. These processes have been more pronounced in males. Our study provided further support to the hypothesis that evolution of these leg structures is driven by females, by changing their use from walking to drumming during oviposition site selection. In males the leg would have been selected against due to absence of function and thus progressively reduced in size, in association with podites fusions and lost. Copyright © 2017 Elsevier Ltd. All rights reserved.

Scaling of rotational inertia of primate mandibles.

PubMed

Ross, Callum F; Iriarte-Diaz, Jose; Platts, Ellen; Walsh, Treva; Heins, Liam; Gerstner, Geoffrey E; Taylor, Andrea B

2017-05-01

The relative importance of pendulum mechanics and muscle mechanics in chewing dynamics has implications for understanding the optimality criteria driving the evolution of primate feeding systems. The Spring Model (Ross et al., 2009b), which modeled the primate chewing system as a forced mass-spring system, predicted that chew cycle time would increase faster than was actually observed. We hypothesized that if mandibular momentum plays an important role in chewing dynamics, more accurate estimates of the rotational inertia of the mandible would improve the accuracy with which the Spring Model predicts the scaling of primate chew cycle period. However, if mass-related momentum effects are of negligible importance in the scaling of primate chew cycle period, this hypothesis would be falsified. We also predicted that greater "robusticity" of anthropoid mandibles compared with prosimians would be associated with higher moments of inertia. From computed tomography scans, we estimated the scaling of the moment of inertia (I j ) of the mandibles of thirty-one species of primates, including 22 anthropoid and nine prosimian species, separating I j into the moment about a transverse axis through the center of mass (I xx ) and the moment of the center of mass about plausible axes of rotation. We found that across primates I j increases with positive allometry relative to jaw length, primarily due to positive allometry of jaw mass and I xx , and that anthropoid mandibles have greater rotational inertia compared with prosimian mandibles of similar length. Positive allometry of I j of primate mandibles actually lowers the predictive ability of the Spring Model, suggesting that scaling of primate chew cycle period, and chewing dynamics in general, are more strongly influenced by factors other than scaling of inertial properties of the mandible, such as the dynamic properties of the jaw muscles and neural control. Differences in cycle period scaling between chewing and locomotion systems reinforce the suggestion that displacement and force control are more important in the design of feeding systems than energetics and speed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Growth laws for sub-delta crevasses in the Mississippi River Delta

NASA Astrophysics Data System (ADS)

Yocum, T. A.; Georgiou, I. Y.; Straub, K. M.

2017-12-01

River deltas are threatened by environmental change, including subsidence, global sea level rise, reduced sediment inputs and other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions to reinitiate the delta cycle. Deltas were studied extensively using numerical models, theoretical and conceptual frameworks, empirical scaling relationships, laboratory models and field observations. But predicting the future of deltas relies on field observations where for most deltas data are still lacking. Moreover, empirical and theoretical scaling laws may be influenced by the data used to develop them, while laboratory deltas may be influenced by scaling issues. Anthropogenic crevasses in the MRD are large enough to overcome limitations of laboratory deltas, and small enough to allow for rapid channel and wetland development, providing an ideal setting to investigate delta development mechanics. Here we assessed growth laws of sub-delta crevasses (SDC) in the MRD, in two experimental laboratory deltas (LD - weakly and strongly cohesive) and compared them to river dominated deltas worldwide. Channel and delta geometry metrics for each system were obtained using geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Results show that SDC follow growth laws similar to large river dominated deltas, with the exception of some that exhibit anomalous behavior with respect to the frequency and distance to a bifurcation and the fraction of wetted delta shoreline (allometry metrics). Most SDC exhibit a systematic decrease of non-dimensional channel geometries with increased bifurcation order, indicating that channels are adjusting to decreased flow after bifurcations occur, and exhibit linear trends for land allometry and width-depth ratio, although geometries decrease more rapidly per bifurcation order. Measured distance to bifurcations in SDC and LD appear longer compared to those predicted by power law metrics. With less channel splitting in some crevasses, channel extension creates wetted perimeter faster than or at the same rate as wetted area, which explains why some SDC displayed fractal growth of the wetted allometry.

Scale-dependence of desease impacts on quaking aspen (Populus tremuloides) mortality risk in the southwestern U.S.

Treesearch

David M. Bell; John B. Bradford; William K. Lauenroth

2015-01-01

Depending on how disease impacts tree exposure to risk, both the prevalence of disease and disease effects on survival may contribute to patterns of mortality risk across a species’ range. Disease may accelerate tree species’ declines in response to global change factors, such as drought, biotic interactions, such as competition, or functional traits, such as allometry...

The relationship between circulating ecdysteroids and chela allometry in male tanner crabs: Evidence for a terminal molt in the genus Chionoecetes

USGS Publications Warehouse

Tamone, S.L.; Taggart, S. James; Andrews, A.G.; Mondragon, Jennifer; Nielsen, J.K.

2007-01-01

Whether male Tanner crabs, Chionoecetes bairdi, undergo a terminal molt associated with a change in claw allometry has long been debated. We measured molting hormone levels in captured male C. bairdi to assess the potential for molting. We plotted a frequency histogram of chela height to carapace width ratios and found a bimodal distribution of crabs with a ratio of approximately 0.18 separating the two modes. Male crabs with a ratio less than 0.18 were classified as "small-clawed" (SC) while crabs with a ratio greater than 0.18 were classified as "large-clawed" (LC). Circulating molting hormones between SC and LC crabs were compared. Significantly lower ecdysteroid levels were found in LC crabs, indicating that this morphotype had negligible potential for molting. Circulating ecdysteroids were measured in SC males of different shell conditions (soft, new, old, and very old) and no significant differences were found. This research suggests that the molt to LC morphology is a terminal molt. The results from this study have important implications for fisheries management because sub-legal LC males will not recruit into the fishery and removal of larger males may have long term effects on population size structure.

Allometric growth in juvenile marine turtles: possible role as an antipredator adaptation.

PubMed

Salmon, Michael; Scholl, Joshua

2014-04-01

Female marine turtles produce hundreds of offspring during their lifetime but few survive because small turtles have limited defenses and are vulnerable to many predators. Little is known about how small turtles improve their survival probabilities with growth though it is assumed that they do. We reared green turtles (Chelonia mydas) and loggerheads (Caretta caretta) from hatchlings to 13 weeks of age and documented that they grew wider faster than they grew longer. This pattern of allometric growth might enable small turtles to more quickly achieve protection from gape-limited predators, such as the dolphinfish (Coryphaena hippurus). As a test of that hypothesis, we measured how dolphinfish gape increased with length, reviewed the literature to determine how dolphinfish populations were size/age structured in nearby waters, and then determined the probability that a small turtle would encounter a fish large enough to consume it if it grew by allometry vs. by isometry (in which case it retained its hatchling proportions). Allometric growth more quickly reduced the probability of a lethal encounter than did isometric growth. On that basis, we suggest that allometry during early ontogeny may have evolved because it provides a survival benefit for small turtles. Copyright © 2014 Elsevier GmbH. All rights reserved.

The study of craniofacial growth patterns using 3D laser scanning and geometric morphometrics

NASA Astrophysics Data System (ADS)

Friess, Martin

2006-02-01

Throughout childhood, braincase and face grow at different rates and therefore exhibit variable proportions and positions relative to each other. Our understanding of the direction and magnitude of these growth patterns is crucial for many ergonomic applications and can be improved by advanced 3D morphometrics. The purpose of this study is to investigate this known growth allometry using 3D imaging techniques. The geometry of the head and face of 840 children, aged 2 to 19, was captured with a laser surface scanner and analyzed statistically. From each scan, 18 landmarks were extracted and registered using General Procrustes Analysis (GPA). GPA eliminates unwanted variation due to position, orientation and scale by applying a least-squares superimposition algorithm to individual landmark configurations. This approach provides the necessary normalization for the study of differences in size, shape, and their interaction (allometry). The results show that throughout adolescence, boys and girls follow a different growth trajectory, leading to marked differences not only in size but also in shape, most notably in relative proportions of the braincase. These differences can be observed during early childhood, but become most noticeable after the age of 13 years, when craniofacial growth in girls slows down significantly, whereas growth in boys continues for at least 3 more years.

Physical trade-offs shape the evolution of buoyancy control in sharks.

PubMed

Gleiss, Adrian C; Potvin, Jean; Goldbogen, Jeremy A

2017-11-15

Buoyancy control is a fundamental aspect of aquatic life that has major implications for locomotor performance and ecological niche. Unlike terrestrial animals, the densities of aquatic animals are similar to the supporting fluid, thus even small changes in body density may have profound effects on locomotion. Here, we analysed the body composition (lipid versus lean tissue) of 32 shark species to study the evolution of buoyancy. Our comparative phylogenetic analyses indicate that although lean tissue displays minor positive allometry, liver volume exhibits pronounced positive allometry, suggesting that larger sharks evolved bulkier body compositions by adding lipid tissue to lean tissue rather than substituting lean for lipid tissue, particularly in the liver. We revealed a continuum of buoyancy control strategies that ranged from more buoyant sharks with larger livers in deeper ecosystems to relatively denser sharks with small livers in epipelagic habitats. Across this eco-morphological spectrum, our hydrodynamic modelling suggests that neutral buoyancy yields lower drag and more efficient steady swimming, whereas negative buoyancy may be more efficient during accelerated movements. The evolution of buoyancy control in sharks suggests that ecological and physiological factors mediate the selective pressures acting on these traits along two major gradients, body size and habitat depth. © 2017 The Author(s).

Differential influences of allometry, phylogeny and environment on the rostral shape diversity of extinct South American notoungulates

NASA Astrophysics Data System (ADS)

Gomes Rodrigues, Helder; Cornette, Raphaël; Clavel, Julien; Cassini, Guillermo; Bhullar, Bhart-Anjan S.; Fernández-Monescillo, Marcos; Moreno, Karen; Herrel, Anthony; Billet, Guillaume

2018-01-01

Understanding the mechanisms responsible for phenotypic diversification, and the associated underlying constraints and ecological factors represents a central issue in evolutionary biology. Mammals present a wide variety of sizes and shapes, and are characterized by a high number of morphological convergences that are hypothesized to reflect similar environmental pressures. Extinct South American notoungulates evolved in isolation from northern mammalian faunas in highly disparate environments. They present a wide array of skeletal phenotypes and convergences, such as ever-growing dentition. Here, we focused on the origins of the rostral diversity of notoungulates by quantifying the shape of 26 genera using three-dimensional geometric morphometric analysis. We tested the influence of allometry and phylogeny on rostral shape and evaluated rates of evolutionary change in the different clades. We found strong allometric and phylogenetic signals concerning the rostral shape of notoungulates. Despite convergent forms, we observed a diffuse diversification of rostral shape, with no significant evidence of influence by large-scaled environmental variation. This contrasts with the increase in dental crown height that occurred in four late-diverging families in response to similar environmental pressures. These results illustrate the importance of considering both biological components and evolutionary rates to better understand some aspects of phenotypic diversity.

Interspecies scaling of a camptothecin analogue: human predictions for intravenous topotecan using animal data.

PubMed

Ahlawat, P; Srinivas, N R

2008-11-01

As a class, camptothecin analogues via market entry of topotecan and irinotecan, have shown promise for the treatment of various solid tumours. Topotecan, in particular, was chosen as the substrate for allometric scaling and prediction of human parameter values for both total clearance (CL) and volume of distribution (V(ss)). The availability of published data in mouse, rat, dog, and monkey paved the way for interspecies scaling via allometry. Although it appeared that at a minimum mouse, rat, and dog would reasonably fit in a three-species allometry scale-up, the inclusion of monkey data enabled a better prediction of the human parameter values for total topotecan-e.g., CL: allometric equation: 1.5234W(0.7865); predicted value = 43.04 l h(-1): observed CL = 24-53 l h(-1); V(ss): allometric equation: 1.1939W(1.0208); predicted value = 91.29 litres: observed V(ss) = 66-146 litres. The proximity of the allometric exponent values of CL (0.7885) and V(ss) (1.0208) to the suggested values of 0.75 and 1.00 was not only encouraging, but also confirmed the applicability of interspecies scaling approach for topotecan. The data suggest that allometric scaling approaches with suitable correction factors could potentially be used to predict the human pharmacokinetics of novel CPT analogues prospectively.

Development of LiDAR aware allometrics for Abies grandis: A Case Study

NASA Astrophysics Data System (ADS)

Stone, G. A.; Tinkham, W. T.; Smith, A. M.; Hudak, A. T.; Falkowski, M. J.; Keefe, R.

2012-12-01

Forest managers rely increasingly on accurate allometric relationships to inform decisions regarding stand rotations, silvilcultural treatments, timber harvesting, and biometric modeling. At the same time, advances in remote sensing techniques like LiDAR (light detection and ranging) have brought about opportunities to advance how we assess forest growth, and thus are contributing to the need for more accurate allometries. Past studies have attempted to relate LiDAR data to both plot and individual tree measures of forest biomass. However, many of these studies have been limited by the accuracy of their coincident observations. In this study, 24 Abies grandis were measured, felled, and dissected for the explicit objective of developing LiDAR aware allometrics. The analysis predicts spatial variables of competition, growth potential (e.g, trees per acre, aspect, elevation, etc.) and common statistical distributional metrics (e.g., mean, mode, percentiles, variance, skewness, kurtosis, etc.) derived from LiDAR point cloud returns to coincident in situ measures of Abies grandis stem biomass. The resulting allometries exemplify a new approach for predicting structural attributes of interest (biomass, basal area, volume, etc.) directly from LiDAR point cloud data, precluding the measurement errors that are propogated by indirectly predicting these structure attributes of interest from LiDAR data using traditional plot-based measurements.

Sexual dimorphism and allometry in the sphecophilous rove beetle Triacrus dilatus.

PubMed

Marlowe, Maxwell H; Murphy, Cheryl A; Chatzimanolis, Stylianos

2015-01-01

The rove beetle Triacrus dilatus is found in the Atlantic forest of South America and lives in the refuse piles of the paper wasp Agelaia vicina. Adults of T. dilatus are among the largest rove beetles, frequently measuring over 3 cm, and exhibit remarkable variation in body size. To examine sexual dimorphism and allometric relationships we measured the length of the left mandible, ocular distance and elytra. We were interested in determining if there are quantifiable differences between sexes, if there are major and minor forms within each sex and if males exhibit mandibular allometry. For all variables, a t-test was run to determine if there were significant differences between the sexes. Linear regressions were run to examine if there were significant relationships between the different measurements. A heterogeneity of slopes test was used to determine if there were significant differences between males and females. Our results indicated that males had significantly larger mandibles and ocular distances than females, but the overall body length was not significantly different between the sexes. Unlike most insects, both sexes showed positive linear allometric relationships for mandible length and head size (as measured by the ocular distance). We found no evidence of major and minor forms in either sex.

Size matters for lice on birds: Coevolutionary allometry of host and parasite body size.

PubMed

Harnos, Andrea; Lang, Zsolt; Petrás, Dóra; Bush, Sarah E; Szabó, Krisztián; Rózsa, Lajos

2017-02-01

Body size is one of the most fundamental characteristics of all organisms. It influences physiology, morphology, behavior, and even interspecific interactions such as those between parasites and their hosts. Host body size influences the magnitude and variability of parasite size according to Harrison's rule (HR: positive relationship between host and parasite body sizes) and Poulin's Increasing Variance Hypothesis (PIVH: positive relationship between host body size and the variability of parasite body size). We analyzed parasite-host body size allometry for 581 species of avian lice (∼15% of known diversity) and their hosts. We applied phylogenetic generalized least squares (PGLS) methods to account for phylogenetic nonindependence controlling for host and parasite phylogenies separately and variance heterogeneity. We tested HR and PIVH for the major families of avian lice (Ricinidae, Menoponidae, Philopteridae), and for distinct ecological guilds within Philopteridae. Our data indicate that most families and guilds of avian lice follow both HR and PIVH; however, ricinids did not follow PIVH and the "body lice" guild of philopterid lice did not follow HR or PIVH. We discuss mathematical and ecological factors that may be responsible for these patterns, and we discuss the potential pervasiveness of these relationships among all parasites on Earth. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Modeling development and quantitative trait mapping reveal independent genetic modules for leaf size and shape.

PubMed

Baker, Robert L; Leong, Wen Fung; Brock, Marcus T; Markelz, R J Cody; Covington, Michael F; Devisetty, Upendra K; Edwards, Christine E; Maloof, Julin; Welch, Stephen; Weinig, Cynthia

2015-10-01

Improved predictions of fitness and yield may be obtained by characterizing the genetic controls and environmental dependencies of organismal ontogeny. Elucidating the shape of growth curves may reveal novel genetic controls that single-time-point (STP) analyses do not because, in theory, infinite numbers of growth curves can result in the same final measurement. We measured leaf lengths and widths in Brassica rapa recombinant inbred lines (RILs) throughout ontogeny. We modeled leaf growth and allometry as function valued traits (FVT), and examined genetic correlations between these traits and aspects of phenology, physiology, circadian rhythms and fitness. We used RNA-seq to construct a SNP linkage map and mapped trait quantitative trait loci (QTL). We found genetic trade-offs between leaf size and growth rate FVT and uncovered differences in genotypic and QTL correlations involving FVT vs STPs. We identified leaf shape (allometry) as a genetic module independent of length and width and identified selection on FVT parameters of development. Leaf shape is associated with venation features that affect desiccation resistance. The genetic independence of leaf shape from other leaf traits may therefore enable crop optimization in leaf shape without negative effects on traits such as size, growth rate, duration or gas exchange. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Unifying principles in terrestrial locomotion: do hopping Australian marsupials fit in?

PubMed

Bennett, M B

2000-01-01

Mammalian terrestrial locomotion has many unifying principles. However, the Macropodoidea are a particularly interesting group that exhibit a number of significant deviations from the principles that seem to apply to other mammals. While the properties of materials that comprise the musculoskeletal system of mammals are similar, evidence suggests that tendon properties in macropodoid marsupials may be size or function dependent, in contrast to the situation in placental mammals. Postural differences related to hopping versus running have a dramatic effect on the scaling of the pelvic limb musculoskeletal system. Ratios of muscle fibre to tendon cross-sectional areas for ankle extensors and digital flexors scale with positive allometry in all mammals, but exponents are significantly higher in macropods. Tendon safety factors decline with increasing body mass in mammals, with eutherians at risk of ankle extensor tendon rupture at a body mass of about 150 kg, whereas kangaroos encounter similar problems at a body mass of approximately 35 kg. Tendon strength appears to limit locomotor performance in these animals. Elastic strain energy storage in tendons is mass dependent in all mammals, but exponents are significantly larger in macropodid. Tibial stresses may scale with positive allometry in kangaroos, which result in lower bone safety factors in macropods compared to eutherian mammals.

Interannual variability of growth and reproduction in Bursera simaruba: the role of allometry and resource variability.

PubMed

Hulshof, Catherine M; Stegen, James C; Swenson, Nathan G; Enquist, Carolyn A F; Enquist, Brian J

2012-01-01

Plants are expected to differentially allocate resources to reproduction, growth, and survival in order to maximize overall fitness. Life history theory predicts that the allocation of resources to reproduction should occur at the expense of vegetative growth. Although it is known that both organism size and resource availability can influence life history traits, few studies have addressed how size dependencies of growth and reproduction and variation in resource supply jointly affect the coupling between growth and reproduction. In order to understand the relationship between growth and reproduction in the context of resource variability, we utilize a long-term observational data set consisting of 670 individual trees over a 10-year period within a local population of Bursera simaruba (L.) Sarg. We (1) quantify the functional form and variability in the growth-reproduction relationship at the population and individual-tree level and (2) develop a theoretical framework to understand the allometric dependence of growth and reproduction. Our findings suggest that the differential responses of allometric growth and reproduction to resource availability, both between years and between microsites, underlie the apparent relationship between growth and reproduction. Finally, we offer an alternative approach for quantifying the relationship between growth and reproduction that accounts for variation in allometries.

Secondary osteons scale allometrically in mammalian humerus and femur

PubMed Central

Phillips, C.; Cornish, H.; Cooke, M.; Hutchinson, J. R.; Doube, M.

2017-01-01

Intra-cortical bone remodelling is a cell-driven process that replaces existing bone tissue with new bone tissue in the bone cortex, leaving behind histological features called secondary osteons. While the scaling of bone dimensions on a macroscopic scale is well known, less is known about how the spatial dimensions of secondary osteons vary in relation to the adult body size of the species. We measured the cross-sectional area of individual intact secondary osteons and their central Haversian canals in transverse sections from 40 stylopodal bones of 39 mammalian species (body mass 0.3–21 000 kg). Scaling analysis of our data shows that mean osteonal resorption area (negative allometry, exponent 0.23,R2 0.54,p<0.005) and Haversian canal area (negative allometry, exponent 0.31,R2 0.45,p<0.005) are significantly related to body mass, independent of phylogeny. This study is the most comprehensive of its kind to date, and allows us to describe overall trends in the scaling behaviour of secondary osteon dimensions, supporting the inference that the osteonal resorption area may be limited by the need to avoid fracture in smaller mammalian species, but the need to maintain osteocyte viability in larger mammalian species. PMID:29291052

Hind limb scaling of kangaroos and wallabies (superfamily Macropodoidea): implications for hopping performance, safety factor and elastic savings

PubMed Central

McGowan, C P; Skinner, J; Biewener, A A

2008-01-01

The aim of this study was to examine hind limb scaling of the musculoskeletal system in the Macropodoidea, the superfamily containing wallabies and kangaroos, to re-examine the effect of size on the locomotor mechanics and physiology of marsupial hopping. Morphometric musculoskeletal analyses were conducted of 15 species and skeletal specimens of 21 species spanning a size range from 0.8 to 80 kg that included representatives of 12 of the 16 extant genera of macropodoids. We found that unlike other groups, macropodoids are able to match force demands associated with increasing body size primarily through a combination of positive allometry in muscle area and muscle moment arms. Isometric scaling of primary hind limb bones suggests, however, that larger species experience relatively greater bone stresses. Muscle to tendon area ratios of the ankle extensors scale with strong positive allometry, indicating that peak tendon stresses also increase with increasing body size but to a lesser degree than previously reported. Consistent with previous morphological and experimental studies, large macropodoids are therefore better suited for elastic strain energy recovery but operate at lower safety factors, which likely poses an upper limit to body size. Scaling patterns for extant macropodoids suggest that extinct giant kangaroos (∼250 kg) were likely limited in locomotor capacity. PMID:18086129

Towards a better prediction of peak concentration, volume of distribution and half-life after oral drug administration in man, using allometry.

PubMed

Sinha, Vikash K; Vaarties, Karin; De Buck, Stefan S; Fenu, Luca A; Nijsen, Marjoleen; Gilissen, Ron A H J; Sanderson, Wendy; Van Uytsel, Kelly; Hoeben, Eva; Van Peer, Achiel; Mackie, Claire E; Smit, Johan W

2011-05-01

It is imperative that new drugs demonstrate adequate pharmacokinetic properties, allowing an optimal safety margin and convenient dosing regimens in clinical practice, which then lead to better patient compliance. Such pharmacokinetic properties include suitable peak (maximum) plasma drug concentration (C(max)), area under the plasma concentration-time curve (AUC) and a suitable half-life (t(½)). The C(max) and t(½) following oral drug administration are functions of the oral clearance (CL/F) and apparent volume of distribution during the terminal phase by the oral route (V(z)/F), each of which may be predicted and combined to estimate C(max) and t(½). Allometric scaling is a widely used methodology in the pharmaceutical industry to predict human pharmacokinetic parameters such as clearance and volume of distribution. In our previous published work, we have evaluated the use of allometry for prediction of CL/F and AUC. In this paper we describe the evaluation of different allometric scaling approaches for the prediction of C(max), V(z)/F and t(½) after oral drug administration in man. Twenty-nine compounds developed at Janssen Research and Development (a division of Janssen Pharmaceutica NV), covering a wide range of physicochemical and pharmacokinetic properties, were selected. The C(max) following oral dosing of a compound was predicted using (i) simple allometry alone; (ii) simple allometry along with correction factors such as plasma protein binding (PPB), maximum life-span potential or brain weight (reverse rule of exponents, unbound C(max) approach); and (iii) an indirect approach using allometrically predicted CL/F and V(z)/F and absorption rate constant (k(a)). The k(a) was estimated from (i) in vivo pharmacokinetic experiments in preclinical species; and (ii) predicted effective permeability in man (P(eff)), using a Caco-2 permeability assay. The V(z)/F was predicted using allometric scaling with or without PPB correction. The t(½) was estimated from the allometrically predicted parameters CL/F and V(z)/F. Predictions were deemed adequate when errors were within a 2-fold range. C(max) and t(½) could be predicted within a 2-fold error range for 59% and 66% of the tested compounds, respectively, using allometrically predicted CL/F and V(z)/F. The best predictions for C(max) were obtained when k(a) values were calculated from the Caco-2 permeability assay. The V(z)/F was predicted within a 2-fold error range for 72% of compounds when PPB correction was applied as the correction factor for scaling. We conclude that (i) C(max) and t(½) are best predicted by indirect scaling approaches (using allometrically predicted CL/F and V(z)/F and accounting for k(a) derived from permeability assay); and (ii) the PPB is an important correction factor for the prediction of V(z)/F by using allometric scaling. Furthermore, additional work is warranted to understand the mechanisms governing the processes underlying determination of C(max) so that the empirical approaches can be fine-tuned further.

Influence of Crown Biomass Estimators and Distribution on Canopy Fuel Characteristics in Ponderosa Pine Stands of the Black Hills

Treesearch

Tara Keyser; Frederick Smith

2009-01-01

Two determinants of crown fire hazard are canopy bulk density (CBD) and canopy base height (CBH). The Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) is a model that predicts CBD and CBH. Currently, FFE-FVS accounts for neither geographic variation in tree allometries nor the nonuniform distribution of crown mass when one is estimating CBH and CBD...

On Allometry Relations

DTIC Science & Technology

2012-07-06

that: B = aM b . (15) The metabolic rate refers to the total utilization of chemical energy for the genera- tion of heat by the body of an animal and...AR was given by Sarrus and Rameaux.188 Schmidt–Nielsen195 records that this team of a mathematician and a physician reasoned that the heat gener- ated...by a warm blooded animal is proportional to the volume and the heat loss is proportional to the animal’s free surface. Experiments on dogs by

Mechanics, Hydrodynamics and Energetics of Blue Whale Lunge Feeding: Efficiency Dependence on Krill Density

DTIC Science & Technology

2011-01-01

obtained these morphometric data from blue whale specimens reposited at the National Museum of Natural History in Washington, DC (USNM 124326), the Santa...mouth-closing stage. The basic distance scale for this force is set by the ratio Ac/whead, calculated from Eqn A4, and the morphometrics of the body...allometry of mammalian metabolic rate supports niether geometric nor quarter-power scaling. Evolution 63, 2658-2667. Williams, T. M. (1999). The

Convergent evolution of sexual shape dimorphism in Diptera.

PubMed

Bonduriansky, Russell

2006-05-01

Several patterns of sexual shape dimorphism, such as male body elongation, eye stalks, or extensions of the exoskeleton, have evolved repeatedly in the true flies (Diptera). Although these dimorphisms may have evolved in response to sexual selection on male body shape, conserved genetic factors may have contributed to this convergent evolution, resulting in stronger phenotypic convergence than might be expected from functional requirements alone. I compared phenotypic variation in body shape in two distantly related species exhibiting sexually dimorphic body elongation: Prochyliza xanthostoma (Piophilidae) and Telostylinus angusticollis (Neriidae). Although sexual selection appears to act differently on male body shape in these species, they exhibited strikingly similar patterns of sexual dimorphism. Likewise, patterns of within-sex shape variation were similar in the two species, particularly in males: relative elongation of the male head capsule, antenna, and legs was associated with reduced head capsule width and wing length, but was nearly independent of variation in thorax length. However, the two species presented contrasting patterns of static allometry: male sexual traits exhibited elevated allometric slopes in T. angusticollis, but not in P. xanthostoma. These results suggest that a shared pattern of covariation among traits may have channeled the evolution of sexually dimorphic body elongation in these species. Nonetheless, static allometries may have been shaped by species-specific selection pressures or genetic architectures. Copyright 2006 Wiley-Liss, Inc.

Is sociality required for the evolution of communicative complexity? Evidence weighed against alternative hypotheses in diverse taxonomic groups

PubMed Central

Ord, Terry J.; Garcia-Porta, Joan

2012-01-01

Complex social communication is expected to evolve whenever animals engage in many and varied social interactions; that is, sociality should promote communicative complexity. Yet, informal comparisons among phylogenetically independent taxonomic groups seem to cast doubt on the putative role of social factors in the evolution of complex communication. Here, we provide a formal test of the sociality hypothesis alongside alternative explanations for the evolution of communicative complexity. We compiled data documenting variations in signal complexity among closely related species for several case study groups—ants, frogs, lizards and birds—and used new phylogenetic methods to investigate the factors underlying communication evolution. Social factors were only implicated in the evolution of complex visual signals in lizards. Ecology, and to some degree allometry, were most likely explanations for complexity in the vocal signals of frogs (ecology) and birds (ecology and allometry). There was some evidence for adaptive evolution in the pheromone complexity of ants, although no compelling selection pressure was identified. For most taxa, phylogenetic null models were consistently ranked above adaptive models and, for some taxa, signal complexity seems to have accumulated in species via incremental or random changes over long periods of evolutionary time. Becoming social presumably leads to the origin of social communication in animals, but its subsequent influence on the trajectory of signal evolution has been neither clear-cut nor general among taxonomic groups. PMID:22641820

Genetic parameters for different growth scales in GIFT strain of Nile tilapia (Oreochromis niloticus).

PubMed

He, J; Gao, H; Xu, P; Yang, R

2015-12-01

Body weight, length, width and depth at two growth stages were observed for a total of 5015 individuals of GIFT strain, along with a pedigree including 5588 individuals from 104 sires and 162 dams was collected. Multivariate animal models and a random regression model were used to genetically analyse absolute and relative growth scales of these growth traits. In absolute growth scale, the observed growth traits had moderate heritabilities ranging from 0.321 to 0.576, while pairwise ratios between body length, width and depth were lowly inherited and maximum heritability was only 0.146 for length/depth. All genetic correlations were above 0.5 between pairwise growth traits and genetic correlation between length/width and length/depth varied between both growth stages. Based on those estimates, selection index of multiple traits of interest can be formulated in future breeding program to improve genetically body weight and morphology of the GIFT strain. In relative growth scale, heritabilities in relative growths of body length, width and depth to body weight were 0.257, 0.412 and 0.066, respectively, while genetic correlations among these allometry scalings were above 0.8. Genetic analysis for joint allometries of body weight to body length, width and depth will contribute to genetically regulate the growth rate between body shape and body weight. © 2015 Blackwell Verlag GmbH.

Response to formal comment on Myhrvold (2016) submitted by Griebeler and Werner (2017)

PubMed Central

2018-01-01

Griebeler and Werner offer a formal comment on Myhrvold, 2016 defending the conclusions of Werner and Griebeler, 2014. Although the comment criticizes several aspects of methodology in Myhrvold, 2016, all three papers concur on a key conclusion: the metabolism of extant endotherms and ectotherms cannot be reliably classified using growth-rate allometry, because the growth rates of extant endotherms and ectotherms overlap. A key point of disagreement is that the 2014 paper concluded that despite this general case, one can nevertheless classify dinosaurs as ectotherms from their growth rate allometry. The 2014 conclusion is based on two factors: the assertion (made without any supporting arguments) that the comparison with dinosaurs must be restricted only to extant sauropsids, ignoring other vertebrate groups, and that extant sauropsid endotherm and ectotherm growth rates in a data set studied in the 2014 work do not overlap. The Griebeler and Werner formal comment presents their first arguments in support of the restriction proposition. In this response I show that this restriction is unsupported by established principles of phylogenetic comparison. In addition, I show that the data set studied in their 2014 work does show overlap, and that this is visible in one of its figures. I explain how either point effectively invalidates the conclusion of their 2014 paper. I also address the other methodological criticisms of Myhrvold 2016, and find them unsupported. PMID:29489880

Response to formal comment on Myhrvold (2016) submitted by Griebeler and Werner (2017).

PubMed

Myhrvold, Nathan P

2018-01-01

Griebeler and Werner offer a formal comment on Myhrvold, 2016 defending the conclusions of Werner and Griebeler, 2014. Although the comment criticizes several aspects of methodology in Myhrvold, 2016, all three papers concur on a key conclusion: the metabolism of extant endotherms and ectotherms cannot be reliably classified using growth-rate allometry, because the growth rates of extant endotherms and ectotherms overlap. A key point of disagreement is that the 2014 paper concluded that despite this general case, one can nevertheless classify dinosaurs as ectotherms from their growth rate allometry. The 2014 conclusion is based on two factors: the assertion (made without any supporting arguments) that the comparison with dinosaurs must be restricted only to extant sauropsids, ignoring other vertebrate groups, and that extant sauropsid endotherm and ectotherm growth rates in a data set studied in the 2014 work do not overlap. The Griebeler and Werner formal comment presents their first arguments in support of the restriction proposition. In this response I show that this restriction is unsupported by established principles of phylogenetic comparison. In addition, I show that the data set studied in their 2014 work does show overlap, and that this is visible in one of its figures. I explain how either point effectively invalidates the conclusion of their 2014 paper. I also address the other methodological criticisms of Myhrvold 2016, and find them unsupported.

Evolution and inheritance of early embryonic patterning in Drosophila simulans and D. sechellia.

PubMed

Lott, Susan E; Ludwig, Michael Z; Kreitman, Martin

2011-05-01

Pattern formation in Drosophila is a widely studied example of a robust developmental system. Such robust systems pose a challenge to adaptive evolution, as they mask variation that selection may otherwise act upon. Yet we find variation in the localization of expression domains (henceforth "stripe allometry") in the pattern formation pathway. Specifically, we characterize differences in the gap genes giant and Kruppel, and the pair-rule gene even-skipped, which differ between the sibling species Drosophila simulans and D. sechellia. In a double-backcross experiment, stripe allometry is consistent with maternal inheritance of stripe positioning and multiple genetic factors, with a distinct genetic basis from embryo length. Embryos produced by F1 and F2 backcross mothers exhibit novel spatial patterns of gene expression relative to the parental species, with no measurable increase in positional variance among individuals. Buffering of novel spatial patterns in the backcross genotypes suggests that robustness need not be disrupted in order for the trait to evolve, and perhaps the system is incapable of evolving to prevent the expression of all genetic variation. This limitation, and the ability of natural selection to act on minute genetic differences that are within the "margin of error" for the buffering mechanism, indicates that developmentally buffered traits can evolve without disruption of robustness. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

The allometry of coarse root biomass: log-transformed linear regression or nonlinear regression?

PubMed

Lai, Jiangshan; Yang, Bo; Lin, Dunmei; Kerkhoff, Andrew J; Ma, Keping

2013-01-01

Precise estimation of root biomass is important for understanding carbon stocks and dynamics in forests. Traditionally, biomass estimates are based on allometric scaling relationships between stem diameter and coarse root biomass calculated using linear regression (LR) on log-transformed data. Recently, it has been suggested that nonlinear regression (NLR) is a preferable fitting method for scaling relationships. But while this claim has been contested on both theoretical and empirical grounds, and statistical methods have been developed to aid in choosing between the two methods in particular cases, few studies have examined the ramifications of erroneously applying NLR. Here, we use direct measurements of 159 trees belonging to three locally dominant species in east China to compare the LR and NLR models of diameter-root biomass allometry. We then contrast model predictions by estimating stand coarse root biomass based on census data from the nearby 24-ha Gutianshan forest plot and by testing the ability of the models to predict known root biomass values measured on multiple tropical species at the Pasoh Forest Reserve in Malaysia. Based on likelihood estimates for model error distributions, as well as the accuracy of extrapolative predictions, we find that LR on log-transformed data is superior to NLR for fitting diameter-root biomass scaling models. More importantly, inappropriately using NLR leads to grossly inaccurate stand biomass estimates, especially for stands dominated by smaller trees.

Evolution of male and female genitalia following release from sexual selection.

PubMed

Cayetano, Luis; Maklakov, Alexei A; Brooks, Robert C; Bonduriansky, Russell

2011-08-01

Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata

USGS Publications Warehouse

Ennen, Joshua R.; Lindeman, Peter V.; Lovich, Jeffrey E.

2015-01-01

Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves.

Modeling aboveground tree woody biomass using national-scale allometric methods and airborne lidar

NASA Astrophysics Data System (ADS)

Chen, Qi

2015-08-01

Estimating tree aboveground biomass (AGB) and carbon (C) stocks using remote sensing is a critical component for understanding the global C cycle and mitigating climate change. However, the importance of allometry for remote sensing of AGB has not been recognized until recently. The overarching goals of this study are to understand the differences and relationships among three national-scale allometric methods (CRM, Jenkins, and the regional models) of the Forest Inventory and Analysis (FIA) program in the U.S. and to examine the impacts of using alternative allometry on the fitting statistics of remote sensing-based woody AGB models. Airborne lidar data from three study sites in the Pacific Northwest, USA were used to predict woody AGB estimated from the different allometric methods. It was found that the CRM and Jenkins estimates of woody AGB are related via the CRM adjustment factor. In terms of lidar-biomass modeling, CRM had the smallest model errors, while the Jenkins method had the largest ones and the regional method was between. The best model fitting from CRM is attributed to its inclusion of tree height in calculating merchantable stem volume and the strong dependence of non-merchantable stem biomass on merchantable stem biomass. This study also argues that it is important to characterize the allometric model errors for gaining a complete understanding of the remotely-sensed AGB prediction errors.

REGULATION OF CARBON SEQUESTRATION AND WATER USE IN A OZARK FOREST: PROPOSING A NEW STRATEGICALLY LOCATED AMERIFLUX TOWER SITE IN MISSOURI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pallardy, Stephen G

2013-04-19

by June 14, 2004, the MOFLUX site was fully instrumented and data streams started to flow. A primary accomplished deliverable for the project period was the data streams of CO{sub 2} and water vapor fluxes and numerous meteorological variables (from which prepared datasets have been submitted to the AmeriFlux data archive for 2004-2006, Additionally, measurements of leaf biochemistry and physiology, biomass inventory, tree allometry, successional trends other variables were obtained.

Body size and allometric variation in facial shape in children.

PubMed

Larson, Jacinda R; Manyama, Mange F; Cole, Joanne B; Gonzalez, Paula N; Percival, Christopher J; Liberton, Denise K; Ferrara, Tracey M; Riccardi, Sheri L; Kimwaga, Emmanuel A; Mathayo, Joshua; Spitzmacher, Jared A; Rolian, Campbell; Jamniczky, Heather A; Weinberg, Seth M; Roseman, Charles C; Klein, Ophir; Lukowiak, Ken; Spritz, Richard A; Hallgrimsson, Benedikt

2018-02-01

Morphological integration, or the tendency for covariation, is commonly seen in complex traits such as the human face. The effects of growth on shape, or allometry, represent a ubiquitous but poorly understood axis of integration. We address the question of to what extent age and measures of size converge on a single pattern of allometry for human facial shape. Our study is based on two large cross-sectional cohorts of children, one from Tanzania and the other from the United States (N = 7,173). We employ 3D facial imaging and geometric morphometrics to relate facial shape to age and anthropometric measures. The two populations differ significantly in facial shape, but the magnitude of this difference is small relative to the variation within each group. Allometric variation for facial shape is similar in both populations, representing a small but significant proportion of total variation in facial shape. Different measures of size are associated with overlapping but statistically distinct aspects of shape variation. Only half of the size-related variation in facial shape can be explained by the first principal component of four size measures and age while the remainder associates distinctly with individual measures. Allometric variation in the human face is complex and should not be regarded as a singular effect. This finding has important implications for how size is treated in studies of human facial shape and for the developmental basis for allometric variation more generally. © 2017 Wiley Periodicals, Inc.

The allometry of the arcuate body in the postembryonic development of the giant house spider Eratigena atrica.

PubMed

Napiórkowska, Teresa; Kobak, Jarosław

2018-03-10

The brain of arachnids contains a special neuropil area called the arcuate body (AB), whose function has been widely discussed. Its growth and proportion in the brain volume during postembryogenesis have been investigated only in several spider species. Our allometric study is aimed at determining to what extent the development of the AB in Eratigena atrica, a spider with unique biology and behaviour, is similar to the development of this body in other species. We put forward a hypothesis of allometric growth of this body in relation to the volume of the central nervous system (CNS) and its neuropil as well as in relation to the volume of the brain and its neuropil. The analysis of paraffin embedded, H + E stained histological preparations confirmed our hypothesis. The AB developed more slowly than the CNS and the neuropil of both the brain and the CNS. In contrast, it exhibited positive allometry in relation to the volume of the brain. This body increased more than nine times within the postembryonic development. Its proportion in the brain volume varied; the lowest was recorded in larvae and nymphs I; then, it increased in nymphs VI and decreased to 2.93% in nymphs X. We conclude that in Eratigena atrica, the AB develops differently that in orb-weaver and wandering spiders. There is no universal model of the AB development, although in adult spiders, regardless of their behaviour, the proportion of this area in the brain volume is similar.

How small could a pup sound? The physical bases of signaling body size in harbor seals

PubMed Central

Gross, Stephanie; Garcia, Maxime; Rubio-Garcia, Ana; de Boer, Bart

2017-01-01

Abstract Vocal communication is a crucial aspect of animal behavior. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered by the geometry and length of the upper vocal tract. Evidence from mammalian anatomy and bioacoustics suggests that some of these three components may covary with an animal’s body size. The framework provided by acoustic allometry suggests that, because vocal tract length (VTL) is more strongly constrained by the growth of the body than vocal fold length (VFL), VTL generates more reliable acoustic cues to an animal’s size. This hypothesis is often tested acoustically but rarely anatomically, especially in pinnipeds. Here, we test the anatomical bases of the acoustic allometry hypothesis in harbor seal pups Phoca vitulina. We dissected and measured vocal tract, vocal folds, and other anatomical features of 15 harbor seals post-mortem. We found that, while VTL correlates with body size, VFL does not. This suggests that, while body growth puts anatomical constraints on how vocalizations are filtered by harbor seals’ vocal tract, no such constraints appear to exist on vocal folds, at least during puppyhood. It is particularly interesting to find anatomical constraints on harbor seals’ vocal tracts, the same anatomical region partially enabling pups to produce individually distinctive vocalizations. PMID:29492005

Surface facial modelling and allometry in relation to sexual dimorphism.

PubMed

Velemínská, J; Bigoni, L; Krajíček, V; Borský, J; Šmahelová, D; Cagáňová, V; Peterka, M

2012-04-01

Sexual dimorphism is responsible for a substantial part of human facial variability, the study of which is essential for many scientific fields ranging from evolution to special biomedical topics. Our aim was to analyse the relationship between size variability and shape facial variability of sexual traits in the young adult Central European population and to construct average surface models of adult males and females. The method of geometric morphometrics allowed not only the identification of dimorphic traits, but also the evaluation of static allometry and the visualisation of sexual facial differences. Facial variability in the studied sample was characterised by a strong relationship between facial size and shape of sexual dimorphic traits. Large size of face was associated with facial elongation and vice versa. Regarding shape sexual dimorphic traits, a wide, vaulted and high forehead in combination with a narrow and gracile lower face were typical for females. Variability in shape dimorphic traits was smaller in females compared to males. For female classification, shape sexual dimorphic traits are more important, while for males the stronger association is with face size. Males generally had a closer inter-orbital distance and a deeper position of the eyes in relation to the facial plane, a larger and wider straight nose and nostrils, and more massive lower face. Using pseudo-colour maps to provide a detailed schematic representation of the geometrical differences between the sexes, we attempted to clarify the reasons underlying the development of such differences. Copyright © 2012 Elsevier GmbH. All rights reserved.

Trilobite spines and beetle horns: sexual selection in the Palaeozoic?

PubMed Central

Knell, Robert J; Fortey, Richard A

2005-01-01

Raphiophorid trilobites commonly bore median cephalic protuberances such as spines or bulbs, showing a remarkable variety of form. It is unlikely that their primary function was for protection or in hydrodynamics. A case is made that they were secondary sexual features, by comparison with similar morphological structures developed on rhinoceros beetles and other arthropods. This interpretation is supported by four lines of evidence: their ontogeny, their diversity, the existence of plausible examples of sexual dimorphs in some cases and the fact that they show positive allometry. PMID:17148165

Trilobite spines and beetle horns: sexual selection in the Palaeozoic?

PubMed

Knell, Robert J; Fortey, Richard A

2005-06-22

Raphiophorid trilobites commonly bore median cephalic protuberances such as spines or bulbs, showing a remarkable variety of form. It is unlikely that their primary function was for protection or in hydrodynamics. A case is made that they were secondary sexual features, by comparison with similar morphological structures developed on rhinoceros beetles and other arthropods. This interpretation is supported by four lines of evidence: their ontogeny, their diversity, the existence of plausible examples of sexual dimorphs in some cases and the fact that they show positive allometry.

Stochastic ontogenetic growth model

NASA Astrophysics Data System (ADS)

West, B. J.; West, D.

2012-02-01

An ontogenetic growth model (OGM) for a thermodynamically closed system is generalized to satisfy both the first and second law of thermodynamics. The hypothesized stochastic ontogenetic growth model (SOGM) is shown to entail the interspecies allometry relation by explicitly averaging the basal metabolic rate and the total body mass over the steady-state probability density for the total body mass (TBM). This is the first derivation of the interspecies metabolic allometric relation from a dynamical model and the asymptotic steady-state distribution of the TBM is fit to data and shown to be inverse power law.

Physiological rules for the heart, lungs and other pressure-based organs

PubMed Central

Camilleri, Liberato; Manché, Alexander; Gatt, Ruben; Gauci, Marilyn; Camilleri-Podesta, Marie-Therese; Grima, Joseph N.; Chetcuti, Stanley

2017-01-01

Background The adherence of the heart to physical laws, such as Laplace’s Law, may act as a measure of the organ’s relative efficiency. Allometric relationships were investigated to assess the heart’s efficiency concerning end-diastolic and end-systolic volumes, cardiac pressurization energy, cardiac output and mass. Methods Data to generate allometric relationships was obtained using a literature search, identifying heart and lung data across different mammalian and bird species. Statistical analysis was carried out using ordinary least squares (OLS) estimation. Results Near isometric relationships exist between body mass and seven parameters indicating no “efficiency of size” with scaling of the heart, and size-matching of the heart to the lungs and whole body. Even though there was equal efficiency in pressurization energy generation, cardiac output was maximally efficient in small mammals <10 kg and birds; the human heart reached only 71% efficiency. This loss in cardiac efficiency with increasing body mass can be explained by the aortic cross-section that scales following the three-quarter allometry law, compared to end-systolic and end-diastolic volumes that scale isometrically. The heart is therefore throttled by a relatively small aorta at large body size. Conclusions Mammalian and avian hearts operate at similar efficiencies, demonstrating a high degree of symmorphosis, however cardiac output efficiency decreases in larger animals due to a relatively negative aortic cross-section allometry. This work has a myriad of potential applications including explaining cardiac dysfunction in athletes, patient-prosthesis mismatch in aortic valve replacement and why heavy exercise is associated with a worse prognosis than mild or moderate exercise. PMID:29268387

The relationships among jaw-muscle fiber architecture, jaw morphology, and feeding behavior in extant apes and modern humans.

PubMed

Taylor, Andrea B; Vinyard, Christopher J

2013-05-01

The jaw-closing muscles are responsible for generating many of the forces and movements associated with feeding. Muscle physiologic cross-sectional area (PCSA) and fiber length are two architectural parameters that heavily influence muscle function. While there have been numerous comparative studies of hominoid and hominin craniodental and mandibular morphology, little is known about hominoid jaw-muscle fiber architecture. We present novel data on masseter and temporalis internal muscle architecture for small- and large-bodied hominoids. Hominoid scaling patterns are evaluated and compared with representative New- (Cebus) and Old-World (Macaca) monkeys. Variation in hominoid jaw-muscle fiber architecture is related to both absolute size and allometry. PCSAs scale close to isometry relative to jaw length in anthropoids, but likely with positive allometry in hominoids. Thus, large-bodied apes may be capable of generating both absolutely and relatively greater muscle forces compared with smaller-bodied apes and monkeys. Compared with extant apes, modern humans exhibit a reduction in masseter PCSA relative to condyle-M1 length but retain relatively long fibers, suggesting humans may have sacrificed relative masseter muscle force during chewing without appreciably altering muscle excursion/contraction velocity. Lastly, craniometric estimates of PCSAs underestimate hominoid masseter and temporalis PCSAs by more than 50% in gorillas, and overestimate masseter PCSA by as much as 30% in humans. These findings underscore the difficulty of accurately estimating jaw-muscle fiber architecture from craniometric measures and suggest models of fossil hominin and hominoid bite forces will be improved by incorporating architectural data in estimating jaw-muscle forces. Copyright © 2013 Wiley Periodicals, Inc.

Wood properties and trunk allometry of co-occurring rainforest canopy trees in a cyclone-prone environment.

PubMed

Read, Jennifer; Evans, Robert; Sanson, Gordon D; Kerr, Stuart; Jaffré, Tanguy

2011-11-01

New Caledonia commonly experiences cyclones, so trees there are expected to have enhanced wood traits and trunk allometry that confer resistance to wind damage. We ask whether there is evidence of a trade-off between these traits and growth rate among species. Wood traits, including density, microfibril angle (MFA), and modulus of elasticity (MOE), ratio of tree height to stem diameter, and growth rate were investigated in mature trees of 15 co-occurring canopy species in a New Caledonian rainforest. In contrast to some studies, wood density did not correlate negatively with growth increment. Among angiosperms, wood density and MOE correlated positively with diameter-adjusted tree height, and MOE correlated positively with stem-diameter growth increment. Tall slender trees achieved high stiffness with high efficiency with respect to wood density, in part by low MFA, and with a higher diameter growth increment but a lower buckling safety factor. However, some tree species of a similar niche differed in whole-tree resistance to wind damage and achieved wood stiffness in different ways. There was no evidence of a growth-safety trade-off in these trees. In forests that regularly experience cyclones, there may be stronger selection for high wood density and/or stiffness in fast-growing trees of the upper canopy, with the potential growth trade-off amortized by access to the upper canopy and by other plant traits. Furthermore, decreasing wood density does not necessarily decrease resistance to wind damage, resistance being influenced by other characteristics including cell-level traits (e.g., MFA) and whole-plant architecture.

Designing a Pediatric Study for an Antimalarial Drug by Using Information from Adults

PubMed Central

Jullien, Vincent; Samson, Adeline; Guedj, Jérémie; Kiechel, Jean-René; Zohar, Sarah; Comets, Emmanuelle

2015-01-01

The objectives of this study were to design a pharmacokinetic (PK) study by using information about adults and evaluate the robustness of the recommended design through a case study of mefloquine. PK data about adults and children were available from two different randomized studies of the treatment of malaria with the same artesunate-mefloquine combination regimen. A recommended design for pediatric studies of mefloquine was optimized on the basis of an extrapolated model built from adult data through the following approach. (i) An adult PK model was built, and parameters were estimated by using the stochastic approximation expectation-maximization algorithm. (ii) Pediatric PK parameters were then obtained by adding allometry and maturation to the adult model. (iii) A D-optimal design for children was obtained with PFIM by assuming the extrapolated design. Finally, the robustness of the recommended design was evaluated in terms of the relative bias and relative standard errors (RSE) of the parameters in a simulation study with four different models and was compared to the empirical design used for the pediatric study. Combining PK modeling, extrapolation, and design optimization led to a design for children with five sampling times. PK parameters were well estimated by this design with few RSE. Although the extrapolated model did not predict the observed mefloquine concentrations in children very accurately, it allowed precise and unbiased estimates across various model assumptions, contrary to the empirical design. Using information from adult studies combined with allometry and maturation can help provide robust designs for pediatric studies. PMID:26711749

Domestic chickens defy Rensch's rule: sexual size dimorphism in chicken breeds.

PubMed

Remeš, V; Székely, T

2010-12-01

Sexual size dimorphism (SSD), i.e. the difference in sizes of males and females, is a key evolutionary feature that is related to ecology, behaviour and life histories of organisms. Although the basic patterns of SSD are well documented for several major taxa, the processes generating SSD are poorly understood. Domesticated animals offer excellent opportunities for testing predictions of functional explanations of SSD theory because domestic stocks were often selected by humans for particular desirable traits. Here, we analyse SSD in 139 breeds of domestic chickens Gallus gallus domesticus and compare them to their wild relatives (pheasants, partridges and grouse; Phasianidae, 53 species). SSD was male-biased in all chicken breeds, because males were 21.5 ± 0.55% (mean ± SE) heavier than females. The extent of SSD did not differ among breed categories (cock fighting, ornamental and breeds selected for egg and meat production). SSD of chicken breeds was not different from wild pheasants and allies (23.5 ± 3.43%), although the wild ancestor of chickens, the red jungle fowl G. gallus, had more extreme SSD (male 68.8% heavier) than any domesticated breed. Male mass and female mass exhibited positive allometry among pheasants and allies, consistently with the Rensch's rule reported from various taxa. However, body mass scaled isometrically across chicken breeds. The latter results suggest that sex-specific selection on males vs. females is necessary to generate positive allometry, i.e. the Rensch's rule, in wild populations. © 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology.

Plant allometry, leaf nitrogen and phosphorus stoichiometry, and interspecific trends in annual growth rates.

PubMed

Niklas, Karl J

2006-02-01

Life forms as diverse as unicellular algae, zooplankton, vascular plants, and mammals appear to obey quarter-power scaling rules. Among the most famous of these rules is Kleiber's (i.e. basal metabolic rates scale as the three-quarters power of body mass), which has a botanical analogue (i.e. annual plant growth rates scale as the three-quarters power of total body mass). Numerous theories have tried to explain why these rules exist, but each has been heavily criticized either on conceptual or empirical grounds. N,P-STOICHIOMETRY: Recent models predicting growth rates on the basis of how total cell, tissue, or organism nitrogen and phosphorus are allocated, respectively, to protein and rRNA contents may provide the answer, particularly in light of the observation that annual plant growth rates scale linearly with respect to standing leaf mass and that total leaf mass scales isometrically with respect to nitrogen but as the three-quarters power of leaf phosphorus. For example, when these relationships are juxtaposed with other allometric trends, a simple N,P-stoichiometric model successfully predicts the relative growth rates of 131 diverse C3 and C4 species. The melding of allometric and N,P-stoichiometric theoretical insights provides a robust modelling approach that conceptually links the subcellular 'machinery' of protein/ribosomal metabolism to observed growth rates of uni- and multicellular organisms. Because the operation of this 'machinery' is basic to the biology of all life forms, its allometry may provide a mechanistic explanation for the apparent ubiquity of quarter-power scaling rules.

Allometry of individual reproduction and defense in eusocial colonies: A comparative approach to trade-offs in social sponge-dwelling Synalpheus shrimps.

PubMed

Bornbusch, Sarah L; Lefcheck, Jonathan S; Duffy, J Emmett

2018-01-01

Eusociality, one of the most complex forms of social organization, is thought to have evolved in several animal clades in response to competition for resources and reproductive opportunities. Several species of snapping shrimp in the genus Synalpheus, the only marine organisms known to exhibit eusociality, form colonies characterized by high reproductive skew, and aggressive territoriality coupled with cooperative defense. In eusocial Synalpheus colonies, individual reproduction is limited to female 'queens', whose fecundity dictates colony growth. Given that individual reproduction and defense are both energetically costly, individual and colony fitness likely depend on the optimal allocation of resources by these reproducing individuals towards these potentially competing demands. Synalpheus species, however, display varying degrees of eusociality, suggesting that reproducing females have adopted different strategies for allocation among reproduction and defense. Here, we use structural equation modeling to characterize the relationships between the allometry of queen reproductive capacity and defensive weaponry, and colony size in six eusocial Synalpheus species, estimating trade-offs between reproduction and defense. We document strong trade-offs between mass of the fighting claw (defense) and egg number (reproduction) in queens from weakly eusocial species, while the trade-off is reduced or absent in those from strongly eusocial species. These results suggest that in less cooperative species, intra-colony conflict selects for queen retention of weapons that have significant costs to fecundity, while reproducing females from highly eusocial species, i.e., those with a single queen, have been able to reduce the cost of weapons as a result of protection by other colony members.

Effects of size and temperature on metabolic rate.

PubMed

Gillooly, J F; Brown, J H; West, G B; Savage, V M; Charnov, E L

2001-09-21

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on metabolic rate. The model fits metabolic rates of microbes, ectotherms, endotherms (including those in hibernation), and plants in temperatures ranging from 0 degrees to 40 degrees C. Mass- and temperature-compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular organisms and plants) is separated from the highest (for endothermic vertebrates) by a factor of about 20. Temperature and body size are primary determinants of biological time and ecological roles.

Scaling in Theropod Dinosaurs: Femoral Bone Dimensions

NASA Astrophysics Data System (ADS)

Lee, Scott A.

2014-05-01

Finding topics that inspire students is an important aspect of any physics course. Virtually everyone is fascinated by Tyrannosaurus rex, and the excitement of the class is palpable when we explore scaling effects in T. rex and other bipedal theropod dinosaurs as part of our discussion of mechanics and elasticity. In this paper, we explore the role of longitudinal stress in the femur bones due to the weight of the dinosaur in determining how the geometry of the femur changes with size of the theropod. This is one area of allometry the study of how different biological characteristics scale with size.

Beak and skull shapes of human commensal and non-commensal house sparrows Passer domesticus

PubMed Central

2013-01-01

Background The granivorous house sparrow Passer domesticus is thought to have developed its commensal relationship with humans with the rise of agriculture in the Middle East some 10,000 years ago, and to have expanded with the spread of agriculture in Eurasia during the last few thousand years. One subspecies, P. d. bactrianus, residing in Central Asia, has apparently maintained the ancestral ecology, however. This subspecies is not associated with human settlements; it is migratory and lives in natural grass- and wetland habitats feeding on wild grass seeds. It is well documented that the agricultural revolution was associated with an increase in grain size and changes in seed structure in cultivated cereals, the preferred food source of commensal house sparrow. Accordingly, we hypothesize that correlated changes may have occurred in beak and skull morphology as adaptive responses to the change in diet. Here, we test this hypothesis by comparing the skull shapes of 101 house sparrows from Iran, belonging to five different subspecies, including the non-commensal P. d. bactrianus, using geometric morphometrics. Results The various commensal house sparrow subspecies share subtle but consistent skeletal features that differ significantly from those of the non-commensal P. d. bactrianus. Although there is a marked overall size allometry in the data set, the shape difference between the ecologically differentiated sparrows cannot be explained by differences in size alone. Relative to the size allometry commensal house sparrows exhibit a skull shape consistent with accelerated development (heterochrony), resulting in a more robust facial cranium and a larger, more pointed beak. Conclusion The difference in skull shape and robustness of the beak between commensal and non-commensal house sparrows is consistent with adaptations to process the larger and rachis encapsulated seeds of domesticated cereals among human associated populations. PMID:24044497

Vision in semi-aquatic snakes: Intraocular morphology, accommodation, and eye: Body allometry

NASA Astrophysics Data System (ADS)

Plylar, Helen Bond

Vision in vertebrates generally relies on the refractive power of the cornea and crystalline lens to facilitate vision. Light from the environment enters the eye and is refracted by the cornea and lens onto the retina for production of an image. When an animal with a system designed for air submerges underwater, the refractive power of the cornea is lost. Semi-aquatic animals (e.g., water snakes, turtles, aquatic mammals) must overcome this loss of corneal refractive power through visual accommodation. Accommodation relies on change of the position or shape of the lens to change the focal length of the optical system. Intraocular muscles and fibers facilitate lenticular displacement and deformation. Snakes, in general, are largely unstudied in terms of visual acuity and intraocular morphology. I used light microscopy and scanning electron microscopy to examine differences in eye anatomy between five sympatric colubrid snake species (Nerodia cyclopion, N. fasciata, N. rhombifer, Pantherophis obsoletus, and Thamnophis proximus) from Southeast Louisiana. I discovered previously undescribed structures associated with the lens in semi-aquatic species. Photorefractive methods were used to assess refractive error. While all species overcame the expected hyperopia imposed by submergence, there was interspecific variation in refractive error. To assess scaling of eye size with body size, I measure of eye size, head size, and body size in Nerodia cyclopion and N. fasciata from the SLU Vertebrate Museum. In both species, body size increases at a significantly faster rate than head size and eye size (negative allometry). Small snakes have large eyes relative to body size, and large snakes have relatively small eyes. There were interspecific differences in scaling of eye size with body size, where N. fasciata had larger eye diameter, but N. cyclopion had longer eyes (axial length).

Geometric morphometric analysis of allometric variation in the mandibular morphology of the hominids of Atapuerca, Sima de los Huesos site.

PubMed

Rosas, Antonio; Bastir, Markus

2004-06-01

Allometry is an important factor of morphological integration that contributes to the organization of the phenotype and its variation. Variation in the allometric shape of the mandible is particularly important in hominid evolution because the mandible carries important taxonomic traits. Some of these traits are known to covary with size, particularly the retromolar space, symphyseal curvature, and position of the mental foramen. The mandible is a well studied system in the context of the evolutionary development of complex morphological structures because it is composed of different developmental units that are integrated within a single bone. In the present study, we investigated the allometric variation of two important developmental units that are separated by the inferior nerve (a branch of CN V3). We tested the null hypothesis that there would be no difference in allometric variation between the two components. Procrustes-based geometric morphometrics of 20 two-dimensional (2D) landmarks were analyzed by multivariate regressions of shape on size in samples from 121 humans, 48 chimpanzees, and 50 gorillas (all recent specimens), eight fossil hominids from Atapuerca, Sima de los Huesos (AT-SH), and 17 Neandertals. The findings show that in all of the examined species, there was significantly greater allometric variation in the supra-nerve unit than in the infra-nerve unit. The formation of the retromolar space exhibited an allometric relationship with the supra-nerve unit in all of the species studied. The formation of the chin-like morphology is an "apodynamic" feature of the infra-nerve unit in the AT-SH hominids. The results of this study support the hypothesis that allometry contributes to the organization of variation in complex morphological structures. Copyright 2004 Wiley-Liss, Inc.

Chewing rates among domestic dog breeds

PubMed Central

Gerstner, Geoffrey E.; Cooper, Meghan; Helvie, Peter

2010-01-01

The mammalian masticatory rhythm is produced by a brainstem timing network. The rhythm is relatively fixed within individual animals but scales allometrically with body mass (Mb) across species. It has been hypothesized that sensory feedback and feed-forward adjust the rhythm to match the jaw's natural resonance frequency, with allometric scaling being an observable consequence. However, studies performed with adult animals show that the rhythm is not affected by jaw mass manipulations, indicating that either developmental or evolutionary mechanisms are required for allometry to become manifest. The present study was performed to tease out the relative effects of development versus natural selection on chewing rate allometry. Thirty-one dog breeds and 31 mass-matched non-domestic mammalian species with a range in Mb from ∼2 kg to 50 kg were studied. Results demonstrated that the chewing rhythm did not scale with Mb among dog breeds (R=0.299, P>0.10) or with jaw length (Lj) (R=0.328, P>0.05). However, there was a significant relationship between the chewing rhythm and Mb among the non-domestic mammals (R=0.634, P<0.001). These results indicate that scaling is not necessary in the adult animal. We conclude that the central timing network and related sensorimotor systems may be necessary for rhythm generation but they do not explain the 1/3rd to 1/4th allometric scaling observed among adult mammals. The rhythm of the timing network is either adjusted to the physical parameters of the jaw system during early development only, is genetically determined independently of the jaw system or is uniquely hard-wired among dogs and laboratory rodents. PMID:20543125

Neighbourhood structure and light availability influence the variations in plant design of shrubs in two cloud forests of different successional status

PubMed Central

Guzmán Q, J. Antonio; Cordero, Roberto A.

2016-01-01

Background and Aims Plant design refers to the construction of the plant body or its constituent parts in terms of form and function. Although neighbourhood structure is recognized as a factor that limits plant survival and species coexistence, its relative importance in plant design is not well understood. We conducted field research to analyse how the surrounding environment of neighbourhood structure and related effects on light availability are associated with changes in plant design in two understorey plants (Palicourea padifolia and Psychotria elata) within two successional stages of a cloud forest in Costa Rica. Methods Features of plant neighbourhood physical structure and light availability, estimated using hemispherical photographs, were used as variables that reflect the surrounding environment. Measures of plant biomechanics, allometry, branching and plant slenderness were used as functional plant attributes that reflect plant design. We propose a framework using a partial least squares path model and used it to test this association. Key Results The multidimensional response of plant design of these species suggests that decreases in the height-based factor of safety and increases in mechanical load and developmental stability are influenced by increases in maximum height of neighbours and a distance-dependence interference index more than neighbourhood plant density or neighbour aggregation. Changes in plant branching and slenderness are associated positively with light availability and negatively with canopy cover. Conclusions Although it has been proposed that plant design varies according to plant density and light availability, we found that neighbour size and distance-dependence interference are associated with changes in biomechanics, allometry and branching, and they must be considered as key factors that contribute to the adaptation and coexistence of these plants in this highly diverse forest community. PMID:27245635

Diversity in olfactory bulb size in birds reflects allometry, ecology, and phylogeny

PubMed Central

Corfield, Jeremy R.; Price, Kasandra; Iwaniuk, Andrew N.; Gutierrez-Ibañez, Cristian; Birkhead, Tim; Wylie, Douglas R.

2015-01-01

The relative size of olfactory bulbs (OBs) is correlated with olfactory capabilities across vertebrates and is widely used to assess the relative importance of olfaction to a species’ ecology. In birds, variations in the relative size of OBs are correlated with some behaviors; however, the factors that have led to the high level of diversity seen in OB sizes across birds are still not well understood. In this study, we use the relative size of OBs as a neuroanatomical proxy for olfactory capabilities in 135 species of birds, representing 21 orders. We examine the scaling of OBs with brain size across avian orders, determine likely ancestral states and test for correlations between OB sizes and habitat, ecology, and behavior. The size of avian OBs varied with the size of the brain and this allometric relationship was for the most part isometric, although species did deviate from this trend. Large OBs were characteristic of more basal species and in more recently derived species the OBs were small. Living and foraging in a semi-aquatic environment was the strongest variable driving the evolution of large OBs in birds; olfaction may provide cues for navigation and foraging in this otherwise featureless environment. Some of the diversity in OB sizes was also undoubtedly due to differences in migratory behavior, foraging strategies and social structure. In summary, relative OB size in birds reflect allometry, phylogeny and behavior in ways that parallel that of other vertebrate classes. This provides comparative evidence that supports recent experimental studies into avian olfaction and suggests that olfaction is an important sensory modality for all avian species. PMID:26283931

Impact of Soil Cadmium on Land Snails: A Two-Stage Exposure Approach under Semi-Field Conditions Using Bioaccumulative and Conchological End-Points of Exposure

PubMed Central

Nica, Dragos V.; Filimon, Marioara Nicoleta; Bordean, Despina-Maria; Harmanescu, Monica; Draghici, George Andrei; Dragan, Simona; Gergen, Iosif I.

2015-01-01

Land snails are highly tolerant to cadmium exposure and are able to accumulate soil cadmium independently of food ingestion. However, little information exists on the kinetics of cadmium retention in terrestrial gastropods exposed to an increase in the soil cadmium content, over time. There is also little knowledge about how exposure to cadmium-polluted soils influences shell growth and architecture. In this context, we examined cadmium accumulation in the hepatopancreas and shell of juvenile Cantareus aspersus exposed to elevating high levels of cadmium in soil. Also, the toxicity of cadmium to snails was assessed using a range of conchological endpoints, including shell height, width, volume, allometry and integrity. Test snails, aged three months, were reared under semi-field conditions, fed an uncontaminated diet and exposed first, for a period of 30 days, to a series of soil cadmium concentrations, and then, for a second period of 30 days, to soils with higher cadmium content. Cadmium showed a dose-dependent accumulation in both the hepatopancreas and shell. The kinetics of cadmium retention in the hepatopancreas of snails previously exposed to cadmium-spiked soils was significantly influenced by a new exposure event. The shell was not a relevant bioaccumulator for soil cadmium. Under the present experimental conditions, only high cadmium exposure significantly affected either the shell growth or snail survival. There was no consistent effect on shell allometry, but the shell integrity, especially in rapidly growing parts, appeared to be affected by high cadmium exposure. Our results attest to the value of hepatopancreas for describing cadmium retention in land snails and to the difficulty of using conchological parameters in field surveys for estimating the environmental hazard of soil cadmium. PMID:25790135

Thermodynamics constrains allometric scaling of optimal development time in insects.

PubMed

Dillon, Michael E; Frazier, Melanie R

2013-01-01

Development time is a critical life-history trait that has profound effects on organism fitness and on population growth rates. For ectotherms, development time is strongly influenced by temperature and is predicted to scale with body mass to the quarter power based on 1) the ontogenetic growth model of the metabolic theory of ecology which describes a bioenergetic balance between tissue maintenance and growth given the scaling relationship between metabolism and body size, and 2) numerous studies, primarily of vertebrate endotherms, that largely support this prediction. However, few studies have investigated the allometry of development time among invertebrates, including insects. Abundant data on development of diverse insects provides an ideal opportunity to better understand the scaling of development time in this ecologically and economically important group. Insects develop more quickly at warmer temperatures until reaching a minimum development time at some optimal temperature, after which development slows. We evaluated the allometry of insect development time by compiling estimates of minimum development time and optimal developmental temperature for 361 insect species from 16 orders with body mass varying over nearly 6 orders of magnitude. Allometric scaling exponents varied with the statistical approach: standardized major axis regression supported the predicted quarter-power scaling relationship, but ordinary and phylogenetic generalized least squares did not. Regardless of the statistical approach, body size alone explained less than 28% of the variation in development time. Models that also included optimal temperature explained over 50% of the variation in development time. Warm-adapted insects developed more quickly, regardless of body size, supporting the "hotter is better" hypothesis that posits that ectotherms have a limited ability to evolutionarily compensate for the depressing effects of low temperatures on rates of biological processes. The remaining unexplained variation in development time likely reflects additional ecological and evolutionary differences among insect species.

Hydraulic architecture and tracheid allometry in mature Pinus palustris and Pinus elliottii trees.

PubMed

Gonzalez-Benecke, C A; Martin, T A; Peter, G F

2010-03-01

Pinus palustris Mill. (longleaf pine, LL) and Pinus elliottii Engelm. var. elliottii (slash pine, SL) frequently co-occur in lower coastal plain flatwoods of the USA, with LL typically inhabiting slightly higher and better-drained microsites than SL. The hydraulic architecture and tracheid dimensions of roots, trunk and branches of mature LL and SL trees were compared to understand their role in species microsite occupation. Root xylem had higher sapwood-specific hydraulic conductivity (k(s)) and was less resistant to cavitation compared with branches and trunk sapwood. Root k(s) of LL was significantly higher than SL, whereas branch and trunk k(s) did not differ between species. No differences in vulnerability to cavitation were observed in any of the organs between species. Across all organs, there was a significant but weak trade-off between water conduction efficiency and safety. Tracheid hydraulic diameter (D(h)) was strongly correlated with k(s) across all organs, explaining >73% of the variation in k(s). In contrast, tracheid length (L(t)) explained only 2.4% of the variability. Nevertheless, for trunk xylem, k(s) was 39.5% higher at 20 m compared with 1.8 m; this increase in k(s) was uncorrelated with D(h) and cell-wall thickness but was strongly correlated with the difference in L(t). Tracheid allometry markedly changed between sapwood of roots, trunks and branches, possibly reflecting different mechanical constraints. Even though vulnerability to cavitation was not different for sapwood of roots, branches or the trunks of LL and SL, higher sapwood to leaf area ratio and higher maximum sapwood-specific hydraulic conductivity in roots of LL are functional traits that may provide LL with a competitive advantage on drier soil microsites.

A stand-alone tree demography and landscape structure module for Earth system models: integration with global forest data

NASA Astrophysics Data System (ADS)

Haverd, V.; Smith, B.; Nieradzik, L. P.; Briggs, P. R.

2014-02-01

Poorly constrained rates of biomass turnover are a key limitation of Earth system models (ESM). In light of this, we recently proposed a new approach encoded in a model called Populations-Order-Physiology (POP), for the simulation of woody ecosystem stand dynamics, demography and disturbance-mediated heterogeneity. POP is suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any ESM. POP bridges the gap between first generation Dynamic Vegetation Models (DVMs) with simple large-area parameterisations of woody biomass (typically used in current ESMs) and complex second generation DVMs, that explicitly simulate demographic processes and landscape heterogeneity of forests. The key simplification in the POP approach, compared with second-generation DVMs, is to compute physiological processes such as assimilation at grid-scale (with CABLE or a similar land surface model), but to partition the grid-scale biomass increment among age classes defined at sub grid-scale, each subject to its own dynamics. POP was successfully demonstrated along a savanna transect in northern Australia, replicating the effects of strong rainfall and fire disturbance gradients on observed stand productivity and structure. Here, we extend the application of POP to a range of forest types around the globe, employing paired observations of stem biomass and density from forest inventory data to calibrate model parameters governing stand demography and biomass evolution. The calibrated POP model is then coupled to the CABLE land surface model and the combined model (CABLE-POP) is evaluated against leaf-stem allometry observations from forest stands ranging in age from 3 to 200 yr. Results indicate that simulated biomass pools conform well with observed allometry. We conclude that POP represents a preferable alternative to large-area parameterisations of woody biomass turnover, typically used in current ESMs.

Biphasic Allometry of Cardiac Growth in the Developing Kangaroo Macropus fuliginosus.

PubMed

Snelling, Edward P; Taggart, David A; Maloney, Shane K; Farrell, Anthony P; Seymour, Roger S

2015-01-01

Interspecific studies of adult mammals show that heart mass (M(h), g) increases in direct proportion to body mass (M(b), kg), such that M(h) ∝ M(b)(1.00). However, intraspecific studies on heart mass in mammals at different stages of development reveal considerable variation between species, M(h) ∝ M(b)(0.70-1.00). Part of this variation may arise as a result of the narrow body size range of growing placental mammals, from birth to adulthood. Marsupial mammals are born relatively small and offer an opportunity to examine the ontogeny of heart mass over a much broader body size range. Data from 29 western grey kangaroos Macropus fuliginosus spanning 800-fold in body mass (0.084-67.5 kg) reveal the exponent for heart mass decreases significantly when the joey leaves the pouch (ca. 5-6 kg body mass). In the pouch, the heart mass of joeys scales with hyperallometry, M(h(in-pouch)) = 6.39 M(b)(1.10 ± 0.05), whereas in free-roaming juveniles and adults, heart mass scales with hypoallometry, M(h(postpouch)) = 14.2 Mb(0.77 ± 0.08). Measurements of heart height, width, and depth support this finding. The relatively steep heart growth allometry during in-pouch development is consistent with the increase in relative cardiac demands as joeys develop endothermy and the capacity for hopping locomotion. Once out of the pouch, the exponent decreases sharply, possibly because the energy required for hopping is independent of speed, and the efficiency of energy storage during hopping increases as the kangaroo grows. The right:left ventricular mass ratios (0.30-0.35) do not change over the body mass range and are similar to those of other mammals, reflecting the principle of Laplace for the heart.

AISLE: an automatic volumetric segmentation method for the study of lung allometry.

PubMed

Ren, Hongliang; Kazanzides, Peter

2011-01-01

We developed a fully automatic segmentation method for volumetric CT (computer tomography) datasets to support construction of a statistical atlas for the study of allometric laws of the lung. The proposed segmentation method, AISLE (Automated ITK-Snap based on Level-set), is based on the level-set implementation from an existing semi-automatic segmentation program, ITK-Snap. AISLE can segment the lung field without human interaction and provide intermediate graphical results as desired. The preliminary experimental results show that the proposed method can achieve accurate segmentation, in terms of volumetric overlap metric, by comparing with the ground-truth segmentation performed by a radiologist.

Evolution of parental incubation behaviour in dinosaurs cannot be inferred from clutch mass in birds.

PubMed

Birchard, Geoffrey F; Ruta, Marcello; Deeming, D Charles

2013-08-23

A recent study proposed that incubation behaviour (i.e. type of parental care) in theropod dinosaurs can be inferred from an allometric analysis of clutch volume in extant birds. However, the study in question failed to account for factors known to affect egg and clutch size in living bird species. A new scaling analysis of avian clutch mass demonstrates that type of parental care cannot be distinguished by conventional allometry because of the confounding effects of phylogeny and hatchling maturity. Precociality of young but not paternal care in the theropod ancestors of birds is consistent with the available data.

An allometric scaling relationship in the brain of preterm infants

PubMed Central

Paul, Rachel A; Smyser, Christopher D; Rogers, Cynthia E; English, Ian; Wallendorf, Michael; Alexopoulos, Dimitrios; Meyer, Erin J; Van Essen, David C; Neil, Jeffrey J; Inder, Terrie E

2014-01-01

Allometry has been used to demonstrate a power–law scaling relationship in the brain of premature born infants. Forty-nine preterm infants underwent neonatal MRI scans and neurodevelopmental testing at age 2. Measures of cortical surface area and total cerebral volume demonstrated a power–law scaling relationship (α = 1.27). No associations were identified between these measures and investigated clinical variables. Term equivalent cortical surface area and total cerebral volume measures and scaling exponents were not related to outcome. These findings confirm a previously reported allometric scaling relationship in the preterm brain, and suggest that scaling is not a sensitive indicator of aberrant cortical maturation. PMID:25540808

Intra-specific variation and allometry of the skull of Late Cretaceous side-necked turtle Bauruemys elegans (Pleurodira, Podocnemididae) and how to deal with morphometric data in fossil vertebrates

PubMed Central

Romano, Pedro S.R.

2017-01-01

Background Previous quantitative studies on Bauruemys elegans (Suárez, 1969) shell variation, as well as the taphonomic interpretation of its type locality, have suggested that all specimens collected in this locality may have belonged to the same population. We rely on this hypothesis in a morphometric study of the skull. Also, we tentatively assessed the eating preference habits differentiation that might be explained as due to ontogenetic changes. Methods We carried out an ANOVA testing 29 linear measurements from 21 skulls of B. elegans taken by using a caliper and through images, using the ImageJ software. First, a Principal Components Analysis (PCA) was performed with 27 measurements (excluding total length and width characters; =raw data) in order to visualize the scatter plots based on the form variance only. Then, a second PCA was carried out using ratios of length and width of each original measurement to assess shape variation among individuals. Finally, original measurements were log-transformed to describe allometries over ontogeny. Results No statistical differences were found between caliper and ImageJ measurements. The first three PCs of the PCA with raw data comprised 70.2% of the variance. PC1 was related to size variation and all others related to shape variation. Two specimens plotted outside the 95% ellipse in PC1∼PC2 axes. The first three PCs of the PCA with ratios comprised 64% of the variance. When considering PC1∼PC2, all specimens plotted inside the 95% ellipse. In allometric analysis, five measurements were positively allometric, 19 were negatively allometric and three represented enantiometric allometry. Many bones of the posterior and the lateral emarginations lengthen due to increasing size, while jugal and the quadratojugal decrease in width. Discussion ImageJ is useful in replacing caliper since there was no statistical differences. Yet iterative imputation is more appropriate to deal with missing data in PCA. Some specimens show small differences in form and shape. Form differences were interpreted as occuring due to ontogeny, whereas shape differences are related to feeding changes during growth. Moreover, all outlier specimens are crushed and/or distorted, thus the form/shape differences may be partially due to taphonomy. The allometric lengthening of the parietal, quadrate, squamosal, maxilla, associated with the narrowing of jugal and quadratojugal may be related to changes in feeding habit between different stages of development. This change in shape might represent a progressive skull stretching and enlargement of posterior and lateral emargination during ontogeny, and consequently, the increment of the feeding-apparatus musculature. Smaller individuals may have fed on softer diet, whereas larger ones probably have had a harder diet, as seen in some living species of Podocnemis. We conclude that the skull variation might be related to differences in feeding habits over ontogeny in B. elegans. PMID:28413719

BOREAS TE-6 Biomass and Foliage Area Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Gower, Stith T.; Vogel, Jason G.

2000-01-01

The BOREAS TE-6 team collected several data sets in support of its efforts to characterize and interpret information on the plant biomass, allometry, biometry, sapwood, leaf area index, net primary production, soil temperature, leaf water potential, soil CO, flux, and multivegetation imagery of boreal vegetation. This data set contains measurements of estimates of the standing biomass and leaf area index for the plant species at the TF, CEV, and AUX sites in the SSA and NSA during the growing seasons of 1994 and 1995. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

Human nakedness: adaptation against ectoparasites?

PubMed

Rantala, M J

1999-12-01

Homo sapiens L. has been described as the naked ape, and this nakedness undoubtedly constitutes one of the most striking differences in appearance between man and the apes. Nakedness has been attributed at various times to sexual selection [1], aquatic stage [2], hunting [3], cooling [4], sex [5], neoteny [6] and allometry [7], most proposed explanations logically revealing some aspect of the phenomenon. However, most fail to account for the distinctiveness of man's hairlessness among mammals of the same size. Unfortunately, fossils cannot help us to explain how denudation occurred, and how it helped hominids to survive. In this paper I will present an old hypothesis with a new point of view incorporating more recent evidence.

[Life cycle strategies: a synthesis of empirical and theoretical approaches].

PubMed

Romanovskiĭ, Iu E

1998-01-01

A scheme of relationships among life-history characters is developed on assumptions of determinate growth and dependence of juvenile mortality on the specific growth rate. It is shown that constraints on the relative neonate size, (W0/W infinity), and minimum value of the biotic potential, (rmax), lead to "triangular" shape of life history set on the plain defined by juvenile and adult mortality. This completely coincides with the Ramenskiĭ++--Grime (C-S-R) classification of life-history strategies. Phylogenetic constraints can reduce this set to a relatively narŕow r/K-continuum specifically oriented for a certain taxon. Similar restrictions generate models of life history optimization which predict interspecific allometries between life-history traits.

Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions

PubMed Central

Griebeler, Eva Maria; Klein, Nicole; Sander, P. Martin

2013-01-01

Information on aging, maturation, and growth is important for understanding life histories of organisms. In extinct dinosaurs, such information can be derived from the histological growth record preserved in the mid-shaft cortex of long bones. Here, we construct growth models to estimate ages at death, ages at sexual maturity, ages at which individuals were fully-grown, and maximum growth rates from the growth record preserved in long bones of six sauropod dinosaur individuals (one indeterminate mamenchisaurid, two Apatosaurus sp., two indeterminate diplodocids, and one Camarasaurus sp.) and one basal sauropodomorph dinosaur individual (Plateosaurus engelhardti). Using these estimates, we establish allometries between body mass and each of these traits and compare these to extant taxa. Growth models considered for each dinosaur individual were the von Bertalanffy model, the Gompertz model, and the logistic model (LGM), all of which have inherently fixed inflection points, and the Chapman-Richards model in which the point is not fixed. We use the arithmetic mean of the age at the inflection point and of the age at which 90% of asymptotic mass is reached to assess respectively the age at sexual maturity or the age at onset of reproduction, because unambiguous indicators of maturity in Sauropodomorpha are lacking. According to an AIC-based model selection process, the LGM was the best model for our sauropodomorph sample. Allometries established are consistent with literature data on other Sauropodomorpha. All Sauropodomorpha reached full size within a time span similar to scaled-up modern mammalian megaherbivores and had similar maximum growth rates to scaled-up modern megaherbivores and ratites, but growth rates of Sauropodomorpha were lower than of an average mammal. Sauropodomorph ages at death probably were lower than that of average scaled-up ratites and megaherbivores. Sauropodomorpha were older at maturation than scaled-up ratites and average mammals, but younger than scaled-up megaherbivores. PMID:23840575

Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions.

PubMed

Griebeler, Eva Maria; Klein, Nicole; Sander, P Martin

2013-01-01

Information on aging, maturation, and growth is important for understanding life histories of organisms. In extinct dinosaurs, such information can be derived from the histological growth record preserved in the mid-shaft cortex of long bones. Here, we construct growth models to estimate ages at death, ages at sexual maturity, ages at which individuals were fully-grown, and maximum growth rates from the growth record preserved in long bones of six sauropod dinosaur individuals (one indeterminate mamenchisaurid, two Apatosaurus sp., two indeterminate diplodocids, and one Camarasaurus sp.) and one basal sauropodomorph dinosaur individual (Plateosaurus engelhardti). Using these estimates, we establish allometries between body mass and each of these traits and compare these to extant taxa. Growth models considered for each dinosaur individual were the von Bertalanffy model, the Gompertz model, and the logistic model (LGM), all of which have inherently fixed inflection points, and the Chapman-Richards model in which the point is not fixed. We use the arithmetic mean of the age at the inflection point and of the age at which 90% of asymptotic mass is reached to assess respectively the age at sexual maturity or the age at onset of reproduction, because unambiguous indicators of maturity in Sauropodomorpha are lacking. According to an AIC-based model selection process, the LGM was the best model for our sauropodomorph sample. Allometries established are consistent with literature data on other Sauropodomorpha. All Sauropodomorpha reached full size within a time span similar to scaled-up modern mammalian megaherbivores and had similar maximum growth rates to scaled-up modern megaherbivores and ratites, but growth rates of Sauropodomorpha were lower than of an average mammal. Sauropodomorph ages at death probably were lower than that of average scaled-up ratites and megaherbivores. Sauropodomorpha were older at maturation than scaled-up ratites and average mammals, but younger than scaled-up megaherbivores.

Body size and allometric shape variation in the molly Poecilia vivipara along a gradient of salinity and predation.

PubMed

Araújo, Márcio S; Perez, S Ivan; Magazoni, Maria Julia C; Petry, Ana C

2014-12-04

Phenotypic diversity among populations may result from divergent natural selection acting directly on traits or via correlated responses to changes in other traits. One of the most frequent patterns of correlated response is the proportional change in the dimensions of anatomical traits associated with changes in growth or absolute size, known as allometry. Livebearing fishes subject to predation gradients have been shown to repeatedly evolve larger caudal peduncles and smaller cranial regions under high predation regimes. Poecilia vivipara is a livebearing fish commonly found in coastal lagoons in the north of the state of Rio de Janeiro, Brazil. Similar to what is observed in other predation gradients, lagoons inhabited by P. vivipara vary in the presence of piscivorous fishes; contrary to other poeciliid systems, populations of P. vivipara vary greatly in body size, which opens the possibility of strong allometric effects on shape variation. Here we investigated body shape diversification among six populations of P. vivipara along a predation gradient and its relationship with allometric trajectories within and among populations. We found substantial body size variation and correlated shape changes among populations. Multivariate regression analysis showed that size variation among populations accounted for 66% of shape variation in females and 38% in males, suggesting that size is the most important dimension underlying shape variation among populations of P. vivipara in this system. Changes in the relative sizes of the caudal peduncle and cranial regions were only partly in line with predictions from divergent natural selection associated with predation regime. Our results suggest the possibility that adaptive shape variation among populations has been partly constrained by allometry in P. vivipara. Processes governing body size changes are therefore important in the diversification of this species. We conclude that in species characterized by substantial among-population differences in body size, ignoring allometric effects when investigating divergent natural selection's role in phenotypic diversification might not be warranted.

Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny.

PubMed

Habegger, Maria L; Motta, Philip J; Huber, Daniel R; Dean, Mason N

2012-12-01

Evaluations of bite force, either measured directly or calculated theoretically, have been used to investigate the maximum feeding performance of a wide variety of vertebrates. However, bite force studies of fishes have focused primarily on small species due to the intractable nature of large apex predators. More massive muscles can generate higher forces and many of these fishes attain immense sizes; it is unclear how much of their biting performance is driven purely by dramatic ontogenetic increases in body size versus size-specific selection for enhanced feeding performance. In this study, we investigated biting performance and feeding biomechanics of immature and mature individuals from an ontogenetic series of an apex predator, the bull shark, Carcharhinus leucas (73-285cm total length). Theoretical bite force ranged from 36 to 2128N at the most anterior bite point, and 170 to 5914N at the most posterior bite point over the ontogenetic series. Scaling patterns differed among the two age groups investigated; immature bull shark bite force scaled with positive allometry, whereas adult bite force scaled isometrically. When the bite force of C. leucas was compared to those of 12 other cartilaginous fishes, bull sharks presented the highest mass-specific bite force, greater than that of the white shark or the great hammerhead shark. A phylogenetic independent contrast analysis of anatomical and dietary variables as determinants of bite force in these 13 species indicated that the evolution of large adult bite forces in cartilaginous fishes is linked predominantly to the evolution of large body size. Multiple regressions based on mass-specific standardized contrasts suggest that the evolution of high bite forces in Chondrichthyes is further correlated with hypertrophication of the jaw adductors, increased leverage for anterior biting, and widening of the head. Lastly, we discuss the ecological significance of positive allometry in bite force as a possible "performance gain" early in the life history of C. leucas. Copyright © 2012 Elsevier GmbH. All rights reserved.

Common allometric response of open-grown leader shoots to tree height in co-occurring deciduous broadleaved trees

PubMed Central

Miyata, Rie; Kubo, Takuya; Nabeshima, Eri; Kohyama, Takashi S.

2011-01-01

Background and Aims Morphology of crown shoots changes with tree height. The height of forest trees is usually correlated with the light environment and this makes it difficult to separate the effects of tree size and of light conditions on the morphological plasticity of crown shoots. This paper addresses the tree-height dependence of shoot traits under full-light conditions where a tree crown is not shaded by other crowns. Methods Focus is given to relationships between tree height and top-shoot traits, which include the shoot's leaf-blades and non-leafy mass, its total leaf-blade area and the length and basal diameter of the shoot's stem. We examine the allometric characteristics of open-grown current-year leader shoots at the tops of forest tree crowns up to 24 m high and quantify their responses to tree height in 13 co-occurring deciduous hardwood species in a cool-temperate forest in northern Japan. Key Results Dry mass allocated to leaf blades in a leader shoot increased with tree height in all 13 species. Specific leaf area decreased with tree height. Stem basal area was almost proportional to total leaf area in a leader shoot, where the proportionality constant did not depend on tree height, irrespective of species. Stem length for a given stem diameter decreased with tree height. Conclusions In the 13 species observed, height-dependent changes in allometry of leader shoots were convergent. This finding suggests that there is a common functional constraint in tree-height development. Under full-light conditions, leader shoots of tall trees naturally experience more severe water stress than those of short trees. We hypothesize that the height dependence of shoot allometry detected reflects an integrated response to height-associated water stress, which contributes to successful crown expansion and height gain. PMID:21914698

Allometric and temporal scaling of movement characteristics in Galapagos tortoises

USGS Publications Warehouse

Bastille-Rousseau, Guillaume; Yackulic, Charles B.; Frair, Jacqueline L.; Cabrera, Freddy; Blake, Stephen

2016-01-01

Understanding how individual movement scales with body size is of fundamental importance in predicting ecological relationships for diverse species. One-dimensional movement metrics scale consistently with body size yet vary over different temporal scales. Knowing how temporal scale influences the relationship between animal body size and movement would better inform hypotheses about the efficiency of foraging behaviour, the ontogeny of energy budgets, and numerous life-history trade-offs.We investigated how the temporal scaling of allometric patterns in movement varies over the course of a year, specifically during periods of motivated (directional and fast movement) and unmotivated (stationary and tortuous movement) behaviour. We focused on a recently diverged group of species that displays wide variation in movement behaviour – giant Galapagos tortoises (Chelonoidis spp.) – to test how movement metrics estimated on a monthly basis scaled with body size.We used state-space modelling to estimate seven different movement metrics of Galapagos tortoises. We used log-log regression of the power law to evaluate allometric scaling for these movement metrics and contrasted relationships by species and sex.Allometric scaling of movement was more apparent during motivated periods of movement. During this period, allometry was revealed at multiple temporal intervals (hourly, daily and monthly), with values observed at daily and monthly intervals corresponding most closely to the expected one-fourth scaling coefficient, albeit with wide credible intervals. We further detected differences in the magnitude of scaling among taxa uncoupled from observed differences in the temporal structuring of their movement rates.Our results indicate that the definition of temporal scales is fundamental to the detection of allometry of movement and should be given more attention in movement studies. Our approach not only provides new conceptual insights into temporal attributes in one-dimensional scaling of movement, but also generates valuable insights into the movement ecology of iconic yet poorly understood Galapagos giant tortoises.

On Allometry Relations

NASA Astrophysics Data System (ADS)

West, Damien; West, Bruce J.

2012-07-01

There are a substantial number of empirical relations that began with the identification of a pattern in data; were shown to have a terse power-law description; were interpreted using existing theory; reached the level of "law" and given a name; only to be subsequently fade away when it proved impossible to connect the "law" with a larger body of theory and/or data. Various forms of allometry relations (ARs) have followed this path. The ARs in biology are nearly two hundred years old and those in ecology, geophysics, physiology and other areas of investigation are not that much younger. In general if X is a measure of the size of a complex host network and Y is a property of a complex subnetwork embedded within the host network a theoretical AR exists between the two when Y = aXb. We emphasize that the reductionistic models of AR interpret X and Y as dynamic variables, albeit the ARs themselves are explicitly time independent even though in some cases the parameter values change over time. On the other hand, the phenomenological models of AR are based on the statistical analysis of data and interpret X and Y as averages to yield the empirical AR: = ab. Modern explanations of AR begin with the application of fractal geometry and fractal statistics to scaling phenomena. The detailed application of fractal geometry to the explanation of theoretical ARs in living networks is slightly more than a decade old and although well received it has not been universally accepted. An alternate perspective is given by the empirical AR that is derived using linear regression analysis of fluctuating data sets. We emphasize that the theoretical and empirical ARs are not the same and review theories "explaining" AR from both the reductionist and statistical fractal perspectives. The probability calculus is used to systematically incorporate both views into a single modeling strategy. We conclude that the empirical AR is entailed by the scaling behavior of the probability density, which is derived using the probability calculus.

A comparative meta-analysis of maximal aerobic metabolism of vertebrates: implications for respiratory and cardiovascular limits to gas exchange.

PubMed

Hillman, Stanley S; Hancock, Thomas V; Hedrick, Michael S

2013-02-01

Maximal aerobic metabolic rates (MMR) in vertebrates are supported by increased conductive and diffusive fluxes of O(2) from the environment to the mitochondria necessitating concomitant increases in CO(2) efflux. A question that has received much attention has been which step, respiratory or cardiovascular, provides the principal rate limitation to gas flux at MMR? Limitation analyses have principally focused on O(2) fluxes, though the excess capacity of the lung for O(2) ventilation and diffusion remains unexplained except as a safety factor. Analyses of MMR normally rely upon allometry and temperature to define these factors, but cannot account for much of the variation and often have narrow phylogenetic breadth. The unique aspect of our comparative approach was to use an interclass meta-analysis to examine cardio-respiratory variables during the increase from resting metabolic rate to MMR among vertebrates from fish to mammals, independent of allometry and phylogeny. Common patterns at MMR indicate universal principles governing O(2) and CO(2) transport in vertebrate cardiovascular and respiratory systems, despite the varied modes of activities (swimming, running, flying), different cardio-respiratory architecture, and vastly different rates of metabolism (endothermy vs. ectothermy). Our meta-analysis supports previous studies indicating a cardiovascular limit to maximal O(2) transport and also implicates a respiratory system limit to maximal CO(2) efflux, especially in ectotherms. Thus, natural selection would operate on the respiratory system to enhance maximal CO(2) excretion and the cardiovascular system to enhance maximal O(2) uptake. This provides a possible evolutionary explanation for the conundrum of why the respiratory system appears functionally over-designed from an O(2) perspective, a unique insight from previous work focused solely on O(2) fluxes. The results suggest a common gas transport blueprint, or Bauplan, in the vertebrate clade.

Allometric and temporal scaling of movement characteristics in Galapagos tortoises.

PubMed

Bastille-Rousseau, Guillaume; Yackulic, Charles B; Frair, Jacqueline L; Cabrera, Freddy; Blake, Stephen

2016-09-01

Understanding how individual movement scales with body size is of fundamental importance in predicting ecological relationships for diverse species. One-dimensional movement metrics scale consistently with body size yet vary over different temporal scales. Knowing how temporal scale influences the relationship between animal body size and movement would better inform hypotheses about the efficiency of foraging behaviour, the ontogeny of energy budgets, and numerous life-history trade-offs. We investigated how the temporal scaling of allometric patterns in movement varies over the course of a year, specifically during periods of motivated (directional and fast movement) and unmotivated (stationary and tortuous movement) behaviour. We focused on a recently diverged group of species that displays wide variation in movement behaviour - giant Galapagos tortoises (Chelonoidis spp.) - to test how movement metrics estimated on a monthly basis scaled with body size. We used state-space modelling to estimate seven different movement metrics of Galapagos tortoises. We used log-log regression of the power law to evaluate allometric scaling for these movement metrics and contrasted relationships by species and sex. Allometric scaling of movement was more apparent during motivated periods of movement. During this period, allometry was revealed at multiple temporal intervals (hourly, daily and monthly), with values observed at daily and monthly intervals corresponding most closely to the expected one-fourth scaling coefficient, albeit with wide credible intervals. We further detected differences in the magnitude of scaling among taxa uncoupled from observed differences in the temporal structuring of their movement rates. Our results indicate that the definition of temporal scales is fundamental to the detection of allometry of movement and should be given more attention in movement studies. Our approach not only provides new conceptual insights into temporal attributes in one-dimensional scaling of movement, but also generates valuable insights into the movement ecology of iconic yet poorly understood Galapagos giant tortoises. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

A stand-alone tree demography and landscape structure module for Earth system models: integration with inventory data from temperate and boreal forests

NASA Astrophysics Data System (ADS)

Haverd, V.; Smith, B.; Nieradzik, L. P.; Briggs, P. R.

2014-08-01

Poorly constrained rates of biomass turnover are a key limitation of Earth system models (ESMs). In light of this, we recently proposed a new approach encoded in a model called Populations-Order-Physiology (POP), for the simulation of woody ecosystem stand dynamics, demography and disturbance-mediated heterogeneity. POP is suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any ESM. POP bridges the gap between first-generation dynamic vegetation models (DVMs) with simple large-area parameterisations of woody biomass (typically used in current ESMs) and complex second-generation DVMs that explicitly simulate demographic processes and landscape heterogeneity of forests. The key simplification in the POP approach, compared with second-generation DVMs, is to compute physiological processes such as assimilation at grid-scale (with CABLE (Community Atmosphere Biosphere Land Exchange) or a similar land surface model), but to partition the grid-scale biomass increment among age classes defined at sub-grid-scale, each subject to its own dynamics. POP was successfully demonstrated along a savanna transect in northern Australia, replicating the effects of strong rainfall and fire disturbance gradients on observed stand productivity and structure. Here, we extend the application of POP to wide-ranging temporal and boreal forests, employing paired observations of stem biomass and density from forest inventory data to calibrate model parameters governing stand demography and biomass evolution. The calibrated POP model is then coupled to the CABLE land surface model, and the combined model (CABLE-POP) is evaluated against leaf-stem allometry observations from forest stands ranging in age from 3 to 200 year. Results indicate that simulated biomass pools conform well with observed allometry. We conclude that POP represents an ecologically plausible and efficient alternative to large-area parameterisations of woody biomass turnover, typically used in current ESMs.

BAAD: a Biomass And Allometry Database for woody plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falster, Daniel; Duursma, Remko; Ishihara, Masae

Quantifying the amount of mass or energy invested in plant tissues is of fundamental interest across a range of disciplines, including ecology, forestry, ecosystem science, and climate change science (Niklas, 1994; Chave et al. 2005; Falster et al. 2011). The allocation of net primary production into different plant components is an important process affecting the lifetime of carbon in ecosystems, and resource use and productivity by plants (Cannell & Dewar, 1994; Litton et al. 2007; Poorter et al. 2012). While many studies in have destructively harvested woody plants in the name of science, most of these data have only beenmore » made available in the form of summary tables or figures included in publications. Until now, the raw data has resided piecemeal on the hard drives of individual scientists spread around the world. Several studies have gathered together the fitted (allometric) equations for separate datasets (Ter-Mikaelian & Korzukhin, 1997; Jenkins et al. 2003; Zianis et al. 2005; Henry et al. 2013), but none have previously attempted to organize and share the raw individual plant data underpinning these equations on a large scale. Gathered together, such data would represent an important resource for the community, meeting a widely recognised need for rich, open data resources to solve ecological problems (Costello et al. 2013; Fady et al. 2014; Harfoot & Roberts, 2014; Costello et al. 2013). We (D.S. Falster and R.A. Duursma, with the help of D.R. Barneche, R.G. FitzJohn and A. Vårhammar) set out to create such a resource, by asking authors directly whether they would be willing to make their raw data files freely available. The response was overwhelming: nearly everyone we contacted was interested to contribute their raw data. Moreover, we were invited to incorporate another compilation led by M. Ishihara and focussing on Japanese literature. As a result, we present BAAD: a Biomass And Allometry Database for woody plants, comprising data collected in 174 different published and unpublished studies.« less

Tree STEM and Canopy Biomass Estimates from Terrestrial Laser Scanning Data

NASA Astrophysics Data System (ADS)

Olofsson, K.; Holmgren, J.

2017-10-01

In this study an automatic method for estimating both the tree stem and the tree canopy biomass is presented. The point cloud tree extraction techniques operate on TLS data and models the biomass using the estimated stem and canopy volume as independent variables. The regression model fit error is of the order of less than 5 kg, which gives a relative model error of about 5 % for the stem estimate and 10-15 % for the spruce and pine canopy biomass estimates. The canopy biomass estimate was improved by separating the models by tree species which indicates that the method is allometry dependent and that the regression models need to be recomputed for different areas with different climate and different vegetation.

Amphibian fertilization and development in microgravity

NASA Technical Reports Server (NTRS)

Souza, K. A.; Black, S. D.

1985-01-01

An experiment investigating the effects of gravity on embryonic development in amphibians is proposed. The planned procedures for the preparation of the frog eggs for launching in the Space Shuttle, for the injection of the eggs with gonadotropin, for the insertion of the eggs into egg chambers, for the storage of one of the chambers in a microgravity area and the second into a centrifuge, and for the fertilization of the eggs are described. The later organogenesis, swimming behavior, cytoplasmic components, cellular formation, neural plate and archenteron expansion, and allometry and expansion of the organ systems will be examined. Normal morphology for embryos and tadpoles developing at microgravity and the formation of the neural plate opposite the sperm entry point meridian are predicted.

Vulnerability of the calcifying larval stage of the Antarctic sea urchin Sterechinus neumayeri to near-future ocean acidification and warming.

PubMed

Byrne, Maria; Ho, Melanie A; Koleits, Lucas; Price, Casandra; King, Catherine K; Virtue, Patti; Tilbrook, Bronte; Lamare, Miles

2013-07-01

Stenothermal polar benthic marine invertebrates are highly sensitive to environmental perturbations but little is known about potential synergistic effects of concurrent ocean warming and acidification on development of their embryos and larvae. We examined the effects of these stressors on development to the calcifying larval stage in the Antarctic sea urchin Sterechinus neumayeri in embryos reared in present and future (2100+) ocean conditions from fertilization. Embryos were reared in 2 temperature (ambient: -1.0 °C, + 2 °C : 1.0 °C) and 3 pH (ambient: pH 8.0, -0.2-0.4 pH units: 7.8,7.6) levels. Principle coordinates analysis on five larval metrics showed a significant effect of temperature and pH on the pattern of growth. Within each temperature, larvae were separated by pH treatment, a pattern primarily influenced by larval arm and body length. Growth was accelerated by temperature with a 20-28% increase in postoral (PO) length at +2 °C across all pH levels. Growth was strongly depressed by reduced pH with a 8-19% decrease in PO length at pH 7.6-7.8 at both temperatures. The boost in growth caused by warming resulted in larvae that were larger than would be observed if acidification was examined in the absence of warming. However, there was no significant interaction between these stressors. The increase in left-right asymmetry and altered body allometry indicated that decreased pH disrupted developmental patterning and acted as a teratogen (agent causing developmental malformation). Decreased developmental success with just a 2 °C warming indicates that development in S. neumayeri is particularly sensitive to increased temperature. Increased temperature also altered larval allometry. Altered body shape impairs swimming and feeding in echinoplutei. In the absence of adaptation, it appears that the larval phase may be a bottleneck for survivorship of S. neumayeri in a changing ocean in a location where poleward migration to escape inhospitable conditions is not possible. © 2013 Blackwell Publishing Ltd.

Scaling of Convex Hull Volume to Body Mass in Modern Primates, Non-Primate Mammals and Birds

PubMed Central

Brassey, Charlotte A.; Sellers, William I.

2014-01-01

The volumetric method of ‘convex hulling’ has recently been put forward as a mass prediction technique for fossil vertebrates. Convex hulling involves the calculation of minimum convex hull volumes (vol CH) from the complete mounted skeletons of modern museum specimens, which are subsequently regressed against body mass (M b) to derive predictive equations for extinct species. The convex hulling technique has recently been applied to estimate body mass in giant sauropods and fossil ratites, however the biomechanical signal contained within vol CH has remained unclear. Specifically, when vol CH scaling departs from isometry in a group of vertebrates, how might this be interpreted? Here we derive predictive equations for primates, non-primate mammals and birds and compare the scaling behaviour of M b to vol CH between groups. We find predictive equations to be characterised by extremely high correlation coefficients (r 2 = 0.97–0.99) and low mean percentage prediction error (11–20%). Results suggest non-primate mammals scale body mass to vol CH isometrically (b = 0.92, 95%CI = 0.85–1.00, p = 0.08). Birds scale body mass to vol CH with negative allometry (b = 0.81, 95%CI = 0.70–0.91, p = 0.011) and apparent density (vol CH/M b) therefore decreases with mass (r 2 = 0.36, p<0.05). In contrast, primates scale body mass to vol CH with positive allometry (b = 1.07, 95%CI = 1.01–1.12, p = 0.05) and apparent density therefore increases with size (r 2 = 0.46, p = 0.025). We interpret such departures from isometry in the context of the ‘missing mass’ of soft tissues that are excluded from the convex hulling process. We conclude that the convex hulling technique can be justifiably applied to the fossil record when a large proportion of the skeleton is preserved. However we emphasise the need for future studies to quantify interspecific variation in the distribution of soft tissues such as muscle, integument and body fat. PMID:24618736

Scale effects and morphological diversification in hindlimb segment mass proportions in neognath birds.

PubMed

Kilbourne, Brandon M

2014-01-01

In spite of considerable work on the linear proportions of limbs in amniotes, it remains unknown whether differences in scale effects between proximal and distal limb segments has the potential to influence locomotor costs in amniote lineages and how changes in the mass proportions of limbs have factored into amniote diversification. To broaden our understanding of how the mass proportions of limbs vary within amniote lineages, I collected data on hindlimb segment masses - thigh, shank, pes, tarsometatarsal segment, and digits - from 38 species of neognath birds, one of the most speciose amniote clades. I scaled each of these traits against measures of body size (body mass) and hindlimb size (hindlimb length) to test for departures from isometry. Additionally, I applied two parameters of trait evolution (Pagel's λ and δ) to understand patterns of diversification in hindlimb segment mass in neognaths. All segment masses are positively allometric with body mass. Segment masses are isometric with hindlimb length. When examining scale effects in the neognath subclade Land Birds, segment masses were again positively allometric with body mass; however, shank, pedal, and tarsometatarsal segment masses were also positively allometric with hindlimb length. Methods of branch length scaling to detect phylogenetic signal (i.e., Pagel's λ) and increasing or decreasing rates of trait change over time (i.e., Pagel's δ) suffer from wide confidence intervals, likely due to small sample size and deep divergence times. The scaling of segment masses appears to be more strongly related to the scaling of limb bone mass as opposed to length, and the scaling of hindlimb mass distribution is more a function of scale effects in limb posture than proximo-distal differences in the scaling of limb segment mass. Though negative allometry of segment masses appears to be precluded by the need for mechanically sound limbs, the positive allometry of segment masses relative to body mass may underlie scale effects in stride frequency and length between smaller and larger neognaths. While variation in linear proportions of limbs appear to be governed by developmental mechanisms, variation in mass proportions does not appear to be constrained so.

Cladistic analysis of extant and fossil African papionins using craniodental data.

PubMed

Gilbert, Christopher C

2013-05-01

This study examines African papionin phylogenetic history through a comprehensive cladistic analysis of extant and fossil craniodental morphology using both quantitative and qualitative characters. To account for the well-documented influence of allometry on the papionin skull, the general allometric coding method was applied to characters determined to be significantly affected by allometry. Results of the analyses suggest that Parapapio, Pliopapio, and Papio izodi are stem African papionin taxa. Crown Plio-Pleistocene African papionin taxa include Gorgopithecus, Lophocebus cf. albigena, Procercocebus, Soromandrillus (new genus defined herein) quadratirostris, and, most likely, Dinopithecus. Furthermore, S. quadratirostris is a member of a clade also containing Mandrillus, Cercocebus, and Procercocebus; ?Theropithecus baringensis is strongly supported as a primitive member of the genus Theropithecus; Gorgopithecus is closely related to Papio and Lophocebus; and Theropithecus is possibly the most primitive crown African papionin taxon. Finally, character transformation analyses identify a series of morphological transformations during the course of papionin evolution. The origin of crown African papionins is diagnosed, at least in part, by the appearance of definitive and well-developed male maxillary ridges and maxillary fossae. Among crown African papionins, Papio, Lophocebus, and Gorgopithecus are further united by the most extensive development of the maxillary fossae. The Soromandrillus/Mandrillus/Cercocebus/Procercocebus clade is diagnosed by upturned nuchal crests (especially in males), widely divergent temporal lines (especially in males), medially oriented maxillary ridges in males, medially oriented inferior petrous processes, and a tendency to enlarge the premolars as an adaptation for hard-object food processing. The adaptive origins of the genus Theropithecus appear associated with a diet requiring an increase in size of the temporalis, the optimal placement of occlusal forces onto the molar battery, and an increase in the life of the posterior dentition. This shift is associated with the evolution of distinctive morphological features such as the anterior union of the temporal lines, increased enamel infoldings on the premolars and molars, a reversed curve of Spee, and delayed molar eruption. Copyright © 2013 Elsevier Ltd. All rights reserved.

Leaf-traits and growth allometry explain competition and differences in response to climatic change in a temperate forest landscape: a simulation study

PubMed Central

Yu, Mei; Gao, Qiong

2011-01-01

Background and Aims The ability to simulate plant competition accurately is essential for plant functional type (PFT)-based models used in climate-change studies, yet gaps and uncertainties remain in our understanding of the details of the competition mechanisms and in ecosystem responses at a landscape level. This study examines secondary succession in a temperate deciduous forest in eastern China with the aim of determining if competition between tree types can be explained by differences in leaf ecophysiological traits and growth allometry, and whether ecophysiological traits and habitat spatial configurations among PFTs differentiate their responses to climate change. Methods A temperate deciduous broadleaved forest in eastern China was studied, containing two major vegetation types dominated by Quercus liaotungensis (OAK) and by birch/poplar (Betula platyphylla and Populus davidiana; BIP), respectively. The Terrestrial Ecosystem Simulator (TESim) suite of models was used to examine carbon and water dynamics using parameters measured at the site, and the model was evaluated against long-term data collected at the site. Key Results Simulations indicated that a higher assimilation rate for the BIP vegetation than OAK led to the former's dominance during early successional stages with relatively low competition. In middle/late succession with intensive competition for below-ground resources, BIP, with its lower drought tolerance/resistance and smaller allocation to leaves/roots, gave way to OAK. At landscape scale, predictions with increased temperature extrapolated from existing weather records resulted in increased average net primary productivity (NPP; +19 %), heterotrophic respiration (+23 %) and net ecosystem carbon balance (+17 %). The BIP vegetation in higher and cooler habitats showed 14 % greater sensitivity to increased temperature than the OAK at lower and warmer locations. Conclusions Drought tolerance/resistance and morphology-related allocation strategy (i.e. more allocation to leaves/roots) played key roles in the competition between the vegetation types. The overall site-average impacts of increased temperature on NPP and carbon stored in plants were found to be positive, despite negative effects of increased respiration and soil water stress, with such impacts being more significant for BIP located in higher and cooler habitats. PMID:21835816

Scale effects and morphological diversification in hindlimb segment mass proportions in neognath birds

PubMed Central

2014-01-01

Introduction In spite of considerable work on the linear proportions of limbs in amniotes, it remains unknown whether differences in scale effects between proximal and distal limb segments has the potential to influence locomotor costs in amniote lineages and how changes in the mass proportions of limbs have factored into amniote diversification. To broaden our understanding of how the mass proportions of limbs vary within amniote lineages, I collected data on hindlimb segment masses – thigh, shank, pes, tarsometatarsal segment, and digits – from 38 species of neognath birds, one of the most speciose amniote clades. I scaled each of these traits against measures of body size (body mass) and hindlimb size (hindlimb length) to test for departures from isometry. Additionally, I applied two parameters of trait evolution (Pagel’s λ and δ) to understand patterns of diversification in hindlimb segment mass in neognaths. Results All segment masses are positively allometric with body mass. Segment masses are isometric with hindlimb length. When examining scale effects in the neognath subclade Land Birds, segment masses were again positively allometric with body mass; however, shank, pedal, and tarsometatarsal segment masses were also positively allometric with hindlimb length. Methods of branch length scaling to detect phylogenetic signal (i.e., Pagel’s λ) and increasing or decreasing rates of trait change over time (i.e., Pagel’s δ) suffer from wide confidence intervals, likely due to small sample size and deep divergence times. Conclusions The scaling of segment masses appears to be more strongly related to the scaling of limb bone mass as opposed to length, and the scaling of hindlimb mass distribution is more a function of scale effects in limb posture than proximo-distal differences in the scaling of limb segment mass. Though negative allometry of segment masses appears to be precluded by the need for mechanically sound limbs, the positive allometry of segment masses relative to body mass may underlie scale effects in stride frequency and length between smaller and larger neognaths. While variation in linear proportions of limbs appear to be governed by developmental mechanisms, variation in mass proportions does not appear to be constrained so. PMID:24876886

Physics of chewing in terrestrial mammals.

PubMed

Virot, Emmanuel; Ma, Grace; Clanet, Christophe; Jung, Sunghwan

2017-03-07

Previous studies on chewing frequency across animal species have focused on finding a single universal scaling law. Controversy between the different models has been aroused without elucidating the variations in chewing frequency. In the present study we show that vigorous chewing is limited by the maximum force of muscle, so that the upper chewing frequency scales as the -1/3 power of body mass for large animals and as a constant frequency for small animals. On the other hand, gentle chewing to mix food uniformly without excess of saliva describes the lower limit of chewing frequency, scaling approximately as the -1/6 power of body mass. These physical constraints frame the -1/4 power law classically inferred from allometry of animal metabolic rates. All of our experimental data stay within these physical boundaries over six orders of magnitude of body mass regardless of food types.

Mandible shape and dwarfism in squirrels (Mammalia, Rodentia): interaction of allometry and adaptation

NASA Astrophysics Data System (ADS)

Hautier, Lionel; Fabre, Pierre-Henri; Michaux, Jacques

2009-06-01

Squirrels include several independent lineages of dwarf forms distributed into two ecological groups: the dwarf tree and flying squirrels. The mandible of dwarf tree squirrels share a highly reduced coronoid process and a condylar process drawn backwards. Dwarf flying squirrels on the other hand, have an elongated coronoid process and a well-differentiated condylar process. To interpret such a difference, Elliptic Fourier Transform was used to evaluate how mandible shape varies with dwarfism in sciurids. The results obtained show that this clear-cut difference cannot be explained by a simple allometric relationship in relation with size decrease. We concluded that the retention of anteriorly positioned eye sockets, in relation with distance estimation, allowed the conservation of a well-differentiated coronoid process in all flying species, despite the trend towards its reduction observed among sciurids as their size decreases.

Left Ventricular Hypertrophy: An allometric comparative analysis of different ECG markers

NASA Astrophysics Data System (ADS)

Bonomini, M. P.; Ingallina, F.; Barone, V.; Valentinuzzi, M. E.; Arini, P. D.

2011-12-01

Allometry, in general biology, measures the relative growth of a part in relation to the whole living organism. Left ventricular hypertrophy (LVH) is the heart adaptation to excessive load (systolic or diastolic). The increase in left ventricular mass leads to an increase in the electrocardiographic voltages. Based on clinical data, we compared the allometric behavior of three different ECG markers of LVH. To do this, the allometric fit AECG = δ + β (VM) relating left ventricular mass (estimated from ecocardiographic data) and ECG amplitudes (expressed as the Cornell-Voltage, Sokolow and the ECG overall voltage indexes) were compared. Besides, sensitivity and specifity for each index were analyzed. The more sensitive the ECG criteria, the better the allometric fit. In conclusion: The allometric paradigm should be regarded as the way to design new and more sensitive ECG-based LVH markers.

Physics of chewing in terrestrial mammals

NASA Astrophysics Data System (ADS)

Virot, Emmanuel; Ma, Grace; Clanet, Christophe; Jung, Sunghwan

2017-03-01

Previous studies on chewing frequency across animal species have focused on finding a single universal scaling law. Controversy between the different models has been aroused without elucidating the variations in chewing frequency. In the present study we show that vigorous chewing is limited by the maximum force of muscle, so that the upper chewing frequency scales as the -1/3 power of body mass for large animals and as a constant frequency for small animals. On the other hand, gentle chewing to mix food uniformly without excess of saliva describes the lower limit of chewing frequency, scaling approximately as the -1/6 power of body mass. These physical constraints frame the -1/4 power law classically inferred from allometry of animal metabolic rates. All of our experimental data stay within these physical boundaries over six orders of magnitude of body mass regardless of food types.

Encephalization quotients and life-history traits in the Sirenia

USGS Publications Warehouse

O'Shea, T.J.; Reep, R.L.

1990-01-01

Relative brain size in the Sirenia is unusually small. Encephalization quotients are 0.27 for Florida manatees (Trichechus manatus) and 0.38 for dugongs (Dugong dugon). Estimates for Steller's sea cow (Hydrodamalis gigas) range from 0.12 to 0.19. These values are among the lowest known for Recent mammals, and seemingly have changed little since the Eocene. A body plan specialized for the aquatic environment does not account for low encephalization quotients; values are substantially less than predicted based on cetacean or pinniped allometry. Life-history, ecological, and behavioral traits of the Sirenia are typical of relatively large-brained species. Low quality food and a low metabolic rate, however, are characteristic of the Sirenia and other small-brained mammals. Acting through prolonged postnatal growth, selection also likely favored large body size in the Sirenia without a correlated increase in brain size.

Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

PubMed Central

Bates, K. T.; Falkingham, P. L.

2012-01-01

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex. Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex, associated with an expansion of prey range in adults to include the largest contemporaneous animals. PMID:22378742

Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics.

PubMed

Bates, K T; Falkingham, P L

2012-08-23

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex. Models predict that adult T. rex generated sustained bite forces of 35 000-57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex, associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Tyrannosaurus en pointe: allometry minimized rotational inertia of large carnivorous dinosaurs.

PubMed Central

Henderson, Donald M; Snively, Eric

2004-01-01

Theropod dinosaurs attained the largest body sizes among terrestrial predators, and were also unique in being exclusively bipedal. With only two limbs for propulsion and balance, theropods would have been greatly constrained in their locomotor performance at large body size. Using three-dimensional restorations of the axial bodies and limbs of 12 theropod dinosaurs, and determining their rotational inertias (RIs) about a vertical axis, we show that these animals expressed a pattern of phyletic size increase that minimized the increase in RI associated with increases in body size. By contrast, the RI of six quadrupedal, carnivorous archosaurs exhibited changes in body proportions that were closer to those predicted by isometry. Correlations of low RI with high agility in lizards suggest that large theropods, with low relative RI, could engage in activities requiring higher agility than would be possible with isometric scaling. PMID:15101419

Allometry and Interspecific Differences in the Facial Cranium of Two Closely Related Macaque Species

PubMed Central

Ito, Tsuyoshi; Nishimura, Takeshi; Takai, Masanaru

2011-01-01

Interpreting evolutionary history of macaque monkeys from fossil evidence is difficult, because their evolutionary fluctuations in body size might have removed or formed important morphological features differently in each lineage. We employed geometric morphometrics to explore allometric trajectories of craniofacial shape in two closely related species, Macaca fascicularis and M. fuscata. These two species exhibit a single shared allometric trajectory in superoinferior deflection of the anterior face, indicating that the differences in this feature can be explained by size variation. In contrast, two parallel trajectories are demonstrated in craniofacial protrusion, indicating that even if they are comparable in size, M. fuscata has a higher and shorter face than M. fascicularis. The degree of facial protrusion is most likely a critical feature for phyletic evaluation in the fascicularis group. Such analyses in various macaques would help to resolve controversies regarding phyletic interpretations of fossil macaques. PMID:22567301

Allometric scaling and accidents at work

PubMed Central

Cempel, Czesław; Tabaszewski, Maciej; Ordysiński, Szymon

2016-01-01

Allometry is the knowledge concerning relations between the features of some beings, like animals, or cities. For example, the daily energy rate is proportional to a mass of mammals rise of 3/4. This way of thinking has spread quickly from biology to many areas of research concerned with sociotechnical systems. It was revealed that the number of innovations, patents or heavy crimes rises as social interaction increases in a bigger city, while other urban indexes such as suicides decrease with social interaction. Enterprise is also a sociotechnical system, where social interaction and accidents at work take place. Therefore, do these interactions increase the number of accidents at work or, on the contrary, are they reduction-driving components? This article tries to catch such links and assess the allometric exponent between the number of accidents at work and the number of employees in an enterprise. PMID:26655044

Sexual selection and the rodent baculum: an intraspecific study in the house mouse (Mus musculus domesticus).

PubMed

Ramm, Steven A; Khoo, Lin; Stockley, Paula

2010-01-01

The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of baculum morphology in the house mouse (Mus musculus domesticus). We find that that baculum size: (a) exhibits no consistent pattern of allometric scaling (baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.

Ornament Complexity Is Correlated with Sexual Selection: (A Comment on Raia et al., "Cope's Rule and the Universal Scaling Law of Ornament Complexity").

PubMed

Holman, Luke; Bro-Jørgensen, Jakob

2016-08-01

Raia et al. propose that the evolution of the shape and complexity of animal ornaments (e.g., deer antlers) can be explained by interspecific variation in body size and is not influenced by sexual selection. They claim to show that ornament complexity is related to body size by an 0.25-power law and argue that this finding precludes a role for sexual selection in the evolution of ornament complexity. However, their study does not test alternative hypotheses and mismeasures antler shape allometry by omitting much of the published data. We show that an index of sexual selection (sexual size dimorphism) is positively correlated with size-corrected antler complexity and that the allometric slope of complexity is substantially greater than 0.25, contra Raia et al. We conclude that sexual selection and physical constraints both affect the evolution of antler shape.

From Evolutionary Allometry to Sexual Display: (A Reply to Holman and Bro-Jørgensen).

PubMed

Raia, Pasquale; Passaro, Federico; Carotenuto, Francesco; Meiri, Shai; Piras, Paolo

2016-08-01

Conventional wisdom holds that the complex shapes of deer antlers are produced under the sole influence of sexual selection. We questioned this view by demonstrating that trends for increased body size evolution passively yield more-complex ornaments, even in organisms where no effect of sexual selection is possible, with similar allometric slopes. Recent investigations suggest that sexual selection on antlers of larger deer species is stronger than that in smaller species; hence, the use of conspicuous antlers for display in large male deer is a secondary function driven by especially intense sexual selection on these large-bodied species. Since ancestral deer were small and had very simple antlers, such an intense selection on antlers shape was probably absent in early deer. Therefore, the evolution of complex ornaments is coupled with body size evolution, even in deer.

Allometry and stoichiometry of unicellular, colonial and multicellular phytoplankton.

PubMed

Beardall, John; Allen, Drew; Bragg, Jason; Finkel, Zoe V; Flynn, Kevin J; Quigg, Antonietta; Rees, T Alwyn V; Richardson, Anthony; Raven, John A

2009-01-01

Phytoplankton life forms, including unicells, colonies, pseudocolonies, and multicellular organisms, span a huge size range. The smallest unicells are less than 1 microm3 (e.g. cyanobacteria), while large unicellular diatoms may attain 10(9) microm3, being visible to the naked eye. Phytoplankton includes chemo-organotrophic unicells, colonies and multicellular organisms that depend on symbionts or kleptoplastids for their capacity to photosynthesize. Analyses of physical (transport within cells, diffusion boundary layers, package effect, turgor, and vertical movements) and biotic (grazing, viruses and other parasitoids) factors indicate potential ecological constraints and opportunities that differ among the life forms. There are also variations among life forms in elemental stoichiometry and in allometric relations between biovolume and specific growth. While many of these factors probably have ecological and evolutionary significance, work is needed to establish those that are most important, warranting explicit description in models. Other factors setting limitations on growth rate (selecting slow-growing species) await elucidation.

Colony size as a buffer against seasonality: Bergmann's rule in social insects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaspari, M.; Vargo, E.

1994-06-01

In eusocial species, the size of the superorganism is the summed sizes of its component individuals. Bergmann's rule, the cline of decreasing size with decreasing latitude, applies to colony size in ants. Using data from the literature and our own collections, we show that colony sizes of tropical ant species are on average 1/10th the size of temperate species. The patterns holds for 5 of 6 subfamilies and 15 of 16 genera tested. What causes this trend Larger colonies of the fire ant, Solenopsis invicta, are better able to protect the queen (the colony's reproductive tissue) against food shortage, likelymore » by sacrificing workers (it's somatic tissue). Days of queen survival follows the allometry M[sup 0.25]. We propose that the shorter growing seasons in temperate latitudes cull small-colony species through over-wintering starvation.« less

Size and diet in the evolution of African ape craniodental form.

PubMed

Shea, B T

1983-01-01

Interspecific differences in craniodental morphology among Pan paniscus, Pan troglodytes, and Gorilla gorilla are analyzed. These apes differ in both diet and body size, and thus present an excellent example in which to apply an allometric criterion of subtraction in order to determine morphological differences which might be related to divergent dietary specialization. The use of ontogenetic allometry in particular as a criterion of subtraction is discussed. Bivariate and multivariate results indicate that most of the variation in skull form among the species relates to the extension of a common growth trend to different sizes. Comparative analysis of growth trajectories reveals a number of differences, but none that appear to relate to a reorganization of skull proportions which might correspond to a dietary shift towards increased folivory. The dentition clearly exhibits non-allometric shape changes corresponding to the dietary differences, however. The meaning of these differences between cranial and dental patterns is discussed.

Flight mode affects allometry of migration range in birds.

PubMed

Watanabe, Yuuki Y

2016-08-01

Billions of birds migrate to exploit seasonally available resources. The ranges of migration vary greatly among species, but the underlying mechanisms are poorly understood. I hypothesise that flight mode (flapping or soaring) and body mass affect migration range through their influence on flight energetics. Here, I compiled the tracks of migratory birds (196 species, weighing 12-10 350 g) recorded by electronic tags in the last few decades. In flapping birds, migration ranges decreased with body mass, as predicted from rapidly increasing flight cost with increasing body mass. The species with higher aspect ratio and lower wing loading had larger migration ranges. In soaring birds, migration ranges were mass-independent and larger than those of flapping birds, reflecting their low flight costs irrespective of body mass. This study demonstrates that many animal-tracking studies are now available to explore the general patterns and the underlying mechanisms of animal migration. © 2016 John Wiley & Sons Ltd/CNRS.

The scaling and temperature dependence of vertebrate metabolism

PubMed Central

White, Craig R; Phillips, Nicole F; Seymour, Roger S

2005-01-01

Body size and temperature are primary determinants of metabolic rate, and the standard metabolic rate (SMR) of animals ranging in size from unicells to mammals has been thought to be proportional to body mass (M) raised to the power of three-quarters for over 40 years. However, recent evidence from rigorously selected datasets suggests that this is not the case for birds and mammals. To determine whether the influence of body mass on the metabolic rate of vertebrates is indeed universal, we compiled SMR measurements for 938 species spanning six orders of magnitude variation in mass. When normalized to a common temperature of 38 °C, the SMR scaling exponents of fish, amphibians, reptiles, birds and mammals are significantly heterogeneous. This suggests both that there is no universal metabolic allometry and that models that attempt to explain only quarter-power scaling of metabolic rate are unlikely to succeed. PMID:17148344

Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate.

PubMed

Martin, Thomas E; Ton, Riccardo; Niklison, Alina

2013-06-01

Intrinsic processes are assumed to underlie life history expression and trade-offs, but extrinsic inputs are theorised to shift trait expression and mask trade-offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass-specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade-off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade-offs across species. © 2013 John Wiley & Sons Ltd/CNRS.

COMPARING 3D FOOT SHAPE MODELS BETWEEN TAIWANESE AND JAPANESE FEMALES.

PubMed

Lee, Yu-Chi; Kouchi, Makiko; Mochimaru, Masaaki; Wang, Mao-Jiun

2015-06-01

This study compares foot shape and foot dimensions between Taiwanese and Japanese females. One hundred Taiwanese and 100 Japanese female 3D foot scanning data were used for comparison. To avoid the allometry effect, data from 23 Taiwanese and 19 Japanese with foot length between 233 to 237 mm were used for shape comparison. Homologous models created for the right feet of the 42 subjects were analyzed by Multidimensional Scaling. The results showed that there were significant differences in the forefoot shape between the two groups, and Taiwanese females had slightly wider feet with straighter big toe than Japanese females. The results of body and foot dimension comparison indicated that Taiwanese females were taller, heavier and had larger feet than Japanese females, while Japanese females had significantly larger toe 1 angle. Since some Taiwanese shoemakers adopt the Japanese shoe sizing system for making shoes, appropriateness of the shoe sizing system was also discussed. The present results provide very useful information for improving shoe last design and footwear fit for Taiwanese females.

Comparative Physiology of Fatigue.

PubMed

Jones, James H

2016-11-01

This review attempts to provide insights into factors associated with fatigue in human and nonhuman animals by using the two fundamental approaches of comparative physiology: determining common principles that govern structure and function in animals that are relatively invariant between animals and evaluating animals that have been highly adapted by natural selection to demonstrate extreme performance. In this review, I approach the topic of fatigue by considering factors that are associated with its reciprocal or inverse or duration of sustained performance before fatigue sets in to end the performance. The two general factors that I consider that affect endurance time more than any other are body temperature and body mass. The former affects endurance time because of thermodynamic effects on chemical reaction rates and metabolism; the latter acts through the mechanism of allometry or scaling. The examples of extreme animal performance that I discuss are two examples of bird migration, the diving performance of marine mammals, and the unique relationship that governs energy cost of locomotion in hopping kangaroos.

On the origin and evolutionary diversification of beetle horns

PubMed Central

Emlen, Douglas J.; Corley Lavine, Laura; Ewen-Campen, Ben

2007-01-01

Many scarab beetles produce rigid projections from the body called horns. The exaggerated sizes of these structures and the staggering diversity of their forms have impressed biologists for centuries. Recent comparative studies using DNA sequence-based phylogenies have begun to reconstruct the historical patterns of beetle horn evolution. At the same time, developmental genetic experiments have begun to elucidate how beetle horns grow and how horn growth is modulated in response to environmental variables, such as nutrition. We bring together these two perspectives to show that they converge on very similar conclusions regarding beetle evolution. Horns do not appear to be difficult structures to gain or lose, and they can diverge both dramatically and rapidly in form. Although much of this work is still preliminary, we use available information to propose a conceptual developmental model for the major trajectories of beetle horn evolution. We illustrate putative mechanisms underlying the evolutionary origin of horns and the evolution of horn location, shape, allometry, and dimorphism. PMID:17494751

Scaling of flow distance in random self-similar channel networks

USGS Publications Warehouse

Troutman, B.M.

2005-01-01

Natural river channel networks have been shown in empirical studies to exhibit power-law scaling behavior characteristic of self-similar and self-affine structures. Of particular interest is to describe how the distribution of distance to the outlet changes as a function of network size. In this paper, networks are modeled as random self-similar rooted tree graphs and scaling of distance to the root is studied using methods in stochastic branching theory. In particular, the asymptotic expectation of the width function (number of nodes as a function of distance to the outlet) is derived under conditions on the replacement generators. It is demonstrated further that the branching number describing rate of growth of node distance to the outlet is identical to the length ratio under a Horton-Strahler ordering scheme as order gets large, again under certain restrictions on the generators. These results are discussed in relation to drainage basin allometry and an application to an actual drainage network is presented. ?? World Scientific Publishing Company.

The structure of tropical forests and sphere packings

PubMed Central

Jahn, Markus Wilhelm; Dobner, Hans-Jürgen; Wiegand, Thorsten; Huth, Andreas

2015-01-01

The search for simple principles underlying the complex architecture of ecological communities such as forests still challenges ecological theorists. We use tree diameter distributions—fundamental for deriving other forest attributes—to describe the structure of tropical forests. Here we argue that tree diameter distributions of natural tropical forests can be explained by stochastic packing of tree crowns representing a forest crown packing system: a method usually used in physics or chemistry. We demonstrate that tree diameter distributions emerge accurately from a surprisingly simple set of principles that include site-specific tree allometries, random placement of trees, competition for space, and mortality. The simple static model also successfully predicted the canopy structure, revealing that most trees in our two studied forests grow up to 30–50 m in height and that the highest packing density of about 60% is reached between the 25- and 40-m height layer. Our approach is an important step toward identifying a minimal set of processes responsible for generating the spatial structure of tropical forests. PMID:26598678

Bat Species Comparisons Based on External Morphology: A Test of Traditional versus Geometric Morphometric Approaches

PubMed Central

Schmieder, Daniela A.; Benítez, Hugo A.; Borissov, Ivailo M.; Fruciano, Carmelo

2015-01-01

External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species – in this case European horseshoe bats (Rhinolophidae, Chiroptera) – based on morphology of the wing, body and tail. In addition to comparing morphometric methods, we used geometric morphometrics to detect interspecies differences as shape changes. Geometric morphometrics yielded improved species discrimination relative to traditional methods. The predicted shape for the variation along the between group principal components revealed that the largest differences between species lay in the extent to which the wing reaches in the direction of the head. This strong trend in interspecific shape variation is associated with size, which we interpret as an evolutionary allometry pattern. PMID:25965335

Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

USGS Publications Warehouse

Martin, Thomas E.; Ton, Riccardo; Nikilson, Alina

2013-01-01

Intrinsic processes are assumed to underlie life history expression and trade-offs, but extrinsic inputs are theorised to shift trait expression and mask trade-offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass-specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade-off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade-offs across species.

Mammalian basal metabolic rate is proportional to body mass2/3

PubMed Central

White, Craig R.; Seymour, Roger S.

2003-01-01

The relationship between mammalian basal metabolic rate (BMR, ml of O2 per h) and body mass (M, g) has been the subject of regular investigation for over a century. Typically, the relationship is expressed as an allometric equation of the form BMR = aMb. The scaling exponent (b) is a point of contention throughout this body of literature, within which arguments for and against geometric (b = 2/3) and quarter-power (b = 3/4) scaling are made and rebutted. Recently, interest in the topic has been revived by published explanations for quarter-power scaling based on fractal nutrient supply networks and four-dimensional biology. Here, a new analysis of the allometry of mammalian BMR that accounts for variation associated with body temperature, digestive state, and phylogeny finds no support for a metabolic scaling exponent of 3/4. Data encompassing five orders of magnitude variation in M and featuring 619 species from 19 mammalian orders show that BMR ∝ M2/3. PMID:12637681

Nonlinear growth dynamics and the origin of fluctuating asymmetry

USGS Publications Warehouse

Emlen, J.M.; Freeman, D.C.; Graham, J.H.

1993-01-01

The nonlinear, complex nature of biosynthesis magnifies the impacts of small, random perturbations on organism growth, leading to distortions in adaptive allometries and, in particular, to fluctuating asymmetry. These distortions can be partly checked by cell-cell and inter-body part feedback during growth and development, though the latter mechanism also may lead to complex patterns in right-left asymmetry. Stress can be expected to increase the degree to which random growth perturbations are magnified and may also result in disruption of the check mechanisms, thus exaggerating fluctuating asymmetry.The processes described not only provide one explanation for the existence of fluctuating asymmetry and its augmentation under stress, but suggest additional effects of stress as well. Specifically, stress is predicted to lead to decreased fractal dimension of bone sutures and branching structures in animals, and in increased dimension of growth trace patterns such as those found in mollusc shells and fish otoliths and scales.A basic yet broad primer on fractals and chaos is provided as background for the theoretical development in this manuscript.

Optimality Based Dynamic Plant Allocation Model: Predicting Acclimation Response to Climate Change

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Drewry, D.; Kumar, P.; Sivapalan, M.

2009-12-01

Allocation of assimilated carbon to different plant parts determines the future plant status and is important to predict long term (months to years) vegetated land surface fluxes. Plants have the ability to modify their allometry and exhibit plasticity by varying the relative proportions of the structural biomass contained in each of its tissue. The ability of plants to be plastic provides them with the potential to acclimate to changing environmental conditions in order to enhance their probability of survival. Allometry based allocation models and other empirical allocation models do not account for plant plasticity cause by acclimation due to environmental changes. In the absence of a detailed understanding of the various biophysical processes involved in plant growth and development an optimality approach is adopted here to predict carbon allocation in plants. Existing optimality based models of plant growth are either static or involve considerable empiricism. In this work, we adopt an optimality based approach (coupled with limitations on plant plasticity) to predict the dynamic allocation of assimilated carbon to different plant parts. We explore the applicability of this approach using several optimization variables such as net primary productivity, net transpiration, realized growth rate, total end of growing season reproductive biomass etc. We use this approach to predict the dynamic nature of plant acclimation in its allocation of carbon to different plant parts under current and future climate scenarios. This approach is designed as a growth sub-model in the multi-layer canopy plant model (MLCPM) and is used to obtain land surface fluxes and plant properties over the growing season. The framework of this model is such that it retains the generality and can be applied to different types of ecosystems. We test this approach using the data from free air carbon dioxide enrichment (FACE) experiments using soybean crop at the Soy-FACE research site. Our results show that there are significant changes in the allocation patterns of vegetation when subjected to elevated CO2 indicating that our model is able to account for plant plasticity arising from acclimation. Soybeans when grown under elevated CO2, increased their allocation to structural components such as leaves and decreased their allocation to reproductive biomass. This demonstrates that plant acclimation causes lower than expected crop yields when grown under elevated CO2. Our findings can have serious implications in estimating future crop yields under climate change scenarios where it is widely expected that rising CO2 will fully offset losses due to climate change.

The potential influence of morphology on the evolutionary divergence of an acoustic signal

PubMed Central

Pitchers, W. R.; Klingenberg, C.P.; Tregenza, Tom; Hunt, J.; Dworkin, I.

2014-01-01

The evolution of acoustic behaviour and that of the morphological traits mediating its production are often coupled. Lack of variation in the underlying morphology of signalling traits has the potential to constrain signal evolution. This relationship is particularly likely in field crickets, where males produce acoustic advertisement signals to attract females by stridulating with specialized structures on their forewings. In this study, we characterise the size and geometric shape of the forewings of males from six allopatric populations of the black field cricket (Teleogryllus commodus) known to have divergent advertisement calls. We sample from each of these populations using both wild-caught and common-garden reared cohorts, allowing us to test for multivariate relationships between wing morphology and call structure. We show that the allometry of shape has diverged across populations. However, there was a surprisingly small amount of covariation between wing shape and call structure within populations. Given the importance of male size for sexual selection in crickets, the divergence we observe among populations has the potential to influence the evolution of advertisement calls in this species. PMID:25223712

Comparison of female foot morphology and last design in athletic footwear--are men's lasts appropriate for women?

PubMed

Krauss, Inga; Valiant, Gordon; Horstmann, Thomas; Grau, Stefan

2010-04-01

The purpose of this study was to investigate differences between female feet and last design. Four hundred twenty-four feet and four men's running shoe lasts (U.S. women 6.0-9.5), which also are used for the manufacturing of women's shoes, were scanned in three dimensions. Six foot measures were quantified. Different foot types were classified using a cluster analysis. Comparisons were made between last measures and averaged as well as foot type specific foot measures. Differences in width measures between lasts and foot types vary substantially (0-9 mm). Length grading is similar for lasts and feet (differences < 1mm). Width grading is larger in lasts in comparison with average grading in feet (3.5-5.9 mm). Last design and grading should account for the sex-specific allometry in foot measures. The use of down-graded men's lasts for women's shoes has to be questioned. Therefore, sex-specific reference measures and wear tests should incorporate different foot types in different sizes to allow suitable implications for a proper design and grading of lasts.

Developmental instability in Rhus copallinum L.: multiple stressors, years, and responses

USGS Publications Warehouse

Freeman, D. Carl; Brown, Michelle L.; Duda, Jeffrey J.; Graham, John H.; Emlen, John M.; Krzysik, Anthony J.; Balbach, Harold E.; Kovacic, Dave A.; Zak, John C.

2004-01-01

Developmental instability, as assessed by leaf fluctuating asymmetry and stem internode allometry, was examined at nine sites, representing three levels of disturbance, over multiple years. Site selection was based on land‐use disturbance classes related to training of mechanized infantry and other land management activities at Fort Benning, Georgia. Developmental instability varied among sites and years, and there was a strong site‐by‐year interaction for many traits. Indeed, depending on the year, the same site could be ranked as having the greatest and least amount of leaf fluctuating asymmetry. Burning a site the year prior to collecting the leaves profoundly influenced measures of leaf fluctuating asymmetry. In the absence of recent burning, leaf fluctuating asymmetry declined with increasing disturbance, but burning the year prior to collecting the leaves reversed this trend. Total plant cover, proportion of bare ground, and amount of plant litter influenced the amount of leaf asymmetry in a site‐dependent manner. Overall, burning influenced the levels of developmental instability more than either disturbance or microhabitat variables such as total plant cover, which should reflect competition in a plant’s immediate neighborhood.

Why are reproductively parasitic fish males so small?—influence of tactic-specific selection

NASA Astrophysics Data System (ADS)

Ota, Kazutaka; Kohda, Masanori; Sato, Tetsu

2010-12-01

Despite the wide prevalence of alternative reproductive tactics, little attention has been paid to why reproductively parasitic males are so small. In this study, we tackled this issue in a shell-brooding fish Lamprologus callipterus. Sneaky `dwarf males' of this fish remain much smaller than bourgeois conspecifics throughout their life and employ a unique parasitic tactic, i.e. entering into a gastropod shell where a female is spawning, passing through the space between the female and shell wall and staying behind her to ejaculate throughout the spawning event. Here, we tested the prediction that they remain small to get past her through the shell spaces by interpopulation comparison. We showed, across populations, a negative allometry for sexual size dimorphism, an exponential increase of female size with an increase in shell size and a negative correlation between the magnitude of sexual size dimorphism and shell size. These results suggest that the inner spaces strongly regulate dwarf male size. We conclude that the small bodies of dwarf males arise from adaptation to their unique reproductive behaviour.

Integrated phenotypes: understanding trait covariation in plants and animals

PubMed Central

Armbruster, W. Scott; Pélabon, Christophe; Bolstad, Geir H.; Hansen, Thomas F.

2014-01-01

Integration and modularity refer to the patterns and processes of trait interaction and independence. Both terms have complex histories with respect to both conceptualization and quantification, resulting in a plethora of integration indices in use. We review briefly the divergent definitions, uses and measures of integration and modularity and make conceptual links to allometry. We also discuss how integration and modularity might evolve. Although integration is generally thought to be generated and maintained by correlational selection, theoretical considerations suggest the relationship is not straightforward. We caution here against uncontrolled comparisons of indices across studies. In the absence of controls for trait number, dimensionality, homology, development and function, it is difficult, or even impossible, to compare integration indices across organisms or traits. We suggest that care be invested in relating measurement to underlying theory or hypotheses, and that summative, theory-free descriptors of integration generally be avoided. The papers that follow in this Theme Issue illustrate the diversity of approaches to studying integration and modularity, highlighting strengths and pitfalls that await researchers investigating integration in plants and animals. PMID:25002693

Trophic divergence despite morphological convergence in a continental radiation of snakes

PubMed Central

Grundler, Michael C.; Rabosky, Daniel L.

2014-01-01

Ecological and phenotypic convergence is a potential outcome of adaptive radiation in response to ecological opportunity. However, a number of factors may limit convergence during evolutionary radiations, including interregional differences in biogeographic history and clade-specific constraints on form and function. Here, we demonstrate that a single clade of terrestrial snakes from Australia—the oxyuranine elapids—exhibits widespread morphological convergence with a phylogenetically diverse and distantly related assemblage of snakes from North America. Australian elapids have evolved nearly the full spectrum of phenotypic modalities that occurs among North American snakes. Much of the convergence appears to involve the recurrent evolution of stereotyped morphologies associated with foraging mode, locomotion and habitat use. By contrast, analysis of snake diets indicates striking divergence in feeding ecology between these faunas, partially reflecting regional differences in ecological allometry between Australia and North America. Widespread phenotypic convergence with the North American snake fauna coupled with divergence in feeding ecology are clear examples of how independent continental radiations may converge along some ecological axes yet differ profoundly along others. PMID:24920479

A giant on the ground: another large-bodied Atractus (Serpentes: Dipsadinae) from Ecuadorian Andes, with comments on the dietary specializations of the goo-eaters snakes.

PubMed

Passos, Paulo; Scanferla, Agustín; Melo-Sampaio, Paulo R; Brito, Jorge; Almendariz, Ana

2018-05-17

Body-size is significantly correlated with the number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that somitogenesis process is an important factor dictating evolutionary change associated to phyletic allometry and, consequently, species fitness and diversification. However, the role of the evolution of extreme body sizes (dwarfism and gigantism) remains elusive in snakes, mainly with respect to postnatal ontogeny in dietary preferences associated with evolution of gigantism in many lineages. We described herein a new species in the highly diversified and species-rich genus Atractus on the basis of four specimens from the southeastern slopes of the Ecuadorian Andes. The new species is morphologically similar and apparently closely related to two other allopatric giant congeners (A. gigas and A. touzeti), from which it can be distinguished by their distinct dorsal and ventral coloration, the number of supralabial and infralabial scales, the number of maxillary teeth, and relative width of the head. In addition, we discuss on the ontogenetic trajectories hypotheses and dietary specializations related to evolution of gigantism in the goo-eaters genus Atractus.

New formulae for estimating stature in the Balkans.

PubMed

Ross, Ann H; Konigsberg, Lyle W

2002-01-01

Recent studies of secular change and allometry have observed differential limb proportions between the sexes, among and within populations. These studies suggest that stature prediction formulae developed from American Whites may be inappropriate for European populations. The purpose of this investigation is to present more appropriate stature prediction equations for use in the Balkans to aid present-day identifications of the victims of genocide. The reference sample totals 545 white males obtained from World War II data. The Eastern European sample totals 177 males and includes both Bosnian and Croatian victims of the recent war. Mean stature for Eastern Europeans was obtained from the literature. Results show that formulae based on Trotter and Gleser systematically underestimate stature in the Balkans. Because Eastern Europeans are taller than American Whites it is appropriate to use this as an "informative prior" that can be applied to future cases. This informative prior can be used in predictive formulae, since it is probably similar to the sample from which the Balkan forensic cases were drawn. Based on Bayes' Theorem new predictive stature formulae are presented for Eastern Europeans.

Trophic divergence despite morphological convergence in a continental radiation of snakes.

PubMed

Grundler, Michael C; Rabosky, Daniel L

2014-07-22

Ecological and phenotypic convergence is a potential outcome of adaptive radiation in response to ecological opportunity. However, a number of factors may limit convergence during evolutionary radiations, including interregional differences in biogeographic history and clade-specific constraints on form and function. Here, we demonstrate that a single clade of terrestrial snakes from Australia--the oxyuranine elapids--exhibits widespread morphological convergence with a phylogenetically diverse and distantly related assemblage of snakes from North America. Australian elapids have evolved nearly the full spectrum of phenotypic modalities that occurs among North American snakes. Much of the convergence appears to involve the recurrent evolution of stereotyped morphologies associated with foraging mode, locomotion and habitat use. By contrast, analysis of snake diets indicates striking divergence in feeding ecology between these faunas, partially reflecting regional differences in ecological allometry between Australia and North America. Widespread phenotypic convergence with the North American snake fauna coupled with divergence in feeding ecology are clear examples of how independent continental radiations may converge along some ecological axes yet differ profoundly along others. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Estimating mangrove aboveground biomass from airborne LiDAR data: a case study from the Zambezi River delta

NASA Astrophysics Data System (ADS)

Fatoyinbo, Temilola; Feliciano, Emanuelle A.; Lagomasino, David; Kuk Lee, Seung; Trettin, Carl

2018-02-01

Mangroves are ecologically and economically important forested wetlands with the highest carbon (C) density of all terrestrial ecosystems. Because of their exceptionally large C stocks and importance as a coastal buffer, their protection and restoration has been proposed as an effective mitigation strategy for climate change. The inclusion of mangroves in mitigation strategies requires the quantification of C stocks (both above and belowground) and changes to accurately calculate emissions and sequestration. A growing number of countries are becoming interested in using mitigation initiatives, such as REDD+ (reducing emissions from deforestation and forest degradation), in these unique coastal forests. However, it is not yet clear how methods to measure C traditionally used for other ecosystems can be modified to estimate biomass in mangroves with the precision and accuracy needed for these initiatives. Airborne Lidar (ALS) data has often been proposed as the most accurate way for larger scale assessments but the application of ALS for coastal wetlands is scarce, primarily due to a lack of contemporaneous ALS and field measurements. Here, we evaluated the variability in field and Lidar-based estimates of aboveground biomass (AGB) through the combination of different local and regional allometric models and standardized height metrics that are comparable across spatial resolutions and sensor types, the end result being a simplified approach for accurately estimating mangrove AGB at large scales and determining the uncertainty by combining multiple allometric models. We then quantified wall-to-wall AGB stocks of a tall mangrove forest in the Zambezi Delta, Mozambique. Our results indicate that the Lidar H100 height metric correlates well with AGB estimates, with R 2 between 0.80 and 0.88 and RMSE of 33% or less. When comparing Lidar H100 AGB derived from three allometric models, mean AGB values range from 192 Mg ha-1 up to 252 Mg ha-1. We suggest the best model to predict AGB was based on the East Africa specific allometry and a power-based regression that used Lidar H100 as the height input with an R 2 of 0.85 and an RMSE of 122 Mg ha-1 or 33%. The total AGB of the Lidar inventoried mangrove area (6654 ha) was 1 350 902 Mg with a mean AGB of 203 Mg ha-1 ±166 Mg ha-1. Because the allometry suggested here was developed using standardized height metrics, it is recommended that the models can generate AGB estimates using other remote sensing instruments that are more readily accessible over other mangrove ecosystems on a large scale, and as part of future carbon monitoring efforts in mangroves.

Sagittal crest formation in great apes and gibbons.

PubMed

Balolia, Katharine L; Soligo, Christophe; Wood, Bernard

2017-06-01

The frequency of sagittal crest expression and patterns of sagittal crest growth and development have been documented in hominoids, including some extinct hominin taxa, and the more frequent expression of the sagittal crest in males has been traditionally linked with the need for larger-bodied individuals to have enough attachment area for the temporalis muscle. In the present study, we investigate sagittal cresting in a dentally mature sample of four hominoid taxa (Pan troglodytes schweinfurthii, Gorilla gorilla gorilla, Pongo pygmaeus pygmaeus and Hylobates lar). We investigate whether sagittal crest size increases with age beyond dental maturity in males and females of G. g. gorilla and Po. pyg. pygmaeus, and whether these taxa show sex differences in the timing of sagittal crest development. We evaluate the hypothesis that the larger sagittal crest of males may not be solely due to the requirement for a larger surface area than the un-crested cranial vault can provide for the attachment of the temporalis muscle, and present data on sex differences in temporalis muscle attachment area and sagittal crest size relative to cranial size. Gorilla g. gorilla and Po. pyg. pygmaeus males show significant relationships between tooth wear rank and sagittal crest size, and they show sagittal crest size differences between age groups that are not found in females. The sagittal crest emerges in early adulthood in the majority of G. g. gorilla males, whereas the percentage of G. g. gorilla females possessing a sagittal crest increases more gradually. Pongo pyg. pygmaeus males experience a three-fold increase in the number of specimens exhibiting a sagittal crest in mid-adulthood, consistent with a secondary growth spurt. Gorilla g. gorilla and Po. pyg. pygmaeus show significant sex differences in the size of the temporalis muscle attachment area, relative to cranial size, with males of both taxa showing positive allometry not shown in females. Gorilla g. gorilla males also show positive allometry for sagittal crest size relative to cranial size. Our results suggest that although patterns of sagittal crest expression have limited utility for taxonomy and phylogeny reconstruction, they could be useful for reconstructing aspects of social behaviour in some extinct hominin taxa. In particular, our results in G. g. gorilla and Po. pyg. pygmaeus, which suggest that the size of sagittal crests in males cannot be solely explained by the surface area required for attachment of the temporalis muscle, offer partial support for the hypothesis that large sagittal crests form in response to sexual selection and may play a role in social signalling. © 2017 Anatomical Society.

An approach to scoring cursorial limb proportions in carnivorous dinosaurs and an attempt to account for allometry.

PubMed

Persons, W Scott; Currie, Philip J

2016-01-27

From an initial dataset of 53 theropod species, the general relationship between theropod lower-leg length and body mass is identified. After factoring out this allometric relationship, theropod hindlimb proportions are assessed irrespective of body mass. Cursorial-limb-proportion (CLP) scores derived for each of the considered theropod taxa offer a measure of the extent to which a particular species deviates in favour of higher or lower running speeds. Within the same theropod species, these CLP scores are found to be consistent across multiple adult specimens and across disparate ontogenetic stages. Early theropods are found to have low CLP scores, while the coelurosaurian tyrannosauroids and compsognathids are found to have high CLP scores. Among deinonychosaurs, troodontids have consistently high CLP scores, while many dromaeosaur taxa, including Velociraptor and Deinonychus, have low CLP scores. This indicates that dromaeosaurs were not, overall, a particularly cursorily adapted group. Comparisons between the CLP scores of Tyrannosaurus and specimens referred to the controversial genus Nanotyrannus indicate a strong discrepancy in cursorial adaptations, which supports the legitimacy of Nanotyrannus and the previous suggestions of ecological partitioning between Nanotyrannus and the contemporaneous Tyrannosaurus.

Apparent plasticity in functional traits determining competitive ability and spatial distribution: a case from desert.

PubMed

Xie, Jiang-Bo; Xu, Gui-Qing; Jenerette, G Darrel; Bai, Yong-fei; Wang, Zhong-Yuan; Li, Yan

2015-07-20

Species competitive abilities and their distributions are closely related to functional traits such as biomass allocation patterns. When we consider how nutrient supply affects competitive abilities, quantifying the apparent and true plasticity in functional traits is important because the allometric relationships among traits are universal in plants. We propose to integrate the notion of allometry and the classical reaction norm into a composite theoretical framework that quantifies the apparent and true plasticity. Combining the framework with a meta-analysis, a series of field surveys and a competition experiment, we aimed to determine the causes of the dune/interdune distribution patterns of two Haloxylon species in the Gurbantonggut Desert. We found that (1) the biomass allocation patterns of both Haloxylon species in responses to environmental conditions were apparent rather than true plasticity and (2) the allometric allocation patterns affected the plants' competition for soil nutrient supply. A key implication of our results is that the apparent plasticity in functional traits of plants determines their response to environmental change. Without identifying the apparent and true plasticity, we would substantially overestimate the magnitude, duration and even the direction of plant responses in functional traits to climate change.

Apparent plasticity in functional traits determining competitive ability and spatial distribution: a case from desert

PubMed Central

Xie, Jiang-Bo; Xu, Gui-Qing; Jenerette, G. Darrel; Bai, Yong-fei; Wang, Zhong-Yuan; Li, Yan

2015-01-01

Species competitive abilities and their distributions are closely related to functional traits such as biomass allocation patterns. When we consider how nutrient supply affects competitive abilities, quantifying the apparent and true plasticity in functional traits is important because the allometric relationships among traits are universal in plants. We propose to integrate the notion of allometry and the classical reaction norm into a composite theoretical framework that quantifies the apparent and true plasticity. Combining the framework with a meta-analysis, a series of field surveys and a competition experiment, we aimed to determine the causes of the dune/interdune distribution patterns of two Haloxylon species in the Gurbantonggut Desert. We found that (1) the biomass allocation patterns of both Haloxylon species in responses to environmental conditions were apparent rather than true plasticity and (2) the allometric allocation patterns affected the plants’ competition for soil nutrient supply. A key implication of our results is that the apparent plasticity in functional traits of plants determines their response to environmental change. Without identifying the apparent and true plasticity, we would substantially overestimate the magnitude, duration and even the direction of plant responses in functional traits to climate change. PMID:26190745

Developing animals flout prominent assumptions of ecological physiology.

PubMed

Burggren, Warren W

2005-08-01

Every field of biology has its assumptions, but when they grow to be dogma, they can become constraining. This essay presents data-based challenges to several prominent assumptions of developmental physiologists. The ubiquity of allometry is such an assumption, yet animal development is characterized by rate changes that are counter to allometric predictions. Physiological complexity is assumed to increase with development, but examples are provided showing that complexity can be greatest at intermediate developmental stages. It is assumed that organs have functional equivalency in embryos and adults, yet embryonic structures can have quite different functions than inferred from adults. Another assumption challenged is the duality of neural control (typically sympathetic and parasympathetic), since one of these two regulatory mechanisms typically considerably precedes in development the appearance of the other. A final assumption challenged is the notion that divergent phylogeny creates divergent physiologies in embryos just as in adults, when in fact early in development disparate vertebrate taxa show great quantitative as well as qualitative similarity. Collectively, the inappropriateness of these prominent assumptions based on adult studies suggests that investigation of embryos, larvae and fetuses be conducted with appreciation for their potentially unique physiologies.

Testing the performance of a fragment of the COI gene to identify western Palaearctic stag beetle species (Coleoptera, Lucanidae).

PubMed

Cox, Karen; Thomaes, Arno; Antonini, Gloria; Zilioli, Michele; De Gelas, Koen; Harvey, Deborah; Solano, Emanuela; Audisio, Paolo; McKeown, Niall; Shaw, Paul; Minetti, Robert; Bartolozzi, Luca; Mergeay, Joachim

2013-12-30

Lucanidae) remains challenging, mainly due to the sexual dimorphism and the strong allometry in males. Such conjecture confounds taxonomic based conservation efforts that are urgently needed due to numerous threats to stag beetle biodiversity. Molecular tools could help solve the problem of identification of the different recognized taxa in the "Lucanus cervus complex" and in some related Palaearctic species. We investigated the potential use of a 670 bp region at the 3' end of the mitochondrial cytochrome c oxidase subunit I gene (COI) for barcoding purposes (different from the standard COI barcoding region). Well resolved species and subspecies were L. tetraodon, L. cervusakbesianus, L. c. laticornis, as well as the two eastern Asian outgroup taxa L. formosanus and L. hermani. Conversely, certain taxa could not be distinguished from each other based on K2P-distances and tree topologies: L. c. fabiani / L. (P.) barbarossa, L. c. judaicus / an unknown Lucanus species, L. c. cervus / L. c. turcicus / L. c. pentaphyllus / L. (P.) macrophyllus / L. ibericus. The relative roles of phenotypic plasticity, recurrent hybridisation and incomplete lineage sorting underlying taxonomic and phylogenetic discordances are discussed.

Modelling foot height and foot shape-related dimensions.

PubMed

Xiong, Shuping; Goonetilleke, Ravindra S; Witana, Channa P; Lee Au, Emily Yim

2008-08-01

The application of foot anthropometry to design good-fitting footwear has been difficult due to the lack of generalised models. This study seeks to model foot dimensions so that the characteristic shapes of feet, especially in the midfoot region, can be understood. Fifty Hong Kong Chinese adults (26 males and 24 females) participated in this study. Their foot lengths, foot widths, ball girths and foot heights were measured and then evaluated using mathematical models. The results showed that there were no significant allometry (p > 0.05) effects of foot length on ball girth and foot width. Foot height showed no direct relationship with foot length. However, a normalisation with respect to foot length and foot height resulted in a significant relationship for both males and females with R(2) greater than 0.97. Due to the lack of a direct relationship between foot height and foot length, the current practice of grading shoes with a constant increase in height or proportionate scaling in response to foot length is less than ideal. The results when validated with other populations can be a significant way forward in the design of footwear that has an improved fit in the height dimension.

Mammal population regulation, keystone processes and ecosystem dynamics.

PubMed Central

Sinclair, A R E

2003-01-01

The theory of regulation in animal populations is fundamental to understanding the dynamics of populations, the causes of mortality and how natural selection shapes the life history of species. In mammals, the great range in body size allows us to see how allometric relationships affect the mode of regulation. Resource limitation is the fundamental cause of regulation. Top-down limitation through predators is determined by four factors: (i). body size; (ii). the diversity of predators and prey in the system; (iii). whether prey are resident or migratory; and (iv). the presence of alternative prey for predators. Body size in mammals has two important consequences. First, mammals, particularly large species, can act as keystones that determine the diversity of an ecosystem. I show how keystone processes can, in principle, be measured using the example of the wildebeest in the Serengeti ecosystem. Second, mammals act as ecological landscapers by altering vegetation succession. Mammals alter physical structure, ecological function and species diversity in most terrestrial biomes. In general, there is a close interaction between allometry, population regulation, life history and ecosystem dynamics. These relationships are relevant to applied aspects of conservation and pest management. PMID:14561329

Allometry in dinosaurs and mammals

NASA Astrophysics Data System (ADS)

Lee, Scott

2015-03-01

The proportions of the leg bones change as the size of an animal becomes larger since the mass of the animal increases at a faster rate than the cross-sectional area of its leg bones. For the case of elastic similarity (in which the longitudinal stress in the legs remains constant in animals of all sizes), the diameter d and length L of the femur should be related as d = A L3/2. For geometric similarity (in which all dimensions are scaled by the same factor), d = A L. For animals with femora longer than 20 cm, we find the power law relationship to be d = A Lb with b = 1.13 +/- 0.06 for extant mammals (the largest mammal being Loxodonta africana with a 1.00-m-long femur) and b = 1.18 +/- 0.02 for dinosaurs (the largest dinosaur being Brachiosaurus brancai with a 2.03-m-long femur). These data show that extinct dinosaurs and extant animals scale in the same basic manner. The large sauropods (with femora twice as long as found in elephants) scale in a manner consistent with extrapolation of the scaling shown by extant mammals. These results argue that extinct dinosaurs moved in a manner very similar to extant mammals.

Concerted and mosaic evolution of functional modules in songbird brains

PubMed Central

DeVoogd, Timothy J.

2017-01-01

Vertebrate brains differ in overall size, composition and functional capacities, but the evolutionary processes linking these traits are unclear. Two leading models offer opposing views: the concerted model ascribes major dimensions of covariation in brain structures to developmental events, whereas the mosaic model relates divergent structures to functional capabilities. The models are often cast as incompatible, but they must be unified to explain how adaptive changes in brain structure arise from pre-existing architectures and developmental mechanisms. Here we show that variation in the sizes of discrete neural systems in songbirds, a species-rich group exhibiting diverse behavioural and ecological specializations, supports major elements of both models. In accordance with the concerted model, most variation in nucleus volumes is shared across functional domains and allometry is related to developmental sequence. Per the mosaic model, residual variation in nucleus volumes is correlated within functional systems and predicts specific behavioural capabilities. These comparisons indicate that oscine brains evolved primarily as a coordinated whole but also experienced significant, independent modifications to dedicated systems from specific selection pressures. Finally, patterns of covariation between species and brain areas hint at underlying developmental mechanisms. PMID:28490627

Mapping the global potential for marine aquaculture.

PubMed

Gentry, Rebecca R; Froehlich, Halley E; Grimm, Dietmar; Kareiva, Peter; Parke, Michael; Rust, Michael; Gaines, Steven D; Halpern, Benjamin S

2017-09-01

Marine aquaculture presents an opportunity for increasing seafood production in the face of growing demand for marine protein and limited scope for expanding wild fishery harvests. However, the global capacity for increased aquaculture production from the ocean and the relative productivity potential across countries are unknown. Here, we map the biological production potential for marine aquaculture across the globe using an innovative approach that draws from physiology, allometry and growth theory. Even after applying substantial constraints based on existing ocean uses and limitations, we find vast areas in nearly every coastal country that are suitable for aquaculture. The development potential far exceeds the space required to meet foreseeable seafood demand; indeed, the current total landings of all wild-capture fisheries could be produced using less than 0.015% of the global ocean area. This analysis demonstrates that suitable space is unlikely to limit marine aquaculture development and highlights the role that other factors, such as economics and governance, play in shaping growth trajectories. We suggest that the vast amount of space suitable for marine aquaculture presents an opportunity for countries to develop aquaculture in a way that aligns with their economic, environmental and social objectives.

The evolution of cranial base and face in Cercopithecoidea and Hominoidea: Modularity and morphological integration.

PubMed

Profico, Antonio; Piras, Paolo; Buzi, Costantino; Di Vincenzo, Fabio; Lattarini, Flavio; Melchionna, Marina; Veneziano, Alessio; Raia, Pasquale; Manzi, Giorgio

2017-12-01

The evolutionary relationship between the base and face of the cranium is a major topic of interest in primatology. Such areas of the skull possibly respond to different selective pressures. Yet, they are often said to be tightly integrated. In this paper, we analyzed shape variability in the cranial base and the facial complex in Cercopithecoidea and Hominoidea. We used a landmark-based approach to single out the effects of size (evolutionary allometry), morphological integration, modularity, and phylogeny (under Brownian motion) on skull shape variability. Our results demonstrate that the cranial base and the facial complex exhibit different responses to different factors, which produces a little degree of morphological integration between them. Facial shape variation appears primarily influenced by body size and sexual dimorphism, whereas the cranial base is mostly influenced by functional factors. The different adaptations affecting the two modules suggest they are best studied as separate and independent units, and that-at least when dealing with Catarrhines-caution must be posed with the notion of strong cranial integration that is commonly invoked for the evolution of their skull shape. © 2017 Wiley Periodicals, Inc.

Did saber-tooth kittens grow up musclebound? A study of postnatal limb bone allometry in felids from the Pleistocene of Rancho La Brea.

PubMed

Long, Katherine; Prothero, Donald; Madan, Meena; Syverson, Valerie J P

2017-01-01

Previous studies have demonstrated that the Pleistocene saber-toothed cat Smilodon fatalis had many forelimb adaptations for increased strength, presumably to grapple with and subdue prey. The Rancho La Brea tar pits yield large samples of juvenile limb bones forming a growth series that allow us to examine how Smilodon kittens grew up. Almost all available juvenile limb bones were measured, and reduced major axis fits were calculated to determine the allometric growth trends. Contrary to expectations based on their robust limbs, Smilodon kittens show the typical pattern of growth found in other large felids (such as the Ice Age lion, Panthera atrox, as well as living tigers, cougars, servals, and wildcats) where the limb grows longer and more slender faster than they grow thick. This adaptation is thought to give felids greater running speed. Smilodon kittens do not grow increasingly more robust with age. Instead, they start out robust and follow the ancestral felid growth pattern, while maintaining their robustness compared to other felids. Apparently, the growth of felid forelimbs is highly canalized and their ontogeny is tightly constrained.

Unified approach for extrapolation and bridging of adult information in early-phase dose-finding paediatric studies.

PubMed

Petit, Caroline; Samson, Adeline; Morita, Satoshi; Ursino, Moreno; Guedj, Jérémie; Jullien, Vincent; Comets, Emmanuelle; Zohar, Sarah

2018-06-01

The number of trials conducted and the number of patients per trial are typically small in paediatric clinical studies. This is due to ethical constraints and the complexity of the medical process for treating children. While incorporating prior knowledge from adults may be extremely valuable, this must be done carefully. In this paper, we propose a unified method for designing and analysing dose-finding trials in paediatrics, while bridging information from adults. The dose-range is calculated under three extrapolation options, linear, allometry and maturation adjustment, using adult pharmacokinetic data. To do this, it is assumed that target exposures are the same in both populations. The working model and prior distribution parameters of the dose-toxicity and dose-efficacy relationships are obtained using early-phase adult toxicity and efficacy data at several dose levels. Priors are integrated into the dose-finding process through Bayesian model selection or adaptive priors. This calibrates the model to adjust for misspecification, if the adult and pediatric data are very different. We performed a simulation study which indicates that incorporating prior adult information in this way may improve dose selection in children.

Crown development in a pioneer tree, Rhus trichocarpa, in relation to the structure and growth of individual branches.

PubMed

Osada, Noriyuki

2006-01-01

Based on an allometric reconstruction, the structure and biomass-allocation patterns of branches and current-year shoots were investigated in branches of various heights in the pioneer tree Rhus trichocarpa, to evaluate how crown development is achieved and limited in association with height. Path analysis was conducted to explore the effects of light availability, basal height and size of individual branches on branch structure and growth. Branch angle was affected by basal height, whereas branch mass was influenced primarily by light availability. This result suggests that branch structure is strongly constrained by basal height, and that trees mediate such constraints under different light environments. Previous-year leaf area and light availability showed positive effects on current-year stem mass. In contrast, branch basal height and mass negatively affected current-year stem mass. Moreover, the length of stems of a given diameter decreased with increasing branch height. Therefore the cost of biomass investment for a unit growth in length is greater for branches of larger size and at upper positions. Vertical growth rate in length decreased with increasing height. Height-dependent changes in stem allometry and angle influenced the reduction in vertical growth rate to a similar degree.

The influence of mating system on the intensity of parent-offspring conflict in primates.

PubMed

Long, T A F

2005-05-01

An evolutionary conflict of interest exists between parents and their offspring over the partitioning of parental investment (PI) among siblings. When the direct fitness benefits to offspring of increased PI, outweigh the inclusive fitness costs from lost future sibling fitness, selection should favour the evolution of offspring selfishness over altruism. In theory, this conflict is heightened when females are not strictly monogamous, as current offspring should be less altruistic towards future half-siblings than they would be towards full-siblings. Using data collected on foetal growth rate (representing prenatal PI) in primates, I test the prediction from theory that the resolution of the parent-offspring conflict will be closer to the offspring's evolutionary optima in polyandrous species than in more monandrous species. Using phylogenetic comparative analysis, and controlling for allometry, I show that offspring are able to obtain more PI when the probability of future full-siblings decreases, and that this is most pronounced in taxa where there is the opportunity for direct foetal access to the maternal bloodstream. These results support the hypothesis that the resolution of prenatal PI conflict is influenced by both a species' mating system and by its placental structure.

An approach to scoring cursorial limb proportions in carnivorous dinosaurs and an attempt to account for allometry

PubMed Central

Persons IV, W. Scott; Currie, Philip J.

2016-01-01

From an initial dataset of 53 theropod species, the general relationship between theropod lower-leg length and body mass is identified. After factoring out this allometric relationship, theropod hindlimb proportions are assessed irrespective of body mass. Cursorial-limb-proportion (CLP) scores derived for each of the considered theropod taxa offer a measure of the extent to which a particular species deviates in favour of higher or lower running speeds. Within the same theropod species, these CLP scores are found to be consistent across multiple adult specimens and across disparate ontogenetic stages. Early theropods are found to have low CLP scores, while the coelurosaurian tyrannosauroids and compsognathids are found to have high CLP scores. Among deinonychosaurs, troodontids have consistently high CLP scores, while many dromaeosaur taxa, including Velociraptor and Deinonychus, have low CLP scores. This indicates that dromaeosaurs were not, overall, a particularly cursorily adapted group. Comparisons between the CLP scores of Tyrannosaurus and specimens referred to the controversial genus Nanotyrannus indicate a strong discrepancy in cursorial adaptations, which supports the legitimacy of Nanotyrannus and the previous suggestions of ecological partitioning between Nanotyrannus and the contemporaneous Tyrannosaurus. PMID:26813782

Morphological allometry and intersexuality in horsehair-worm-infected mantids, Hierodula formosana (Mantodea: Mantidae).

PubMed

Chiu, Ming-Chung; Huang, Chin-Gi; Wu, Wen-Jer; Shiao, Shiuh-Feng

2015-07-01

Parasitic castration is a strategy used by parasites to minimize damage to the host by consuming its reproductive system, which results in the morphological alteration of the host. We determined that the forewing shape and density of the antennal sensilla of field-collected adult male mantids (Hierodula formosana), infected by horsehair worms (Chordodes formosanus) was partially feminized (intersexuality), and both male and female mantids infected by horsehair worms exhibited allometric changes in their wings and walking legs. In addition, the testes of most infected male adults disappeared or reduced in size, whereas the number of ovarioles in infected female adults was unaffected. The infection mainly influenced the structures related to host reproduction and locomotion, suggesting unbalanced energy exploitation and the reduction of parasitic virulence. In addition, the intersexuality of infected male adults indicated that sexual differentiation in insects, which researchers have considered to be an autonomous process, was influenced by the infection. The similarity of the antennae of infected male adults with those of last-instar female nymphs suggested that parasitic juvenilization may cause such feminization, but the mechanism of parasitic influence on insect sex characteristics should be studied further.

Size variation, growth strategies, and the evolution of modularity in the mammalian skull.

PubMed

Porto, Arthur; Shirai, Leila Teruko; de Oliveira, Felipe Bandoni; Marroig, Gabriel

2013-11-01

Allometry is a major determinant of within-population patterns of association among traits and, therefore, a major component of morphological integration studies. Even so, the influence of size variation over evolutionary change has been largely unappreciated. Here, we explore the interplay between allometric size variation, modularity, and life-history strategies in the skull from representatives of 35 mammalian families. We start by removing size variation from within-species data and analyzing its influence on integration magnitudes, modularity patterns, and responses to selection. We also carry out a simulation in which we artificially alter the influence of size variation in within-taxa matrices. Finally, we explore the relationship between size variation and different growth strategies. We demonstrate that a large portion of the evolution of modularity in the mammalian skull is associated to the evolution of growth strategies. Lineages with highly altricial neonates have adult variation patterns dominated by size variation, leading to high correlations among traits regardless of any underlying modular process and impacting directly their potential to respond to selection. Greater influence of size variation is associated to larger intermodule correlations, less individualized modules, and less flexible responses to natural selection. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis

PubMed Central

Hurford, Amy; Ellison, Amy R.

2017-01-01

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish–macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289257

Size matters: plasticity in metabolic scaling shows body-size may modulate responses to climate change.

PubMed

Carey, Nicholas; Sigwart, Julia D

2014-08-01

Variability in metabolic scaling in animals, the relationship between metabolic rate ( R: ) and body mass ( M: ), has been a source of debate and controversy for decades. R: is proportional to MB: , the precise value of B: much debated, but historically considered equal in all organisms. Recent metabolic theory, however, predicts B: to vary among species with ecology and metabolic level, and may also vary within species under different abiotic conditions. Under climate change, most species will experience increased temperatures, and marine organisms will experience the additional stressor of decreased seawater pH ('ocean acidification'). Responses to these environmental changes are modulated by myriad species-specific factors. Body-size is a fundamental biological parameter, but its modulating role is relatively unexplored. Here, we show that changes to metabolic scaling reveal asymmetric responses to stressors across body-size ranges; B: is systematically decreased under increasing temperature in three grazing molluscs, indicating smaller individuals were more responsive to warming. Larger individuals were, however, more responsive to reduced seawater pH in low temperatures. These alterations to the allometry of metabolism highlight abiotic control of metabolic scaling, and indicate that responses to climate warming and ocean acidification may be modulated by body-size. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis.

PubMed

Walker, Josephine G; Hurford, Amy; Cable, Jo; Ellison, Amy R; Price, Stephen J; Cressler, Clayton E

2017-05-05

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists-infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish-macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Authors.

Differential scaling patterns of vertebrae and the evolution of neck length in mammals.

PubMed

Arnold, Patrick; Amson, Eli; Fischer, Martin S

2017-06-01

Almost all mammals have seven vertebrae in their cervical spines. This consistency represents one of the most prominent examples of morphological stasis in vertebrae evolution. Hence, the requirements associated with evolutionary modifications of neck length have to be met with a fixed number of vertebrae. It has not been clear whether body size influences the overall length of the cervical spine and its inner organization (i.e., if the mammalian neck is subject to allometry). Here, we provide the first large-scale analysis of the scaling patterns of the cervical spine and its constituting cervical vertebrae. Our findings reveal that the opposite allometric scaling of C1 and C2-C7 accommodate the increase of neck bending moment with body size. The internal organization of the neck skeleton exhibits surprisingly uniformity in the vast majority of mammals. Deviations from this general pattern only occur under extreme loading regimes associated with particular functional and allometric demands. Our results indicate that the main source of variation in the mammalian neck stems from the disparity of overall cervical spine length. The mammalian neck reveals how evolutionary disparity manifests itself in a structure that is otherwise highly restricted by meristic constraints. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Time-limited environments affect the evolution of egg-body size allometry.

PubMed

Eckerström-Liedholm, Simon; Sowersby, Will; Gonzalez-Voyer, Alejandro; Rogell, Björn

2017-07-01

Initial offspring size is a fundamental component of absolute growth rate, where large offspring will reach a given adult body size faster than smaller offspring. Yet, our knowledge regarding the coevolution between offspring and adult size is limited. In time-constrained environments, organisms need to reproduce at a high rate and reach a reproductive size quickly. To rapidly attain a large adult body size, we hypothesize that, in seasonal habitats, large species are bound to having a large initial size, and consequently, the evolution of egg size will be tightly matched to that of body size, compared to less time-limited systems. We tested this hypothesis in killifishes, and found a significantly steeper allometric relationship between egg and body sizes in annual, compared to nonannual species. We also found higher rates of evolution of egg and body size in annual compared to nonannual species. Our results suggest that time-constrained environments impose strong selection on rapidly reaching a species-specific body size, and reproduce at a high rate, which in turn imposes constraints on the evolution of egg sizes. In combination, these distinct selection pressures result in different relationships between egg and body size among species in time-constrained versus permanent habitats. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Relative growth and morphological sexual maturity size of the freshwater crab Trichodactylus borellianus (Crustacea, Decapoda, Trichodactylidae) in the Middle Paraná River, Argentina

PubMed Central

Williner, Verónica; Torres, María Victoria; Carvalho, Débora Azevedo; König, Natalia

2014-01-01

Abstract The relative growth of a number of morphological dimensions of the South American freshwater crab Trichodactylus borellianus (Trichodactylidae) were compared and related to sexual dimorphism. Crabs were collected from ponds in the Middle Paraná River in Argentina. A regression model with segmented relationship was used to test for relative growth between these measurements where breakpoints infer the body size at which crabs reach sexual maturity. In both sexes the carapace width and the length, height, and thickness of the right and left chelae were measured, as well as the male pleopod length and the female abdomen width. All of these measurements were found to show positive allometry with the exception of the male pleopod length and the left chelae, which did not show a breakpoint. In females the breakpoint for the abdomen width inferred a morphological sexual maturity at carapace width 6.9 mm. In males the break point for the pleopod length was at carapace width 6.6 mm, with that for the chelae measurements was between carapace widths 6.4 and 6.9 mm. The relative growth pattern in Trichodactylus borellianus was found to be similar to that recorded for other species of the family Trichodactylidae. PMID:25561835

Diet and body shape changes of pāroko Kelloggella disalvoi (Gobiidae) from intertidal pools of Easter Island.

PubMed

Vera-Duarte, J; Bustos, C A; Landaeta, M F

2017-11-01

This study assesses seasonal variation in the morphology and diet of juveniles and adults of the Easter Island endemic goby Kelloggella disalvoi from intertidal pools during September-October 2015 (spring) and June-July 2016 (winter), utilizing geometric morphometric and gut-content analyses. A set of 16 landmarks was digitized in 128 individuals. Shape changes related to size changes (i.e. allometry) were low (18·6%) and were seasonally similar. Body shape changes were mainly dorsoventral (44·2% of variance) and comprised posteroventral displacement of the premaxilla and bending of the body. The latter included vertical displacement of the anterior portion of the first and second dorsal fins and the entire base of the caudal fin. Diets mainly comprised developmental stages of harpacticoid copepods (from eggs to adults), ostracods, isopods, gastropods and bivalves. Also, trophic niche breadth remained constant throughout development and did not vary between seasons. Nonetheless, significant dietary differences were detected in specimens collected during spring (main prey items: harpacticoid copepods and copepod eggs) and winter (harpacticoid copepods and copepod nauplii). Finally, there was weak but significant covariation between diet and morphology: molluscivores were characterized by having an inferior mouth gape, whereas planktivores had an anteriorly directed premaxilla. © 2017 The Fisheries Society of the British Isles.

Influences of Brain Size, Sex, and Sex Chromosome Complement on the Architecture of Human Cortical Folding.

PubMed

Fish, Ari M; Cachia, Arnaud; Fischer, Clara; Mankiw, Catherine; Reardon, P K; Clasen, Liv S; Blumenthal, Jonathan D; Greenstein, Deanna; Giedd, Jay N; Mangin, Jean-François; Raznahan, Armin

2017-12-01

Gyrification is a fundamental property of the human cortex that is increasingly studied by basic and clinical neuroscience. However, it remains unclear if and how the global architecture of cortical folding varies with 3 interwoven sources of anatomical variation: brain size, sex, and sex chromosome dosage (SCD). Here, for 375 individuals spanning 7 karyotype groups (XX, XY, XXX, XYY, XXY, XXYY, XXXXY), we use structural neuroimaging to measure a global sulcation index (SI, total sulcal/cortical hull area) and both determinants of sulcal area: total sulcal length and mean sulcal depth. We detail large and patterned effects of sex and SCD across all folding metrics, but show that these effects are in fact largely consistent with the normative scaling of cortical folding in health: larger human brains have disproportionately high SI due to a relative expansion of sulcal area versus hull area, which arises because disproportionate sulcal lengthening overcomes a lack of proportionate sulcal deepening. Accounting for these normative allometries reveals 1) brain size-independent sulcal lengthening in males versus females, and 2) insensitivity of overall folding architecture to SCD. Our methodology and findings provide a novel context for future studies of human cortical folding in health and disease. Published by Oxford University Press 2016.

A meta-analysis of zooplankton functional traits influencing ecosystem function.

PubMed

Hébert, Marie-Pier; Beisner, Beatrix E; Maranger, Roxane

2016-04-01

The use of functional traits to characterize community composition has been proposed as a more effective way to link community structure to ecosystem functioning. Organismal morphology, body stoichiometry, and physiology can be readily linked to large-scale ecosystem processes through functional traits that inform on interspecific and species-environment interactions; yet such effect traits are still poorly included in trait-based approaches. Given their key trophic position in aquatic ecosystems, individual zooplankton affect energy fluxes and elemental processing. We compiled a large database of zooplankton traits contributing to carbon, nitrogen, and phosphorus cycling and examined the effect of classification and habitat (marine vs. freshwater) on trait relationships. Respiration and nutrient excretion rates followed mass-dependent scaling in both habitats, with exponents ranging from 0.70 to 0.90. Our analyses revealed surprising differences in allometry and respiration between habitats, with freshwater species having lower length-specific mass and three times higher mass-specific respiration rates. These differences in traits point to implications for ecological strategies as well as overall carbon storage and fluxes based on habitat type. Our synthesis quantifies multiple trait relationships and links organisms to ecosystem processes they influence, enabling a more complete integration of aquatic community ecology and biogeochemistry through the promising use of effect traits.

Testing the performance of a fragment of the COI gene to identify western Palaearctic stag beetle species (Coleoptera, Lucanidae)

PubMed Central

Cox, Karen; Thomaes, Arno; Antonini, Gloria; Zilioli, Michele; De Gelas, Koen; Harvey, Deborah; Solano, Emanuela; Audisio, Paolo; McKeown, Niall; Shaw, Paul; Minetti, Robert; Bartolozzi, Luca; Mergeay, Joachim

2013-01-01

Abstract The taxonomy of stag beetles (Coleoptera: Lucanidae) remains challenging, mainly due to the sexual dimorphism and the strong allometry in males. Such conjecture confounds taxonomic based conservation efforts that are urgently needed due to numerous threats to stag beetle biodiversity. Molecular tools could help solve the problem of identification of the different recognized taxa in the “Lucanus cervus complex” and in some related Palaearctic species. We investigated the potential use of a 670 bp region at the 3’ end of the mitochondrial cytochrome c oxidase subunit I gene (COI) for barcoding purposes (different from the standard COI barcoding region). Well resolved species and subspecies were L. tetraodon, L. cervusakbesianus, L. c. laticornis, as well as the two eastern Asian outgroup taxa L. formosanus and L. hermani. Conversely, certain taxa could not be distinguished from each other based on K2P-distances and tree topologies: L. c. fabiani / L. (P.) barbarossa, L. c. judaicus / an unknown Lucanus species, L. c. cervus / L. c. turcicus / L. c. pentaphyllus / L. (P.) macrophyllus / L. ibericus. The relative roles of phenotypic plasticity, recurrent hybridisation and incomplete lineage sorting underlying taxonomic and phylogenetic discordances are discussed. PMID:24453554

A Three-Dimensional Analysis of Morphological Evolution and Locomotor Performance of the Carnivoran Forelimb

PubMed Central

Martín-Serra, Alberto; Figueirido, Borja; Palmqvist, Paul

2014-01-01

In this study, three-dimensional landmark-based methods of geometric morphometrics are used for estimating the influence of phylogeny, allometry and locomotor performance on forelimb shape in living and extinct carnivorans (Mammalia, Carnivora). The main objective is to investigate morphological convergences towards similar locomotor strategies in the shape of the major forelimb bones. Results indicate that both size and phylogeny have strong effects on the anatomy of all forelimb bones. In contrast, bone shape does not correlate in the living taxa with maximum running speed or daily movement distance, two proxies closely related to locomotor performance. A phylomorphospace approach showed that shape variation in forelimb bones mainly relates to changes in bone robustness. This indicates the presence of biomechanical constraints resulting from opposite demands for energetic efficiency in locomotion –which would require a slender forelimb– and resistance to stress –which would be satisfied by a robust forelimb–. Thus, we interpret that the need of maintaining a trade-off between both functional demands would limit shape variability in forelimb bones. Given that different situations can lead to one or another morphological solution, depending on the specific ecology of taxa, the evolution of forelimb morphology represents a remarkable “one-to-many mapping” case between anatomy and ecology. PMID:24454891

Go big or go fish: morphological specializations in carnivorous bats.

PubMed

Santana, Sharlene E; Cheung, Elena

2016-05-11

Specialized carnivory is relatively uncommon across mammals, and bats constitute one of the few groups in which this diet has evolved multiple times. While size and morphological adaptations for carnivory have been identified in other taxa, it is unclear what phenotypic traits characterize the relatively recent evolution of carnivory in bats. To address this gap, we apply geometric morphometric and phylogenetic comparative analyses to elucidate which characters are associated with ecological divergence of carnivorous bats from insectivorous ancestors, and if there is morphological convergence among independent origins of carnivory within bats, and with other carnivorous mammals. We find that carnivorous bats are larger and converged to occupy a subset of the insectivorous morphospace, characterized by skull shapes that enhance bite force at relatively wide gapes. Piscivorous bats are morphologically distinct, with cranial shapes that enable high bite force at narrow gapes, which is necessary for processing fish prey. All animal-eating species exhibit positive allometry in rostrum elongation with respect to skull size, which could allow larger bats to take relatively larger prey. The skull shapes of carnivorous bats share similarities with generalized carnivorans, but tend to be more suited for increased bite force production at the expense of gape, when compared with specialized carnivorans. © 2016 The Author(s).

Go big or go fish: morphological specializations in carnivorous bats

PubMed Central

Santana, Sharlene E.; Cheung, Elena

2016-01-01

Specialized carnivory is relatively uncommon across mammals, and bats constitute one of the few groups in which this diet has evolved multiple times. While size and morphological adaptations for carnivory have been identified in other taxa, it is unclear what phenotypic traits characterize the relatively recent evolution of carnivory in bats. To address this gap, we apply geometric morphometric and phylogenetic comparative analyses to elucidate which characters are associated with ecological divergence of carnivorous bats from insectivorous ancestors, and if there is morphological convergence among independent origins of carnivory within bats, and with other carnivorous mammals. We find that carnivorous bats are larger and converged to occupy a subset of the insectivorous morphospace, characterized by skull shapes that enhance bite force at relatively wide gapes. Piscivorous bats are morphologically distinct, with cranial shapes that enable high bite force at narrow gapes, which is necessary for processing fish prey. All animal-eating species exhibit positive allometry in rostrum elongation with respect to skull size, which could allow larger bats to take relatively larger prey. The skull shapes of carnivorous bats share similarities with generalized carnivorans, but tend to be more suited for increased bite force production at the expense of gape, when compared with specialized carnivorans. PMID:27170718

How sexual selection can drive the evolution of costly sperm ornamentation

NASA Astrophysics Data System (ADS)

Lüpold, Stefan; Manier, Mollie K.; Puniamoorthy, Nalini; Schoff, Christopher; Starmer, William T.; Luepold, Shannon H. Buckley; Belote, John M.; Pitnick, Scott

2016-05-01

Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male-male competition and female choice as discrete processes.

Unveiling relationships between crime and property in England and Wales via density scale-adjusted metrics and network tools.

PubMed

Ribeiro, Haroldo V; Hanley, Quentin S; Lewis, Dan

2018-01-01

Scale-adjusted metrics (SAMs) are a significant achievement of the urban scaling hypothesis. SAMs remove the inherent biases of per capita measures computed in the absence of isometric allometries. However, this approach is limited to urban areas, while a large portion of the world's population still lives outside cities and rural areas dominate land use worldwide. Here, we extend the concept of SAMs to population density scale-adjusted metrics (DSAMs) to reveal relationships among different types of crime and property metrics. Our approach allows all human environments to be considered, avoids problems in the definition of urban areas, and accounts for the heterogeneity of population distributions within urban regions. By combining DSAMs, cross-correlation, and complex network analysis, we find that crime and property types have intricate and hierarchically organized relationships leading to some striking conclusions. Drugs and burglary had uncorrelated DSAMs and, to the extent property transaction values are indicators of affluence, twelve out of fourteen crime metrics showed no evidence of specifically targeting affluence. Burglary and robbery were the most connected in our network analysis and the modular structures suggest an alternative to "zero-tolerance" policies by unveiling the crime and/or property types most likely to affect each other.

A model for allometric scaling of mammalian metabolism with ambient heat loss.

PubMed

Kwak, Ho Sang; Im, Hong G; Shim, Eun Bo

2016-03-01

Allometric scaling, which represents the dependence of biological traits or processes on body size, is a long-standing subject in biological science. However, there has been no study to consider heat loss to the ambient and an insulation layer representing mammalian skin and fur for the derivation of the scaling law of metabolism. A simple heat transfer model is proposed to analyze the allometry of mammalian metabolism. The present model extends existing studies by incorporating various external heat transfer parameters and additional insulation layers. The model equations were solved numerically and by an analytic heat balance approach. A general observation is that the present heat transfer model predicted the 2/3 surface scaling law, which is primarily attributed to the dependence of the surface area on the body mass. External heat transfer effects introduced deviations in the scaling law, mainly due to natural convection heat transfer, which becomes more prominent at smaller mass. These deviations resulted in a slight modification of the scaling exponent to a value < 2/3. The finding that additional radiative heat loss and the consideration of an outer insulation fur layer attenuate these deviation effects and render the scaling law closer to 2/3 provides in silico evidence for a functional impact of heat transfer mode on the allometric scaling law in mammalian metabolism.

Unveiling relationships between crime and property in England and Wales via density scale-adjusted metrics and network tools

PubMed Central

Hanley, Quentin S.; Lewis, Dan

2018-01-01

Scale-adjusted metrics (SAMs) are a significant achievement of the urban scaling hypothesis. SAMs remove the inherent biases of per capita measures computed in the absence of isometric allometries. However, this approach is limited to urban areas, while a large portion of the world’s population still lives outside cities and rural areas dominate land use worldwide. Here, we extend the concept of SAMs to population density scale-adjusted metrics (DSAMs) to reveal relationships among different types of crime and property metrics. Our approach allows all human environments to be considered, avoids problems in the definition of urban areas, and accounts for the heterogeneity of population distributions within urban regions. By combining DSAMs, cross-correlation, and complex network analysis, we find that crime and property types have intricate and hierarchically organized relationships leading to some striking conclusions. Drugs and burglary had uncorrelated DSAMs and, to the extent property transaction values are indicators of affluence, twelve out of fourteen crime metrics showed no evidence of specifically targeting affluence. Burglary and robbery were the most connected in our network analysis and the modular structures suggest an alternative to “zero-tolerance” policies by unveiling the crime and/or property types most likely to affect each other. PMID:29470499

Annual reversible plasticity of feeding structures: cyclical changes of jaw allometry in a sea urchin

PubMed Central

Ebert, Thomas A.; Hernández, José Carlos; Clemente, Sabrina

2014-01-01

A wide variety of organisms show morphologically plastic responses to environmental stressors but in general these changes are not reversible. Though less common, reversible morphological structures are shown by a range of species in response to changes in predators, competitors or food. Theoretical analysis indicates that reversible plasticity increases fitness if organisms are long-lived relative to the frequency of changes in the stressor and morphological changes are rapid. Many sea urchin species show differences in the sizes of jaws (demi-pyramids) of the feeding apparatus, Aristotle's lantern, relative to overall body size, and these differences have been correlated with available food. The question addressed here is whether reversible changes of relative jaw size occur in the field as available food changes with season. Monthly samples of the North American Pacific coast sea urchin Strongylocentrotus purpuratus were collected from Gregory Point on the Oregon (USA) coast and showed an annual cycle of relative jaw size together with a linear trend from 2007 to 2009. Strongylocentrotus purpuratus is a long-lived species and under field conditions individuals experience multiple episodes of changes in food resources both seasonally and from year to year. Their rapid and reversible jaw plasticity fits well with theoretical expectations. PMID:24500161

Evolution and inheritance of early embryonic patterning in D. simulans and D. sechellia

PubMed Central

Lott, Susan E.; Ludwig, Michael Z.; Kreitman, Martin

2010-01-01

Pattern formation in Drosophila is a widely studied example of a robust developmental system. Such robust systems pose a challenge to adaptive evolution, as they mask variation which selection may otherwise act upon. Yet we find variation in the localization of expression domains (henceforth ‘stripe allometry’) in the pattern formation pathway. Specifically, we characterize differences in the gap genes giant and Kruppel, and the pair-rule gene even-skipped, which differ between the sibling species D. simulans and D. sechellia. In a double-backcross experiment, stripe allometry is consistent with maternal inheritance of stripe positioning and multiple genetic factors, with a distinct genetic basis from embryo length. Embryos produced by F1 and F2 backcross mothers exhibit novel spatial patterns of gene expression relative to the parental species, with no measurable increase in positional variance among individuals. Buffering of novel spatial patterns in the backcross genotypes suggests that robustness need not be disrupted in order for the trait to evolve, and perhaps the system is incapable of evolving to prevent the expression of all genetic variation. This limitation, and the ability of natural selection to act on minute genetic differences that are within the “margin of error” for the buffering mechanism, indicates that developmentally buffered traits can evolve without disruption of robustness PMID:21121913

Comparative analyses of animal-tracking data reveal ecological significance of endothermy in fishes

PubMed Central

Watanabe, Yuuki Y.; Goldman, Kenneth J.; Caselle, Jennifer E.; Chapman, Demian D.; Papastamatiou, Yannis P.

2015-01-01

Despite long evolutionary separations, several sharks and tunas share the ability to maintain slow-twitch, aerobic red muscle (RM) warmer than ambient water. Proximate causes of RM endothermy are well understood, but ultimate causes are unclear. Two advantages often proposed are thermal niche expansion and elevated cruising speeds. The thermal niche hypothesis is generally supported, because fishes with RM endothermy often exhibit greater tolerance to broad temperature ranges. In contrast, whether fishes with RM endothermy cruise faster, and achieve any ecological benefits from doing so, remains unclear. Here, we compiled data recorded by modern animal-tracking tools for a variety of free-swimming marine vertebrates. Using phylogenetically informed allometry, we show that both cruising speeds and maximum annual migration ranges of fishes with RM endothermy are 2–3 times greater than fishes without it, and comparable to nonfish endotherms (i.e., penguins and marine mammals). The estimated cost of transport of fishes with RM endothermy is twice that of fishes without it. We suggest that the high energetic cost of RM endothermy in fishes is offset by the benefit of elevated cruising speeds, which not only increase prey encounter rates, but also enable larger-scale annual migrations and potentially greater access to seasonally available resources. PMID:25902489

Conservative whole-organ scaling contrasts with highly labile suborgan scaling differences among compound eyes of closely related Formica ants.

PubMed

Perl, Craig D; Rossoni, Sergio; Niven, Jeremy E

2017-03-01

Static allometries determine how organ size scales in relation to body mass. The extent to which these allometric relationships are free to evolve, and how they differ among closely related species, has been debated extensively and remains unclear; changes in intercept appear common, but changes in slope are far rarer. Here, we compare the scaling relationships that govern the structure of compound eyes of four closely related ant species from the genus Formica . Comparison among these species revealed changes in intercept but not slope in the allometric scaling relationships governing eye area, facet number, and mean facet diameter. Moreover, the scaling between facet diameter and number was conserved across all four species. In contrast, facet diameters from distinct regions of the compound eye differed in both intercept and slope within a single species and when comparing homologous regions among species. Thus, even when species are conservative in the scaling of whole organs, they can differ substantially in regional scaling within organs. This, at least partly, explains how species can produce organs that adhere to genus wide scaling relationships while still being able to invest differentially in particular regions of organs to produce specific features that match their ecology.

Nonhuman Primate Ocular Biometry

PubMed Central

Augusteyn, Robert C.; Maceo Heilman, Bianca; Ho, Arthur; Parel, Jean-Marie

2016-01-01

Purpose To examine ocular growth in nonhuman primates (NHPs) from measurements on ex vivo eyes. Methods We obtained NHP eyes from animals that had been killed as part of other studies or because of health-related issues. Digital calipers were used to measure the horizontal, vertical, and anteroposterior globe diameters as well as corneal horizontal and vertical diameters of excised globes from 98 hamadryas baboons, 551 cynomolgus monkeys, and 112 rhesus monkeys, at ages ranging from 23 to 360 months. Isolated lens sagittal thickness and equatorial diameter were measured by shadowphotogrammetry. Wet and fixed dry weights were obtained for lenses. Results Nonhuman primate globe growth continues throughout life, slowing toward an asymptotic maximum. The final globe size scales with negative allometry to adult body size. Corneal growth ceases at around 20 months. Lens diameter increases but thickness decreases with increasing age. Nonhuman primate lens wet and dry weight accumulation is monophasic, continuing throughout life toward asymptotic maxima. The dry/wet weight ratio reaches a maximum of 0.33. Conclusions Nonhuman primate ocular globe and lens growth differ in several respects from those in humans. Although age-related losses of lens power and accommodative amplitude are similar, lens growth and properties are different indicating care should be taken in extrapolating NHP observations to the study of human accommodation. PMID:26780314

Cranial shape evolution in adaptive radiations of birds: comparative morphometrics of Darwin's finches and Hawaiian honeycreepers

PubMed Central

Tokita, Masayoshi; Yano, Wataru; James, Helen F.

2017-01-01

Adaptive radiation is the rapid evolution of morphologically and ecologically diverse species from a single ancestor. The two classic examples of adaptive radiation are Darwin's finches and the Hawaiian honeycreepers, which evolved remarkable levels of adaptive cranial morphological variation. To gain new insights into the nature of their diversification, we performed comparative three-dimensional geometric morphometric analyses based on X-ray microcomputed tomography (µCT) scanning of dried cranial skeletons. We show that cranial shapes in both Hawaiian honeycreepers and Coerebinae (Darwin's finches and their close relatives) are much more diverse than in their respective outgroups, but Hawaiian honeycreepers as a group display the highest diversity and disparity of all other bird groups studied. We also report a significant contribution of allometry to skull shape variation, and distinct patterns of evolutionary change in skull morphology in the two lineages of songbirds that underwent adaptive radiation on oceanic islands. These findings help to better understand the nature of adaptive radiations in general and provide a foundation for future investigations on the developmental and molecular mechanisms underlying diversification of these morphologically distinguished groups of birds. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’. PMID:27994122

Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates

PubMed Central

Glazier, Douglas S.; Hirst, Andrew G.; Atkinson, David

2015-01-01

Metabolism fuels all biological activities, and thus understanding its variation is fundamentally important. Much of this variation is related to body size, which is commonly believed to follow a 3/4-power scaling law. However, during ontogeny, many kinds of animals and plants show marked shifts in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR < 1), or the reverse, are associated with significant changes in body shape (indexed by bL = the scaling exponent of the relationship between body mass and body length). The observed inverse correlations between bR and bL are predicted by metabolic scaling theory that emphasizes resource/waste fluxes across external body surfaces, but contradict theory that emphasizes resource transport through internal networks. Geometric estimates of the scaling of surface area (SA) with body mass (bA) further show that ontogenetic shifts in bR and bA are positively correlated. These results support new metabolic scaling theory based on SA influences that may be applied to ontogenetic shifts in bR shown by many kinds of animals and plants. PMID:25652833

Comparative height crown allometry and mechanical design in 22 tree species of Kuala Belalong rainforest, Brunei, Borneo.

PubMed

Osunkoya, Olusegun O; Omar-Ali, Kharunnisa; Amit, Norratna; Dayan, Juita; Daud, Dayanawati S; Sheng, Tan K

2007-12-01

In rainforests, trunk size, strength, crown position, and geometry of a tree affect light interception and the likelihood of mechanical failure. Allometric relationships of tree diameter, wood density, and crown architecture vs. height are described for a diverse range of rainforest trees in Brunei, northern Borneo. The understory species follow a geometric model in their diameter-height relationship (slope, β = 1.08), while the stress-elasticity models prevail (β = 1.27-1.61) for the midcanopy and canopy/emergent species. These relationships changed with ontogeny, especially for the understory species. Within species, the tree stability safety factor (SSF) and relative crown width decreased exponentially with increasing tree height. These trends failed to emerge in across-species comparisons and were reversed at a common (low) height. Across species, the relative crown depth decreased with maximum potential height and was indistinguishable at a common (low) height. Crown architectural traits influence SSF more than structural property of wood density. These findings emphasize the importance of applying a common reference size in comparative studies and suggest that forest trees (especially the understory group) may adapt to low light by having deeper rather than wider crowns due to an efficient distribution and geometry of their foliage.

The Fat-Dachsous signaling pathway regulates growth of horns in Trypoxylus dichotomus, but does not affect horn allometry.

PubMed

Hust, James; Lavine, Mark D; Worthington, Amy M; Zinna, Robert; Gotoh, Hiroki; Niimi, T; Lavine, Laura

Males of the Asian rhinoceros beetle, Trypoxylus dichotomus, possess exaggerated head and thoracic horns that scale dramatically out of proportion to body size. While studies of insulin signaling suggest that this pathway regulates nutrition-dependent growth including exaggerated horns, what regulates disproportionate growth has yet to be identified. The Fat signaling pathway is a potential candidate for regulating disproportionate growth of sexually-selected traits, a hypothesis we advanced in a previous paper (Gotoh et al., 2015). To investigate the role of Fat signaling in the growth and scaling of the sexually dimorphic, condition-dependent traits of the in the Asian rhinoceros beetle T. dichotomus, we used RNA interference to knock down expression of fat and its co-receptor dachsous. Knockdown of fat, and to a lesser degree dachsous, caused shortening and widening of appendages, including the head and thoracic horns. However, scaling of horns to body size was not affected. Our results show that Fat signaling regulates horn growth in T. dichotomus as it does in appendage growth in other insects. However, we provide evidence that Fat signaling does not mediate the disproportionate, positive allometric growth of horns in T. dichotomus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Patterns of trunk spine growth in two congeneric species of acanthocephalan: investment in attachment may differ between sexes and species.

PubMed

Hernández-Orts, Jesús S; Timi, Juan T; Raga, Juan A; García-Varela, M; Crespo, Enrique A; Aznar, Francisco J

2012-06-01

Acanthocephalans have evolved a hooked proboscis and some taxa have trunk spines to attach to their definitive hosts. These structures are generated before being used, thus a key question is how investment in attachment could optimally be allocated through the ontogeny. The number and arrangement of hooks and spines are never modified in the definitive host, but it is unclear whether these structures grow during adult development. A comparison of the size of trunk spines between cystacanths and adults of Corynosoma cetaceum and C. australe indicated that spines grow in both species, but only in females, which also had significantly larger spines than males. This sexual dimorphism did not result from pure allometry because the body of females was smaller, and did not grow more than that of males. However, having a longer lifespan, females would need to withstand the extreme flow conditions prevailing in marine mammals for longer, inducing different investment and development schedules for spines. Patterns of spine growth also differed between species: fore-trunk spines grew in both species, but hind-trunk spines did only in C. cetaceum. In conclusion, investment strategies on attachment may differ, not only between congeneric species of acanthocephalan, but also between sexes of the same species.

Cope's Rule and the Universal Scaling Law of Ornament Complexity.

PubMed

Raia, Pasquale; Passaro, Federico; Carotenuto, Francesco; Maiorino, Leonardo; Piras, Paolo; Teresi, Luciano; Meiri, Shai; Itescu, Yuval; Novosolov, Maria; Baiano, Mattia Antonio; Martínez, Ricard; Fortelius, Mikael

2015-08-01

Luxuriant, bushy antlers, bizarre crests, and huge, twisting horns and tusks are conventionally understood as products of sexual selection. This view stems from both direct observation and from the empirical finding that the size of these structures grows faster than body size (i.e., ornament size shows positive allometry). We contend that the familiar evolutionary increase in the complexity of ornaments over time in many animal clades is decoupled from ornament size evolution. Increased body size comes with extended growth. Since growth scales to the quarter power of body size, we predicted that ornament complexity should scale according to the quarter power law as well, irrespective of the role of sexual selection in the evolution and function of the ornament. To test this hypothesis, we selected three clades (ammonites, deer, and ceratopsian dinosaurs) whose species bore ornaments that differ in terms of the importance of sexual selection to their evolution. We found that the exponent of the regression of ornament complexity to body size is the same for the three groups and is statistically indistinguishable from 0.25. We suggest that the evolution of ornament complexity is a by-product of Cope's rule. We argue that although sexual selection may control size in most ornaments, it does not influence their shape.

Volitional exaggeration of body size through fundamental and formant frequency modulation in humans

PubMed Central

Pisanski, Katarzyna; Mora, Emanuel C.; Pisanski, Annette; Reby, David; Sorokowski, Piotr; Frackowiak, Tomasz; Feinberg, David R.

2016-01-01

Several mammalian species scale their voice fundamental frequency (F0) and formant frequencies in competitive and mating contexts, reducing vocal tract and laryngeal allometry thereby exaggerating apparent body size. Although humans’ rare capacity to volitionally modulate these same frequencies is thought to subserve articulated speech, the potential function of voice frequency modulation in human nonverbal communication remains largely unexplored. Here, the voices of 167 men and women from Canada, Cuba, and Poland were recorded in a baseline condition and while volitionally imitating a physically small and large body size. Modulation of F0, formant spacing (∆F), and apparent vocal tract length (VTL) were measured using Praat. Our results indicate that men and women spontaneously and systemically increased VTL and decreased F0 to imitate a large body size, and reduced VTL and increased F0 to imitate small size. These voice modulations did not differ substantially across cultures, indicating potentially universal sound-size correspondences or anatomical and biomechanical constraints on voice modulation. In each culture, men generally modulated their voices (particularly formants) more than did women. This latter finding could help to explain sexual dimorphism in F0 and formants that is currently unaccounted for by sexual dimorphism in human vocal anatomy and body size. PMID:27687571

A macroevolutionary explanation for energy equivalence in the scaling of body size and population density.

PubMed

Damuth, John

2007-05-01

Across a wide array of animal species, mean population densities decline with species body mass such that the rate of energy use of local populations is approximately independent of body size. This "energetic equivalence" is particularly evident when ecological population densities are plotted across several or more orders of magnitude in body mass and is supported by a considerable body of evidence. Nevertheless, interpretation of the data has remained controversial, largely because of the difficulty of explaining the origin and maintenance of such a size-abundance relationship in terms of purely ecological processes. Here I describe results of a simulation model suggesting that an extremely simple mechanism operating over evolutionary time can explain the major features of the empirical data. The model specifies only the size scaling of metabolism and a process where randomly chosen species evolve to take resource energy from other species. This process of energy exchange among particular species is distinct from a random walk of species abundances and creates a situation in which species populations using relatively low amounts of energy at any body size have an elevated extinction risk. Selective extinction of such species rapidly drives size-abundance allometry in faunas toward approximate energetic equivalence and maintains it there.

Sex-related differences in foot shape.

PubMed

Krauss, I; Grau, S; Mauch, M; Maiwald, C; Horstmann, T

2008-11-01

The purpose of the study was to investigate sex-related differences in foot morphology. In total, 847 subjects were scanned using a 3-D-footscanner. Three different analysis methods were used: (1) comparisons were made for absolute foot measures within 250-270 mm foot length (FL); (2) and for averaged measures (% FL) across all sizes; (3) the feet were then classified using a cluster analysis. Within 250-270 mm FL, male feet were wider and higher (mean differences (MD) 1.3-5.9 mm). No relevant sex-related differences could be found in the comparison of averaged measures (MD 0.3-0.6% FL). Foot types were categorised into voluminous, flat-pointed and slender. Shorter feet were more often voluminous, longer feet were more likely to be narrow and flat. However, the definition of 'short' and 'long' was sex-related; thus, allometry of foot measures was different. For shoe design, measures should be derived for each size and sex separately. Different foot types should be considered to account for the variety in foot shape. Improper footwear can cause foot pain and deformity. Therefore, knowledge of sex-related differences in foot measures is important to assist proper shoe fit in both men and women. The present study supplements the field of knowledge within this context with recommendations for the manufacturing of shoes.

Morphometric relations in the grey eel catfish Plotosus canius in the coastal waters of Port Dickson, Peninsular Malaysia.

PubMed

Usman, B I; Amin, S M N; Arshad, A; Kamarudin, M S

2016-07-01

Samples of grey eel catfish Plotosus canius were collected from the coastal waters of Port Dickson, Malaysia from January to December, 2012. A total of 341 specimens (172 males and 169 females) were used to estimate the length-weight relationship parameters. Mean population size of females were 0.72 cm taller than the males, however difference was not significant (t-test, P > 0.05). The overall relationship equations between total length (TL) and body weight (BW) were established for males as Log TW = 2.71 Log TL - 1.85 (R2 = 0.95) and for females as Log TW = 2.88 Log TL-2.10 (R2 = 0.95). The estimated relative growth co-efficient (b) values were 2.71 for males and 2.88 for females. It is revealed that growth pattern of the species showed negative allometry. In both males and females, relationship between TL and SL gave highest regression coefficient (0.99). While relationship between TL and EL gave lowest regression coefficient in both males and females (0.87 and 0.81 respectively). The findings from this study contributed first information on morphometric relations of the fish from Malaysian coastal waters and could be useful for sustainable management options of P. canius in Malaysia.

Craniofacial variation and dietary adaptations of African colobines.

PubMed

Koyabu, Daisuke B; Endo, Hideki

2009-06-01

African colobine monkeys show considerable craniofacial variation among species, although the evolutionary causes of this diversity are unclear. In light of growing evidence that diet varies considerably among colobine species, we investigated whether colobine craniofacial morphology varies as a function of their diet. We compared craniofacial morphology among five African species: Colobus angolensis, C. guereza, C. polykomos, Piliocolobus badius, and P. verus. Matrix correlation analysis indicated a significant correlation between species-specific morphological distance and dietary distance matrices. The mechanical advantage of the masseter muscle was higher in seed-eaters (C. angolensis and C. polykomos) and lower in those that eat mainly young leaves (C. guereza, P. badius, and P. verus). Canonical correspondence analysis revealed that the durophagous colobines possess relatively wider bigonial breadths, anteroposteriorly shorter faces, shorter postcanine tooth rows, more medially positioned dental batteries, wider bizygomatic arches, and anteroposteriorly longer zygomatic arches. Under the constrained lever model, these morphological features suggest that durophagous colobines have the capacity to generate relatively greater maximum bite forces. However, no consistent relationship was observed between diet and variation in the mandibular corpus and symphysis, implying that robust mandibles are not necessarily adaptations for stress resistance. Factors that may influence mandibular robusticity include allometry of symphyseal curvature and canine tooth support. Finally, linear measures of mandibular robusticity may suffer from error.

Shell shape variation of queen conch Strombus gigas (Mesograstropoda: Strombidae) from Southwest Caribbean.

PubMed

Márquez, Edna Judith; Restrepo-Escobar, Natalia; Montoya-Herrera, Francisco Luis

2016-12-01

The endangered species Strombus gigas is a marine gastropod of significant economic importance through the Greater Caribbean region. In contrast to phenotypic plasticity, the role of genetics on shell variations in S. gigas has not been addressed so far, despite its importance in evolution, management and conservation of this species. This work used geometric morphometrics to investigate the phenotypic variation of 219 shells of S. gigas from eight sites of the Colombian Southwest Caribbean. Differences in mean size between sexes and among sites were contrasted by analysis of variance. Allometry was tested by multivariate regression and the hypothesis of common slope was contrasted by covariance multivariate analysis. Differences in the shell shape among sites were analyzed by principal component analysis. Sexual size dimorphism was not significant, whereas sexual shape dimorphism was significant and variable across sites. Differences in the shell shape among sites were concordant with genetic differences based on microsatellite data, supporting its genetic background. Besides, differences in the shell shape between populations genetically similar suggest a role of phenotypic plasticity in the morphometric variation of the shell shape. These outcomes evidence the role of genetic background and phenotypic plasticity in the shell shape of S. gigas. Thus, geometric morphometrics of shell shape may constitute a complementary tool to explore the genetic diversity of this species.

Theophylline Population Pharmacokinetics and Dosing in Children Following Congenital Heart Surgery With Cardiopulmonary Bypass.

PubMed

Frymoyer, Adam; Su, Felice; Grimm, Paul C; Sutherland, Scott M; Axelrod, David M

2016-09-01

Children undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) frequently develop acute kidney injury due to renal ischemia. Theophylline, which improves renal perfusion via adenosine receptor inhibition, is a potential targeted therapy. However, children undergoing cardiac surgery and CPB commonly have alterations in drug pharmacokinetics. To help understand optimal aminophylline (salt formulation of theophylline) dosing strategies in this population, a population-based pharmacokinetic model was developed using nonlinear mixed-effects modeling (NONMEM) from 71 children (median age 5 months; 90% range 1 week to 10 years) who underwent cardiac surgery requiring CPB and received aminophylline as part of a previous randomized controlled trial. A 1-compartment model with linear elimination adequately described the pharmacokinetics of theophylline. Weight scaled via allometry was a significant predictor of clearance and volume. In addition, allometric scaled clearance increased with age implemented as a power maturation function. Compared to prior reports in noncardiac children, theophylline clearance was markedly reduced across age. In the final population pharmacokinetic model, optimized empiric dosing regimens were developed via Monte Carlo simulations. Doses 50% to 75% lower than those recommended in noncardiac children were needed to achieve target serum concentrations of 5 to 10 mg/L. © 2016, The American College of Clinical Pharmacology.

δ18O of apatite phosphate in small pelagic fish: insights from wild-caught and tank-grown specimens

NASA Astrophysics Data System (ADS)

Lambert, T.; Javor, B.; Paytan, A.

2011-12-01

Oxygen isotope ratios of mineralized structures in fish reflect the temperature and isotopic composition of the water in which they grow. For bulk samples (e.g., whole scales, bones, and otoliths), understanding how this signal is integrated across time and space is critical, especially for organisms exposed to high variability in growth conditions. Here, we assess the response of fish scale δ18O (from apatite phosphate) to experimentally manipulated water conditions. Wild-caught sardines were grown at controlled temperatures (13°C, 17°C, and 21°C) for 11 months. Higher growth temperatures correlated to lower δ18O values, representing a combination of scale apatite deposited before and after the temperature manipulation. Models that account for both biomineral allometry and exposure to varying water properties (e.g., by overlaying migration routes, isoscapes, and temperature maps) have the potential to quantify the varying contributions of minerals grown under different conditions. We use this method to predict δ18O of apatite phosphate for small pelagic fish found in California coastal waters, then compare expected values to those obtained from collected samples. Since phosphate oxygen is relatively resistant to diagenesis, this modern calibration establishes a framework for paleo studies.

Allometric biomass partitioning under nitrogen enrichment: Evidence from manipulative experiments around the world.

PubMed

Peng, Yunfeng; Yang, Yuanhe

2016-06-28

Allometric and optimal hypotheses have been widely used to explain biomass partitioning in response to resource changes for individual plants; however, little evidence has been reported from measurements at the community level across a broad geographic scale. This study assessed the nitrogen (N) effect on community-level root to shoot (R/S) ratios and biomass partitioning functions by synthesizing global manipulative experiments. Results showed that, in aggregate, N addition decreased the R/S ratios in various biomes. However, the scaling slopes of the allometric equations were not significantly altered by the N enrichment, possibly indicating that N-induced reduction of the R/S ratio is a consequence of allometric allocation as a function of increasing plant size rather than an optimal partitioning model. To further illustrate this point, we developed power function models to explore the relationships between aboveground and belowground biomass for various biomes; then, we generated the predicted root biomass from the observed shoot biomass and predicted R/S ratios. The comparison of predicted and observed N-induced changes of the R/S ratio revealed no significant differences between each other, supporting the allometric allocation hypothesis. These results suggest that allometry, rather than optimal allocation, explains the N-induced reduction in the R/S ratio across global biomes.

Chewing on the trees: Constraints and adaptation in the evolution of the primate mandible.

PubMed

Meloro, Carlo; Cáceres, Nilton Carlos; Carotenuto, Francesco; Sponchiado, Jonas; Melo, Geruza Leal; Passaro, Federico; Raia, Pasquale

2015-07-01

Chewing on different food types is a demanding biological function. The classic assumption in studying the shape of feeding apparatuses is that animals are what they eat, meaning that adaptation to different food items accounts for most of their interspecific variation. Yet, a growing body of evidence points against this concept. We use the primate mandible as a model structure to investigate the complex interplay among shape, size, diet, and phylogeny. We find a weak but significant impact of diet on mandible shape variation in primates as a whole but not in anthropoids and catarrhines as tested in isolation. These clades mainly exhibit allometric shape changes, which are unrelated to diet. Diet is an important factor in the diversification of strepsirrhines and platyrrhines and a phylogenetic signal is detected in all primate clades. Peaks in morphological disparity occur during the Oligocene (between 37 and 25 Ma) supporting the notion that an adaptive radiation characterized the evolution of South American monkeys. In all primate clades, the evolution of mandible size is faster than its shape pointing to a strong effect of allometry on ecomorphological diversification in this group. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Allometric relationships among body mass, MUZZLE-tail length, and tibia length during the growth of Wistar rats.

PubMed

Santiago, Hildemberg Agostinho Rocha de; De Pierro, Lucas Rodolfo; Reis, Rafael Menezes; Caluz, Antônio Gabriel Ricardo Engracia; Ribeiro, Victor Barbosa; Volpon, José Batista

2015-11-01

To investigate allometric relationships among body mass (BM), muzzle-tail length (MTL), and tibia length (TL) in Wistar rats and establish their growth rate change parameters. Eighteen male and 18 female Wistar rats were studied from the 3rd to the 21st week of age. BM, MTL, and TL were measured daily, and relative growth was compared using allometry. A positive correlation between BM and MTL (p<0.05) and BM and TL (p<0.05) was observed. Males and females showed comparable curves; however, females had turning points at a younger age. The allometric relationship between BM and MTL presented a regular increase until reaching a mass of 351 g (males) and 405 g (females). BM and TL showed an initial increase until 185 g (males) and 182 g (females), and then reached a plateau that finished at 412 g (males) and 334 g (females), to display another increase. The allometric relationship of body mass with animal length and tibia length was comparable for male and female rats, with female rats maturing earlier. Animal longitudinal growth occurred in a single stage. In contrast, tibia length depicted two stages of accelerated growth with an intermediate period of deceleration.

Quantitative assessment of human body shape using Fourier analysis

NASA Astrophysics Data System (ADS)

Friess, Martin; Rohlf, F. J.; Hsiao, Hongwei

2004-04-01

Fall protection harnesses are commonly used to reduce the number and severity of injuries. Increasing the efficiency of harness design requires the size and shape variation of the user population to be assessed as detailed and as accurately as possible. In light of the unsatisfactory performance of traditional anthropometry with respect to such assessments, we propose the use of 3D laser surface scans of whole bodies and the statistical analysis of elliptic Fourier coefficients. Ninety-eight male and female adults were scanned. Key features of each torso were extracted as a 3D curve along front, back and the thighs. A 3D extension of Elliptic Fourier analysis4 was used to quantify their shape through multivariate statistics. Shape change as a function of size (allometry) was predicted by regressing the coefficients onto stature, weight and hip circumference. Upper and lower limits of torso shape variation were determined and can be used to redefine the design of the harness that will fit most individual body shapes. Observed allometric changes are used for adjustments to the harness shape in each size. Finally, the estimated outline data were used as templates for a free-form deformation of the complete torso surface using NURBS models (non-uniform rational B-splines).

Development of facial sexual dimorphism in children aged between 12 and 15 years: a three-dimensional longitudinal study.

PubMed

Koudelová, J; Brůžek, J; Cagáňová, V; Krajíček, V; Velemínská, J

2015-08-01

To evaluate sexual dimorphism of facial form and shape and to describe differences between the average female and male face from 12 to 15 years. Overall 120 facial scans from healthy Caucasian children (17 boys, 13 girls) were longitudinally evaluated over a 4-year period between the ages of 12 and 15 years. Facial surface scans were obtained using a three-dimensional optical scanner Vectra-3D. Variation in facial shape and form was evaluated using geometric morphometric and statistical methods (DCA, PCA and permutation test). Average faces were superimposed, and the changes were evaluated using colour-coded maps. There were no significant sex differences (p > 0.05) in shape in any age category and no differences in form in the 12- and 13-year-olds, as the female faces were within the area of male variability. From the age of 14, a slight separation occurred, which was statistically confirmed. The differences were mainly associated with size. Generally boys had more prominent eyebrow ridges, more deeply set eyes, a flatter cheek area, and a more prominent nose and chin area. The development of facial sexual dimorphism during pubertal growth is connected with ontogenetic allometry. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A general model for the scaling of offspring size and adult size.

PubMed

Falster, Daniel S; Moles, Angela T; Westoby, Mark

2008-09-01

Understanding evolutionary coordination among different life-history traits is a key challenge for ecology and evolution. Here we develop a general quantitative model predicting how offspring size should scale with adult size by combining a simple model for life-history evolution with a frequency-dependent survivorship model. The key innovation is that larger offspring are afforded three different advantages during ontogeny: higher survivorship per time, a shortened juvenile phase, and advantage during size-competitive growth. In this model, it turns out that size-asymmetric advantage during competition is the factor driving evolution toward larger offspring sizes. For simplified and limiting cases, the model is shown to produce the same predictions as the previously existing theory on which it is founded. The explicit treatment of different survival advantages has biologically important new effects, mainly through an interaction between total maternal investment in reproduction and the duration of competitive growth. This goes on to explain alternative allometries between log offspring size and log adult size, as observed in mammals (slope = 0.95) and plants (slope = 0.54). Further, it suggests how these differences relate quantitatively to specific biological processes during recruitment. In these ways, the model generalizes across previous theory and provides explanations for some differences between major taxa.

Final Harvest of Above-Ground Biomass and Allometric Analysis of the Aspen FACE Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mark E. Kubiske

The Aspen FACE experiment, located at the US Forest Service Harshaw Research Facility in Oneida County, Wisconsin, exposes the intact canopies of model trembling aspen forests to increased concentrations of atmospheric CO2 and O3. The first full year of treatments was 1998 and final year of elevated CO2 and O3 treatments is scheduled for 2009. This proposal is to conduct an intensive, analytical harvest of the above-ground parts of 24 trees from each of the 12, 30 m diameter treatment plots (total of 288 trees) during June, July & August 2009. This above-ground harvest will be carefully coordinated with themore » below-ground harvest proposed by D.F. Karnosky et al. (2008 proposal to DOE). We propose to dissect harvested trees according to annual height growth increment and organ (main stem, branch orders, and leaves) for calculation of above-ground biomass production and allometric comparisons among aspen clones, species, and treatments. Additionally, we will collect fine root samples for DNA fingerprinting to quantify biomass production of individual aspen clones. This work will produce a thorough characterization of above-ground tree and stand growth and allocation above ground, and, in conjunction with the below ground harvest, total tree and stand biomass production, allocation, and allometry.« less

Structure and function of bordered pits: new discoveries and impacts on whole-plant hydraulic function.

PubMed

Choat, Brendan; Cobb, Alexander R; Jansen, Steven

2008-01-01

Bordered pits are cavities in the lignified cell walls of xylem conduits (vessels and tracheids) that are essential components in the water-transport system of higher plants. The pit membrane, which lies in the center of each pit, allows water to pass between xylem conduits but limits the spread of embolism and vascular pathogens in the xylem. Averaged across a wide range of species, pits account for > 50% of total xylem hydraulic resistance, indicating that they are an important factor in the overall hydraulic efficiency of plants. The structure of pits varies dramatically across species, with large differences evident in the porosity and thickness of pit membranes. Because greater porosity reduces hydraulic resistance but increases vulnerability to embolism, differences in pit structure are expected to correlate with trade-offs between efficiency and safety of water transport. However, trade-offs in hydraulic function are influenced both by pit-level differences in structure (e.g. average porosity of pit membranes) and by tissue-level changes in conduit allometry (average length, diameter) and the total surface area of pit membranes that connects vessels. In this review we address the impact of variation in pit structure on water transport in plants from the level of individual pits to the whole plant.

Optimal allocation of leaf epidermal area for gas exchange.

PubMed

de Boer, Hugo J; Price, Charles A; Wagner-Cremer, Friederike; Dekker, Stefan C; Franks, Peter J; Veneklaas, Erik J

2016-06-01

A long-standing research focus in phytology has been to understand how plants allocate leaf epidermal space to stomata in order to achieve an economic balance between the plant's carbon needs and water use. Here, we present a quantitative theoretical framework to predict allometric relationships between morphological stomatal traits in relation to leaf gas exchange and the required allocation of epidermal area to stomata. Our theoretical framework was derived from first principles of diffusion and geometry based on the hypothesis that selection for higher anatomical maximum stomatal conductance (gsmax ) involves a trade-off to minimize the fraction of the epidermis that is allocated to stomata. Predicted allometric relationships between stomatal traits were tested with a comprehensive compilation of published and unpublished data on 1057 species from all major clades. In support of our theoretical framework, stomatal traits of this phylogenetically diverse sample reflect spatially optimal allometry that minimizes investment in the allocation of epidermal area when plants evolve towards higher gsmax . Our results specifically highlight that the stomatal morphology of angiosperms evolved along spatially optimal allometric relationships. We propose that the resulting wide range of viable stomatal trait combinations equips angiosperms with developmental and evolutionary flexibility in leaf gas exchange unrivalled by gymnosperms and pteridophytes. © 2016 The Authors New Phytologist © 2016 New Phytologist Trust.

Allometry of wing twist and camber in a flower chafer during free flight: How do wing deformations scale with body size?

PubMed Central

Ribak, Gal

2017-01-01

Intraspecific variation in adult body mass can be particularly high in some insect species, mandating adjustment of the wing's structural properties to support the weight of the larger body mass in air. Insect wings elastically deform during flapping, dynamically changing the twist and camber of the relatively thin and flat aerofoil. We examined how wing deformations during free flight scale with body mass within a species of rose chafers (Coleoptera: Protaetia cuprea) in which individuals varied more than threefold in body mass (0.38–1.29 g). Beetles taking off voluntarily were filmed using three high-speed cameras and the instantaneous deformation of their wings during the flapping cycle was analysed. Flapping frequency decreased in larger beetles but, otherwise, flapping kinematics remained similar in both small and large beetles. Deflection of the wing chord-wise varied along the span, with average deflections at the proximal trailing edge higher by 0.2 and 0.197 wing lengths compared to the distal trailing edge in the downstroke and the upstroke, respectively. These deflections scaled with wing chord to the power of 1.0, implying a constant twist and camber despite the variations in wing and body size. This suggests that the allometric growth in wing size includes adjustment of the flexural stiffness of the wing structure to preserve wing twist and camber during flapping. PMID:29134103

Allometry of wing twist and camber in a flower chafer during free flight: How do wing deformations scale with body size?

PubMed

Meresman, Yonatan; Ribak, Gal

2017-10-01

Intraspecific variation in adult body mass can be particularly high in some insect species, mandating adjustment of the wing's structural properties to support the weight of the larger body mass in air. Insect wings elastically deform during flapping, dynamically changing the twist and camber of the relatively thin and flat aerofoil. We examined how wing deformations during free flight scale with body mass within a species of rose chafers (Coleoptera: Protaetia cuprea ) in which individuals varied more than threefold in body mass (0.38-1.29 g). Beetles taking off voluntarily were filmed using three high-speed cameras and the instantaneous deformation of their wings during the flapping cycle was analysed. Flapping frequency decreased in larger beetles but, otherwise, flapping kinematics remained similar in both small and large beetles. Deflection of the wing chord-wise varied along the span, with average deflections at the proximal trailing edge higher by 0.2 and 0.197 wing lengths compared to the distal trailing edge in the downstroke and the upstroke, respectively. These deflections scaled with wing chord to the power of 1.0, implying a constant twist and camber despite the variations in wing and body size. This suggests that the allometric growth in wing size includes adjustment of the flexural stiffness of the wing structure to preserve wing twist and camber during flapping.

Energetic benefits and adaptations in mammalian limbs: Scale effects and selective pressures.

PubMed

Kilbourne, Brandon M; Hoffman, Louwrens C

2015-06-01

Differences in limb size and shape are fundamental to mammalian morphological diversity; however, their relevance to locomotor costs has long been subject to debate. In particular, it remains unknown if scale effects in whole limb morphology could partially underlie decreasing mass-specific locomotor costs with increasing limb length. Whole fore- and hindlimb inertial properties reflecting limb size and shape-moment of inertia (MOI), mass, mass distribution, and natural frequency-were regressed against limb length for 44 species of quadrupedal mammals. Limb mass, MOI, and center of mass position are negatively allometric, having a strong potential for lowering mass-specific locomotor costs in large terrestrial mammals. Negative allometry of limb MOI results in a 40% reduction in MOI relative to isometry's prediction for our largest sampled taxa. However, fitting regression residuals to adaptive diversification models reveals that codiversification of limb mass, limb length, and body mass likely results from selection for differing locomotor modes of running, climbing, digging, and swimming. The observed allometric scaling does not result from selection for energetically beneficial whole limb morphology with increasing size. Instead, our data suggest that it is a consequence of differing morphological adaptations and body size distributions among quadrupedal mammals, highlighting the role of differing limb functions in mammalian evolution. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Hybridization and adaptation to introduced balloon vines in an Australian soapberry bug.

PubMed

Andres, J A; Thampy, P R; Mathieson, M T; Loye, J; Zalucki, M P; Dingle, H; Carroll, S P

2013-12-01

Contemporary adaptation of plant feeding insects to introduced hosts provides clear cases of ecologically based population divergence. In most cases the mechanisms permitting rapid differentiation are not well known. Here we study morphological and genetic variation associated with recent shifts by the Australian soapberry bug Leptocoris tagalicus onto two naturalized Neotropical balloon vines, Cardiospermum halicacabum and C. grandiflorum that differ in time since introduction. Our results show that these vines have much larger fruits than the native hosts (Whitewood tree -Atalaya hemiglauca- and Woolly Rambutan -Alectryon tomentosus-) and that bugs living on them have evolved significantly longer beaks and new allometries. Genetic analyses of mitochondrial haplotypes and amplified fragment length polymorphic (AFLP) markers indicate that the lineage of bugs on the annual vine C. halicacabum, the older introduction, is intermediate between the two subspecies of L. tagalicus found on native hosts. Moreover, where the annual vine and Whitewood tree co-occur, the morphology and genomic composition of the bugs are similar to those occurring in allopatry. These results show that hybridization provided the genetic elements underlying the strongly differentiated 'Halicacabum bugs'. In contrast, the bugs feeding on the recently introduced perennial balloon vine (C. grandiflorum) showed no evidence of admixture, and are genetically indistinguishable from the nearby populations on a native host. © 2013 John Wiley & Sons Ltd.

Modelling Size Structured Food Webs Using a Modified Niche Model with Two Predator Traits

PubMed Central

Klecka, Jan

2014-01-01

The structure of food webs is frequently described using phenomenological stochastic models. A prominent example, the niche model, was found to produce artificial food webs resembling real food webs according to a range of summary statistics. However, the size structure of food webs generated by the niche model and real food webs has not yet been rigorously compared. To fill this void, I use a body mass based version of the niche model and compare prey-predator body mass allometry and predator-prey body mass ratios predicted by the model to empirical data. The results show that the model predicts weaker size structure than observed in many real food webs. I introduce a modified version of the niche model which allows to control the strength of size-dependence of predator-prey links. In this model, optimal prey body mass depends allometrically on predator body mass and on a second trait, such as foraging mode. These empirically motivated extensions of the model allow to represent size structure of real food webs realistically and can be used to generate artificial food webs varying in several aspects of size structure in a controlled way. Hence, by explicitly including the role of species traits, this model provides new opportunities for simulating the consequences of size structure for food web dynamics and stability. PMID:25119999

Preliminary shape analysis of the outline of the baropodometric foot: patterns of covariation, allometry, sex and age differences, and loading variations.

PubMed

Bruner, E; Mantini, S; Guerrini, V; Ciccarelli, A; Giombini, A; Borrione, P; Pigozzi, F; Ripani, M

2009-09-01

Baropodometrical digital techniques map the pressures exerted on the foot plant during both static and dynamic loadings. The study of the distribution of such pressures makes it possible to evaluate the postural and locomotory biomechanics together with its pathological variations. This paper is aimed at evaluating the integration between baropodometric analysis (pressure distribution) and geometrical models (shape of the footprints), investigating the pattern of variation associated with normal plantar morphology. The sample includes 91 individuals (47 males, 44 females), ranging from 5 to 85 years of age (mean and standard deviation = 40 + or - 24).The first component of variation is largely associated with the breadth of the isthmus, along a continuous gradient of increasing/decreasing flattening of the foot plant. This character being dominant upon the whole set of morphological components even in a non-pathological sample, such multivariate computation may represent a good diagnostic tool to quantify its degree of expression in individual subject or group samples. Sexual differences are not significant, and allometric variations associated with increasing plantar surface or stature are not quantitatively relevant. There are some differences between adult and young individuals, associated in the latter with a widening of the medial and posterior areas. These results provide a geometrical framework of baropodometrical analysis, suggesting possible future applications in diagnosis and basic research.

Mechanics of evolutionary digit reduction in fossil horses (Equidae).

PubMed

McHorse, Brianna K; Biewener, Andrew A; Pierce, Stephanie E

2017-08-30

Digit reduction is a major trend that characterizes horse evolution, but its causes and consequences have rarely been quantitatively tested. Using beam analysis on fossilized centre metapodials, we tested how locomotor bone stresses changed with digit reduction and increasing body size across the horse lineage. Internal bone geometry was captured from 13 fossil horse genera that covered the breadth of the equid phylogeny and the spectrum of digit reduction and body sizes, from Hyracotherium to Equus To account for the load-bearing role of side digits, a novel, continuous measure of digit reduction was also established-toe reduction index (TRI). Our results show that without accounting for side digits, three-toed horses as late as Parahippus would have experienced physiologically untenable bone stresses. Conversely, when side digits are modelled as load-bearing, species at the base of the horse radiation through Equus probably maintained a similar safety factor to fracture stress. We conclude that the centre metapodial compensated for evolutionary digit reduction and body mass increases by becoming more resistant to bending through substantial positive allometry in internal geometry. These results lend support to two historical hypotheses: that increasing body mass selected for a single, robust metapodial rather than several smaller ones; and that, as horse limbs became elongated, the cost of inertia from the side toes outweighed their utility for stabilization or load-bearing. © 2017 The Author(s).

Sexual Dimorphism and Allometric Effects Associated With the Wing Shape of Seven Moth Species of Sphingidae (Lepidoptera: Bombycoidea)

PubMed Central

de Camargo, Nícholas Ferreira; Corrêa, Danilo do Carmo Vieira; de Camargo, Amabílio J. Aires; Diniz, Ivone Rezende

2015-01-01

Sexual dimorphism is a pronounced pattern of intraspecific variation in Lepidoptera. However, moths of the family Sphingidae (Lepidoptera: Bombycoidea) are considered exceptions to this rule. We used geometric morphometric techniques to detect shape and size sexual dimorphism in the fore and hindwings of seven hawkmoth species. The shape variables produced were then subjected to a discriminant analysis. The allometric effects were measured with a simple regression between the canonical variables and the centroid size. We also used the normalized residuals to assess the nonallometric component of shape variation with a t-test. The deformations in wing shape between sexes per species were assessed with a regression between the nonreduced shape variables and the residuals. We found sexual dimorphism in both wings in all analyzed species, and that the allometric effects were responsible for much of the wing shape variation between the sexes. However, when we removed the size effects, we observed shape sexual dimorphism. It is very common for females to be larger than males in Lepidoptera, so it is expected that the shape of structures such as wings suffers deformations in order to preserve their function. However, sources of variation other than allometry could be a reflection of different reproductive flight behavior (long flights in search for sexual mates in males, and flight in search for host plants in females). PMID:26206895

Ontogeny of the cranial system in Laonastes aenigmamus

PubMed Central

Herrel, Anthony; Fabre, Anne-Claire; Hugot, Jean-Pierre; Keovichit, Kham; Adriaens, Dominique; Brabant, Loes; Van Hoorebeke, Luc; Cornette, Raphael

2012-01-01

Rodents, together with bats, are among the ecologically most diverse and most speciose groups of mammals. Moreover, rodents show elaborate specializations of the feeding apparatus in response to the predominantly fore-aft movements of the lower jaw. The Laotian rock rat Laonastes aenigmamus was recently discovered and originally thought to belong to a new family. The difficulties in classifying L. aenigmamus based on morphological characters stem from the fact that it presents a mixture of sciurognathous and hystricognathous characteristics, including the morphology of the jaw adductors. The origin of the unusual muscular organization in this species remains, however, unclear. Here, we investigate the development of the masticatory system in Laonastes to better understand the origin of its derived morphology relative to other rodents. Our analyses show that skull and mandible development is characterized by an overall elongation of the snout region. Muscle mass increases with positive allometry during development and growth, and so does the force-generating capacity of the jaw adductor muscles (i.e. physiological cross-sectional area). Whereas fetal crania and musculature are more similar to those of typical rodents, adults diverge in the elongation of the rostral part of the skull and the disproportionate development of the zygomaticomandibularis. Our data suggest a functional signal in the development of the unusual cranial morphology, possibly associated with the folivorous trophic ecology of the species. PMID:22607030

Sheldon spectrum and the plankton paradox: two sides of the same coin-a trait-based plankton size-spectrum model.

PubMed

Cuesta, José A; Delius, Gustav W; Law, Richard

2018-01-01

The Sheldon spectrum describes a remarkable regularity in aquatic ecosystems: the biomass density as a function of logarithmic body mass is approximately constant over many orders of magnitude. While size-spectrum models have explained this phenomenon for assemblages of multicellular organisms, this paper introduces a species-resolved size-spectrum model to explain the phenomenon in unicellular plankton. A Sheldon spectrum spanning the cell-size range of unicellular plankton necessarily consists of a large number of coexisting species covering a wide range of characteristic sizes. The coexistence of many phytoplankton species feeding on a small number of resources is known as the Paradox of the Plankton. Our model resolves the paradox by showing that coexistence is facilitated by the allometric scaling of four physiological rates. Two of the allometries have empirical support, the remaining two emerge from predator-prey interactions exactly when the abundances follow a Sheldon spectrum. Our plankton model is a scale-invariant trait-based size-spectrum model: it describes the abundance of phyto- and zooplankton cells as a function of both size and species trait (the maximal size before cell division). It incorporates growth due to resource consumption and predation on smaller cells, death due to predation, and a flexible cell division process. We give analytic solutions at steady state for both the within-species size distributions and the relative abundances across species.

Scaling and allometry in the building geometries of Greater London

NASA Astrophysics Data System (ADS)

Batty, M.; Carvalho, R.; Hudson-Smith, A.; Milton, R.; Smith, D.; Steadman, P.

2008-06-01

Many aggregate distributions of urban activities such as city sizes reveal scaling but hardly any work exists on the properties of spatial distributions within individual cities, notwithstanding considerable knowledge about their fractal structure. We redress this here by examining scaling relationships in a world city using data on the geometric properties of individual buildings. We first summarise how power laws can be used to approximate the size distributions of buildings, in analogy to city-size distributions which have been widely studied as rank-size and lognormal distributions following Zipf [ Human Behavior and the Principle of Least Effort (Addison-Wesley, Cambridge, 1949)] and Gibrat [ Les Inégalités Économiques (Librarie du Recueil Sirey, Paris, 1931)]. We then extend this analysis to allometric relationships between buildings in terms of their different geometric size properties. We present some preliminary analysis of building heights from the Emporis database which suggests very strong scaling in world cities. The data base for Greater London is then introduced from which we extract 3.6 million buildings whose scaling properties we explore. We examine key allometric relationships between these different properties illustrating how building shape changes according to size, and we extend this analysis to the classification of buildings according to land use types. We conclude with an analysis of two-point correlation functions of building geometries which supports our non-spatial analysis of scaling.

Distilling allometric and environmental information from time series of conduit size: the standardization issue and its relationship to tree hydraulic architecture.

PubMed

Carrer, Marco; von Arx, Georg; Castagneri, Daniele; Petit, Giai

2015-01-01

Trees are among the best natural archives of past environmental information. Xylem anatomy preserves information related to tree allometry and ecophysiological performance, which is not available from the more customary ring-width or wood-density proxy parameters. Recent technological advances make tree-ring anatomy very attractive because time frames of many centuries can now be covered. This calls for the proper treatment of time series of xylem anatomical attributes. In this article, we synthesize current knowledge on the biophysical and physiological mechanisms influencing the short- to long-term variation in the most widely used wood-anatomical feature, namely conduit size. We also clarify the strong mechanistic link between conduit-lumen size, tree hydraulic architecture and height growth. Among the key consequences of these biophysical constraints is the pervasive, increasing trend of conduit size during ontogeny. Such knowledge is required to process time series of anatomical parameters correctly in order to obtain the information of interest. An appropriate standardization procedure is fundamental when analysing long tree-ring-related chronologies. When dealing with wood-anatomical parameters, this is even more critical. Only an interdisciplinary approach involving ecophysiology, wood anatomy and dendrochronology will help to distill the valuable information about tree height growth and past environmental variability correctly. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Polonium-210 in marine mussels (bivalve molluscs) inhabiting the southern coast of India.

PubMed

Khan, M Feroz; Wesley, S Godwin; Rajan, M P

2014-12-01

The present study focused on the determination of the alpha-emitter, (210)Po, in two species of marine mussels (bivalve molluscs) commonly available in the southern coastal region of India. The brown mussel, Perna indica was collected from the west coast and the green mussel, Perna viridis from the east coast. The concentration of (210)Po was related to the allometry (length of shell, wet/dry weight of shell/soft tissue) of the mussels and significant results were found. The study period focused on three seasons namely, pre-monsoon, monsoon and post-monsoon for a 1-year period (2010-2011). The results revealed higher activity levels in smaller-sized mussels compared to larger ones. Marked variation in (210)Po activity concentration was noted in the whole-body soft tissues between seasons and sampling site (p < 0.05). The dose rate assessment for mussels was performed using the ERICA Assessment tool. The chronic exposure to mussels due to (210)Po was found to be lesser than the global benchmark dose rate of 10 μGy h(-1). The effective ingestion dose to adults who intake mussels was estimated to be in the range 5.1-34.9 μSv y(-1). The measurement contributes to the furthering of knowledge of (210)Po, since no data exist in this region. Copyright © 2014 Elsevier Ltd. All rights reserved.

Complex constraints on allometry revealed by artificial selection on the wing of Drosophila melanogaster

PubMed Central

Bolstad, Geir H.; Cassara, Jason A.; Márquez, Eladio; Hansen, Thomas F.; van der Linde, Kim; Houle, David; Pélabon, Christophe

2015-01-01

Precise exponential scaling with size is a fundamental aspect of phenotypic variation. These allometric power laws are often invariant across taxa and have long been hypothesized to reflect developmental constraints. Here we test this hypothesis by investigating the evolutionary potential of an allometric scaling relationship in drosophilid wing shape that is nearly invariant across 111 species separated by at least 50 million years of evolution. In only 26 generations of artificial selection in a population of Drosophila melanogaster, we were able to drive the allometric slope to the outer range of those found among the 111 sampled species. This response was rapidly lost when selection was suspended. Only a small proportion of this reversal could be explained by breakup of linkage disequilibrium, and direct selection on wing shape is also unlikely to explain the reversal, because the more divergent wing shapes produced by selection on the allometric intercept did not revert. We hypothesize that the reversal was instead caused by internal selection arising from pleiotropic links to unknown traits. Our results also suggest that the observed selection response in the allometric slope was due to a component expressed late in larval development and that variation in earlier development did not respond to selection. Together, these results are consistent with a role for pleiotropic constraints in explaining the remarkable evolutionary stability of allometric scaling. PMID:26371319

Density-dependence as a size-independent regulatory mechanism.

PubMed

de Vladar, Harold P

2006-01-21

The growth function of populations is central in biomathematics. The main dogma is the existence of density-dependence mechanisms, which can be modelled with distinct functional forms that depend on the size of the population. One important class of regulatory functions is the theta-logistic, which generalizes the logistic equation. Using this model as a motivation, this paper introduces a simple dynamical reformulation that generalizes many growth functions. The reformulation consists of two equations, one for population size, and one for the growth rate. Furthermore, the model shows that although population is density-dependent, the dynamics of the growth rate does not depend either on population size, nor on the carrying capacity. Actually, the growth equation is uncoupled from the population size equation, and the model has only two parameters, a Malthusian parameter rho and a competition coefficient theta. Distinct sign combinations of these parameters reproduce not only the family of theta-logistics, but also the van Bertalanffy, Gompertz and Potential Growth equations, among other possibilities. It is also shown that, except for two critical points, there is a general size-scaling relation that includes those appearing in the most important allometric theories, including the recently proposed Metabolic Theory of Ecology. With this model, several issues of general interest are discussed such as the growth of animal population, extinctions, cell growth and allometry, and the effect of environment over a population.

The erethizontid fossil from the Uquía formation of Argentina should not be referred to the genus Erethizon

NASA Astrophysics Data System (ADS)

Sussman, David R.

2011-04-01

In 2007, Reguero et al. described a 2.5 Ma erethizontid dentary from the Uquía Formation in Argentina (MACN5376) and referred it to the genus Erethizon, a genus found at present only in North America. They based their generic identification on the presence in the fossil of a markedly inflected angular process. I argue in this commentary that this single trait (the angular process) in a single incomplete fossil is insufficient evidence for the Erethizon attribution, for the following reasons: 1. The trait (the inflected angular process) is variable in modern South and North American porcupines and observer bias and/or allometry may be responsible for observed differences; 2. Among fossil South American porcupines, the inflected angular process is not unique to the Uquían fossil; 3. The fossil possesses other traits (including one trait newly described in this paper) associated with modern South American ( Coendou) porcupines and not modern Erethizon; and 4. The traits by which we recognize modern Erethizon, primarily related to the genus's ability to survive severe winters, are most readily explained by evolution driven by the South American porcupine immigrants' exposure in North America to that severe weather. The Uquían fossil is not Erethizon and should be attributed for the present to the genus Coendou.

Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates.

PubMed

Glazier, Douglas S; Hirst, Andrew G; Atkinson, David

2015-03-07

Metabolism fuels all biological activities, and thus understanding its variation is fundamentally important. Much of this variation is related to body size, which is commonly believed to follow a 3/4-power scaling law. However, during ontogeny, many kinds of animals and plants show marked shifts in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR < 1), or the reverse, are associated with significant changes in body shape (indexed by bL = the scaling exponent of the relationship between body mass and body length). The observed inverse correlations between bR and bL are predicted by metabolic scaling theory that emphasizes resource/waste fluxes across external body surfaces, but contradict theory that emphasizes resource transport through internal networks. Geometric estimates of the scaling of surface area (SA) with body mass (bA) further show that ontogenetic shifts in bR and bA are positively correlated. These results support new metabolic scaling theory based on SA influences that may be applied to ontogenetic shifts in bR shown by many kinds of animals and plants. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Patterns of sexual size dimorphism in horseshoe bats: Testing Rensch's rule and potential causes.

PubMed

Wu, Hui; Jiang, Tinglei; Huang, Xiaobin; Feng, Jiang

2018-02-08

Rensch's rule, stating that sexual size dimorphism (SSD) becomes more evident and male-biased with increasing body size, has been well supported for taxa that exhibit male-biased SSD. Bats, primarily having female-biased SSD, have so far been tested for whether SSD allometry conforms to Rensch's rule in only three studies. However, these studies did not consider phylogeny, and thus the mechanisms underlying SSD variations in bats remain unclear. Thus, the present study reviewed published and original data, including body size, baculum size, and habitat types in 45 bats of the family Rhinolophidae to determine whether horseshoe bats follow Rensch's rule using a phylogenetic comparative framework. We also investigated the potential effect of postcopulatory sexual selection and habitat type on SSD. Our findings indicated that Rensch's rule did not apply to Rhinolophidae, suggesting that SSD did not significantly vary with increasing size. This pattern may be attributable interactions between weak sexual selection to male body size and strong fecundity selection for on female body size. The degree of SSD among horseshoe bats may be attributed to a phylogenetic effect rather than to the intersexual competition for food or to baculum length. Interestingly, we observed that species in open habitats exhibited greater SSD than those in dense forests, suggesting that habitat types may be associated with variations in SSD in horseshoe bats.

DBH Prediction Using Allometry Described by Bivariate Copula Distribution

NASA Astrophysics Data System (ADS)

Xu, Q.; Hou, Z.; Li, B.; Greenberg, J. A.

2017-12-01

Forest biomass mapping based on single tree detection from the airborne laser scanning (ALS) usually depends on an allometric equation that relates diameter at breast height (DBH) with per-tree aboveground biomass. The incapability of the ALS technology in directly measuring DBH leads to the need to predict DBH with other ALS-measured tree-level structural parameters. A copula-based method is proposed in the study to predict DBH with the ALS-measured tree height and crown diameter using a dataset measured in the Lassen National Forest in California. Instead of exploring an explicit mathematical equation that explains the underlying relationship between DBH and other structural parameters, the copula-based prediction method utilizes the dependency between cumulative distributions of these variables, and solves the DBH based on an assumption that for a single tree, the cumulative probability of each structural parameter is identical. Results show that compared with the bench-marking least-square linear regression and the k-MSN imputation, the copula-based method obtains better accuracy in the DBH for the Lassen National Forest. To assess the generalization of the proposed method, prediction uncertainty is quantified using bootstrapping techniques that examine the variability of the RMSE of the predicted DBH. We find that the copula distribution is reliable in describing the allometric relationship between tree-level structural parameters, and it contributes to the reduction of prediction uncertainty.

Variation in the cranium shape of wall lizards (Podarcis spp.): effects of phylogenetic constraints, allometric constraints and ecology.

PubMed

Urošević, Aleksandar; Ljubisavljević, Katarina; Jelić, Dušan; Ivanović, Ana

2012-08-01

We used geometric morphometrics to explore the influence of phylogenetic and allometric constraints as well as ecology on variation in cranium shape in five species of monophyletic, morphologically similar Podarcis lizards (Podarcis erhardii, Podarcis melisellensis, Podarcis muralis, Podarcis sicula and Podarcis taurica). These species belong to different clades, they differ in their habitat preferences and can be classified into two distinct morphotypes: saxicolous and terrestrial. We found (i) no phylogenetic signal in cranium shape, (ii) diverging allometric slopes among species, and (iii) a significant effect of habitat on cranium shape. The saxicolous species (P. erhardii and P. muralis) had crania with elongated parietals, elongated cranium bases, shortened anterior parts of the dorsal cranium, reduced chambers of the jaw adductor muscles and larger subocular foramina. These cranial features are adaptations that compensate for a flattened cranium, dwelling on vertical surfaces and seeking refuge in crevices. The crania of the terrestrial species (P. melisellensis, P. sicula and P. taurica) tended to be more elongate and robust, with enlarged chambers of the jaw adductor muscle, reduced skull bases and shortened parietals. Terrestrial species exhibited more variation in cranium shape than saxicolous species. Our study suggests that shape variation in Podarcis sp. lizards is largely influenced by ecology, which likely affects species-specific patterns of static allometry. Copyright © 2012 Elsevier GmbH. All rights reserved.

The Gavialis-Tomistoma debate: the contribution of skull ontogenetic allometry and growth trajectories to the study of crocodylian relationships.

PubMed

Piras, Paolo; Colangelo, Paolo; Adams, Dean C; Buscalioni, Angela; Cubo, Jorge; Kotsakis, Tassos; Meloro, Carlo; Raia, Pasquale

2010-01-01

The phylogenetic placement of Tomistoma and Gavialis crocodiles depends largely upon whether molecular or morphological data are utilized. Molecular analyses consider them as sister taxa, whereas morphological/paleontological analyses set Gavialis apart from Tomistoma and other crocodylian species. Here skull allometric trajectories of Tomistoma and Gavialis were contrasted with those of two longirostral crocodylian taxa, Crocodylus acutus and Mecistops cataphractus, to examine similarities in growth trajectories in light of this phylogenetic controversy. Entire skull shape and its two main modules, rostrum and postrostrum, were analyzed separately. We tested differences for both multivariate angles between trajectories and for shape differences at early and late stages of development. Based on a multivariate regression of shape data and size, Tomistoma seems to possess a peculiar rate of growth in comparison to the remaining taxa. However, its morphology at both juvenile and adult sizes is always closer to those of Brevirostres crocodylians, for the entire head shape, as well as the shape of the postrostrum and rostrum. By contrast, the allometric trajectory of Gavialis always begins and ends in a unique region of the multidimensional morphospace. These findings concur with a morphological hypothesis that places Gavialis separate from Brevirostres, and Tomistoma closer to other crocodylids, and provides an additional, and independent, data set to inform on this ongoing phylogenetic discussion. © 2010 Wiley Periodicals, Inc.

Allometry indicates giant eyes of giant squid are not exceptional.

PubMed

Schmitz, Lars; Motani, Ryosuke; Oufiero, Christopher E; Martin, Christopher H; McGee, Matthew D; Gamarra, Ashlee R; Lee, Johanna J; Wainwright, Peter C

2013-02-18

The eyes of giant and colossal squid are among the largest eyes in the history of life. It was recently proposed that sperm whale predation is the main driver of eye size evolution in giant squid, on the basis of an optical model that suggested optimal performance in detecting large luminous visual targets such as whales in the deep sea. However, it is poorly understood how the eye size of giant and colossal squid compares to that of other aquatic organisms when scaling effects are considered. We performed a large-scale comparative study that included 87 squid species and 237 species of acanthomorph fish. While squid have larger eyes than most acanthomorphs, a comparison of relative eye size among squid suggests that giant and colossal squid do not have unusually large eyes. After revising constants used in a previous model we found that large eyes perform equally well in detecting point targets and large luminous targets in the deep sea. The eyes of giant and colossal squid do not appear exceptionally large when allometric effects are considered. It is probable that the giant eyes of giant squid result from a phylogenetically conserved developmental pattern manifested in very large animals. Whatever the cause of large eyes, they appear to have several advantages for vision in the reduced light of the deep mesopelagic zone.

Demography of birds in a neotropical forest: Effects of allometry, taxonomy, and ecology

USGS Publications Warehouse

Brawn, J.D.; Karr, J.R.; Nichols, J.D.

1995-01-01

Comparative demographic studies of terrestrial vertebrates have included few samples of species from tropical forests. We analyzed 9 yr of mark-recapture data and estimated demographic parameters for 25 species of birds inhabiting lowland forests in central Panama. These species were all songbirds (Order Passeriformes) ranging in mass from 7 to 57 g. Using Jolly-Seber stochastic models for open populations, we estimated annual survival rate, population size, and recruitment between sampling periods for each species. We then explored relationships between these parameters and attributes such as body size, phylogenetic affiliation, foraging guild, and social behavior. Larger birds had comparatively long life-spans and low recruitment, but body size was not associated with population size. After adjusting for effects of body size, we found no association between phylogenetic affiliation and any demographic trait. Ecological attributes, especially foraging guild, were more clearly associated with interspecific variation in all demographic traits. Ant-followers had comparatively long life-spans, but species that participate in flocks did not live longer than solitary species. The allometric associations we observed were consistent with those demonstrated in other studies of vertebrates; thus. these relationships appear to be robust. Our finding that ecological factors were more influential than phylogenetic affiliation contrasts with comparative studies of temperate-zone birds and suggests that the relative importance of environmental vs. historical factors varies geographically.

Diversity among African Pygmies

PubMed Central

Ramírez Rozzi, Fernando V.; Sardi, Marina L.

2010-01-01

Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies. PMID:21049030

Diversity among African pygmies.

PubMed

Ramírez Rozzi, Fernando V; Sardi, Marina L

2010-10-26

Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.

Trait-specific processes of convergence and conservatism shape ecomorphological evolution in ground-dwelling squirrels.

PubMed

McLean, Bryan S; Helgen, Kristofer M; Goodwin, H Thomas; Cook, Joseph A

2018-03-01

Our understanding of mechanisms operating over deep timescales to shape phenotypic diversity often hinges on linking variation in one or few trait(s) to specific evolutionary processes. When distinct processes are capable of similar phenotypic signatures, however, identifying these drivers is difficult. We explored ecomorphological evolution across a radiation of ground-dwelling squirrels whose history includes convergence and constraint, two processes that can yield similar signatures of standing phenotypic diversity. Using four ecologically relevant trait datasets (body size, cranial, mandibular, and molariform tooth shape), we compared and contrasted variation, covariation, and disparity patterns in a new phylogenetic framework. Strong correlations existed between body size and two skull traits (allometry) and among skull traits themselves (integration). Inferred evolutionary modes were also concordant across traits (Ornstein-Uhlenbeck with two adaptive regimes). However, despite these broad similarities, we found divergent dynamics on the macroevolutionary landscape, with phenotypic disparity being differentially shaped by convergence and conservatism. Such among-trait heterogeneity in process (but not always pattern) reiterates the mosaic nature of morphological evolution, and suggests ground squirrel evolution is poorly captured by single process descriptors. Our results also highlight how use of single traits can bias macroevolutionary inference, affirming the importance of broader trait-bases in understanding phenotypic evolutionary dynamics. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Morphological and phenological shoot plasticity in a Mediterranean evergreen oak facing long-term increased drought.

PubMed

Limousin, Jean-Marc; Rambal, Serge; Ourcival, Jean-Marc; Rodríguez-Calcerrada, Jesus; Pérez-Ramos, Ignacio M; Rodríguez-Cortina, Raquel; Misson, Laurent; Joffre, Richard

2012-06-01

Mediterranean trees must adjust their canopy leaf area to the unpredictable timing and severity of summer drought. The impact of increased drought on the canopy dynamics of the evergreen Quercus ilex was studied by measuring shoot growth, leaf production, litterfall, leafing phenology and leaf demography in a mature forest stand submitted to partial throughfall exclusion for 7 years. The leaf area index rapidly declined in the throughfall-exclusion plot and was 19% lower than in the control plot after 7 years of treatment. Consequently, leaf litterfall was significantly lower in the dry treatment. Such a decline in leaf area occurred through a change in branch allometry with a decreased number of ramifications produced and a reduction of the leaf area supported per unit sapwood area of the shoot (LA/SA). The leafing phenology was slightly delayed and the median leaf life span was slightly longer in the dry treatment. The canopy dynamics in both treatments were driven by water availability with a 1-year lag: leaf shedding and production were reduced following dry years; in contrast, leaf turnover was increased following wet years. The drought-induced decrease in leaf area, resulting from both plasticity in shoot development and slower leaf turnover, appeared to be a hydraulic adjustment to limit canopy transpiration and maintain leaf-specific hydraulic conductivity under drier conditions.

Development and evaluation of height diameter at breast models for native Chinese Metasequoia.

PubMed

Liu, Mu; Feng, Zhongke; Zhang, Zhixiang; Ma, Chenghui; Wang, Mingming; Lian, Bo-Ling; Sun, Renjie; Zhang, Li

2017-01-01

Accurate tree height and diameter at breast height (dbh) are important input variables for growth and yield models. A total of 5503 Chinese Metasequoia trees were used in this study. We studied 53 fitted models, of which 7 were linear models and 46 were non-linear models. These models were divided into two groups of single models and multivariate models according to the number of independent variables. The results show that the allometry equation of tree height which has diameter at breast height as independent variable can better reflect the change of tree height; in addition the prediction accuracy of the multivariate composite models is higher than that of the single variable models. Although tree age is not the most important variable in the study of the relationship between tree height and dbh, the consideration of tree age when choosing models and parameters in model selection can make the prediction of tree height more accurate. The amount of data is also an important parameter what can improve the reliability of models. Other variables such as tree height, main dbh and altitude, etc can also affect models. In this study, the method of developing the recommended models for predicting the tree height of native Metasequoias aged 50-485 years is statistically reliable and can be used for reference in predicting the growth and production of mature native Metasequoia.

Development and evaluation of height diameter at breast models for native Chinese Metasequoia

PubMed Central

Feng, Zhongke; Zhang, Zhixiang; Ma, Chenghui; Wang, Mingming; Lian, Bo-ling; Sun, Renjie; Zhang, Li

2017-01-01

Accurate tree height and diameter at breast height (dbh) are important input variables for growth and yield models. A total of 5503 Chinese Metasequoia trees were used in this study. We studied 53 fitted models, of which 7 were linear models and 46 were non-linear models. These models were divided into two groups of single models and multivariate models according to the number of independent variables. The results show that the allometry equation of tree height which has diameter at breast height as independent variable can better reflect the change of tree height; in addition the prediction accuracy of the multivariate composite models is higher than that of the single variable models. Although tree age is not the most important variable in the study of the relationship between tree height and dbh, the consideration of tree age when choosing models and parameters in model selection can make the prediction of tree height more accurate. The amount of data is also an important parameter what can improve the reliability of models. Other variables such as tree height, main dbh and altitude, etc can also affect models. In this study, the method of developing the recommended models for predicting the tree height of native Metasequoias aged 50–485 years is statistically reliable and can be used for reference in predicting the growth and production of mature native Metasequoia. PMID:28817600

Small queens and big-headed workers in a monomorphic ponerine ant

NASA Astrophysics Data System (ADS)

Kikuchi, Tomonori; Miyazaki, Satoshi; Ohnishi, Hitoshi; Takahashi, Junichi; Nakajima, Yumiko; Tsuji, Kazuki

2008-10-01

Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest the following three patterns: (1) a positive correlation between queen worker size dimorphism and the divergence in reproductive ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability, and (3) a positive correlation between queen worker body shape difference and the diversity in worker morphology. We conducted morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped, mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately larger than that of queens. This pattern of queen worker dimorphism is novel in ants with monomorphic workers and a clear exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack of reproductive ability, influences morphological modification in ants.

Environmental drivers of sapwood and heartwood proportions

NASA Astrophysics Data System (ADS)

Thurner, Martin; Beer, Christian

2017-04-01

Recent advances combining information on stem volume from remote sensing with allometric relationships derived from forest inventory databases have led to spatially continuous estimates of stem, branch, root and foliage biomass in northern boreal and temperate forests. However, a separation of stem biomass into sapwood and heartwood mass has remained unsolved, despite their important differences in biogeochemical function, for instance concerning their contribution to tree respiratory costs. Although relationships between sapwood cross-sectional area and supported leaf area are well established, less is known about relations between sapwood or heartwood mass and other traits (e.g. stem mass), since these biomass compartments are more difficult to measure in practice. Here we investigate the variability in sapwood and heartwood proportions and determining environmental factors. For this task we explore an available biomass and allometry database (BAAD) and study relative sapwood and heartwood area, volume, mass and density in dependence of tree species, age and climate. First, a theoretical framework on how to estimate sap- and heartwood mass from stem mass is developed. Subsequently, the underlying assumptions and relationships are explored with the help of the BAAD. The established relationships can be used to derive spatially continuous sapwood and heartwood mass estimates by applying them to remote sensing based stem volume products. This would be a fundamental step forward to a data-driven estimate of autotrophic respiration.

Rain, prey and predators: climatically driven shifts in frog abundance modify reproductive allometry in a tropical snake.

PubMed

Brown, Gregory P; Shine, Richard

2007-11-01

To predict the impacts of climate change on animal populations, we need long-term data sets on the effects of annual climatic variation on the demographic traits (growth, survival, reproductive output) that determine population viability. One frequent complication is that fecundity also depends upon maternal body size, a trait that often spans a wide range within a single population. During an eight-year field study, we measured annual variation in weather conditions, frog abundance and snake reproduction on a floodplain in the Australian wet-dry tropics. Frog numbers varied considerably from year to year, and were highest in years with hotter wetter conditions during the monsoonal season ("wet season"). Mean maternal body sizes, egg sizes and post-partum maternal body conditions of frog-eating snakes (keelback, Tropidonophis mairii, Colubridae) showed no significant annual variation over this period, but mean clutch sizes were higher in years with higher prey abundance. Larger females were more sensitive to frog abundance in this respect than were smaller conspecifics, so that the rate at which fecundity increased with body size varied among years, and was highest when prey availability was greatest. Thus, the link between female body size and reproductive output varied among years, with climatic factors modifying the relative reproductive rates of larger (older) versus smaller (younger) animals within the keelback population.

Adapting to an invasive species: toxic cane toads induce morphological change in Australian snakes.

PubMed

Phillips, Ben L; Shine, Richard

2004-12-07

The arrival of invasive species can devastate natural ecosystems, but the long-term effects of invasion are less clear. If native organisms can adapt to the presence of the invader, the severity of impact will decline with time. In Australia, invasive cane toads (Bufo marinus) are highly toxic to most snakes that attempt to eat them. Because snakes are gape-limited predators with strong negative allometry for head size, maximum relative prey mass (and thus, the probability of eating a toad large enough to be fatal) decreases with an increase in snake body size. Thus, the arrival of toads should exert selection on snake morphology, favoring an increase in mean body size and a decrease in relative head size. We tested these predictions with data from specimens of four species of Australian snakes, collected over >80 years. Geographic information system layers provided data on the duration of toad exposure for each snake population, as well as environmental variables (latitude, precipitation, and temperature). As predicted, two toad-vulnerable species (Pseudechis porphyriacus and Dendrelaphis punctulatus) showed a steady reduction in gape size and a steady increase in body length with time since exposure to toads. In contrast, two species at low risk from toads (Hemiaspis signata and Tropidonophis mairii) showed no consistent change in these morphological traits as a function of the duration of toad exposure. These results provide strong evidence of adaptive changes in native predators as a result of the invasion of toxic prey.

An online database for informing ecological network models: http://kelpforest.ucsc.edu.

PubMed

Beas-Luna, Rodrigo; Novak, Mark; Carr, Mark H; Tinker, Martin T; Black, August; Caselle, Jennifer E; Hoban, Michael; Malone, Dan; Iles, Alison

2014-01-01

Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/databaseui).

An Online Database for Informing Ecological Network Models: http://kelpforest.ucsc.edu

PubMed Central

Beas-Luna, Rodrigo; Novak, Mark; Carr, Mark H.; Tinker, Martin T.; Black, August; Caselle, Jennifer E.; Hoban, Michael; Malone, Dan; Iles, Alison

2014-01-01

Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/databaseui). PMID:25343723

Energy efficiency and allometry of movement of swimming and flying animals.

PubMed

Bale, Rahul; Hao, Max; Bhalla, Amneet Pal Singh; Patankar, Neelesh A

2014-05-27

Which animals use their energy better during movement? One metric to answer this question is the energy cost per unit distance per unit weight. Prior data show that this metric decreases with mass, which is considered to imply that massive animals are more efficient. Although useful, this metric also implies that two dynamically equivalent animals of different sizes will not be considered equally efficient. We resolve this longstanding issue by first determining the scaling of energy cost per unit distance traveled. The scale is found to be M(2/3) or M(1/2), where M is the animal mass. Second, we introduce an energy-consumption coefficient (CE) defined as energy per unit distance traveled divided by this scale. CE is a measure of efficiency of swimming and flying, analogous to how drag coefficient quantifies aerodynamic drag on vehicles. Derivation of the energy-cost scale reveals that the assumption that undulatory swimmers spend energy to overcome drag in the direction of swimming is inappropriate. We derive allometric scalings that capture trends in data of swimming and flying animals over 10-20 orders of magnitude by mass. The energy-consumption coefficient reveals that swimmers beyond a critical mass, and most fliers are almost equally efficient as if they are dynamically equivalent; increasingly massive animals are not more efficient according to the proposed metric. Distinct allometric scalings are discovered for large and small swimmers. Flying animals are found to require relatively more energy compared with swimmers.

A potential mechanism for allometric trabecular bone scaling in terrestrial mammals.

PubMed

Christen, Patrik; Ito, Keita; van Rietbergen, Bert

2015-03-01

Trabecular bone microstructural parameters, including trabecular thickness, spacing, and number, have been reported to scale with animal size with negative allometry, whereas bone volume fraction is animal size-invariant in terrestrial mammals. As for the majority of scaling patterns described in animals, its underlying mechanism is unknown. However, it has also been found that osteocyte density is inversely related to animal size, possibly adapted to metabolic rate, which shows a negative relationship as well. In addition, the signalling reach of osteocytes is limited by the extent of the lacuno-canalicular network, depending on trabecular dimensions and thus also on animal size. Here we propose animal size-dependent variations in osteocyte density and their signalling influence distance as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. Using an established and tested computational model of bone modelling and remodelling, we run simulations with different osteocyte densities and influence distances mimicking six terrestrial mammals covering a large range of body masses. Simulated trabecular structures revealed negative allometric scaling for trabecular thickness, spacing, and number, constant bone volume fraction, and bone turnover rates inversely related to animal size. These results are in agreement with previous observations supporting our proposal of osteocyte density and influence distance variation as a potential mechanism for negative allometric trabecular bone scaling in terrestrial mammals. The inverse relationship between bone turnover rates and animal size further indicates that trabecular bone scaling may be linked to metabolic rather than mechanical adaptations. © 2015 Anatomical Society.

Babes in the wood – a unique window into sea scorpion ontogeny

PubMed Central

2013-01-01

Background Few studies on eurypterids have taken into account morphological changes that occur throughout postembryonic development. Here two species of eurypterid are described from the Pragian Beartooth Butte Formation of Cottonwood Canyon in Wyoming and included in a phylogenetic analysis. Both species comprise individuals from a number of instars, and this allows for changes that occur throughout their ontogeny to be documented, and how ontogenetically variable characters can influence phylogenetic analysis to be tested. Results The two species of eurypterid are described as Jaekelopterus howelli (Kjellesvig-Waering and Størmer, 1952) and Strobilopterus proteus sp. nov. Phylogenetic analysis places them within the Pterygotidae and Strobilopteridae respectively, both families within the Eurypterina. Jaekelopterus howelli shows positive allometry of the cheliceral denticles throughout ontogeny, while a number of characteristics including prosomal appendage length, carapace shape, lateral eye position, and relative breadth all vary during the growth of Strobilopterus proteus. Conclusions The ontogeny of Strobilopterus proteus shares much in common with that of modern xiphosurans, however certain characteristics including apparent true direct development suggest a closer affinity to arachnids. The ontogenetic development of the genital appendage also supports the hypothesis that the structure is homologous to the endopods of the trunk limbs of other arthropods. Including earlier instars in the phylogenetic analysis is shown to destabilise the retrieved topology. Therefore, coding juveniles as individual taxa in an analysis is shown to be actively detrimental and alternative ways of coding ontogenetic data into phylogenetic analyses should be explored. PMID:23663507

An exceptionally preserved armored dinosaur reveals the morphology and allometry of osteoderms and their horny epidermal coverings.

PubMed

Brown, Caleb M

2017-01-01

Although the evolution and function of "exaggerated" bony projections in ornithischian dinosaurs has been subject to significant debate recently, our understanding of the structure and morphology of their epidermal keratinized coverings is greatly limited. The holotype of Borealopelta , a new nodosaurid ankylosaur, preserves osteoderms and extensive epidermal structures (dark organic residues), in anatomic position across the entire precaudal length. Contrasting previous specimens, organic epiosteodermal scales, often in the form of horn-like (keratinous) sheaths, cap and exaggerate nearly all osteoderms, allowing for morphometric and allometric analyses of both the bony osteoderms and their horny sheaths. A total of 172 osteoderms were quantified, with osteoderm spine length and height being positively allometric with respect to basal length and width. Despite tight correlations between the different measures amongst all other osteoderms, the large parascapular spines represent consistent outliers. Thickness and relative contribution of the keratinized epiosteodermal scales/sheaths varies greatly by region, ranging from 2% to 6% for posterior thoracics, to ∼25% (1.3×) for the parascapular spines-similar to horn sheaths in some bovid analogues. Relative to the bony cores, the horny portions of the spines are strongly positively allometric (slope = 2.3, CI = 1.8-2.8). Strong allometric scaling, species-specific morphology, and significant keratinous extension of the cervicoscapular spines is consistent with elaboration under socio-sexual selection. This marks the first allometric analysis of ornithischian soft tissues.

An online database for informing ecological network models: http://kelpforest.ucsc.edu

USGS Publications Warehouse

Beas-Luna, Rodrigo; Tinker, M. Tim; Novak, Mark; Carr, Mark H.; Black, August; Caselle, Jennifer E.; Hoban, Michael; Malone, Dan; Iles, Alison C.

2014-01-01

Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/data​baseui).

The relationship between allometry and preferred transition speed in human locomotion.

PubMed

Ranisavljev, Igor; Ilic, Vladimir; Soldatovic, Ivan; Stefanovic, Djordje

2014-04-01

The purpose of this study was to explore the relationships between preferred transition speed (PTS) and anthropometric characteristics, body composition and different human body proportions in males. In a sample of 59 male students, we collected anthropometric and body composition data and determined individual PTS using increment protocol. The relationships between PTS and other variables were determined using Pearson correlation, stepwise linear and hierarchical regression. Body ratios were formed as quotient of two variables whereby at least one significantly correlated to PTS. Circular and transversal (except bitrochanteric diameter) body dimensions did not correlate with PTS. Moderate correlations were found between longitudinal leg dimensions (foot, leg and thigh length) and PTS, while the highest correlation was found for lower leg length (r=.488, p<.01). Two parameters related to body composition showed weak correlation with PTS: body fat mass (r=-.250, p<.05) and amount of lean leg mass scaled to body weight (r=.309, p<.05). Segmental body proportions correlated more significantly with PTS, where thigh/lower leg length ratio showed the highest correlation (r=.521, p<.01). Prediction model with individual variables (lower leg and foot length) have explained just 31% of PTS variability, while model with body proportions showed almost 20% better prediction (R(2)=.504). These results suggests that longitudinal leg dimensions have moderate influence on PTS and that segmental body proportions significantly more explain PTS than single anthropometric variables. Copyright © 2014 Elsevier B.V. All rights reserved.

The ontogeny of the chin: an analysis of allometric and biomechanical scaling

PubMed Central

Holton, N E; Bonner, L L; Scott, J E; Marshall, S D; Franciscus, R G; Southard, T E

2015-01-01

The presence of a prominent chin in modern humans has been viewed by some researchers as an architectural adaptation to buttress the anterior corpus from bending stresses during mastication. In contrast, ontogenetic studies of mandibular symphyseal form suggest that a prominent chin results from the complex spatial interaction between the symphysis and surrounding soft tissue and skeletal anatomy during development. While variation in chin prominence is clearly influenced by differential growth and spatial constraints, it is unclear to what degree these developmental dynamics influence the mechanical properties of the symphysis. That is, do ontogenetic changes in symphyseal shape result in increased symphyseal bending resistance? We examined ontogenetic changes in the mechanical properties and shape of the symphysis using subjects from a longitudinal cephalometric growth study with ages ranging from 3 to 20+ years. We first examined whether ontogenetic changes in symphyseal shape were correlated with symphyseal vertical bending and wishboning resistance using multivariate regression. Secondly, we examined ontogenetic scaling of bending resistance relative to bending moment arm lengths. An ontogenetic increase in chin prominence was associated with decreased vertical bending resistance, while wishboning resistance was uncorrelated with ontogenetic development of the chin. Relative to bending moment arm lengths, vertical bending resistance scaled with significant negative allometry whereas wishboning resistance scaled isometrically. These results suggest a complex interaction between symphyseal ontogeny and bending resistance, and indicate that ontogenetic increases in chin projection do not provide greater bending resistance to the mandibular symphysis. PMID:25865897

Herbivory and body size: allometries of diet quality and gastrointestinal physiology, and implications for herbivore ecology and dinosaur gigantism.

PubMed

Clauss, Marcus; Steuer, Patrick; Müller, Dennis W H; Codron, Daryl; Hummel, Jürgen

2013-01-01

Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM.

Herbivory and Body Size: Allometries of Diet Quality and Gastrointestinal Physiology, and Implications for Herbivore Ecology and Dinosaur Gigantism

PubMed Central

Clauss, Marcus; Steuer, Patrick; Müller, Dennis W. H.; Codron, Daryl; Hummel, Jürgen

2013-01-01

Digestive physiology has played a prominent role in explanations for terrestrial herbivore body size evolution and size-driven diversification and niche differentiation. This is based on the association of increasing body mass (BM) with diets of lower quality, and with putative mechanisms by which a higher BM could translate into a higher digestive efficiency. Such concepts, however, often do not match empirical data. Here, we review concepts and data on terrestrial herbivore BM, diet quality, digestive physiology and metabolism, and in doing so give examples for problems in using allometric analyses and extrapolations. A digestive advantage of larger BM is not corroborated by conceptual or empirical approaches. We suggest that explanatory models should shift from physiological to ecological scenarios based on the association of forage quality and biomass availability, and the association between BM and feeding selectivity. These associations mostly (but not exclusively) allow large herbivores to use low quality forage only, whereas they allow small herbivores the use of any forage they can physically manage. Examples of small herbivores able to subsist on lower quality diets are rare but exist. We speculate that this could be explained by evolutionary adaptations to the ecological opportunity of selective feeding in smaller animals, rather than by a physiologic or metabolic necessity linked to BM. For gigantic herbivores such as sauropod dinosaurs, other factors than digestive physiology appear more promising candidates to explain evolutionary drives towards extreme BM. PMID:24204552

Phylogeny determines flower size-dependent sex allocation at flowering in a hermaphroditic family.

PubMed

Teixido, A L; Guzmán, B; Staggemeier, V G; Valladares, F

2017-11-01

In animal-pollinated hermaphroditic plants, optimal floral allocation determines relative investment into sexes, which is ultimately dependent on flower size. Larger flowers disproportionally increase maleness whereas smaller and less rewarding flowers favour female function. Although floral traits are considered strongly conserved, phylogenetic relationships in the interspecific patterns of resource allocation to floral sex remain overlooked. We investigated these patterns in Cistaceae, a hermaphroditic family. We reconstructed phylogenetic relationships among Cistaceae species and quantified phylogenetic signal for flower size, dry mass and nutrient allocation to floral structures in 23 Mediterranean species using Blomberg's K-statistic. Lastly, phylogenetically-controlled correlational and regression analyses were applied to examine flower size-based allometry in resource allocation to floral structures. Sepals received the highest dry mass allocation, followed by petals, whereas sexual structures increased nutrient allocation. Flower size and resource allocation to floral structures, except for carpels, showed a strong phylogenetic signal. Larger-flowered species allometrically allocated more resources to maleness, by increasing allocation to corollas and stamens. Our results suggest a major role of phylogeny in determining interspecific changes in flower size and subsequent floral sex allocation. This implies that flower size balances the male-female function over the evolutionary history of Cistaceae. While allometric resource investment in maleness is inherited across species diversification, allocation to the female function seems a labile trait that varies among closely related species that have diversified into different ecological niches. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Pharmacokinetics of Epsilon-Aminocaproic Acid in Neonates

PubMed Central

Eaton, Michael P.; Alfieris, George M; Sweeney, Dawn M; Angona, Ronald E; Cholette, Jill M; Venuto, Charles; Anderson, Brian

2016-01-01

Background Antifibrinolytic medications such as epsilon-aminocaproic acid (EACA) are used in pediatric heart surgery to decrease surgical bleeding and transfusion. Dosing schemes for neonates are often based on adult regimens, or are simply empiric, in part due to the lack of neonatal pharmacokinetic information. We sought to determine the pharmacokinetics of EACA in neonates undergoing cardiac surgery and to devise a dosing regimen for this population. Methods Ten neonates undergoing cardiac surgery with cardiopulmonary bypass were given EACA according to standard practice, and blood was drawn at 10 time points to determine drug concentrations. Time-concentration profiles were analyzed using nonlinear mixed effects models. Parameter estimates (standardized to a 70 kg person) were used to develop a dosing regimen intended to maintain a target concentration shown to inhibit fibrinolysis in neonatal plasma (50 mg/L). Results Pharmacokinetics were described using a two compartment model plus an additional compartment for the cardiopulmonary bypass pump. First order elimination was described with a clearance of 5.07 L/h*(WT/70) 0.75. Simulation showed a dosing regimen with a loading dose of 40 mg/kg, and an infusion of 30 mg/kg/h, with a pump prime concentration of 100 mg/L maintained plasma concentrations above 50 mg/L in 90% of neonates during cardiopulmonary bypass surgery. Conclusions EACA clearance, expressed using allometry, is reduced in neonates compared to older children and adults. Loading dose and infusion dose are approximately half those required in children and adults. PMID:25723765

Pharmacokinetics of ε-Aminocaproic Acid in Neonates Undergoing Cardiac Surgery with Cardiopulmonary Bypass.

PubMed

Eaton, Michael P; Alfieris, George M; Sweeney, Dawn M; Angona, Ronald E; Cholette, Jill M; Venuto, Charles; Anderson, Brian

2015-05-01

Antifibrinolytic medications such as ε-aminocaproic acid (EACA) are used in pediatric heart surgery to decrease surgical bleeding and transfusion. Dosing schemes for neonates are often based on adult regimens, or are simply empiric, in part due to the lack of neonatal pharmacokinetic information. The authors sought to determine the pharmacokinetics of EACA in neonates undergoing cardiac surgery and to devise a dosing regimen for this population. Ten neonates undergoing cardiac surgery with cardiopulmonary bypass were given EACA according to standard practice, and blood was drawn at 10 time points to determine drug concentrations. Time-concentration profiles were analyzed using nonlinear mixed effects models. Parameter estimates (standardized to a 70-kg person) were used to develop a dosing regimen intended to maintain a target concentration shown to inhibit fibrinolysis in neonatal plasma (50 mg/l). Pharmacokinetics were described using a two-compartment model plus an additional compartment for the cardiopulmonary bypass pump. First-order elimination was described with a clearance of 5.07 l/h × (WT/70). Simulation showed a dosing regimen with a loading dose of 40 mg/kg and an infusion of 30 mg · kg · h, with a pump prime concentration of 100 mg/l maintained plasma concentrations above 50 mg/l in 90% of neonates during cardiopulmonary bypass surgery. EACA clearance, expressed using allometry, is reduced in neonates compared with older children and adults. Loading dose and infusion dose are approximately half those required in children and adults.

Incisor crown bending strength correlates with diet and incisor curvature in anthropoid primates.

PubMed

Deane, Andrew S

2015-02-01

Anthropoid incisors are large relative to the postcanine dentition and function in the preprocessing of food items. Previous analyses of anthropoid incisor allometry and shape demonstrate that incisor morphology is correlated with preferred foods and that more frugivorous anthropoids have larger and more curved incisors. Although the relationship between incisal crown curvature and preferred foods has been well documented in extant and fossil anthropoids, the functional significance of curvature variation has yet to be conclusively established. Given that an increase in crown curvature will increase maximum linear crown dimensions, and bending resistance is a function of linear crown dimensions, it is hypothesized that incisor crown curvature functons to increase incisor crown resistance to bending forces. This study uses beam theory to calculate the mesiodistal and labiolingual bending strengths of the maxillary and mandibular incisors of hominoid and platyrrhine taxa with differing diets and variable degrees of incisal curvature. Results indicate that bending strength correlates with incisal curvature and that frugivores have elevated incisor bending resistance relative to folivores. Maxillary central incisor bending strengths further discriminate platyrrhine and hominoid hard- and soft-object frugivores suggesting this crown is subjected to elevated occlusal loading relative to other incisors. These results are consistent with the hypothesis that incisor crown curvature functions to increase incisor crown resistance to bending forces but does not preclude the possibility that incisor bending strength is a composite function of multiple dentognathic variables including, but not limited to, incisor crown curvature. © 2014 Wiley Periodicals, Inc.

A morphological and life history comparison between desert populations of a sit-and-pursue antlion, in reference to a co-occurring pit-building antlion.

PubMed

Scharf, Inon; Filin, Ido; Subach, Aziz; Ovadia, Ofer

2009-10-01

Although most antlion species do not construct pits, the vast majority of studies on antlions focused on pit-building species. We report here on a transplant experiment aiming to test for morphological and life history differences between two desert populations of a sit-and-pursue antlion species, Lopezus fedtschenkoi (Neuroptera: Myrmeleontidae), originating from habitats, which mainly differ in plant cover and productivity. We raised the antlion larvae in environmental chambers simulating either hyper-arid or Mediterranean climate. We found significant differences in the morphology and life history of L. fedtschenkoi larvae between the two populations. For example, the larvae originating from the more productive habitat pupated faster and had a higher growth rate. In agreement with the temperature-size rule, antlions reached higher final mass in the colder Mediterranean climate and exhibited a higher growth rate, but there was no difference in their developmental time. Observed differences in morphology between populations as well as those triggered by climate growing conditions could be explained by differences in size allometry. We also provide a quantitative description of the allometric growth axis, based on 12 morphological traits. Comparing the responses of L. fedtschenkoi with those observed in a co-occurring pit-building antlion indicated that there were neither shape differences that are independent of size nor was there a difference in the plasticity level between the two species.

Components of soft tissue deformations in subjects with untreated angle's Class III malocclusions: thin-plate spline analysis.

PubMed

Singh, G D; McNamara, J A; Lozanoff, S

1998-01-01

While the dynamics of maxillo-mandibular allometry associated with treatment modalities available for the management of Class III malocclusions currently are under investigation, developmental aberration of the soft tissues in untreated Class III malocclusions requires specification. In this study, lateral cephalographs of 124 prepubertal European-American children (71 with untreated Class III malocclusion; 53 with Class I occlusion) were traced, and 12 soft-tissue landmarks digitized. Resultant geometries were scaled to an equivalent size and mean Class III and Class I configurations compared. Procrustes analysis established statistical difference (P < 0.001) between the mean configurations. Comparing the overall untreated Class III and Class I configurations, thin-plate spline (TPS) analysis indicated that both affine and non-affine transformations contribute towards the deformation (total spline) of the averaged Class III soft tissue configuration. For non-affine transformations, partial warp 8 had the highest magnitude, indicating large-scale deformations visualized as a combination of columellar retrusion and lower labial protrusion. In addition, partial warp 5 also had a high magnitude, demonstrating upper labial vertical compression with antero-inferior elongation of the lower labio-mental soft tissue complex. Thus, children with Class III malocclusions demonstrate antero-posterior and vertical deformations of the maxillary soft tissue complex in combination with antero-inferior mandibular soft tissue elongation. This pattern of deformations may represent gene-environment interactions, resulting in Class III malocclusions with characteristic phenotypes, that are amenable to orthodontic and dentofacial orthopedic manipulations.

Second to fourth digit ratio and face shape

PubMed Central

Fink, Bernhard; Grammer, Karl; Mitteroecker, Philipp; Gunz, Philipp; Schaefer, Katrin; Bookstein, Fred L; Manning, John T

2005-01-01

The average human male face differs from the average female face in size and shape of the jaws, cheek-bones, lips, eyes and nose. It is possible that this dimorphism is determined by sex steroids such as testosterone (T) and oestrogen (E), and several studies on the perception of such characteristics have been based on this assumption, but those studies focussed mainly on the relationship of male faces with circulating hormone levels; the corresponding biology of the female face remains mainly speculative. This paper is concerned with the relative importance of prenatal T and E levels (assessed via the 2D : 4D finger length ratio, a proxy for the ratio of T/E) and sex in the determination of facial form as characterized by 64 landmark points on facial photographs of 106 Austrians of college age. We found that (i) prenatal sex steroid ratios (in terms of 2D : 4D) and actual chromosomal sex dimorphism operate differently on faces, (ii) 2D : 4D affects male and female face shape by similar patterns, but (iii) is three times more intense in men than in women. There was no evidence that these effects were confounded by allometry or facial asymmetry. Our results suggest that studies on the perception of facial characteristics need to consider differential effects of prenatal hormone exposure and actual chromosomal gender in order to understand how characteristics have come to be rated ‘masculine’ or ‘feminine’ and the consequences of these perceptions in terms of mate preferences. PMID:16191608

Sexual Dimorphism and Allometric Effects Associated With the Wing Shape of Seven Moth Species of Sphingidae (Lepidoptera: Bombycoidea).

PubMed

de Camargo, Willian Rogers Ferreira; de Camargo, Nícholas Ferreira; Corrêa, Danilo do Carmo Vieira; de Camargo, Amabílio J Aires; Diniz, Ivone Rezende

2015-01-01

Sexual dimorphism is a pronounced pattern of intraspecific variation in Lepidoptera. However, moths of the family Sphingidae (Lepidoptera: Bombycoidea) are considered exceptions to this rule. We used geometric morphometric techniques to detect shape and size sexual dimorphism in the fore and hindwings of seven hawkmoth species. The shape variables produced were then subjected to a discriminant analysis. The allometric effects were measured with a simple regression between the canonical variables and the centroid size. We also used the normalized residuals to assess the nonallometric component of shape variation with a t-test. The deformations in wing shape between sexes per species were assessed with a regression between the nonreduced shape variables and the residuals. We found sexual dimorphism in both wings in all analyzed species, and that the allometric effects were responsible for much of the wing shape variation between the sexes. However, when we removed the size effects, we observed shape sexual dimorphism. It is very common for females to be larger than males in Lepidoptera, so it is expected that the shape of structures such as wings suffers deformations in order to preserve their function. However, sources of variation other than allometry could be a reflection of different reproductive flight behavior (long flights in search for sexual mates in males, and flight in search for host plants in females). © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Growing Eremanthus erythropappus in crushed laterite: A promising alternative to topsoil for bauxite-mine revegetation.

PubMed

Machado, Naiara Amaral de Miranda; Leite, Mariangela Garcia Praça; Figueiredo, Maurílio Assis; Kozovits, Alessandra Rodrigues

2013-11-15

Topsoil is the preferred substrate for areas requiring rehabilitation after bauxite mining. However, topsoil is sometimes lacking and so there is a need to test the suitability of other, locally available substrates. In an abandoned bauxite mine in Southeastern Brazil, small patches of native vegetation spontaneously established in shallow depressions over weathered laterite, suggesting that granulometric reduction may have facilitated the establishment of plants. To test this hypothesis, blocks of laterite collected in the area were crushed to simulate texture observed in the vegetation patches. Topsoil collected in a preserved ferruginous field near to the extraction area was also used as a substrate in which Eremanthus erythropappus seedlings, a native woody species, were grown. Seedlings were cultivated without fertilizers in these two substrates and also directly over the exposed and uncrushed laterite. The species proved to be very promising for the revegetation, showing a high survival rate in all substrates. Higher annual growth rates and higher final biomass values were observed in topsoil, but the granulometric reduction of laterite doubled plant growth rate in comparison to the exposed laterite. This result was likely due to the increased availability of essential nutrients to plants and to the improvement in physical conditions for root growth and functioning. Moreover, seedling allometry was not altered by the type of substrate, suggesting that the species was highly tolerant to the new substrate conditions, a fundamental characteristic for success of revegetation of bauxite extraction degraded areas. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nasal bone length in human fetuses by X-ray.

PubMed

Moura, Felipe Nobre; Fernandes, Pablo Lourenco; de Oliveira Silva-Junior, Geraldo; Gomes de Souza, Margareth Maria; Mandarim-de-Lacerda, Carlos Alberto

2008-07-01

To construct a normal range for the prenatal nasal bone length (NBL) in Brazilians irrespective to the knowledge of the ethnic genetic background. We studied 35 human fetuses (20 males, 15 females) ranging from 14 to 22 weeks of gestation. Gestational age (GA), crown-rump length (CRL), foot length (FL) and body mass (BM) were measured. The X-ray of the head lateral view was made with the specimens placed directly on the film and the NBL was measured. The NBL was correlated with the GA, the CRL, the FL, and the BM using log-transformed data and the allometric model log y=log a+b log x. Correlations of the NBL growth with GA, CRL, FL, and BM were positive and significant (P<0.05), but NBL vs. BM showed the smallest R indicating this correlation as of little practical use. No sexual dimorphism in the NBL growth in the second trimester fetuses was observed. The NBL grew with positive allometry relative to GA, CRL and BM, but it was allometrically slightly negative relative to the FL in both genders. The NBL be allometrically positive against GA, CRL and BM means the bone grew with growth rates higher than those indices in the period analyzed, but not against FL. NBL could be considered an auxiliary measurement in the assessment of the 2nd trimester fetal development because its strong correlation with GA, CRL and FL, even when nothing is known about the ethnicity of the population.

Energy efficiency and allometry of movement of swimming and flying animals

PubMed Central

Bale, Rahul; Hao, Max; Bhalla, Amneet Pal Singh; Patankar, Neelesh A.

2014-01-01

Which animals use their energy better during movement? One metric to answer this question is the energy cost per unit distance per unit weight. Prior data show that this metric decreases with mass, which is considered to imply that massive animals are more efficient. Although useful, this metric also implies that two dynamically equivalent animals of different sizes will not be considered equally efficient. We resolve this longstanding issue by first determining the scaling of energy cost per unit distance traveled. The scale is found to be M2/3 or M1/2, where M is the animal mass. Second, we introduce an energy-consumption coefficient (CE) defined as energy per unit distance traveled divided by this scale. CE is a measure of efficiency of swimming and flying, analogous to how drag coefficient quantifies aerodynamic drag on vehicles. Derivation of the energy-cost scale reveals that the assumption that undulatory swimmers spend energy to overcome drag in the direction of swimming is inappropriate. We derive allometric scalings that capture trends in data of swimming and flying animals over 10–20 orders of magnitude by mass. The energy-consumption coefficient reveals that swimmers beyond a critical mass, and most fliers are almost equally efficient as if they are dynamically equivalent; increasingly massive animals are not more efficient according to the proposed metric. Distinct allometric scalings are discovered for large and small swimmers. Flying animals are found to require relatively more energy compared with swimmers. PMID:24821764

Adaptation, allometry, and hypertension.

PubMed

Weder, A B; Schork, N J

1994-08-01

Essential hypertension is a "disease of civilization" but has a clear genetic component. From an evolutionary perspective, persistence in the human genome of elements capable of raising blood pressure presupposes their adaptive significance. Recently, two hypotheses that explicitly appeal to selectionist arguments, the "slavery" and "thrifty gene" theories, have been forwarded. We find neither completely successful, and we advance an alternative explanation of the adaptive importance of genes responsible for hypertension. We propose that blood pressure rises during childhood and adolescence to subserve homeostatic needs of the organism. Specifically, we contend that blood pressure is a flexible element in the repertoire of renal homeostatic mechanisms serving to match renal function to growth. The effect of modern diet and lifestyle on human growth stimulates earlier and more vigorous development, straining biologically necessary relationships between renal and general somatic growth and requiring compensation via homeostatic mechanisms preserved during evolution. Prime among such mechanisms is blood pressure, which rises as a compensation to maintain renal function in the face of greater growth. Since virtually all members of acculturated societies share in the modern lifestyle, the demands imposed by accelerated growth and development result in a populational shift to higher blood pressures, with a consequent increase in the prevalence of hypertension. We propose that hypertension is the product of maladaptation of highly genetically conserved mechanisms subserving important biological homeostatic needs. Elucidation of the mechanisms underlying hypertension will require approaches that examine the developmental processes linking growth to blood pressure.

Insights into the development and evolution of exaggerated traits using de novo transcriptomes of two species of horned scarab beetles.

PubMed

Warren, Ian A; Vera, J Cristobal; Johns, Annika; Zinna, Robert; Marden, James H; Emlen, Douglas J; Dworkin, Ian; Lavine, Laura C

2014-01-01

Scarab beetles exhibit an astonishing variety of rigid exo-skeletal outgrowths, known as "horns". These traits are often sexually dimorphic and vary dramatically across species in size, shape, location, and allometry with body size. In many species, the horn exhibits disproportionate growth resulting in an exaggerated allometric relationship with body size, as compared to other traits, such as wings, that grow proportionately with body size. Depending on the species, the smallest males either do not produce a horn at all, or they produce a disproportionately small horn for their body size. While the diversity of horn shapes and their behavioural ecology have been reasonably well studied, we know far less about the proximate mechanisms that regulate horn growth. Thus, using 454 pyrosequencing, we generated transcriptome profiles, during horn growth and development, in two different scarab beetle species: the Asian rhinoceros beetle, Trypoxylus dichotomus, and the dung beetle, Onthophagus nigriventris. We obtained over half a million reads for each species that were assembled into over 6,000 and 16,000 contigs respectively. We combined these data with previously published studies to look for signatures of molecular evolution. We found a small subset of genes with horn-biased expression showing evidence for recent positive selection, as is expected with sexual selection on horn size. We also found evidence of relaxed selection present in genes that demonstrated biased expression between horned and horn-less morphs, consistent with the theory of developmental decoupling of phenotypically plastic traits.

Disproportionate Cochlear Length in Genus Homo Shows a High Phylogenetic Signal during Apes' Hearing Evolution.

PubMed

Braga, J; Loubes, J-M; Descouens, D; Dumoncel, J; Thackeray, J F; Kahn, J-L; de Beer, F; Riberon, A; Hoffman, K; Balaresque, P; Gilissen, E

2015-01-01

Changes in lifestyles and body weight affected mammal life-history evolution but little is known about how they shaped species' sensory systems. Since auditory sensitivity impacts communication tasks and environmental acoustic awareness, it may have represented a deciding factor during mammal evolution, including apes. Here, we statistically measure the influence of phylogeny and allometry on the variation of five cochlear morphological features associated with hearing capacities across 22 living and 5 fossil catarrhine species. We find high phylogenetic signals for absolute and relative cochlear length only. Comparisons between fossil cochleae and reconstructed ape ancestral morphotypes show that Australopithecus absolute and relative cochlear lengths are explicable by phylogeny and concordant with the hypothetized ((Pan,Homo),Gorilla) and (Pan,Homo) most recent common ancestors. Conversely, deviations of the Paranthropus oval window area from these most recent common ancestors are not explicable by phylogeny and body weight alone, but suggest instead rapid evolutionary changes (directional selection) of its hearing organ. Premodern (Homo erectus) and modern human cochleae set apart from living non-human catarrhines and australopiths. They show cochlear relative lengths and oval window areas larger than expected for their body mass, two features corresponding to increased low-frequency sensitivity more recent than 2 million years ago. The uniqueness of the "hypertrophied" cochlea in the genus Homo (as opposed to the australopiths) and the significantly high phylogenetic signal of this organ among apes indicate its usefulness to identify homologies and monophyletic groups in the hominid fossil record.

Disproportionate Cochlear Length in Genus Homo Shows a High Phylogenetic Signal during Apes’ Hearing Evolution

PubMed Central

Braga, J.; Loubes, J-M.; Descouens, D.; Dumoncel, J.; Thackeray, J. F.; Kahn, J-L.; de Beer, F.; Riberon, A.; Hoffman, K.; Balaresque, P.; Gilissen, E.

2015-01-01

Changes in lifestyles and body weight affected mammal life-history evolution but little is known about how they shaped species’ sensory systems. Since auditory sensitivity impacts communication tasks and environmental acoustic awareness, it may have represented a deciding factor during mammal evolution, including apes. Here, we statistically measure the influence of phylogeny and allometry on the variation of five cochlear morphological features associated with hearing capacities across 22 living and 5 fossil catarrhine species. We find high phylogenetic signals for absolute and relative cochlear length only. Comparisons between fossil cochleae and reconstructed ape ancestral morphotypes show that Australopithecus absolute and relative cochlear lengths are explicable by phylogeny and concordant with the hypothetized ((Pan,Homo),Gorilla) and (Pan,Homo) most recent common ancestors. Conversely, deviations of the Paranthropus oval window area from these most recent common ancestors are not explicable by phylogeny and body weight alone, but suggest instead rapid evolutionary changes (directional selection) of its hearing organ. Premodern (Homo erectus) and modern human cochleae set apart from living non-human catarrhines and australopiths. They show cochlear relative lengths and oval window areas larger than expected for their body mass, two features corresponding to increased low-frequency sensitivity more recent than 2 million years ago. The uniqueness of the “hypertrophied” cochlea in the genus Homo (as opposed to the australopiths) and the significantly high phylogenetic signal of this organ among apes indicate its usefulness to identify homologies and monophyletic groups in the hominid fossil record. PMID:26083484

Convergent evolution of vascular optimization in kelp (Laminariales).

PubMed

Drobnitch, Sarah Tepler; Jensen, Kaare H; Prentice, Paige; Pittermann, Jarmila

2015-10-07

Terrestrial plants and mammals, although separated by a great evolutionary distance, have each arrived at a highly conserved body plan in which universal allometric scaling relationships govern the anatomy of vascular networks and key functional metabolic traits. The universality of allometric scaling suggests that these phyla have each evolved an 'optimal' transport strategy that has been overwhelmingly adopted by extant species. To truly evaluate the dominance and universality of vascular optimization, however, it is critical to examine other, lesser-known, vascularized phyla. The brown algae (Phaeophyceae) are one such group--as distantly related to plants as mammals, they have convergently evolved a plant-like body plan and a specialized phloem-like transport network. To evaluate possible scaling and optimization in the kelp vascular system, we developed a model of optimized transport anatomy and tested it with measurements of the giant kelp, Macrocystis pyrifera, which is among the largest and most successful of macroalgae. We also evaluated three classical allometric relationships pertaining to plant vascular tissues with a diverse sampling of kelp species. Macrocystis pyrifera displays strong scaling relationships between all tested vascular parameters and agrees with our model; other species within the Laminariales display weak or inconsistent vascular allometries. The lack of universal scaling in the kelps and the presence of optimized transport anatomy in M. pyrifera raises important questions about the evolution of optimization and the possible competitive advantage conferred by optimized vascular systems to multicellular phyla. © 2015 The Author(s).

Postnatal temporal bone ontogeny in Pan, Gorilla, and Homo, and the implications for temporal bone ontogeny in Australopithecus afarensis.

PubMed

Terhune, Claire E; Kimbel, William H; Lockwood, Charles A

2013-08-01

Assessments of temporal bone morphology have played an important role in taxonomic and phylogenetic evaluations of fossil taxa, and recent three-dimensional analyses of this region have supported the utility of the temporal bone for testing taxonomic and phylogenetic hypotheses. But while clinical analyses have examined aspects of temporal bone ontogeny in humans, the ontogeny of the temporal bone in non-human taxa is less well documented. This study examines ontogenetic allometry of the temporal bone in order to address several research questions related to the pattern and trajectory of temporal bone shape change during ontogeny in the African apes and humans. We further apply these data to a preliminary analysis of temporal bone ontogeny in Australopithecus afarensis. Three-dimensional landmarks were digitized on an ontogenetic series of specimens of Homo sapiens, Pan troglodytes, Pan paniscus, and Gorilla gorilla. Data were analyzed using geometric morphometric methods, and shape changes throughout ontogeny in relation to size were compared. Results of these analyses indicate that, despite broadly similar patterns, African apes and humans show marked differences in development of the mandibular fossa and tympanic portions of the temporal bone. These findings indicate divergent, rather than parallel, postnatal ontogenetic allometric trajectories for temporal bone shape in these taxa. The pattern of temporal bone shape change with size exhibited by A. afarensis showed some affinities to that of humans, but was most similar to extant African apes, particularly Gorilla. Copyright © 2013 Wiley Periodicals, Inc.

Reconsidering the evolution of brain, cognition, and behavior in birds and mammals

PubMed Central

Willemet, Romain

2013-01-01

Despite decades of research, some of the most basic issues concerning the extraordinarily complex brains and behavior of birds and mammals, such as the factors responsible for the diversity of brain size and composition, are still unclear. This is partly due to a number of conceptual and methodological issues. Determining species and group differences in brain composition requires accounting for the presence of taxon-cerebrotypes and the use of precise statistical methods. The role of allometry in determining brain variables should be revised. In particular, bird and mammalian brains appear to have evolved in response to a variety of selective pressures influencing both brain size and composition. “Brain” and “cognition” are indeed meta-variables, made up of the variables that are ecologically relevant and evolutionarily selected. External indicators of species differences in cognition and behavior are limited by the complexity of these differences. Indeed, behavioral differences between species and individuals are caused by cognitive and affective components. Although intra-species variability forms the basis of species evolution, some of the mechanisms underlying individual differences in brain and behavior appear to differ from those between species. While many issues have persisted over the years because of a lack of appropriate data or methods to test them; several fallacies, particularly those related to the human brain, reflect scientists' preconceptions. The theoretical framework on the evolution of brain, cognition, and behavior in birds and mammals should be reconsidered with these biases in mind. PMID:23847570

A repeatable geometric morphometric approach to the analysis of hand entheseal three-dimensional form.

PubMed

Karakostis, Fotios Alexandros; Hotz, Gerhard; Scherf, Heike; Wahl, Joachim; Harvati, Katerina

2018-05-01

The purpose of this study was to put forth a precise landmark-based technique for reconstructing the three-dimensional shape of human entheseal surfaces, to investigate whether the shape of human entheses is related to their size. The effects of age-at-death and bone length on entheseal shapes were also assessed. The sample comprised high-definition three-dimensional models of three right hand entheseal surfaces, which correspond to 45 male adult individuals of known age. For each enthesis, a particular landmark configuration was introduced, whose precision was tested both within and between observers. The effect of three-dimensional size, age-at-death, and bone length on shape was investigated through shape regression. The method presented high intra-observer and inter-observer repeatability. All entheses showed significant allometry, with the area of opponens pollicis demonstrating the most substantial relationship. This was particularly due to variation related to its proximal elongated ridge. The effect of age-at-death and bone length on entheses was limited. The introduced methodology can set a reliable basis for further research on the factors affecting entheseal shape. Using both size and shape, variables can provide further information on entheseal variation and its biomechanical implications. The low entheseal variation by age verifies that specimens under 50 years of age are not substantially affected by age-related changes. The lack of correlation between entheseal shape and bone length or age implies that other factors may regulate entheseal surfaces. Future research should focus on multivariate shape patterns among entheses and their association with occupation. © 2018 Wiley Periodicals, Inc.

Static allometry of unicellular green algae: scaling of cellular surface area and volume in the genus Micrasterias (Desmidiales).

PubMed

Neustupa, J

2016-02-01

The surface area-to-volume ratio of cells is one of the key factors affecting fundamental biological processes and, thus, fitness of unicellular organisms. One of the general models for allometric increase in surface-to-volume scaling involves fractal-like elaboration of cellular surfaces. However, specific data illustrating this pattern in natural populations of the unicellular organisms have not previously been available. This study shows that unicellular green algae of the genus Micrasterias (Desmidiales) have positive allometric surface-to-volume scaling caused by changes in morphology of individual species, especially in the degree of cell lobulation. This allometric pattern was also detected within most of the cultured and natural populations analysed. Values of the allometric S:V scaling within individual populations were closely correlated to the phylogenetic structure of the clade. In addition, they were related to species-specific cellular morphology. Individual populations differed in their allometric patterns, and their position in the allometric space was strongly correlated with the degree of allometric S:V scaling. This result illustrates that allometric shape patterns are an important correlate of the capacity of individual populations to compensate for increases in their cell volumes by increasing the surface area. However, variation in allometric patterns was not associated with phylogenetic structure. This indicates that the position of the populations in the allometric space was not evolutionarily conserved and might be influenced by environmental factors. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Sex-related shape dimorphism in the human radiocarpal and midcarpal joints.

PubMed

Kivell, Tracy L; Guimont, Isabelle; Wall, Christine E

2013-01-01

Previous research has revealed significant size differences between human male and female carpal bones but it is unknown if there are significant shape differences as well. This study investigated sex-related shape variation and allometric patterns in five carpal bones that make up the radiocarpal and midcarpal joints in modern humans. We found that many aspects of carpal shape (76% of all variables quantified) were similar between males and females, despite variation in size. However, 10 of the shape ratios were significantly different between males and females, with at least one significant shape difference observed in each carpal bone. Within-sex standard major axis regressions (SMA) of the numerator (i.e., the linear variables) on the denominator (i.e., the geometric mean) for each significantly different shape ratio indicated that most linear variables scaled with positive allometry in both males and females, and that for eight of the shape ratios, sex-related shape variation is associated with statistically similar sex-specific scaling relationships. Only the length of the scaphoid body and the height of the lunate triquetrum facet showed a significantly higher SMA slope in females compared with males. These findings indicate that the significant differences in the majority of the shape ratios are a function of subtle (i.e., not statistically significant) scaling differences between males and females. There are a number of potential developmental, functional, and evolutionary factors that may cause sex-related shape differences in the human carpus. The results highlight the potential for subtle differences in scaling to result in functionally significant differences in shape. Copyright © 2012 Wiley Periodicals, Inc.

Linear regression analysis for comparing two measurers or methods of measurement: but which regression?

PubMed

Ludbrook, John

2010-07-01

1. There are two reasons for wanting to compare measurers or methods of measurement. One is to calibrate one method or measurer against another; the other is to detect bias. Fixed bias is present when one method gives higher (or lower) values across the whole range of measurement. Proportional bias is present when one method gives values that diverge progressively from those of the other. 2. Linear regression analysis is a popular method for comparing methods of measurement, but the familiar ordinary least squares (OLS) method is rarely acceptable. The OLS method requires that the x values are fixed by the design of the study, whereas it is usual that both y and x values are free to vary and are subject to error. In this case, special regression techniques must be used. 3. Clinical chemists favour techniques such as major axis regression ('Deming's method'), the Passing-Bablok method or the bivariate least median squares method. Other disciplines, such as allometry, astronomy, biology, econometrics, fisheries research, genetics, geology, physics and sports science, have their own preferences. 4. Many Monte Carlo simulations have been performed to try to decide which technique is best, but the results are almost uninterpretable. 5. I suggest that pharmacologists and physiologists should use ordinary least products regression analysis (geometric mean regression, reduced major axis regression): it is versatile, can be used for calibration or to detect bias and can be executed by hand-held calculator or by using the loss function in popular, general-purpose, statistical software.

Size relationships of different body parts in the three dipteran species Drosophila melanogaster, Ceratitis capitata and Musca domestica.

PubMed

Siomava, Natalia; Wimmer, Ernst A; Posnien, Nico

2016-06-01

Body size is an integral feature of an organism that influences many aspects of life such as fecundity, life span and mating success. Size of individual organs and the entire body size represent quantitative traits with a large reaction norm, which are influenced by various environmental factors. In the model system Drosophila melanogaster, pupal size and adult traits, such as tibia and thorax length or wing size, accurately estimate the overall body size. However, it is unclear whether these traits can be used in other flies. Therefore, we studied changes in size of pupae and adult organs in response to different rearing temperatures and densities for D. melanogaster, Ceratitis capitata and Musca domestica. We confirm a clear sexual size dimorphism (SSD) for Drosophila and show that the SSD is less uniform in the other species. Moreover, the size response to changing growth conditions is sex dependent. Comparison of static and evolutionary allometries of the studied traits revealed that response to the same environmental variable is genotype specific but has similarities between species of the same order. We conclude that the value of adult traits as estimators of the absolute body size may differ among species and the use of a single trait may result in wrong assumptions. Therefore, we suggest using a body size coefficient computed from several individual measurements. Our data is of special importance for monitoring activities of natural populations of the three dipteran flies, since they are harmful species causing economical damage (Drosophila, Ceratitis) or transferring diseases (Musca).

Additive genetic variation in the craniofacial skeleton of baboons (genus Papio) and its relationship to body and cranial size.

PubMed

Joganic, Jessica L; Willmore, Katherine E; Richtsmeier, Joan T; Weiss, Kenneth M; Mahaney, Michael C; Rogers, Jeffrey; Cheverud, James M

2018-02-01

Determining the genetic architecture of quantitative traits and genetic correlations among them is important for understanding morphological evolution patterns. We address two questions regarding papionin evolution: (1) what effect do body and cranial size, age, and sex have on phenotypic (V P ) and additive genetic (V A ) variation in baboon crania, and (2) how might additive genetic correlations between craniofacial traits and body mass affect morphological evolution? We use a large captive pedigreed baboon sample to estimate quantitative genetic parameters for craniofacial dimensions (EIDs). Our models include nested combinations of the covariates listed above. We also simulate the correlated response of a given EID due to selection on body mass alone. Covariates account for 1.2-91% of craniofacial V P . EID V A decreases across models as more covariates are included. The median genetic correlation estimate between each EID and body mass is 0.33. Analysis of the multivariate response to selection reveals that observed patterns of craniofacial variation in extant baboons cannot be attributed solely to correlated response to selection on body mass, particularly in males. Because a relatively large proportion of EID V A is shared with body mass variation, different methods of correcting for allometry by statistically controlling for size can alter residual V P patterns. This may conflate direct selection effects on craniofacial variation with those resulting from a correlated response to body mass selection. This shared genetic variation may partially explain how selection for increased body mass in two different papionin lineages produced remarkably similar craniofacial phenotypes. © 2017 Wiley Periodicals, Inc.

Preclinical pharmacokinetics of the novel PI3K inhibitor GDC-0941 and prediction of its pharmacokinetics and efficacy in human.

PubMed

Salphati, Laurent; Pang, Jodie; Plise, Emile G; Chou, Bilin; Halladay, Jason S; Olivero, Alan G; Rudewicz, Patrick J; Tian, Qingping; Wong, Susan; Zhang, Xiaolin

2011-12-01

The phosphatidylinositol 3-kinase (PI3K) pathway is a major determinant of cell cycling and proliferation. Its deregulation is associated with the development of many cancers. GDC-0941, a potent and selective inhibitor of PI3K, was characterised preclinically in in vitro and in vivo studies. Plasma protein binding was extensive, with free fraction less than 7%, and blood-to-plasma ratio ranged from 0.6 to 1.2 among the species tested. GDC-0941 human hepatic clearance was predicted to be moderate by liver microsomal incubations. GDC-0941 had high permeability in Madin-Darby canine kidney cells. The clearance of GDC-0941 was high in mouse (63.7 mL/min/kg), rat (49.3 mL/min/kg) and cynomolgus monkey (58.6 mL/min/kg), and moderate in dog (11.9 mL/min/kg). The volume of distribution ranged from 2.52 L/kg in rat to 2.94 L/kg in monkey. Oral bioavailability ranged from 18.6% in monkey to 77.9% in mouse. Predicted human clearance and volume of distribution using allometry were 6 mL/min/kg and 2.9 L/kg, respectively. The human efficacious doses were predicted based on results from preclinical pharmacokinetic studies and xenograft models. GDC-0941 preclinical characterisation and predictions of its properties in human supported its progression towards clinical development. GDC-0941 is currently in phase II clinical trials.

Tree allometry and improved estimation of carbon stocks and balance in tropical forests.

PubMed

Chave, J; Andalo, C; Brown, S; Cairns, M A; Chambers, J Q; Eamus, D; Fölster, H; Fromard, F; Higuchi, N; Kira, T; Lescure, J-P; Nelson, B W; Ogawa, H; Puig, H; Riéra, B; Yamakura, T

2005-08-01

Tropical forests hold large stores of carbon, yet uncertainty remains regarding their quantitative contribution to the global carbon cycle. One approach to quantifying carbon biomass stores consists in inferring changes from long-term forest inventory plots. Regression models are used to convert inventory data into an estimate of aboveground biomass (AGB). We provide a critical reassessment of the quality and the robustness of these models across tropical forest types, using a large dataset of 2,410 trees >or= 5 cm diameter, directly harvested in 27 study sites across the tropics. Proportional relationships between aboveground biomass and the product of wood density, trunk cross-sectional area, and total height are constructed. We also develop a regression model involving wood density and stem diameter only. Our models were tested for secondary and old-growth forests, for dry, moist and wet forests, for lowland and montane forests, and for mangrove forests. The most important predictors of AGB of a tree were, in decreasing order of importance, its trunk diameter, wood specific gravity, total height, and forest type (dry, moist, or wet). Overestimates prevailed, giving a bias of 0.5-6.5% when errors were averaged across all stands. Our regression models can be used reliably to predict aboveground tree biomass across a broad range of tropical forests. Because they are based on an unprecedented dataset, these models should improve the quality of tropical biomass estimates, and bring consensus about the contribution of the tropical forest biome and tropical deforestation to the global carbon cycle.

Forearm articular proportions and the antebrachial index in Homo sapiens, Australopithecus afarensis and the great apes.

PubMed

Williams, Frank L'Engle; Cunningham, Deborah L; Amaral, Lia Q

2015-12-01

When hominin bipedality evolved, the forearms were free to adopt nonlocomotor tasks which may have resulted in changes to the articular surfaces of the ulna and the relative lengths of the forearm bones. Similarly, sex differences in forearm proportions may be more likely to emerge in bipeds than in the great apes given the locomotor constraints in Gorilla, Pan and Pongo. To test these assumptions, ulnar articular proportions and the antebrachial index (radius length/ulna length) in Homo sapiens (n=51), Gorilla gorilla (n=88), Pan troglodytes (n=49), Pongo pygmaeus (n=36) and Australopithecus afarensis A.L. 288-1 and A.L. 438-1 are compared. Intercept-adjusted ratios are used to control for size and minimize the effects of allometry. Canonical scores axes show that the proximally broad and elongated trochlear notch with respect to size in H. sapiens and A. afarensis is largely distinct from G. gorilla, P. troglodytes and P. pygmaeus. A cluster analysis of scaled ulnar articular dimensions groups H. sapiens males with A.L. 438-1 ulna length estimates, while one A.L. 288-1 ulna length estimate groups with Pan and another clusters most closely with H. sapiens, G. gorilla and A.L. 438-1. The relatively low antebrachial index characterizing H. sapiens and non-outlier estimates of A.L. 288-1 and A.L. 438-1 differs from those of the great apes. Unique sex differences in H. sapiens suggest a link between bipedality and forearm functional morphology. Copyright © 2015 Elsevier GmbH. All rights reserved.

Functional specialization and ontogenetic scaling of limb anatomy in Alligator mississippiensis

PubMed Central

Allen, Vivian; Elsey, Ruth M; Jones, Nicola; Wright, Jordon; Hutchinson, John R

2010-01-01

Crocodylians exhibit a fascinating diversity of terrestrial gaits and limb motions that remain poorly described and are of great importance to understanding their natural history and evolution. Their musculoskeletal anatomy is pivotal to this diversity and yet only qualitative studies of muscle-tendon unit anatomy exist. The relative masses and internal architecture (fascicle lengths and physiological cross-sectional areas) of muscles of the pectoral and pelvic limbs of American alligators (Alligator mississippiensis Daudin 1801) were recorded for an ontogenetic series of wild specimens (n = 15, body masses from 0.5 to 60 kg). The data were analysed by reduced major axis regression to determine scaling relationships with body mass. Physiological cross-sectional areas and therefore muscle force-generating capacity were found to be greater in the extensor (anti-gravity) muscles of the pelvic limb than in the pectoral limb, reflecting how crocodylians differ from mammals in having greater loading of the hindlimbs than the forelimbs. Muscle masses and architecture were generally found to scale isometrically with body mass, suggesting an ontogenetic decrease in terrestrial athleticism. This concurs with the findings of previous studies showing ontogenetic decreases in limb bone length and the general scaling principle of a decline of strength : weight ratios with increasing size in animals. Exceptions to isometric scaling found included positive allometry in fascicle length for extensor musculature of both limbs, suggesting an ontogenetic increase in working range interpreted as increasing postural variability – in particular the major hip extensors – the interpretation of which is complicated by previous described ontogenetic increase of moment arms for these muscles. PMID:20148991

Clutch and egg allometry of the turtle Mauremys leprosa (Chelonia: Geoemydidae) from a polluted peri-urban river in west-central Morocco

USGS Publications Warehouse

Naimi, Mohamed; Znari, Mohammed; Lovich, Jeffrey E.; Feddadi, Youssef; Baamrane, Moulay Abdeljalil Ait

2012-01-01

We examined the relationships of clutch size (CS) and egg size to female body size (straight-line carapace length, CL) in a population of the turtle Mauremys leprosa from a polluted segment of oued (river) Tensift in arid west-central Morocco. Twenty-eight adult females were collected in May–July, 2009 and all were gravid. Each was weighed, measured, humanely euthanized and then dissected. Oviductal shelled eggs were removed, weighed (egg mass, EM) and measured for length (EL) and width (EW). Clutch mass (CM) was the sum of EM for a clutch. Pelvic aperture width (PAW) was measured at the widest point between the ilia bones through which eggs must pass at oviposition. The smallest gravid female had a CL of 124.0 mm. Mean CS was relatively large (9.7±2.0 eggs, range: 3–13) and may reflect high productivity associated with polluted (eutrophic) waters. Regression analyses were conducted using log-transformed data. CM increased isometrically with maternal body size. CS, EW and EM were all significantly hypoallometric in their relationship with CL. EL did not change significantly with increases in CL. EW increased at a hypoallometric rate with increasing CL but was unconstrained by PAW since the widest egg was smaller than the narrowest PAW measurement when excluding the three smallest females. Smaller females may have EW constrained by PAW. As females increase in size they increase both clutch size and egg width in contradiction to predictions of optimal egg size theory.

Temperature-induced plasticity in morphology and relative shell weight in the invasive apple snail Pomacea canaliculata.

PubMed

Tamburi, Nicolás E; Seuffert, María E; Martín, Pablo R

2018-05-01

Temperature has a great influence on the life-history traits of freshwater snails. In this study we investigated the long term effects of a range of temperatures on shell morphology of the apple snail Pomacea canaliculata, a highly invasive species and an important pest of rice. Analysis of shells using geometric morphometrics showed that the main source of morphological variation was allometry, which was detected in males but not in females. This intersexual divergence in allometric trajectories generates much of the morphological variation evidenced. In females, the monotonic relationship with temperature produced narrower shells in the snails reared at lower temperatures, and more expanded apertures, relatively bigger than the body whorl, at higher temperatures. We also found an inverse relationship between relative shell weight, a proxy for shell thickness, and temperature. The differences in shape and relative shell weight are attributable to the different growth rates associated with different temperatures. Temperature fluctuation around a mean of 23.2 °C seemed to have no influence in shell shape and relative weight when is compared with a constant temperature of 25 °C. Information on the influence of temperature on freshwater snails is important for understanding and predicting changes in the face of global climatic change, especially in traits exhibiting great plasticity, such as shell shape and thickness. This work showed that higher temperatures could result in a relatively thinner shell, implying a greater significance of corrosion in flowing waters and a lower resistance to crushing by predators, especially in low latitude areas. Copyright © 2018 Elsevier Ltd. All rights reserved.

Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis)

PubMed Central

Owerkowicz, Tomasz; Elsey, Ruth M.; Hicks, James W.

2009-01-01

Summary Recent palaeoatmospheric models suggest large-scale fluctuations in ambient oxygen level over the past 550 million years. To better understand how global hypoxia and hyperoxia might have affected the growth and physiology of contemporary vertebrates, we incubated eggs and raised hatchlings of the American alligator. Crocodilians are one of few vertebrate taxa that survived these global changes with distinctly conservative morphology. We maintained animals at 30°C under chronic hypoxia (12% O2), normoxia (21% O2) or hyperoxia (30% O2). At hatching, hypoxic animals were significantly smaller than their normoxic and hyperoxic siblings. Over the course of 3 months, post-hatching growth was fastest under hyperoxia and slowest under hypoxia. Hypoxia, but not hyperoxia, caused distinct scaling of major visceral organs–reduction of liver mass, enlargement of the heart and accelerated growth of lungs. When absorptive and post-absorptive metabolic rates were measured in juvenile alligators, the increase in oxygen consumption rate due to digestion/absorption of food was greatest in hyperoxic alligators and smallest in hypoxic ones. Hyperoxic alligators exhibited the lowest breathing rate and highest oxygen consumption per breath. We suggest that, despite compensatory cardiopulmonary remodelling, growth of hypoxic alligators is constrained by low atmospheric oxygen supply, which may limit their food utilisation capacity. Conversely, the combination of elevated metabolism and low cost of breathing in hyperoxic alligators allows for a greater proportion of metabolised energy to be available for growth. This suggests that growth and metabolic patterns of extinct vertebrates would have been significantly affected by changes in the atmospheric oxygen level. PMID:19376944

Geographic variation in floral allometry suggests repeated transitions between selfing and outcrossing in a mixed mating plant.

PubMed

Summers, Holly E; Hartwick, Sally M; Raguso, Robert A

2015-05-01

Isometric and allometric scaling of a conserved floral plan could provide a parsimonious mechanism for rapid and reversible transitions between breeding systems. This scaling may occur during transitions between predominant autogamy and xenogamy, contributing to the maintenance of a stable mixed mating system. We compared nine disjunct populations of the polytypic, mixed mating species Oenothera flava (Onagraceae) to two parapatric relatives, the obligately xenogamous species O. acutissima and the mixed mating species O. triloba. We compared floral morphology of all taxa using principal component analysis (PCA) and developmental trajectories of floral organs using ANCOVA homogeneity of slopes. The PCA revealed both isometric and allometric scaling of a conserved floral plan. Three principal components (PCs) explained 92.5% of the variation in the three species. PC1 predominantly loaded on measures of floral size and accounts for 36% of the variation. PC2 accounted for 35% of the variation, predominantly in traits that influence pollinator handling. PC3 accounted for 22% of the variation, primarily in anther-stigma distance (herkogamy). During O. flava subsp. taraxacoides development, style elongation was accelerated relative to anthers, resulting in positive herkogamy. During O. flava subsp. flava development, style elongation was decelerated, resulting in zero or negative herkogamy. Of the two populations with intermediate morphology, style elongation was accelerated in one population and decelerated in the other. Isometric and allometric scaling of floral organs in North American Oenothera section Lavauxia drive variation in breeding system. Multiple developmental paths to intermediate phenotypes support the likelihood of multiple mating system transitions. © 2015 Botanical Society of America, Inc.

Support for maternal manipulation of developmental nutrition in a facultatively eusocial bee, Megalopta genalis (Halictidae).

PubMed

Kapheim, Karen M; Bernal, Sandra P; Smith, Adam R; Nonacs, Peter; Wcislo, William T

2011-06-01

Developmental maternal effects are a potentially important source of phenotypic variation, but they can be difficult to distinguish from other environmental factors. This is an important distinction within the context of social evolution, because if variation in offspring helping behavior is due to maternal manipulation, social selection may act on maternal phenotypes, as well as those of offspring. Factors correlated with social castes have been linked to variation in developmental nutrition, which might provide opportunity for females to manipulate the social behavior of their offspring. Megalopta genalis is a mass-provisioning facultatively eusocial sweat bee for which production of males and females in social and solitary nests is concurrent and asynchronous. Female offspring may become either gynes (reproductive dispersers) or workers (non-reproductive helpers). We predicted that if maternal manipulation plays a role in M. genalis caste determination, investment in daughters should vary more than for sons. The mass and protein content of pollen stores provided to female offspring varied significantly more than those of males, but volume and sugar content did not. Sugar content varied more among female eggs in social nests than in solitary nests. Provisions were larger, with higher nutrient content, for female eggs and in social nests. Adult females and males show different patterns of allometry, and their investment ratio ranged from 1.23 to 1.69. Adult body weight varied more for females than males, possibly reflecting increased variation in maternal investment in female offspring. These differences are consistent with a role for maternal manipulation in the social plasticity observed in M. genalis.

Evolution of skull shape in the family Salamandridae (Amphibia: Caudata).

PubMed

Ivanović, Ana; Arntzen, Jan W

2018-03-01

We carried out a comparative morphometric analysis of 56 species of salamandrid salamanders, representing 19 out of 21 extant genera, with the aim of uncovering the major patterns of skull shape diversification, and revealing possible trends and directions of evolutionary change. To do this we used micro-computed tomography scanning and three-dimensional geometric morphometrics, along with a well-resolved molecular phylogeny. We found that allometry explains a relatively small amount of shape variation across taxa. Congeneric species of salamandrid salamanders are more similar to each other and cluster together producing distinct groups in morphospace. We detected a strong phylogenetic signal and little homoplasy. The most pronounced changes in the skull shape are related to the changes of the frontosquamosal arch, a unique feature of the cranial skeleton for the family Salamandridae, which is formed by processes arising from the frontal and squamosal bones that arch over the orbits. By mapping character states over the phylogeny, we found that a reduction of the frontosquamosal arch occurs independently in three lineages of the subfamily Pleurodelinae. This reduction can probably be attributed to changes in the development and ossification rates of the frontosquamosal arch. In general, our results are similar to those obtained for caecilian amphibians, with an early expansion into the available morphospace and a complex history characterizing evolution of skull shape in both groups. To evaluate the specificity of the inferred evolutionary trajectories and Caudata-wide trends in the diversity of skull morphology, information from additional groups of tailed amphibians is needed. © 2017 Anatomical Society.

Histomorphometry and cortical robusticity of the adult human femur.

PubMed

Miszkiewicz, Justyna Jolanta; Mahoney, Patrick

2018-01-13

Recent quantitative analyses of human bone microanatomy, as well as theoretical models that propose bone microstructure and gross anatomical associations, have started to reveal insights into biological links that may facilitate remodeling processes. However, relationships between bone size and the underlying cortical bone histology remain largely unexplored. The goal of this study is to determine the extent to which static indicators of bone remodeling and vascularity, measured using histomorphometric techniques, relate to femoral midshaft cortical width and robusticity. Using previously published and new quantitative data from 450 adult human male (n = 233) and female (n = 217) femora, we determine if these aspects of femoral size relate to bone microanatomy. Scaling relationships are explored and interpreted within the context of tissue form and function. Analyses revealed that the area and diameter of Haversian canals and secondary osteons, and densities of secondary osteons and osteocyte lacunae from the sub-periosteal region of the posterior midshaft femur cortex were significantly, but not consistently, associated with femoral size. Cortical width and bone robusticity were correlated with osteocyte lacunae density and scaled with positive allometry. Diameter and area of osteons and Haversian canals decreased as the width of cortex and bone robusticity increased, revealing a negative allometric relationship. These results indicate that microscopic products of cortical bone remodeling and vascularity are linked to femur size. Allometric relationships between more robust human femora with thicker cortical bone and histological products of bone remodeling correspond with principles of bone functional adaptation. Future studies may benefit from exploring scaling relationships between bone histomorphometric data and measurements of bone macrostructure.

Condition dependence of male and female genital structures in the seed beetle Callosobruchus maculatus (Coleoptera: Bruchidae).

PubMed

Cayetano, L; Bonduriansky, R

2015-07-01

Theory predicts that costly secondary sexual traits will evolve heightened condition dependence, and many studies have reported strong condition dependence of signal and weapon traits in a variety of species. However, although genital structures often play key roles in intersexual interactions and appear to be subject to sexual or sexually antagonistic selection, few studies have examined the condition dependence of genital structures, especially in both sexes simultaneously. We investigated the responses of male and female genital structures to manipulation of larval diet quality (new versus once-used mung beans) in the bruchid seed beetle Callosobruchus maculatus. We quantified effects on mean relative size and static allometry of the male aedeagus, aedeagal spines, flap and paramere and the female reproductive tract and bursal spines. None of the male traits showed a significant effect of diet quality. In females, we found that longer bursal spines (relative to body size) were expressed on low-quality diet. Although the function of bursal spines is poorly understood, we suggest that greater bursal spine length in low-condition females may represent a sexually antagonistic adaptation. Overall, we found no evidence that genital traits in C. maculatus are expressed to a greater extent when nutrients are more abundant. This suggests that, even though some genital traits appear to function as secondary sexual traits, genital traits do not exhibit heightened condition dependence in this species. We discuss possible reasons for this finding. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Size Scaling in Western North Atlantic Loggerhead Turtles Permits Extrapolation between Regions, but Not Life Stages.

PubMed

Marn, Nina; Klanjscek, Tin; Stokes, Lesley; Jusup, Marko

2015-01-01

Sea turtles face threats globally and are protected by national and international laws. Allometry and scaling models greatly aid sea turtle conservation and research, and help to better understand the biology of sea turtles. Scaling, however, may differ between regions and/or life stages. We analyze differences between (i) two different regional subsets and (ii) three different life stage subsets of the western North Atlantic loggerhead turtles by comparing the relative growth of body width and depth in relation to body length, and discuss the implications. Results suggest that the differences between scaling relationships of different regional subsets are negligible, and models fitted on data from one region of the western North Atlantic can safely be used on data for the same life stage from another North Atlantic region. On the other hand, using models fitted on data for one life stage to describe other life stages is not recommended if accuracy is of paramount importance. In particular, young loggerhead turtles that have not recruited to neritic habitats should be studied and modeled separately whenever practical, while neritic juveniles and adults can be modeled together as one group. Even though morphometric scaling varies among life stages, a common model for all life stages can be used as a general description of scaling, and assuming isometric growth as a simplification is justified. In addition to linear models traditionally used for scaling on log-log axes, we test the performance of a saturating (curvilinear) model. The saturating model is statistically preferred in some cases, but the accuracy gained by the saturating model is marginal.

The mechanosensory calcium-selective ion channel: key component of a plasmalemmal control centre?

NASA Technical Reports Server (NTRS)

Pickard, B. G.; Ding, J. P.

1993-01-01

Mechanosensory calcium-selective ion channels probably serve to detect not only mechanical stress but also electrical, thermal, and diverse chemical stimuli. Because all stimuli result in a common output, most notably a shift in second messenger calcium concentration, the channels are presumed to serve as signal integrators. Further, insofar as second messenger calcium in turn gives rise to mechanical, electrical, and diverse chemical changes, the channels are postulated to initiate regulatory feedbacks. It is proposed that the channels and the feedback loops play a wide range of roles in regulating normal plant function, as well as in mediating disturbance of normal function by environmental stressors and various pathogens. In developing evidence for the physiological performance of the channel, a model for a cluster of regulatory plasmalemmal proteins and cytoskeletal elements grouped around a set of wall-to-membrane and transmembrane linkers has proved useful. An illustration of how the model might operate is presented. It is founded on the demonstration that several xenobiotics interfere both with normal channel behaviour and with gravitropic reception. Accordingly, the first part of the illustration deals with how the channels and the control system within which they putatively operate might initiate gravitropism. Assuming that gravitropism is an asymmetric expression of growth, the activities of the channels and the plasmalemmal control system are extrapolated to account for regulation of both rate and allometry of cell expansion. Finally, it is discussed how light, hormones, redox agents and herbicides could in principle affect growth via the putative plasmalemmal control cluster or centre.

Evolution of sexual dimorphism and Rensch’s rule in the beetle genus Limnebius (Hydraenidae): is sexual selection opportunistic?

PubMed Central

Rudoy, Andrey

2017-01-01

Sexual size dimorphism (SSD) is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch’s rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae), measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC) in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation. PMID:28286715

Evolution of sexual dimorphism and Rensch's rule in the beetle genus Limnebius (Hydraenidae): is sexual selection opportunistic?

PubMed

Rudoy, Andrey; Ribera, Ignacio

2017-01-01

Sexual size dimorphism (SSD) is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch's rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae), measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC) in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation.

Quantitative Assessment of Food Effect on the Pharmacokinetics of Nano-Crystallized Megestrol Acetate.

PubMed

Guk, Jinju; Son, Hankil; Chae, Dong Woo; Park, Kyungsoo

2017-03-01

Megestrol acetate, an appetite stimulant with low bioavailability, shows increased bioavailability when taken together with food. However, the pharmacokinetic characteristics of megestrol acetate and its relation with food are not well understood. This study aimed to investigate the food effect on the pharmacokinetics (PK) of the recently developed nano-crystallized megestrol acetate (NCMA), using a model-based approach. Data were obtained from an NCMA PK study consisting of a single dose in fasting (39 individuals) and fed conditions (40 individuals). Plasma concentrations were measured up to 120 hr after dosing. With the incorporation of body-weight via allometry, NONMEM 7.3 was used to develop a PK model, which was then used to simulate an optimal fasting dose yielding an area under concentration (AUC) and maximum concentration (C max ) of NCMA close to those obtained with the fed dose. NCMA concentrations were best characterized by a two-compartment model with first-order absorption linked to a recycling compartment to account for the multiple concentration peaks observed. Food increased bioavailability 2.2 times and decreased the absorption rate constant 0.58 times. Recycling event times were estimated to be 3.56, 7.99 and 24.0 hr. The optimal fast dose was 2.0 times higher than the fed dose, and the resulting difference in drug exposure between the fasting and fed dose was 7.5%. This work suggests that the PK model developed can be applied to an optimal dosage regimen design for NCMA treatment. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Testing functional and morphological interpretations of enamel thickness along the deciduous tooth row in human children.

PubMed

Mahoney, Patrick

2013-08-01

The significance of a gradient in enamel thickness along the human permanent molar row has been debated in the literature. Some attribute increased enamel thickness from first to third molars to greater bite force during chewing. Others argue that thicker third molar enamel relates to a smaller crown size facilitated by a reduced dentin component. Thus, differences in morphology, not function, explains enamel thickness. This study draws on these different interpretive models to assess enamel thickness along the entire human deciduous tooth row. Average enamel thickness (AET), the area and proportion of crown enamel and dentin, and a crown size proxy are calculated for incisors, canines, and molars. Allometric scaling relationships are assessed within each tooth class, and then comparisons are undertaken along the row. Generally, AET was correlated with crown size and scaled with isometry, except for second molars which scaled with positive allometry. Mean AET increased along the row and was greater on molars, where bite forces are reported to be higher. Second molars combined the largest crown size with the thickest enamel and the smallest proportion of dentin, which is consistent with a reduction in the potential for cusp fracture under high bite forces. Resistance to wear may also account for some enamel thickness variation between tooth classes. Dental reduction did not explain the trend in AET from central to lateral incisors, or from first to second molars. The gradient in AET along the deciduous tooth row is partly consistent with a functional interpretation of enamel thickness. Copyright © 2013 Wiley Periodicals, Inc.

Snout allometry in seahorses: insights on optimisation of pivot feeding performance during ontogeny.

PubMed

Roos, Gert; Van Wassenbergh, Sam; Herrel, Anthony; Adriaens, Dominique; Aerts, Peter

2010-07-01

As juvenile life-history stages are subjected to strong selection, these stages often show levels of performance approaching those of adults, or show a disproportionately rapid increase of performance with age. Although testing performance capacity in aquatic suction feeders is often problematic, in pivot feeders such as seahorses models have been proposed to estimate whether snout length is optimal to minimise the time needed to reach the prey. Here, we investigate whether the same model can also explain the snout lengths in an ontogenetic series of seahorses, explore how pivot feeding kinematics change during ontogeny, and test whether juveniles show disproportionate levels of performance. Our analysis shows that the dimensions of the snout change during ontogeny from short and broad to long and narrow. Model calculations show that the snout lengths of newborn and juvenile seahorses are nearly optimal for minimising prey reach time. However, in juveniles the centre of head rotation in the earth-bound frame of reference is located near the posterior end of the head, whereas in adults it is shifted forward and is located approximately above the eye. Modelling shows that this forward shift in the centre of rotation has the advantage of decreasing the moment of inertia and the torque required to rotate the head, but has the disadvantage of slightly increasing the time needed to reach the prey. Thus, the snout lengths of juvenile seahorses appear to be close to optimal, suggesting that they reach levels of performance close to adult levels, which illustrates the pervasive nature of selection on performance in juveniles.

Effects of snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses.

PubMed

Roos, Gert; Van Wassenbergh, Sam; Aerts, Peter; Herrel, Anthony; Adriaens, Dominique

2011-01-21

Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the snout is observed during which the snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of the suction performance, this snout allometry will inevitably affect the suction feeding ability. To test whether the snout is optimised for suction feeding throughout an ontogeny, we simulated the expansion of different snout shapes varying from extremely long and slender to short and broad for juvenile and adult snout sizes, using computational fluid dynamic models. Our results showed that the snout diameter at the start of the simulations is involved in a trade-off between the realizable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing snout length. However, an increase in snout length decreases the time to reach the prey by the cranial rotation, which may explain the prevalence of long snouts among syngnathid fishes despite the reduced suction performance. Thus, the design of the seahorse snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by the cranial rotation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Sex differences in gait utilization and energy metabolism during terrestrial locomotion in two varieties of chicken (Gallus gallus domesticus) selected for different body size

PubMed Central

Rose, Kayleigh A.; Nudds, Robert L.; Butler, Patrick J.; Codd, Jonathan R.

2015-01-01

ABSTRACT In leghorn chickens (Gallus gallus domesticus) of standard breed (large) and bantam (small) varieties, artificial selection has led to females being permanently gravid and sexual selection has led to male-biased size dimorphism. Using respirometry, videography and morphological measurements, sex and variety differences in metabolic cost of locomotion, gait utilisation and maximum sustainable speed (Umax) were investigated during treadmill locomotion. Males were capable of greater Umax than females and used a grounded running gait at high speeds, which was only observed in a few bantam females and no standard breed females. Body mass accounted for variation in the incremental increase in metabolic power with speed between the varieties, but not the sexes. For the first time in an avian species, a greater mass-specific incremental cost of locomotion, and minimum measured cost of transport (CoTmin) were found in males than in females. Furthermore, in both varieties, the female CoTmin was lower than predicted from interspecific allometry. Even when compared at equivalent speeds (using Froude number), CoT decreased more rapidly in females than in males. These trends were common to both varieties despite a more upright limb in females than in males in the standard breed, and a lack of dimorphism in posture in the bantam variety. Females may possess compensatory adaptations for metabolic efficiency during gravidity (e.g. in muscle specialization/posture/kinematics). Furthermore, the elevated power at faster speeds in males may be linked to their muscle properties being suited to inter-male aggressive combat. PMID:26405047

Plasticity in reproduction and growth among 52 range-wide populations of a Mediterranean conifer: adaptive responses to environmental stress.

PubMed

Santos-Del-Blanco, L; Bonser, S P; Valladares, F; Chambel, M R; Climent, J

2013-09-01

A plastic response towards enhanced reproduction is expected in stressful environments, but it is assumed to trade off against vegetative growth and efficiency in the use of available resources deployed in reproduction [reproductive efficiency (RE)]. Evidence supporting this expectation is scarce for plants, particularly for long-lived species. Forest trees such as Mediterranean pines provide ideal models to study the adaptive value of allocation to reproduction vs. vegetative growth given their among-population differentiation for adaptive traits and their remarkable capacity to cope with dry and low-fertility environments. We studied 52 range-wide Pinus halepensis populations planted into two environmentally contrasting sites during their initial reproductive stage. We investigated the effect of site, population and their interaction on vegetative growth, threshold size for female reproduction, reproductive-vegetative size relationships and RE. We quantified correlations among traits and environmental variables to identify allocation trade-offs and ecotypic trends. Genetic variation for plasticity was high for vegetative growth, whereas it was nonsignificant for reproduction. Size-corrected reproduction was enhanced in the more stressful site supporting the expectation for adverse conditions to elicit plastic responses in reproductive allometry. However, RE was unrelated with early reproductive investment. Our results followed theoretical predictions and support that phenotypic plasticity for reproduction is adaptive under stressful environments. Considering expectations of increased drought in the Mediterranean, we hypothesize that phenotypic plasticity together with natural selection on reproductive traits will play a relevant role in the future adaptation of forest tree species. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Examination of the Potential of Structure-from-Motion (SfM) Photogrammetry and Terrestrial Laser Scanning (TLS) for Rapid Nondestructive Field Measurement of Grass Biomass

NASA Astrophysics Data System (ADS)

Cooper, S. D.; Roy, D. P.; Sathyachandran, S. K.

2016-12-01

Quantifying the above ground biomass of grasslands is needed for a number of applications including monitoring grass productivity, wildlife habitat, carbon storage, and fuel bed characteristics. Destructive biomass measurements, although highly accurate, are time consuming and are not easily undertaken on a repeat basis or over large areas. A number of non-destructive techniques have been developed that relate vegetation structural properties to above ground biomass. Conventionally, the disc pasture meter is used for rapid grass biomass estimation and uses the settling height of a disk placed on the grass and allometry. Structure-from-Motion (SfM) photogrammetry and Terrestrial Laser Scanning (TLS) are two technologies that have the potential to yield highly precise three-dimensional (3D) structural measurements of vegetation quite rapidly. Recent advances in computing and data acquisition technologies have led to the successful application of TLS and SfM in woody biomass estimation, but application in grassland systems remains largely untested. The Canopy Biomass Lidar (CBL) is one such advance and is a highly portable and relatively inexpensive TLS unit allowing for rapid and widespread data collection. We investigated the efficacy of a CBL unit as well as SfM in allometric estimation of grassland biomass from volumetric measurements derived from these two technologies, both separately and through the merging of the two independently generated 3D point clouds. The results are compared to biomass estimation from a pasture disc meter. Best use practices for grassland applications of these technologies are also presented.

Mass and energy budgets of animals: Behavioral and ecological implications: Progress report for period December 1, 1986-July 1987

DOE Office of Scientific and Technical Information (OSTI.GOV)

Porter, W.P.

1987-08-01

The vacuum gas-analysis system is running and we use doubly labeled water routinely in our research. We have the computer-controlled respirometer system running, and can routinely measure respiratory gases and body temperatures in small, living mammals. Our heat- and mass-balance model calculations of field metabolism and water loss agree exceptionally well with doubly labeled water measurements of the field metabolism and water loss for Sceloporus undulatus in the sandhill country of western Nebraska. We established theoretical links between our biophysical models of individual animals and population dynamics and community models in the literature. Our general, dry, porous-media model works formore » bird feathers as well as fur. Now heat and mass fluxes for any endotherm in any physical environment can be calculated with accuracy knowing only allometry, insulation properties, core or skin temperature and environmental conditions. We developed a general respiratory water-loss model using a coupled molar and heat balance. We developed a general counter-current heat exchange model with a peripheral heat generation and iterative skin temperature solution. We are testing our endotherm model on four species of temperate and tropical birds. We are completing parameter measurements for a test of the ectotherm model on an herbivorous lizard, like the test described above for the carnivorous lizard, Sceloporus undulatus. We have begun lab and field studies of the energetic costs of parasitism and climate on a small endotherm (using tapeworm infection of white-footed mice, Peromyscus leucopus). 8 figs.« less

Assessing allometric models to predict vegetative growth of mango (Mangifera indica; Anacardiaceae) at the current-year branch scale.

PubMed

Normand, Frédéric; Lauri, Pierre-Éric

2012-03-01

Accurate and reliable predictive models are necessary to estimate nondestructively key variables for plant growth studies such as leaf area and leaf, stem, and total biomass. Predictive models are lacking at the current-year branch scale despite the importance of this scale in plant science. We calibrated allometric models to estimate leaf area and stem and branch (leaves + stem) mass of current-year branches, i.e., branches several months old studied at the end of the vegetative growth season, of four mango cultivars on the basis of their basal cross-sectional area. The effects of year, site, and cultivar were tested. Models were validated with independent data and prediction accuracy was evaluated with the appropriate statistics. Models revealed a positive allometry between dependent and independent variables, whose y-intercept but not the slope, was affected by the cultivar. The effects of year and site were negligible. For each branch characteristic, cultivar-specific models were more accurate than common models built with pooled data from the four cultivars. Prediction quality was satisfactory but with data dispersion around the models, particularly for large values. Leaf area and stem and branch mass of mango current-year branches could be satisfactorily estimated on the basis of branch basal cross-sectional area with cultivar-specific allometric models. The results suggested that, in addition to the heteroscedastic behavior of the variables studied, model accuracy was probably related to the functional plasticity of branches in relation to the light environment and/or to the number of growth units composing the branches.

Sperm competition games between sneaks and guards: a comparative analysis using dimorphic male beetles.

PubMed

Simmons, Leigh W; Emlen, Douglas J; Tomkins, Joseph L

2007-11-01

Sperm competition is widely recognized as a pervasive force of sexual selection. Theory predicts that across species increased risk of sperm competition should favor an increased expenditure on the ejaculate, a prediction for which there is much evidence. Sperm competition games have also been developed specifically for systems in which males adopt the alternative male mating tactics of sneaking copulations or guarding females. These models have not yet been tested in a comparative context, but predict that: across species male expenditure on the ejaculate should increase with increasing probability of a sneak mating; within species, sneaks should have the greater expenditure on the ejaculate; and the disparity in expenditure between sneaks and guards should be greatest in species with moderate risk of a sneak mating, and decline toward parity in species with low or high risk. Beetles in the genus Onthophagus are often characterized by dimorphic male morphologies that reflect the alternative mating tactics of sneak (minor males) and guard (major males). We conducted a comparative analysis across 16 species of male dimorphic onthophagines, finding that testes size increased across species with increasing frequency of the minor male phenotype. Minor males generally had the greater testes size, but across species the disparity between morphs was independent of the frequency of minor males. We present data on testes allometry from two populations of O. taurus that have undergone genetic divergence in the frequency of minor males. Consistent with the comparative analysis, these data support the notion that the relative frequency of sneaks in the population influences male expenditure on the ejaculate.

Root Systems of Individual Plants, and the Biotic and Abiotic Factors Controlling Their Depth and Distribution: a Synthesis Using a Global Database.

NASA Astrophysics Data System (ADS)

Tumber-Davila, S. J.; Schenk, H. J.; Jackson, R. B.

2017-12-01

This synthesis examines plant rooting distributions globally, by doubling the number of entries in the Root Systems of Individual Plants database (RSIP) created by Schenk and Jackson. Root systems influence many processes, including water and nutrient uptake and soil carbon storage. Root systems also mediate vegetation responses to changing climatic and environmental conditions. Therefore, a collective understanding of the importance of rooting systems to carbon sequestration, soil characteristics, hydrology, and climate, is needed. Current global models are limited by a poor understanding of the mechanisms affecting rooting, carbon stocks, and belowground biomass. This improved database contains an extensive bank of records describing the rooting system of individual plants, as well as detailed information on the climate and environment from which the observations are made. The expanded RSIP database will: 1) increase our understanding of rooting depths, lateral root spreads and above and belowground allometry; 2) improve the representation of plant rooting systems in Earth System Models; 3) enable studies of how climate change will alter and interact with plant species and functional groups in the future. We further focus on how plant rooting behavior responds to variations in climate and the environment, and create a model that can predict rooting behavior given a set of environmental conditions. Preliminary results suggest that high potential evapotranspiration and seasonality of precipitation are indicative of deeper rooting after accounting for plant growth form. When mapping predicted deep rooting by climate, we predict deepest rooting to occur in equatorial South America, Africa, and central India.

Insights into the Development and Evolution of Exaggerated Traits Using De Novo Transcriptomes of Two Species of Horned Scarab Beetles

PubMed Central

Warren, Ian A.; Vera, J. Cristobal; Johns, Annika; Zinna, Robert; Marden, James H.; Emlen, Douglas J.; Dworkin, Ian; Lavine, Laura C.

2014-01-01

Scarab beetles exhibit an astonishing variety of rigid exo-skeletal outgrowths, known as “horns”. These traits are often sexually dimorphic and vary dramatically across species in size, shape, location, and allometry with body size. In many species, the horn exhibits disproportionate growth resulting in an exaggerated allometric relationship with body size, as compared to other traits, such as wings, that grow proportionately with body size. Depending on the species, the smallest males either do not produce a horn at all, or they produce a disproportionately small horn for their body size. While the diversity of horn shapes and their behavioural ecology have been reasonably well studied, we know far less about the proximate mechanisms that regulate horn growth. Thus, using 454 pyrosequencing, we generated transcriptome profiles, during horn growth and development, in two different scarab beetle species: the Asian rhinoceros beetle, Trypoxylus dichotomus, and the dung beetle, Onthophagus nigriventris. We obtained over half a million reads for each species that were assembled into over 6,000 and 16,000 contigs respectively. We combined these data with previously published studies to look for signatures of molecular evolution. We found a small subset of genes with horn-biased expression showing evidence for recent positive selection, as is expected with sexual selection on horn size. We also found evidence of relaxed selection present in genes that demonstrated biased expression between horned and horn-less morphs, consistent with the theory of developmental decoupling of phenotypically plastic traits. PMID:24586317

Sexual dimorphism in sister species of Leucoraja skate and its relationship to reproductive strategy and life history.

PubMed

Martinez, Christopher M; Rohlf, F James; Frisk, Michael G

2016-01-01

Instances of sexual dimorphism occur in a great variety of forms and manifestations. Most skates (Batoidea: Rajoidei) display some level of body shape dimorphism in which the pectoral fins of mature males develop to create a distinct bell-shaped body not found in females. This particular form of dimorphism is present in each of the sister species Leucoraja erinacea and Leucoraja ocellata, but differences between sexes are much greater in the former. In order to understand the nature and potential causes of pectoral dimorphism, we used geometric morphometrics to investigate allometry of fin shape in L. erinacea and L. ocellata and its relationship to the development of reproductive organs, based on previous work on the bonnethead shark, Sphyrna tiburo. We found that allometric trajectories of overall pectoral shape were different in both species of skate, but only L. erinacea varied significantly with respect to endoskeleton development. Male maturation was characterized by a number of sex-specific morphological changes, which appeared concurrently in developmental timing with elongation of cartilage-supported claspers. We suggest that external sexual dimorphism of pectoral fins in skates is a byproduct of skeletal growth needed for clasper development. Further, the magnitude of male shape change appears to be linked to the differential life histories of species. This work reports for the first time that pectoral dimorphism is a persistent feature in rajoid fishes, occurring in varying degrees across several genera. Lastly, our results suggest that pectoral morphology may be useful as a relative indicator of reproductive strategy in some species. © 2016 Wiley Periodicals, Inc.

Axial allometry in a neutrally buoyant environment: effects of the terrestrial-aquatic transition on vertebral scaling.

PubMed

Jones, K E; Pierce, S E

2016-03-01

Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Temperate forest fragments maintain aboveground carbon stocks out to the forest edge despite changes in community composition.

PubMed

Ziter, Carly; Bennett, Elena M; Gonzalez, Andrew

2014-11-01

Edge effects are among the primary mechanisms by which forest fragmentation can influence the link between biodiversity and ecosystem processes, but relatively few studies have quantified these mechanisms in temperate regions. Carbon storage is an important ecosystem function altered by edge effects, with implications for climate change mitigation. Two opposing hypotheses suggest that aboveground carbon (AGC) stocks at the forest edge will (a) decrease due to increased tree mortality and compositional shifts towards smaller, lower wood density species (e.g., as seen in tropical systems) or, less often, (b) increase due to light/temperature-induced increases in diversity and productivity. We used field-based measurements, allometry, and mixed models to investigate the effects of proximity to the forest edge on AGC stocks, species richness, and community composition in 24 forest fragments in southern Quebec. We also asked whether fragment size or connectivity with surrounding forests altered these edge effects. AGC stocks remained constant across a 100 m edge-to-interior gradient in all fragment types, despite changes in tree community composition and stem density consistent with expectations of forest edge effects. We attribute this constancy primarily to compensatory effects of small trees at the forest edge; however, it is due in some cases to the retention of large trees at forest edges, likely a result of forest management. Our results suggest important differences between temperate and tropical fragments with respect to mechanisms linking biodiversity and AGC dynamics. Small temperate forest fragments may be valuable in conservation efforts based on maintaining biodiversity and multiple ecosystem services.

A new twist on an old regression: transfer of chemicals to beef and milk in human and ecological risk assessment.

PubMed

Hendriks, A Jan; Smítková, Hana; Huijbregts, Mark A J

2007-11-01

Exposure of humans to chemicals in beef or milk is part of almost all risk evaluation procedures carried out to reduce emissions or to remediate sites. Concentrations of substances in these livestock products are often estimated using log-log regressions that relate the biotransfer factor BTF to the octanol-water partition ratio K(ow). However, the correctness of these empirical correlations has been questioned. Here, we compare them to the mechanistic model OMEGA that describes the distribution of substances in organisms by integrating theory on chemical fugacity and biological allometry. OMEGA has been calibrated and validated on thousands of laboratory and field data, reflecting many chemical substances and biological species. Overall fluxes of water, food, tissue (growth), milk and stable substances calculated by OMEGA are within a factor of two from independent data obtained in experiments. Rate constants measured for elimination of individual compounds of a recalcitrant nature vary around the level expected from the model for output to faeces and milk. Both data and model suggest that biotransfer BTF of stable substances to beef and milk is independent of the octanol-water partition ratio K(ow) in the range of 10(3)-10(6). This contradicts empirical regressions including stable and labile compounds. As expected, levels of labile substances vary widely around a tentative indication derived from the model. Transformation and accumulation of labile substances remains highly specific for the chemical and organism concerned but depends weakly on the octanol-water partition ratio K(ow). Several possibilities for additional refinement are identified.

Allometry and Ecology of the Bilaterian Gut Microbiome

PubMed Central

Sherrill-Mix, Scott; McCormick, Kevin; Lauder, Abigail; Bailey, Aubrey; Zimmerman, Laurie; Li, Yingying; Django, Jean-Bosco N.; Bertolani, Paco; Colin, Christelle; Hart, John A.; Hart, Terese B.; Georgiev, Alexander V.; Sanz, Crickette M.; Morgan, David B.; Atencia, Rebeca; Cox, Debby; Muller, Martin N.; Sommer, Volker; Piel, Alexander K.; Stewart, Fiona A.; Speede, Sheri; Roman, Joe; Wu, Gary; Taylor, Josh; Bohm, Rudolf; Rose, Heather M.; Carlson, John; Mjungu, Deus; Schmidt, Paul; Gaughan, Celeste; Bushman, Joyslin I.; Schmidt, Ella; Bittinger, Kyle; Collman, Ronald G.; Hahn, Beatrice H.

2018-01-01

ABSTRACT Classical ecology provides principles for construction and function of biological communities, but to what extent these apply to the animal-associated microbiota is just beginning to be assessed. Here, we investigated the influence of several well-known ecological principles on animal-associated microbiota by characterizing gut microbial specimens from bilaterally symmetrical animals (Bilateria) ranging from flies to whales. A rigorously vetted sample set containing 265 specimens from 64 species was assembled. Bacterial lineages were characterized by 16S rRNA gene sequencing. Previously published samples were also compared, allowing analysis of over 1,098 samples in total. A restricted number of bacterial phyla was found to account for the great majority of gut colonists. Gut microbial composition was associated with host phylogeny and diet. We identified numerous gut bacterial 16S rRNA gene sequences that diverged deeply from previously studied taxa, identifying opportunities to discover new bacterial types. The number of bacterial lineages per gut sample was positively associated with animal mass, paralleling known species-area relationships from island biogeography and implicating body size as a determinant of community stability and niche complexity. Samples from larger animals harbored greater numbers of anaerobic communities, specifying a mechanism for generating more-complex microbial environments. Predictions for species/abundance relationships from models of neutral colonization did not match the data set, pointing to alternative mechanisms such as selection of specific colonists by environmental niche. Taken together, the data suggest that niche complexity increases with gut size and that niche selection forces dominate gut community construction. PMID:29588401

Allometric constraints to inversion of canopy structure from remote sensing

NASA Astrophysics Data System (ADS)

Wolf, A.; Berry, J. A.; Asner, G. P.

2008-12-01

Canopy radiative transfer models employ a large number of vegetation architectural and leaf biochemical attributes. Studies of leaf biochemistry show a wide array of chemical and spectral diversity that suggests that several leaf biochemical constituents can be independently retrieved from multi-spectral remotely sensed imagery. In contrast, attempts to exploit multi-angle imagery to retrieve canopy structure only succeed in finding two or three of the many unknown canopy arhitectural attributes. We examine a database of over 5000 destructive tree harvests from Eurasia to show that allometry - the covariation of plant form across a broad range of plant size and canopy density - restricts the architectural diversity of plant canopies into a single composite variable ranging from young canopies with many short trees with small crowns to older canopies with fewer trees and larger crowns. Moreover, these architectural attributes are closely linked to biomass via allometric constraints such as the "self-thinning law". We use the measured variance and covariance of plant canopy architecture in these stands to drive the radiative transfer model DISORD, which employs the Li-Strahler geometric optics model. This correlations introduced in the Monte Carlo study are used to determine which attributes of canopy architecture lead to important variation that can be observed by multi-angle or multi-spectral satellite observations, using the sun-view geometry characteristic of MODIS observations in different biomes located at different latitude bands. We conclude that although multi-angle/multi-spectral remote sensing is only sensitive to some of the many unknown canopy attributes that ecologists would wish to know, the strong allometric covariation between these attributes and others permits a large number of inferrences, such as forest biomass, that will be meaningful next-generation vegetation products useful for data assimilation.

The role of extrahepatic metabolism in the pharmacokinetics of the targeted covalent inhibitors afatinib, ibrutinib, and neratinib.

PubMed

Shibata, Yoshihiro; Chiba, Masato

2015-03-01

Despite the fact that much progress has been made recently in the development of targeted covalent inhibitors (TCIs), their pharmacokinetics (PK) have not been well characterized in the light of extrahepatic clearance (CLextH) by glutathione (GSH)/glutathione S-transferase (GST)-dependent conjugation attributable to the unique electrophilic structure (e.g., acrylamide moiety) of TCI compounds. In the present study, CLextH values were examined in rat, dog, and monkey to predict the contribution of CLextH to the PK of the TCIs afatinib, ibrutinib, and neratinib in humans. Afatinib and neratinib both underwent extensive conjugation with GSH in buffer and cytosol fractions of liver and kidney, whereas ibrutinib showed much lower reactivity/susceptibility to GSH/GST-dependent conjugation. The CLextH in each species was calculated from the difference between observed total body clearance and predicted hepatic clearance (CLH) in cryopreserved hepatocytes suspended in 100% serum of the corresponding species. The power-based simple allometry relating the CLextH for the unbound compound to animal body weight was applicable across species for afatinib and neratinib (R(2) ≥ 0.9) but not for ibrutinib (R(2) = 0.04). The predicted AUC after oral administration of afatinib and neratinib agreed reasonably closely with reported values in phase I dose-escalation studies. Comparisons of CLextH and CLH predicted that CLextH largely determined the PK of afatinib (>90% as a proportion of total body clearance) and neratinib (∼34%) in humans. The present method can serve as one of the tools for the optimization of PK in humans at the discovery stage for the development of TCI candidates. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Peatland Woody Plant Growth Responses to Warming and Elevated CO2 in a Southern-boreal Raised Bog Ecosystem

NASA Astrophysics Data System (ADS)

Phillips, J. R.; Hanson, P. J.; Warren, J.; Ward, E. J.; Brice, D. J.; Graham, J.

2017-12-01

Spruce and Peatland Responses Under Changing Environments (SPRUCE) is an in situ warming by elevated CO2 manipulation located in a high-carbon, spruce peatland in northern Minnesota. Warming treatments combined a 12-m diameter open topped chamber with internally recirculating warm air and soil deep heating to simulate a broad range of future warming treatments. Deep below ground soil warming rates are 0, +2.25, +4.5, +6.75, and +9 °C. Deep belowground warming was initiated in June 2014 followed by air warming in August 2015. In June 2016, elevated CO2 atmospheres (eCO2 at + 500 ppm) were added to half of the warming treatments in a regression design. Our objective was to track long-term vegetation responses to warming and eCO2. Annual tree growth is based on winter measurement of circumference of all Picea mariana and Larix laricina trees within each 113 m2 plot, automated dendrometers, terrestrial LIDAR scanning of tree heights and canopy volumes, and destructive allometry. Annual shrub growth is measured in late summer by destructive clipping in two 0.25 m2 sub-plots and separation of the current year tissues. During the first year of warming, tree basal area growth was reduced for Picea, but not Larix trees. Growth responses for the woody shrub vegetation remains highly variable with a trend towards increasing growth with warming. Elevated CO2 enhancements of growth are not yet evident in the data. Second-year results will also be reported. Long-term hypotheses for increased woody plant growth under warming include potential enhancements driven by increased nutrient availability from warming induced decomposition of surface peats.

Intraspecific scaling in frog calls: the interplay of temperature, body size and metabolic condition.

PubMed

Ziegler, Lucia; Arim, Matías; Bozinovic, Francisco

2016-07-01

Understanding physiological and environmental determinants of strategies of reproductive allocation is a pivotal aim in biology. Because of their high metabolic cost, properties of sexual acoustic signals may correlate with body size, temperature, and an individual's energetic state. A quantitative theory of acoustic communication, based on the metabolic scaling with temperature and mass, was recently proposed, adding to the well-reported empirical patterns. It provides quantitative predictions for frequencies, call rate, and durations. Here, we analysed the mass, temperature, and body condition scaling of spectral and temporal attributes of the advertisement call of the treefrog Hypsiboas pulchellus. Mass dependence of call frequency followed metabolic expectations (f~M (-0.25), where f is frequency and M is mass) although non-metabolic allometry could also account for the observed pattern. Temporal variables scaled inversely with mass contradicting metabolic expectations (d~M (0.25), where d is duration), supporting instead empirical patterns reported to date. Temperature was positively associated with call rate and negatively with temporal variables, which is congruent with metabolic predictions. We found no significant association between temperature and frequencies, adding to the bulk of empirical evidence. Finally, a result of particular relevance was that body condition consistently determined call characteristics, in interaction with temperature or mass. Our intraspecific study highlights that even if proximate determinants of call variability are rather well understood, the mechanisms through which they operate are proving to be more complex than previously thought. The determinants of call characteristics emerge as a key topic of research in behavioural and physiological biology, with several clear points under debate which need to be analysed on theoretical and empirical grounds.

Tree-centric mapping of forest carbon density from airborne laser scanning and hyperspectral data.

PubMed

Dalponte, Michele; Coomes, David A

2016-10-01

Forests are a major component of the global carbon cycle, and accurate estimation of forest carbon stocks and fluxes is important in the context of anthropogenic global change. Airborne laser scanning (ALS) data sets are increasingly recognized as outstanding data sources for high-fidelity mapping of carbon stocks at regional scales.We develop a tree-centric approach to carbon mapping, based on identifying individual tree crowns (ITCs) and species from airborne remote sensing data, from which individual tree carbon stocks are calculated. We identify ITCs from the laser scanning point cloud using a region-growing algorithm and identifying species from airborne hyperspectral data by machine learning. For each detected tree, we predict stem diameter from its height and crown-width estimate. From that point on, we use well-established approaches developed for field-based inventories: above-ground biomasses of trees are estimated using published allometries and summed within plots to estimate carbon density.We show this approach is highly reliable: tests in the Italian Alps demonstrated a close relationship between field- and ALS-based estimates of carbon stocks ( r 2  = 0·98). Small trees are invisible from the air, and a correction factor is required to accommodate this effect.An advantage of the tree-centric approach over existing area-based methods is that it can produce maps at any scale and is fundamentally based on field-based inventory methods, making it intuitive and transparent. Airborne laser scanning, hyperspectral sensing and computational power are all advancing rapidly, making it increasingly feasible to use ITC approaches for effective mapping of forest carbon density also inside wider carbon mapping programs like REDD++.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans.

PubMed

Green, Patrick A; Van Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-12-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Root-shoot allometry of tropical forest trees determined in a large-scale aeroponic system.

PubMed

Eshel, Amram; Grünzweig, José M

2013-07-01

This study is a first step in a multi-stage project aimed at determining allometric relationships among the tropical tree organs, and carbon fluxes between the various tree parts and their environment. Information on canopy-root interrelationships is needed to improve understanding of above- and below-ground processes and for modelling of the regional and global carbon cycle. Allometric relationships between the sizes of different plant parts will be determined. Two tropical forest species were used in this study: Ceiba pentandra (kapok), a fast-growing tree native to South and Central America and to Western Africa, and Khaya anthotheca (African mahogany), a slower-growing tree native to Central and Eastern Africa. Growth and allometric parameters of 12-month-old saplings grown in a large-scale aeroponic system and in 50-L soil containers were compared. The main advantage of growing plants in aeroponics is that their root systems are fully accessible throughout the plant life, and can be fully recovered for harvesting. The expected differences in shoot and root size between the fast-growing C. pentandra and the slower-growing K. anthotheca were evident in both growth systems. Roots were recovered from the aeroponically grown saplings only, and their distribution among various diameter classes followed the patterns expected from the literature. Stem, branch and leaf allometric parameters were similar for saplings of each species grown in the two systems. The aeroponic tree growth system can be utilized for determining the basic allometric relationships between root and shoot components of these trees, and hence can be used to study carbon allocation and fluxes of whole above- and below-ground tree parts.

Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes.

PubMed

Zouache, Moussa A; Eames, Ian; Samsudin, Amir

2016-01-01

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

The effects of replacing Dichantium hay with banana (Musa paradisiaca) leaves and pseudo-stem on carcass traits of Ovin Martinik sheep.

PubMed

Marie-Magdeleine, Carine; Liméa, Léticia; Etienne, Tatiana; Lallo, Cicero H O; Archimède, Harry; Alexandre, Gisele

2009-10-01

A study was done to evaluate banana (Musa paradisiaca) as a forage (leaves and pseudo-stems) for feeding Ovin Martinik lambs (OMK), with the aim to test its impact on carcass quality. Forty four intact OMK male were used after weaning with an initial mean live weight of 14.4 (+/- 3.3) kg, reared in individual pens. Animals were offered either Dichantium hay (control diet, Dh) or cut chopped leaves and pseudo-stems of banana (experimental diet, Blps). They were fed 200-250 g x d(-1) of commercial concentrate. Lambs were slaughtered according to 3 classes of slaughter weight (SW): SW20, SW23 and SW26. Growth and carcass performances of both groups were not significantly different, 77 vs. 81 g x d(-1) and 42% vs. 43% hot carcass yield, for Dh vs. Blps, respectively. There was a significant (P < 0.05) decrease (31.0 vs. 29.7%) for the dry matter content of the shoulder for lambs fed the banana diet. However, there was no effect observed for the other chemical component (CP, lipid and mineral 585, 317 and 95 g x kg(-1) DM, respectively). The shoulder (20% of the carcass whatever the SW) was precocious as demonstrated by the allometry coefficient relative to carcass weight (0.894) significantly (P < 0.01) less than 1. It was concluded that, the use of Blps had no significant effect on growth, carcass weights and yields of the OMK lambs, irrespective of the class of the slaughter weight. From these initial results, the use of banana foliages and pseudo-stems could be recommended as sources of forages.

Intraspecific scaling of the minimum metabolic cost of transport in leghorn chickens (Gallus gallus domesticus): links with limb kinematics, morphometrics and posture.

PubMed

Rose, Kayleigh A; Nudds, Robert L; Codd, Jonathan R

2015-04-01

The minimum metabolic cost of transport (CoTmin; J kg(-1) m(-1)) scales negatively with increasing body mass (∝Mb (-1/3)) across species from a wide range of taxa associated with marked differences in body plan. At the intraspecific level, or between closely related species, however, CoTmin does not always scale with Mb. Similarity in physiology, dynamics of movement, skeletal geometry and posture between closely related individuals is thought to be responsible for this phenomenon, despite the fact that energetic, kinematic and morphometric data are rarely collected together. We examined the relationship between these integrated components of locomotion in leghorn chickens (Gallus gallus domesticus) selectively bred for large and bantam (miniature) varieties. Interspecific allometry predicts a CoTmin ∼16% greater in bantams compared with the larger variety. However, despite 38% and 23% differences in Mb and leg length, respectively, the two varieties shared an identical walking CoTmin, independent of speed and equal to the allometric prediction derived from interspecific data for the larger variety. Furthermore, the two varieties moved with dynamic similarity and shared geometrically similar appendicular and axial skeletons. Hip height, however, did not scale geometrically and the smaller variety had more erect limbs, contrary to interspecific scaling trends. The lower than predicted CoTmin in bantams for their Mb was associated with both the more erect posture and a lower cost per stride (J kg(-1) stride(-1)). Therefore, our findings are consistent with the notion that a more erect limb is associated with a lower CoTmin and with the previous assumption that similarity in skeletal shape, inherently linked to walking dynamics, is associated with similarity in CoTmin. © 2015. Published by The Company of Biologists Ltd.

The role of cross-sectional geometry, curvature, and limb posture in maintaining equal safety factors: a computed tomography study.

PubMed

Brassey, Charlotte A; Kitchener, Andrew C; Withers, Philip J; Manning, Phillip L; Sellers, William I

2013-03-01

The limb bones of an elephant are considered to experience similar peak locomotory stresses as a shrew. "Safety factors" are maintained across the entire range of body masses through a combination of robusticity of long bones, postural variation, and modification of gait. The relative contributions of these variables remain uncertain. To test the role of shape change, we undertook X-ray tomographic scans of the leg bones of 60 species of mammals and birds, and extracted geometric properties. The maximum resistible forces the bones could withstand before yield under compressive, bending, and torsional loads were calculated using standard engineering equations incorporating curvature. Positive allometric scaling of cross-sectional properties with body mass was insufficient to prevent negative allometry of bending (F(b) ) and torsional maximum force (F(t) ) (and hence decreasing safety factors) in mammalian (femur F(b) ∞M(b) (0.76) , F(t) ∞M(b) (0.80) ; tibia F(b) ∞M(b) (0.80) , F(t) ∞M(b) (0.76) ) and avian hindlimbs (tibiotarsus F(b) ∞M(b) (0.88) , F(t) ∞M(b) (0.89) ) with the exception of avian femoral F(b) and F(t) . The minimum angle from horizontal a bone must be held while maintaining a given safety factor under combined compressive and bending loads increases with M(b) , with the exception of the avian femur. Postural erectness is shown as an effective means of achieving stress similarity in mammals. The scaling behavior of the avian femur is discussed in light of unusual posture and kinematics. Copyright © 2013 Wiley Periodicals, Inc.

Intraspecific scaling of the minimum metabolic cost of transport in leghorn chickens (Gallus gallus domesticus): links with limb kinematics, morphometrics and posture

PubMed Central

Rose, Kayleigh A.; Nudds, Robert L.; Codd, Jonathan R.

2015-01-01

ABSTRACT The minimum metabolic cost of transport (CoTmin; J kg−1 m−1) scales negatively with increasing body mass (∝Mb−1/3) across species from a wide range of taxa associated with marked differences in body plan. At the intraspecific level, or between closely related species, however, CoTmin does not always scale with Mb. Similarity in physiology, dynamics of movement, skeletal geometry and posture between closely related individuals is thought to be responsible for this phenomenon, despite the fact that energetic, kinematic and morphometric data are rarely collected together. We examined the relationship between these integrated components of locomotion in leghorn chickens (Gallus gallus domesticus) selectively bred for large and bantam (miniature) varieties. Interspecific allometry predicts a CoTmin ∼16% greater in bantams compared with the larger variety. However, despite 38% and 23% differences in Mb and leg length, respectively, the two varieties shared an identical walking CoTmin, independent of speed and equal to the allometric prediction derived from interspecific data for the larger variety. Furthermore, the two varieties moved with dynamic similarity and shared geometrically similar appendicular and axial skeletons. Hip height, however, did not scale geometrically and the smaller variety had more erect limbs, contrary to interspecific scaling trends. The lower than predicted CoTmin in bantams for their Mb was associated with both the more erect posture and a lower cost per stride (J kg−1 stride−1). Therefore, our findings are consistent with the notion that a more erect limb is associated with a lower CoTmin and with the previous assumption that similarity in skeletal shape, inherently linked to walking dynamics, is associated with similarity in CoTmin. PMID:25657211

Evolutionary diversification of the auditory organ sensilla in Neoconocephalus katydids (Orthoptera: Tettigoniidae) correlates with acoustic signal diversification over phylogenetic relatedness and life history.

PubMed

Strauß, J; Alt, J A; Ekschmitt, K; Schul, J; Lakes-Harlan, R

2017-06-01

Neoconocephalus Tettigoniidae are a model for the evolution of acoustic signals as male calls have diversified in temporal structure during the radiation of the genus. The call divergence and phylogeny in Neoconocephalus are established, but in tettigoniids in general, accompanying evolutionary changes in hearing organs are not studied. We investigated anatomical changes of the tympanal hearing organs during the evolutionary radiation and divergence of intraspecific acoustic signals. We compared the neuroanatomy of auditory sensilla (crista acustica) from nine Neoconocephalus species for the number of auditory sensilla and the crista acustica length. These parameters were correlated with differences in temporal call features, body size, life histories and different phylogenetic positions. By this, adaptive responses to shifting frequencies of male calls and changes in their temporal patterns can be evaluated against phylogenetic constraints and allometry. All species showed well-developed auditory sensilla, on average 32-35 between species. Crista acustica length and sensillum numbers correlated with body size, but not with phylogenetic position or life history. Statistically significant correlations existed also with specific call patterns: a higher number of auditory sensilla occurred in species with continuous calls or slow pulse rates, and a longer crista acustica occurred in species with double pulses or slow pulse rates. The auditory sensilla show significant differences between species despite their recent radiation, and morphological and ecological similarities. This indicates the responses to natural and sexual selection, including divergence of temporal and spectral signal properties. Phylogenetic constraints are unlikely to limit these changes of the auditory systems. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Differential growth and development of the upper and lower human thorax.

PubMed

Bastir, Markus; García Martínez, Daniel; Recheis, Wolfgang; Barash, Alon; Coquerelle, Michael; Rios, Luis; Peña-Melián, Angel; García Río, Francisco; O'Higgins, Paul

2013-01-01

The difficulties in quantifying the 3D form and spatial relationships of the skeletal components of the ribcage present a barrier to studies of the growth of the thoracic skeleton. Thus, most studies to date have relied on traditional measurements such as distances and indices from single or few ribs. It is currently known that adult-like thoracic shape is achieved early, by the end of the second postnatal year, with the circular cross-section of the newborn thorax transforming into the ovoid shape of adults; and that the ribs become inclined such that their anterior borders come to lie inferior to their posterior. Here we present a study that revisits growth changes using geometric morphometrics applied to extensive landmark data taken from the ribcage. We digitized 402 (semi) landmarks on 3D reconstructions to assess growth changes in 27 computed tomography-scanned modern humans representing newborns to adults of both sexes. Our analyses show a curved ontogenetic trajectory, resulting from different ontogenetic growth allometries of upper and lower thoracic units. Adult thoracic morphology is achieved later than predicted, by diverse modifications in different anatomical regions during different ontogenetic stages. Besides a marked increase in antero-posterior dimensions, there is an increase in medio-lateral dimensions of the upper thorax, relative to the lower thorax. This transforms the pyramidal infant thorax into the barrel-shaped one of adults. Rib descent is produced by complex changes in 3D curvature. Developmental differences between upper and lower thoracic regions relate to differential timings and rates of maturation of the respiratory and digestive systems, the spine and the locomotor system. Our findings are relevant to understanding how changes in the relative rates of growth of these systems and structures impacted on the development and evolution of modern human body shape.

Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico

PubMed Central

Pompa-García, Marín; Venegas-González, Alejandro

2016-01-01

Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass) was estimated from a specific allometric equation for this species based on: (i) variation of intra-annual wood density and (ii) diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries. PMID:27272519

Ontogenetic shifts of heart position in snakes.

PubMed

Lillywhite, Harvey B; Lillywhite, Steven M

2017-08-01

Heart position relative to total body length (TL) varies among snakes, with anterior hearts in arboreal species and more centrally located hearts in aquatic or ground-dwelling species. Anterior hearts decrease the cardiac work associated with cranial blood flow and minimize drops in cranial pressure and flow during head-up climbing. Here, we investigate whether heart position shifts intraspecifically during ontogenetic increases in TL. Insular Florida cottonmouth snakes, Agkistrodon conanti, are entirely ground-dwelling and have a mean heart position that is 33.32% TL from the head. In contrast, arboreal rat snakes, Pantherophis obsoleta, of similar lengths have a mean heart position that is 17.35% TL from the head. In both species, relative heart position shifts craniad during ontogeny, with negative slopes = -.035 and -.021% TL/cm TL in Agkistrodon and Pantherophis, respectively. Using a large morphometric data set available for Agkistrodon (N = 192 individuals, 23-140 cm TL), we demonstrate there is an anterior ontogenetic shift of the heart position within the trunk (= 4.56% trunk length from base of head to cloacal vent), independent of head and tail allometry which are both negative. However, in longer snakes > 100 cm, the heart position reverses and shifts caudally in longer Agkistrodon but continues toward the head in longer individuals of Pantherophis. Examination of data sets for two independent lineages of fully marine snakes (Acrochordus granulatus and Hydrophis platurus), which do not naturally experience postural gravity stress, demonstrate both ontogenetic patterns for heart position that are seen in the terrestrial snakes. The anterior migration of the heart is greater in the terrestrial species, even if TL is standardized to that of the longer P. obsoleta, and compensates for about 5 mmHg gravitational pressure head if they are fully upright. © 2017 Wiley Periodicals, Inc.

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale.

PubMed

Carnicer, Jofre; Barbeta, Adrià; Sperlich, Dominik; Coll, Marta; Peñuelas, Josep

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit (VPD), xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC), wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines.

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale

PubMed Central

Carnicer, Jofre; Barbeta, Adrià; Sperlich, Dominik; Coll, Marta; Peñuelas, Josep

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit (VPD), xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC), wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines. PMID:24146668

Development of the movement of the epiglottis in infant and juvenile pigs

PubMed Central

Crompton, Alfred W.; German, Rebecca Z.; Thexton, Allan J.

2008-01-01

Although backward folding of the epiglottis is one of the signal events of the mammalian adult swallow, the epiglottis does not fold during the infant swallow. How this functional change occurs is unknown, but we hypothesize that a change in swallow mechanism occurs with maturation, prior to weaning. Using videofluoroscopy, we found three characteristic patterns of swallowing movement at different ages in the pig: an infant swallow, a transitional swallow and a post-weaning (juvenile or adult) swallow. In animals of all ages, the dorsal region of the epiglottis and larynx was held in an intranarial position by a muscular sphincter formed by the palatopharyngeal arch. In the infant swallow, increasing pressure in the oropharynx forced a liquid bolus through the piriform recesses on either side of a relatively stationary epiglottis into the esophagus. As the infant matured, the palatopharyngeal arch and the soft palate elevated at the beginning of the swallow, so exposing a larger area of the epiglottis to bolus pressure. In transitional swallows, the epiglottis was tilted backward relatively slowly by a combination of bolus pressure and squeezing of the epiglottis by closure of the palatopharyngeal sphincter. The bolus, however, traveled alongside but never over the tip of the epiglottis. In the juvenile swallow, the bolus always passed over the tip of the epiglottis. The tilting of the epiglottis resulted from several factors, including the action of the palatopharyngeal sphincter, higher bolus pressure exerted on the epiglottis and the allometry of increased size. In both transitional and juvenile swallows, the subsequent relaxation of the palatopharyngeal sphincter released the epiglottis, which sprang back to its original intranarial position. PMID:18387794

Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.

PubMed

Maidment, Susannah C R; Linton, Deborah H; Upchurch, Paul; Barrett, Paul M

2012-01-01

The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. The transition to quadrupedality from bipedal ancestors is rare in the history of terrestrial vertebrate evolution, and extant analogues do not exist. Constraints imposed on quadrupedal ornithischians by their ancestral bipedal bauplan remain unexplored, and consequently, debate continues about their stance and gait. For example, it has been proposed that some ornithischians could run, while others consider that none were cursorial. Drawing on biomechanical concepts of limb bone scaling and locomotor theory developed for extant taxa, we use the largest dataset of ornithischian postcranial measurements so far compiled to examine stance and gait in quadrupedal ornithischians. Differences in femoral midshaft eccentricity in hadrosaurs and ceratopsids may indicate that hadrosaurs placed their feet on the midline during locomotion, while ceratopsids placed their feet more laterally, under the hips. More robust humeri in the largest ceratopsids relative to smaller taxa may be due to positive allometry in skull size with body mass in ceratopsids, while slender humeri in the largest stegosaurs may be the result of differences in dermal armor distribution within the clade. Hadrosaurs are found to display the most cursorial morphologies of the quadrupedal ornithischian cades, indicating higher locomotor performance than in ceratopsids and thyreophorans. Limb bone scaling indicates that a previously unrealised diversity of stances and gaits were employed by quadrupedal ornithischians despite apparent convergence in limb morphology. Grouping quadrupedal ornithischians together as a single functional group hides this disparity. Differences in limb proportions and scaling are likely due to the possession of display structures such as horns, frills and dermal armor that may have affected the center of mass of the animal, and differences in locomotor behaviour such as migration, predator escape or home range size.

Differential investment in pre- vs. post-copulatory sexual selection reinforces a cross-continental reversal of sexual size dimorphism in Sepsis punctum (Diptera: Sepsidae).

PubMed

Puniamoorthy, Nalini; Blanckenhorn, W U; Schäfer, M A

2012-11-01

Theory predicts that males have a limited amount of resources to invest in reproduction, suggesting a trade-off between traits that enhance mate acquisition and those that enhance fertilization success. Here, we investigate the relationship between pre- and post-copulatory investment by comparing the mating behaviour and reproductive morphology of four European and five North American populations of the dung fly Sepsis punctum (Diptera) that display a reversal of sexual size dimorphism (SSD). We show that the geographic reversal in SSD between the continents (male biased in Europe, female biased in North America) is accompanied by differential investment in pre- vs. post-copulatory traits. We find higher remating rates in European populations, where larger males acquire more matings and consequently have evolved relatively larger testes and steeper hyper-allometry with body size. American populations, in sharp contrast, display much reduced, if any, effect of body size on those traits. Instead, North American males demonstrate an increased investment in mate acquisition prior to copulation, with more mounting attempts and a distinctive abdominal courtship display that is completely absent in Europe. When controlling for body size, relative female spermathecal size is similar on both continents, so we find no direct evidence for the co-evolution of male and female internal reproductive morphology. By comparing allopatric populations of the same species that apparently have evolved different mating systems and consequently SSD, we thus indirectly demonstrate differential investment in pre- vs. post-copulatory mechanisms increasing reproductive success. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Within-species patterns challenge our understanding of the causes and consequences of trait variation with implications for trait-based models

NASA Astrophysics Data System (ADS)

Anderegg, L. D.; Berner, L. T.; Badgley, G.; Hillerislambers, J.; Law, B. E.

2017-12-01

Functional traits could facilitate ecological prediction by provide scale-free tools for modeling ecosystem function. Yet much of their utility lies in three key assumptions: 1) that global patterns of trait covariation are the result of universal trade-offs independent of taxonomic scale, so empirical trait-trait relationships can be used to constrain vegetation models 2) that traits respond predictably to environmental gradients and can therefore be reliably quantified to parameterize models and 3) that well sampled traits influence productivity. We use an extensive dataset of within-species leaf trait variation in North American conifers combined with global leaf trait datasets to test these assumptions. We examine traits central to the `leaf economics spectrum', and quantify patterns of trait variation at multiple taxonomic scales. We also test whether site environment explains geographic trait variation within conifers, and ask whether foliar traits explain geographic variation in relative growth rates. We find that most leaf traits vary primarily between rather than within species globally, but that a large fraction of within-PFT trait variation is within-species. We also find that some leaf economics spectrum relationships differ in sign within versus between species, particularly the relationship between leaf lifespan and LMA. In conifers, we find weak and inconsistent relationships between site environment and leaf traits, making it difficult capture within-species leaf trait variation for regional model parameterization. Finally, we find limited relationships between tree relative growth rate and any foliar trait other than leaf lifespan, with leaf traits jointly explaining 42% of within-species growth variation but environmental factors explaining 77% of variation. We suggest that additional traits, particularly whole plant allometry/allocation traits may be better than leaf traits for improving vegetation model performance at smaller taxonomic and spatial scales.

Integration of preclinical and clinical knowledge to predict intravenous PK in human: bilastine case study.

PubMed

Vozmediano, Valvanera; Ortega, Ignacio; Lukas, John C; Gonzalo, Ana; Rodriguez, Monica; Lucero, Maria Luisa

2014-03-01

Modern pharmacometrics can integrate and leverage all prior proprietary and public knowledge. Such methods can be used to scale across species or comparators, perform clinical trial simulation across alternative designs, confirm hypothesis and potentially reduce development burden, time and costs. Crucial yet typically lacking in integration is the pre-clinical stage. Prediction of PK in man, using in vitro and in vivo studies in different animal species, is increasingly well theorized but could still find wider application in drug development. The aim of the present work was to explore methods for bridging pharmacokinetic knowledge from animal species (i.v. and p.o.) and man (p.o.) into i.v. in man using the antihistamine drug bilastine as example. A model, predictive of i.v. PK in man, was developed on data from two pre-clinical species (rat and dog) and p.o. in man bilastine trials performed earlier. In the knowledge application stage, two different approaches were used to predict human plasma concentration after i.v. of bilastine: allometry (several scaling methods) and a semi-physiological method. Both approaches led to successful predictions of key i.v. PK parameters of bilastine in man. The predictive i.v. PK model was validated using later data from a clinical study of i.v. bilastine. Introduction of such knowledge in development permits proper leveraging of all emergent knowledge as well as quantification-based exploration of PK scenario, e.g. in special populations (pediatrics, renal insufficiency, comedication). In addition, the methods permit reduction or elimination and certainly optimization of learning trials, particularly those concerning alternative off-label administration routes.

Evolution and Allometry of Calcaneal Elongation in Living and Extinct Primates

PubMed Central

Boyer, Doug M.; Seiffert, Erik R.; Gladman, Justin T.; Bloch, Jonathan I.

2013-01-01

Specialized acrobatic leaping has been recognized as a key adaptive trait tied to the origin and subsequent radiation of euprimates based on its observed frequency in extant primates and inferred frequency in extinct early euprimates. Hypothesized skeletal correlates include elongated tarsal elements, which would be expected to aid leaping by allowing for increased rates and durations of propulsive acceleration at takeoff. Alternatively, authors of a recent study argued that pronounced distal calcaneal elongation of euprimates (compared to other mammalian taxa) was related primarily to specialized pedal grasping. Testing for correlations between calcaneal elongation and leaping versus grasping is complicated by body size differences and associated allometric affects. We re-assess allometric constraints on, and the functional significance of, calcaneal elongation using phylogenetic comparative methods, and present an evolutionary hypothesis for the evolution of calcaneal elongation in primates using a Bayesian approach to ancestral state reconstruction (ASR). Results show that among all primates, logged ratios of distal calcaneal length to total calcaneal length are inversely correlated with logged body mass proxies derived from the area of the calcaneal facet for the cuboid. Results from phylogenetic ANOVA on residuals from this allometric line suggest that deviations are explained by degree of leaping specialization in prosimians, but not anthropoids. Results from ASR suggest that non-allometric increases in calcaneal elongation began in the primate stem lineage and continued independently in haplorhines and strepsirrhines. Anthropoid and lorisid lineages show stasis and decreasing elongation, respectively. Initial increases in calcaneal elongation in primate evolution may be related to either development of hallucal-grasping or a combination of grasping and more specialized leaping behaviors. As has been previously suggested, subsequent increases in calcaneal elongation are likely adaptations for more effective acrobatic leaping, highlighting the importance of this behavior in early euprimate evolution. PMID:23844094

Wing geometry of Culex coronator (Diptera: Culicidae) from South and Southeast Brazil

PubMed Central

2014-01-01

Background The Coronator Group encompasses Culex coronator Dyar & Knab, Culex camposi Dyar, Culex covagarciai Forattini, Culex ousqua Dyar, Culex usquatissimus Dyar, Culex usquatus Dyar and Culex yojoae Strickman. Culex coronator has the largest geographic distribution, occurring in North, Central and South America. Moreover, it is a potential vector-borne mosquito species because females have been found naturally infected with several arboviruses, i.e., Saint Louis Encephalitis Virus, Venezuelan Equine Encephalitis Virus and West Nile Virus. Considering the epidemiological importance of Cx. coronator, we investigated the wing shape diversity of Cx. coronator from South and Southeast Brazil, a method to preliminarily estimate population diversity. Methods Field-collected immature stages of seven populations from a large geographical area in Brazil were maintained in the laboratory to obtain both females and males linked with pupal and/or larval exuviae. For each individual female, 18 landmarks of left wings were marked and digitalized. After Procrustes superimposition, discriminant analysis of shape was employed to quantify wing shape variation among populations. The isometric estimator centroid size was calculated to assess the overall wing size and allometry. Results Wing shape was polymorphic among populations of Cx. coronator. However, dissimilarities among populations were higher than those observed within each population, suggesting populational differentiation in Cx. coronator. Morphological distances between populations were not correlated to geographical distances, indicating that other factors may act on wing shape and thus, determining microevolutionary patterns in Cx. coronator. Despite the population differentiation, intrapopulational wing shape variability was equivalent among all seven populations. Conclusion The wing variability found in Cx. coronator populations brings to light a new biological problem to be investigated: the population genetics of Cx. coronator. Because of differences in the male genitalia, we also transferred Cx. yojoae to the Apicinus Subgroup. PMID:24721508

Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico.

PubMed

Pompa-García, Marín; Venegas-González, Alejandro

2016-01-01

Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass) was estimated from a specific allometric equation for this species based on: (i) variation of intra-annual wood density and (ii) diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries.

Morphometric Differentiation in Cornops aquaticum (Orthoptera: Acrididae): Associations With Sex, Chromosome, and Geographic Conditions

PubMed Central

Romero, María Luciana; Colombo, Pablo César; Remis, María Isabel

2014-01-01

Abstract The water-hyacinth grasshopper Cornops aquaticum (Bruner) (Orthoptera: Acrididae) is native to South America and inhabits lowlands from southern Mexico to central Argentina and Uruguay. This grasshopper feeds and lays eggs on species from the genera Eichhornia and Pontederia. Particularly, Eichhornia crassipes is considered “the world’s worst water weed,” and the release of C. aquaticum was proposed as a form of biological control. Morphometric variation on the chromosomally differentiated populations from the middle and lower Paraná River and its possible association with geographic, sex, and chromosomal conditions was analyzed. Significant phenotype variation in C. aquaticum population was detected. C. aquaticum presents body-size sexual dimorphism, females being bigger than males. Female-biased sexual size dimorphism for all five analyzed traits was detected. The assessment of variation in sexual size dimorphism for tegmen length showed that this trait scaled allometrically, indicating that males and females did not vary in a similar fashion. The detected allometry was consistent with Rensch’s rule demonstrating greater evolutionary divergence in male size than in female size and suggests that males are more sensitive to environmental condition. The analysis of morphometric variation in the context of chromosome constitution showed that the presence of fusion 1/6 was related to body-size variation. Fusion carriers displayed bigger body size than standard homozygotes. Besides, a positive relationship between tegmen length and the number of fused chromosomes was detected, showing a chromosome dose effect. Because the highest frequency of fusions has been found in the lower Paraná River, a marginal environment for this species, the results found would support the hypothesis that some supergenes located in the fusions may be favored in the southern populations, thus contributing to the establishment and maintenance of the polymorphism. PMID:25399431

Slice-push, formation of grooves and the scale effect in cutting.

PubMed

Atkins, A G

2016-06-06

Three separate aspects of cutting are investigated which complement other papers on the mechanics of separation processes presented at this interdisciplinary Theo Murphy meeting. They apply in all types of cutting whether blades are sharp or blunt, and whether the material being cut is 'hard, stiff and strong' or 'soft, compliant and weak'. The first topic discusses why it is easier to cut when there is motion along (parallel to) the blade as well motion across (perpendicular to) the cutting edge, and the analysis is applied to optimization of blade geometries to produce minimum cutting forces and hence minimum damage to cut surfaces. The second topic concerns cutting with more than one edge with particular application to the formation of grooves in surfaces by hard pointed tools. The mechanics are investigated and applied to the topic of abrasive wear by hard particles. Traditional analyses say that abrasive wear resistance increases monotonically with the hardness of the workpiece, but we show that the fracture toughness of the surface material is also important, and that behaviour is determined by the toughness-to-hardness ratio rather than hardness alone. Scaling forms the third subject. As cutting is a branch of elasto-plastic fracture mechanics, cube-square energy scaling applies in which the important length scale is (ER/k (2)), where E is Young's modulus, R is the fracture toughness and k is the shear yield strength. Whether, in cutting, material is removed as ductile ribbons, as semi-ductile discontinuous chips, or by brittle 'knocking lumps out' is shown to depend on the depth of cut relative to this characteristic length parameter. Scaling in biology is called allometry and its relationship with engineering scaling is discussed. Some speculative predictions are made in relation to the action of teeth on food.

The influence of feeding on the evolution of sensory signals: a comparative test of an evolutionary trade-off between masticatory and sensory functions of skulls in southern African horseshoe bats (Rhinolophidae).

PubMed

Jacobs, D S; Bastian, A; Bam, L

2014-12-01

The skulls of animals have to perform many functions. Optimization for one function may mean another function is less optimized, resulting in evolutionary trade-offs. Here, we investigate whether a trade-off exists between the masticatory and sensory functions of animal skulls using echolocating bats as model species. Several species of rhinolophid bats deviate from the allometric relationship between body size and echolocation frequency. Such deviation may be the result of selection for increased bite force, resulting in a decrease in snout length which could in turn lead to higher echolocation frequencies. If so, there should be a positive relationship between bite force and echolocation frequency. We investigated this relationship in several species of southern African rhinolophids using phylogenetically informed analyses of the allometry of their bite force and echolocation frequency and of the three-dimensional shape of their skulls. As predicted, echolocation frequency was positively correlated with bite force, suggesting that its evolution is influenced by a trade-off between the masticatory and sensory functions of the skull. In support of this, variation in skull shape was explained by both echolocation frequency (80%) and bite force (20%). Furthermore, it appears that selection has acted on the nasal capsules, which have a frequency-specific impedance matching function during vocalization. There was a negative correlation between echolocation frequency and capsule volume across species. Optimization of the masticatory function of the skull may have been achieved through changes in the shape of the mandible and associated musculature, elements not considered in this study. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

A universal airborne LiDAR approach for tropical forest carbon mapping.

PubMed

Asner, Gregory P; Mascaro, Joseph; Muller-Landau, Helene C; Vieilledent, Ghislain; Vaudry, Romuald; Rasamoelina, Maminiaina; Hall, Jefferson S; van Breugel, Michiel

2012-04-01

Airborne light detection and ranging (LiDAR) is fast turning the corner from demonstration technology to a key tool for assessing carbon stocks in tropical forests. With its ability to penetrate tropical forest canopies and detect three-dimensional forest structure, LiDAR may prove to be a major component of international strategies to measure and account for carbon emissions from and uptake by tropical forests. To date, however, basic ecological information such as height-diameter allometry and stand-level wood density have not been mechanistically incorporated into methods for mapping forest carbon at regional and global scales. A better incorporation of these structural patterns in forests may reduce the considerable time needed to calibrate airborne data with ground-based forest inventory plots, which presently necessitate exhaustive measurements of tree diameters and heights, as well as tree identifications for wood density estimation. Here, we develop a new approach that can facilitate rapid LiDAR calibration with minimal field data. Throughout four tropical regions (Panama, Peru, Madagascar, and Hawaii), we were able to predict aboveground carbon density estimated in field inventory plots using a single universal LiDAR model (r ( 2 ) = 0.80, RMSE = 27.6 Mg C ha(-1)). This model is comparable in predictive power to locally calibrated models, but relies on limited inputs of basal area and wood density information for a given region, rather than on traditional plot inventories. With this approach, we propose to radically decrease the time required to calibrate airborne LiDAR data and thus increase the output of high-resolution carbon maps, supporting tropical forest conservation and climate mitigation policy.

Macroevolutionary patterns of sexual size dimorphism in copepods

PubMed Central

Hirst, Andrew G.; Kiørboe, Thomas

2014-01-01

Major theories compete to explain the macroevolutionary trends observed in sexual size dimorphism (SSD) in animals. Quantitative genetic theory suggests that the sex under historically stronger directional selection will exhibit greater interspecific variance in size, with covariation between allometric slopes (male to female size) and the strength of SSD across clades. Rensch's rule (RR) also suggests a correlation, but one in which males are always the more size variant sex. Examining free-living pelagic and parasitic Copepoda, we test these competing predictions. Females are commonly the larger sex in copepod species. Comparing clades that vary by four orders of magnitude in their degree of dimorphism, we show that isometry is widespread. As such we find no support for either RR or for covariation between allometry and SSD. Our results suggest that selection on both sexes has been equally important. We next test the prediction that variation in the degree of SSD is related to the adult sex ratio. As males become relatively less abundant, it has been hypothesized that this will lead to a reduction in both inter-male competition and male size. However, the lack of such a correlation across diverse free-living pelagic families of copepods provides no support for this hypothesis. By comparison, in sea lice of the family Caligidae, there is some qualitative support of the hypothesis, males may suffer elevated mortality when they leave the host and rove for sedentary females, and their female-biased SSD is greater than in many free-living families. However, other parasitic copepods which do not appear to have obvious differences in sex-based mate searching risks also show similar or even more extreme SSD, therefore suggesting other factors can drive the observed extremes. PMID:25100692

Evolutionary morphology in shape and size of haptoral anchors in 14 Ligophorus spp. (Monogenea: Dactylogyridae).

PubMed

Rodríguez-González, Abril; Sarabeev, Volodimir; Balbuena, Juan Antonio

2017-01-01

The search for phylogenetic signal in morphological traits using geometric morphometrics represents a powerful approach to estimate the relative weights of convergence and shared evolutionary history in shaping organismal form. We assessed phylogenetic signal in the form of ventral and dorsal haptoral anchors of 14 species of Ligophorus occurring on grey mullets (Osteichthyes: Mugilidae) from the Mediterranean, the Black Sea and the Sea of Azov. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors and two different tests were applied to establish whether the spatial positions in the morphospace were dictated by chance. Overall significant phylogenetic signal was found in the data. Allometric effects on anchor shape were moderate or non-significant in the case of evolutionary allometry. Relatively phylogenetically distant species occurring on the same host differed markedly in anchor morphology indicating little influence of host species on anchor form. Our results suggest that common descent and shared evolutionary history play a major role in determining the shape and, to a lesser degree in the size of haptoral anchors in Ligophorus spp. The present approach allowed tracing paths of morphological evolution in anchor shape. Species with narrow anchors and long shafts were associated predominately with Liza saliens. This morphology was considered to be ancestral relative to anchors of species occurring on Liza haematocheila and M. cephalus possessing shorter shafts and longer roots. Evidence for phylogenetic signal was more compelling for the ventral anchors, than for the dorsal ones, which could reflect different functional roles in attachment to the gills. Although phylogeny and homoplasy may act differently in other monogeneans, the present study delivers a common framework to address effectively the relationships among morphology, phylogeny and other traits, such as host specificity or niche occupancy.

Ethnicity and skeletal Class III morphology: a pubertal growth analysis using thin-plate spline analysis.

PubMed

Alkhamrah, B; Terada, K; Yamaki, M; Ali, I M; Hanada, K

2001-01-01

A longitudinal retrospective study using thin-plate spline analysis was used to investigate skeletal Class III etiology in Japanese female adolescents. Headfilms of 40 subjects were chosen from the archives of the Orthodontic department at Niigata University Dental Hospital, and were traced at IIIB and IVA Hellman dental ages. Twenty-eight homologous landmarks, representing hard and soft tissue, were digitized. These were used to reproduce a consensus for the profilogram, craniomaxillary complex, mandible, and soft tissue for each age and skeletal group. Generalized least-square analysis revealed a significant shape difference between age-matched groups (P < .001), except for the craniomaxillary complex at stage IVA. T test for size analysis showed unequivocally increased mandibular size in skeletal Class III, which directly increased the craniofacial size collectively (P < .05). A deviant profilogram showed anisotropy displaying as maxillary deficiency, acute cranial base, and obtuse gonial angle in addition to increased facial height at stage IIIB. Maxillary retrusion decreased while the mandible showed excessive incremental growth and a forward position caused by deficient orthocephalization at stage IVA. Craniomaxillary complex total spline and partial warps (PW)3 and 2 showed a maxillary retrusion at stage IIIB opposite an acute cranial base at stage IVA. Mandibular total spline and PW4, 5 showed changes affecting most landmarks and their spatial interrelationship, especially a stretch along the articulare-pogonion axis. In soft tissue analysis, PW8 showed large and local changes which paralleled the underlying hard tissue components. Allometry of the mandible and anisotropy of the cranial base, the maxilla, and the mandible asserted the complexity of craniofacial growth and the difficulty of predicting its outcome.

Wing shape allometry and aerodynamics in calopterygid damselflies: a comparative approach.

PubMed

Outomuro, David; Adams, Dean C; Johansson, Frank

2013-06-07

Wing size and shape have important aerodynamic implications on flight performance. We explored how wing size was related to wing shape in territorial males of 37 taxa of the damselfly family Calopterygidae. Wing coloration was also included in the analyses because it is sexually and naturally selected and has been shown to be related to wing shape. We studied wing shape using both the non-dimensional radius of the second moment of wing area (RSM) and geometric morphometrics. Lower values of the RSM result in less energetically demanding flight and wider ranges of flight speed. We also re-analyzed previously published data on other damselflies and dragonflies. The RSM showed a hump-shaped relationship with wing size. However, after correcting for phylogeny using independent contrast, this pattern changed to a negative linear relationship. The basal genus of the study family, Hetaerina, was mainly driving that change. The obtained patterns were specific for the study family and differed from other damselflies and dragonflies. The relationship between the RSM and wing shape measured by geometric morphometrics was linear, but relatively small changes along the RSM axis can result in large changes in wing shape. Our results also showed that wing coloration may have some effect on RSM. We found that RSM showed a complex relationship with size in calopterygid damselflies, probably as a result of other selection pressures besides wing size per se. Wing coloration and specific behavior (e.g. courtship) are potential candidates for explaining the complexity. Univariate measures of wing shape such as RSM are more intuitive but lack the high resolution of other multivariate techniques such as geometric morphometrics. We suggest that the relationship between wing shape and size are taxa-specific and differ among closely-related insect groups.

Growth laws for delta crevasses in the Mississippi River Delta: observations and modeling

NASA Astrophysics Data System (ADS)

Yocum, T. A.; Georgiou, I. Y.

2016-02-01

River deltas are accumulations of sedimentary deposits delivered by rivers via a network of distributary channels. Worldwide they are threatened by environmental changes, including subsidence, global sea level rise and a suite of other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions, thereby reinitiating the delta cycle. While economically efficient, there are too few analogs of small deltas aside from laboratory studies, numerical modeling studies, theoretical approaches, and limited field driven observations. Anthropogenic crevasses in the modern delta are large enough to overcome limitations of laboratory deltas, and small enough to allow for "rapid" channel and wetland development, providing an ideal setting to investigate delta development mechanics. Crevasse metrics were obtained using a combination of geospatial tools, extracting key parameters (bifurcation length and width, channel order and depth) that were non-dimensionalized and compared to river-dominated delta networks previously studied. Analysis showed that most crevasses in the MRD appear to obey delta growth laws and delta allometry relationships, suggesting that crevasses do exhibit similar planform metrics to larger Deltas; the distance to mouth bar versus bifurcation order demonstrated to be a very reasonable first order estimate of delta-top footprint. However, some crevasses exhibited different growth metrics. To better understand the hydrodynamic and geomorphic controls governing crevasse evolution in the MRD, we assess delta dynamics via a suite of field observations and numerical modeling in both well-established and newly constructed crevasses. Our analysis suggests that delta development is affected by the relative influence of external (upstream and downstream) and internal controls on the hydrodynamic and sediment transport patterns in these systems.

Allometric scaling of UK urban emissions: interpretation and implications for air quality management

NASA Astrophysics Data System (ADS)

MacKenzie, Rob; Barnes, Matt; Whyatt, Duncan; Hewitt, Nick

2016-04-01

Allometry uncovers structures and patterns by relating the characteristics of complex systems to a measure of scale. We present an allometric analysis of air quality for UK urban settlements, beginning with emissions and moving on to consider air concentrations. We consider both airshed-average 'urban background' concentrations (cf. those derived from satellites for NO2) and local pollution 'hotspots'. We show that there is a strong and robust scaling (with respect to population) of the non-point-source emissions of the greenhouse gases carbon dioxide and methane, as well as the toxic pollutants nitrogen dioxide, PM2.5, and 1,3-butadiene. The scaling of traffic-related emissions is not simply a reflection of road length, but rather results from the socio-economic patterning of road-use. The recent controversy regarding diesel vehicle emissions is germane to our study but does not affect our overall conclusions. We next develop an hypothesis for the population-scaling of airshed-average air concentrations, with which we demonstrate that, although average air quality is expected to be worse in large urban centres compared to small urban centres, the overall effect is an economy of scale (i.e., large cities reduce the overall burden of emissions compared to the same population spread over many smaller urban settlements). Our hypothesis explains satellite-derived observations of airshed-average urban NO2 concentrations. The theory derived also explains which properties of nature-based solutions (urban greening) can make a significant contribution at city scale, and points to a hitherto unforeseen opportunity to make large cities cleaner than smaller cities in absolute terms with respect to their airshed-average pollutant concentration.

Allometric Convergence in Savanna Trees and Implications for the Use of Plant Scaling Models in Variable Ecosystems

PubMed Central

Tredennick, Andrew T.; Bentley, Lisa Patrick; Hanan, Niall P.

2013-01-01

Theoretical models of allometric scaling provide frameworks for understanding and predicting how and why the morphology and function of organisms vary with scale. It remains unclear, however, if the predictions of ‘universal’ scaling models for vascular plants hold across diverse species in variable environments. Phenomena such as competition and disturbance may drive allometric scaling relationships away from theoretical predictions based on an optimized tree. Here, we use a hierarchical Bayesian approach to calculate tree-specific, species-specific, and ‘global’ (i.e. interspecific) scaling exponents for several allometric relationships using tree- and branch-level data harvested from three savanna sites across a rainfall gradient in Mali, West Africa. We use these exponents to provide a rigorous test of three plant scaling models (Metabolic Scaling Theory (MST), Geometric Similarity, and Stress Similarity) in savanna systems. For the allometric relationships we evaluated (diameter vs. length, aboveground mass, stem mass, and leaf mass) the empirically calculated exponents broadly overlapped among species from diverse environments, except for the scaling exponents for length, which increased with tree cover and density. When we compare empirical scaling exponents to the theoretical predictions from the three models we find MST predictions are most consistent with our observed allometries. In those situations where observations are inconsistent with MST we find that departure from theory corresponds with expected tradeoffs related to disturbance and competitive interactions. We hypothesize savanna trees have greater length-scaling exponents than predicted by MST due to an evolutionary tradeoff between fire escape and optimization of mechanical stability and internal resource transport. Future research on the drivers of systematic allometric variation could reconcile the differences between observed scaling relationships in variable ecosystems and those predicted by ideal models such as MST. PMID:23484003

Differential Growth and Development of the Upper and Lower Human Thorax

PubMed Central

Bastir, Markus; García Martínez, Daniel; Recheis, Wolfgang; Barash, Alon; Coquerelle, Michael; Rios, Luis; Peña-Melián, Ángel; García Río, Francisco; O’Higgins, Paul

2013-01-01

The difficulties in quantifying the 3D form and spatial relationships of the skeletal components of the ribcage present a barrier to studies of the growth of the thoracic skeleton. Thus, most studies to date have relied on traditional measurements such as distances and indices from single or few ribs. It is currently known that adult-like thoracic shape is achieved early, by the end of the second postnatal year, with the circular cross-section of the newborn thorax transforming into the ovoid shape of adults; and that the ribs become inclined such that their anterior borders come to lie inferior to their posterior. Here we present a study that revisits growth changes using geometric morphometrics applied to extensive landmark data taken from the ribcage. We digitized 402 (semi) landmarks on 3D reconstructions to assess growth changes in 27 computed tomography-scanned modern humans representing newborns to adults of both sexes. Our analyses show a curved ontogenetic trajectory, resulting from different ontogenetic growth allometries of upper and lower thoracic units. Adult thoracic morphology is achieved later than predicted, by diverse modifications in different anatomical regions during different ontogenetic stages. Besides a marked increase in antero-posterior dimensions, there is an increase in medio-lateral dimensions of the upper thorax, relative to the lower thorax. This transforms the pyramidal infant thorax into the barrel-shaped one of adults. Rib descent is produced by complex changes in 3D curvature. Developmental differences between upper and lower thoracic regions relate to differential timings and rates of maturation of the respiratory and digestive systems, the spine and the locomotor system. Our findings are relevant to understanding how changes in the relative rates of growth of these systems and structures impacted on the development and evolution of modern human body shape. PMID:24073239

Growth, allometry and shade tolerance of understory saplings of four subalpine conifers in central Japan.

PubMed

Takahashi, Koichi; Obata, Yoshiko

2014-03-01

The conifers Abies veitchii, A. mariesii, Picea jezoensis var. hondoensis, Tsuga diversifolia dominate in subalpine forests in central Japan. We expected that species differences in shade tolerance and in aboveground and belowground architecture are important for their coexistence. We examined net production and carbon allocation of understory saplings. Although the four species allocated similar amounts of biomass to roots at a given trunk height, the root-zone area of T. diversifolia was greater than that of the three other species. T. diversifolia often dominates shallow soil sites, such as ridge and rocky slopes, and, therefore, a wide spread of lateral roots would be an adaptation to such edaphic conditions. Crown width and leaf and branch mass were greatest for T. diversifolia and A. mariesii, followed in order by A. veitchii and P. jezoensis var. hondoensis. Although leaf mass of P. jezoensis var. hondoensis was lowest among the four species, species differences were not found in the net production per sapling because net production per leaf mass was greatest for P. jezoensis var. hondoensis. The leaf lifespan was longer in the order A. mariesii, T. diversifolia, P. jezoensis var. hondoensis and A. veitchii. The minimum rate of net production per leaf mass required to maintain the current sapling leaf mass (MRNP(LM)) was lowest in A. mariesii and T. diversifolia, and increased in the order of A. veitchii and P. jezoensis var. hondoensis. A. mariesii and T. diversifolia may survive in shade conditions by a lower MRNP(LM) than the two other species. Therefore, species differences in aboveground and belowground architecture and MRNPLM reflected their shade tolerance and regeneration strategies, which contribute to their coexistence.

Kleiber's Law: How the Fire of Life ignited debate, fueled theory, and neglected plants as model organisms.

PubMed

Niklas, Karl J; Kutschera, Ulrich

2015-01-01

Size is a key feature of any organism since it influences the rate at which resources are consumed and thus affects metabolic rates. In the 1930s, size-dependent relationships were codified as "allometry" and it was shown that most of these could be quantified using the slopes of log-log plots of any 2 variables of interest. During the decades that followed, physiologists explored how animal respiration rates varied as a function of body size across taxa. The expectation was that rates would scale as the 2/3 power of body size as a reflection of the Euclidean relationship between surface area and volume. However, the work of Max Kleiber (1893-1976) and others revealed that animal respiration rates apparently scale more closely as the 3/4 power of body size. This phenomenology, which is called "Kleiber's Law," has been described for a broad range of organisms, including some algae and plants. It has also been severely criticized on theoretical and empirical grounds. Here, we review the history of the analysis of metabolism, which originated with the works of Antoine L. Lavoisier (1743-1794) and Julius Sachs (1832-1897), and culminated in Kleiber's book The Fire of Life (1961; 2. ed. 1975). We then evaluate some of the criticisms that have been leveled against Kleiber's Law and some examples of the theories that have tried to explain it. We revive the speculation that intracellular exo- and endocytotic processes are resource delivery-systems, analogous to the supercellular systems in multicellular organisms. Finally, we present data that cast doubt on the existence of a single scaling relationship between growth and body size in plants.

Scaling of Primate Forearm Muscle Architecture as It Relates to Locomotion and Posture.

PubMed

Leischner, Carissa L; Crouch, Michael; Allen, Kari L; Marchi, Damiano; Pastor, Francisco; Hartstone-Rose, Adam

2018-03-01

It has been previously proposed that distal humerus morphology may reflect the locomotor pattern and substrate preferred by different primates. However, relationships between these behaviors and the morphological capabilities of muscles originating on these osteological structures have not been fully explored. Here, we present data about forearm muscle architecture in a sample of 44 primate species (N = 55 specimens): 9 strepsirrhines, 15 platyrrhines, and 20 catarrhines. The sample includes all major locomotor and substrate use groups. We isolated each antebrachial muscle and categorized them into functional groups: wrist and digital extensors and flexors, antebrachial mm. that do not cross the wrist, and functional combinations thereof. Muscle mass, physiological cross-sectional area (PCSA), reduced PCSA (RPCSA), and fiber length (FL) are examined in the context of higher taxonomic group, as well as locomotor/postural and substrate preferences. Results show that muscle masses, PCSA, and RPCSA scale with positive allometry while FL scales with isometry indicating that larger primates have relatively stronger, but neither faster nor more flexible, forearms across the sample. When accounting for variation in body size, we found no statistically significant difference in architecture among higher taxonomic groups or locomotor/postural groups. However, we found that arboreal primates have significantly greater FL than terrestrial ones, suggesting that these species are adapted for greater speed and/or flexibility in the trees. These data may affect our interpretation of the mechanisms for variation in humeral morphology and provide information for refining biomechanical models of joint stress and movement in extant and fossil primates. Anat Rec, 301:484-495, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans

PubMed Central

Green, Patrick A; Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-01-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. PMID:23035637

Brain size and visual environment predict species differences in paper wasp sensory processing brain regions (hymenoptera: vespidae, polistinae).

PubMed

O'Donnell, Sean; Clifford, Marie R; DeLeon, Sara; Papa, Christopher; Zahedi, Nazaneen; Bulova, Susan J

2013-01-01

The mosaic brain evolution hypothesis predicts that the relative volumes of functionally distinct brain regions will vary independently and correlate with species' ecology. Paper wasp species (Hymenoptera: Vespidae, Polistinae) differ in light exposure: they construct open versus enclosed nests and one genus (Apoica) is nocturnal. We asked whether light environments were related to species differences in the size of antennal and optic processing brain tissues. Paper wasp brains have anatomically distinct peripheral and central regions that process antennal and optic sensory inputs. We measured the volumes of 4 sensory processing brain regions in paper wasp species from 13 Neotropical genera including open and enclosed nesters, and diurnal and nocturnal species. Species differed in sensory region volumes, but there was no evidence for trade-offs among sensory modalities. All sensory region volumes correlated with brain size. However, peripheral optic processing investment increased with brain size at a higher rate than peripheral antennal processing investment. Our data suggest that mosaic and concerted (size-constrained) brain evolution are not exclusive alternatives. When brain regions increase with brain size at different rates, these distinct allometries can allow for differential investment among sensory modalities. As predicted by mosaic evolution, species ecology was associated with some aspects of brain region investment. Nest architecture variation was not associated with brain investment differences, but the nocturnal genus Apoica had the largest antennal:optic volume ratio in its peripheral sensory lobes. Investment in central processing tissues was not related to nocturnality, a pattern also noted in mammals. The plasticity of neural connections in central regions may accommodate evolutionary shifts in input from the periphery with relatively minor changes in volume. © 2013 S. Karger AG, Basel.

Nondestructive estimation of growth year in ginseng cultivars using the means of mathematical modeling on the basis of allometry.

PubMed

Cheng, Chunsong; Yuan, Qingxi; Zhou, Hua; Huang, Luqi

2016-02-01

Growth-year authentication has extraordinary significance for plant growth, structure and development research, and has a wide range of applications in value assessment of economic crops. Panax ginseng is the most commonly used medicinal plant in Asian countries. The fix number of growth-year is an important quality evaluation which is difficult to be obtained accurately in current technical conditions. Preliminary authentication theory for growth-year has been described in previous studies using a short-lived perennial medicinal plant (Paeonia lactiflora pall.) as the research material. In this research, we focused on the growth-year estimation in ginseng cultivars, and attempt to explore the age estimation method for vascular plants according to mathematical simulation of the root structure development. Micro data was obtained from 204 individuals of 3 different kinds of ginseng cultivars, which have a series of gradient age and a clear growth record. Outer diameter of the vascular cambium (b) and the radius of cross section (r) were measured with ordinary stereo microscope. We further designed and established two different kinds of authentication model based on the taproot structure development for growth year authentication (P =β*M-α and M = K*X1 (a) (1) X2 (a) (2) ). Moreover, the models were applied to identify the growth year of ginseng without damage using Micro-CT or DEI reconstruction. A potential method, have been recently described, the age of ginseng can be analyzed by telomere length and telomerase activity. However, we found that there are different results indicated in other species. We concluded that microscopic methods perceived currently were provided a more effective means for growth-year authentication. © 2016 Wiley Periodicals, Inc.

Stomatal conductance at Duke FACE: Leveraging the lessons from 11 years of scaled sap flux measurements for region-wide analyses

NASA Astrophysics Data System (ADS)

Ward, E. J.; Bell, D.; Clark, J. S.; McCarthy, H. R.; Kim, H.; domec, J.; Noormets, A.; McNulty, D.; Sun, G.; Oren, R.

2013-12-01

A network of thermal dissipation probes (TDPs) monitoring sap flux density was used to estimate leaf-specific transpiration (EL) and canopy-averaged stomatal conductance (GS) in Pinus taeda (L.) exposed to +200 ppm atmospheric CO2 levels (eCO2) and nitrogen fertilization as part of the Duke FACE study. Data from scaling half-hourly measurements from hundreds of sensors over 11 years indicated that P. taeda in eCO2 intermittently (49% of monthly values) decreased stomatal conductance relative to the control, with a mean reduction of 13% in both total EL and mean daytime GS. This intermittent response was related to changes in a hydraulic allometry index (AH), defined as sapwood area per unit leaf area per unit canopy height, which was linearly related to GS at reference conditions (GSR) during the growing season across years (R2=0.67). Overall, AH decreased a mean of 15% with eCO2 over the course of the study, due mostly to a mean 19% increase in leaf area. Throughout the southeastern U.S., other P. taeda stands have been monitored with TDPs, such as the US-NC2 Ameriflux site and four fertilizer × throughfall displacement studies recently begun as part of the PINEMAP research network in VA, GA, FL and OK. We will also discuss the challenges and benefits of using a common modeling platform to combine FACE TDP data with that from a diversity of sites and treatments to draw inferences about EL and GS responses to environmental drivers and climate change, as well as their relation to AH, across the range of P. taeda.

Inherent and environmental patterns in biomass allocation and allometry among higher plants

NASA Astrophysics Data System (ADS)

Poorter, Hendrik

2017-04-01

It is well-known that plants may adjust the distribution of biomass over leaves, stems and roots depending on environmental conditions. It is also clear that size is an important factor as well. However, good quantitative insights are lacking. In this talk I analyse biomass allocation patterns to leaves, stems and roots of herbs and woody species. A database was compiled with 11.000 records of leaf, stem and root biomass for 1200 species. First, I'll derive general dose-response curves that describe the relationship between biomass allocation and the 12 most important a-biotic environmental factors and compare them with the changes in leaf, stem and root morphology. Second, I'll focus on allometric relationships between the various organs and test to what extent they comply with models like that for Metabolic Scaling Theory, where the slope of the log-log relationship between leaf and root biomass is expected to have a value of ¾. Third, I analyse how leaf, stem and root mass fractions change as a function of total plant size. This offers a great opportunity to test to what extent there are systematic differences in allocation patterns related to phylogeny (e.g. Gymnosperms vs. Angiosperms, grasses vs. herbaceous dicots) and functional group (e.g. deciduous vs. evergreens). Poorter et al. (2012) Biomass allocation to leaves, stems and roots: meta-analyses of interspecific variation and environmental control. New Phytol. 193: 30-50. Poorter & Sack (2012) Pitfalls and possibilities in the analysis of biomass allocation patterns in plants. Front. Plant Sci. 3: 259. Poorter et al. (2015) How does biomass distribution change with size and differ among species? New Phytol. 208: 736-749

Conarticular congruence of the hominoid subtalar joint complex with implications for joint function in Plio-Pleistocene hominins.

PubMed

Prang, Thomas C

2016-07-01

The purpose of this study is to test the hypothesis that conarticular surfaces areas and curvatures are correlates of mobility at the hominoid talocalcaneal and talonavicular joints. Articular surface areas and curvatures of the talonavicular, anterior talocalcaneal, and posterior talocalcaneal joints were quantified using a total of 425 three-dimensional surface models of extant hominoid and fossil hominin tali, calcanei, and naviculars. Quadric surface fitting was used to calculate curvatures, pairwise comparisons were used to evaluate statistical differences between taxa, and regression was used to test for the effects of allometry. Pairwise comparisons show that the distributions of values for joint curvature indices follow the predicted arboreal-terrestrial morphocline in hominoid primates with no effect of body mass (PGLS p > 0.05). OH 8 (Homo habilis) and LB 1 (Homo floresiensis) can be accommodated within the range of human variation for the talonavicular joint, whereas MH2 (Australopithecus sediba) falls within the ranges of variation for Pan troglodytes and Gorilla gorilla in measures of posterior talocalcaneal joint congruity. Joint curvature indices are better discriminators than joint surface area indices, which may reflect a greater contribution of rotation, rather than translation, to joint movement in plantigrade taxa due to discrepancies in conarticular congruence and the "convex-concave" rule. The pattern of joint congruence in Au. sediba contributes to other data on the foot and ankle suggesting that the lateral side of the foot was more mobile than the medial side, which is consistent with suggestions of increased medial weight transfer associated with hyperpronation. Am J Phys Anthropol 160:446-457, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Growth of the eye lens: II. Allometric studies.

PubMed

Augusteyn, Robert C

2014-01-01

The purpose of this study was to examine the ontogeny and phylogeny of lens growth in a variety of species using allometry. Data on the accumulation of wet and/or dry lens weight as a function of bodyweight were obtained for 40 species and subjected to allometric analysis to examine ontogenic growth and compaction. Allometric analysis was also used to compare the maximum adult lens weights for 147 species with the maximum adult bodyweight and to compare lens volumes calculated from wet and dry weights with eye volumes calculated from axial length. Linear allometric relationships were obtained for the comparison of ontogenic lens and bodyweight accumulation. The body mass exponent (BME) decreased with increasing animal size from around 1.0 in small rodents to 0.4 in large ungulates for both wet and dry weights. Compaction constants for the ontogenic growth ranged from 1.00 in birds and reptiles up to 1.30 in mammals. Allometric comparison of maximum lens wet and dry weights with maximum bodyweights also yielded linear plots with a BME of 0.504 for all warm blooded species except primates which had a BME of 0.25. When lens volumes were compared with eye volumes, all species yielded a scaling constant of 0.75 but the proportionality constants for primates and birds were lower. Ontogenic lens growth is fastest, relative to body growth, in small animals and slowest in large animals. Fiber cell compaction takes place throughout life in most species, but not in birds and reptiles. Maximum adult lens size scales with eye size with the same exponent in all species, but birds and primates have smaller lenses relative to eye size than other species. Optical properties of the lens are generated through the combination of variations in the rate of growth, rate of compaction, shape and size.

Forest disturbance spurs growth of modeling and technology

NASA Astrophysics Data System (ADS)

Bohrer, G.; Matheny, A. M.; Mirfenderesgi, G.; Morin, T. H.; Rey Sanchez, A. C.; Gough, C. M.; Vogel, C. S.; Nadelhoffer, K. J.; Curtis, P.

2016-12-01

As new opportunities for scientific exploration open, needs for data generate a drive for innovative developments of new research tools. The Forest Accelerated Succession ExperimenT (FASET) was enacted in 2007, continuous flux observations at the University of Michigan Biological Station (UMBS) since 2000. FASET is a large-scale ecological experiment testing the immediate and intermediate term effects of disturbance, and eventually, the role of succession and community composition on forest flux dynamics. Decades-long tree-level observations in the UMBS forest, combined with the long term flux observations allowed us to match the bottom-up accumulated response of individual trees with the top-down whole-plot response measured from the flux tower. However, data describing tree-level canopy structure and hydrological response over an entire plot were not readily available. Unintentionally, FASET became both a motivation and a test-bed for new research tools and approaches. We expanded the operation and analysis approach for a portable canopy LiDARfor 3-D measurements meter-scale canopy structure. We matched canopy LiDAR measurements with root measurements from ground penetrating radar. To study the hydrological effects of the disturbance, we instrumented a large number of trees with Granier-style sap flux sensors. We further developed an approach to use frequency domain reflectometry sensors for continuous measurements of tree water content. We developed an approach to combine plot census, allometry and sap-flux observations in a bottom-up fashion to compare with plot-level EC transpiration rates. We found that while the transpirational water demand in the disturbance plot increased, overall evapotranspiration decreased. This decrease, however, is not uniform across species. A new individual-plant to ecosystem scale hydrodynamic model (FETCH2) demonstrates how specific traits translate to intra-daily differences in plot-level transpiration dynamics.

Larval green and white sturgeon swimming performance in relation to water-diversion flows

PubMed Central

Verhille, Christine E.; Poletto, Jamilynn B.; Cocherell, Dennis E.; DeCourten, Bethany; Baird, Sarah; Cech, Joseph J.; Fangue, Nann A.

2014-01-01

Little is known of the swimming capacities of larval sturgeons, despite global population declines in many species due in part to fragmentation of their spawning and rearing habitats by man-made water-diversion structures. Larval green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) inhabit the highly altered Sacramento–San Joaquin watershed, making them logical species to examine vulnerability to entrainment by altered water flows. The risk of larval sturgeon entrainment is influenced by the ontogeny of swimming capacity and dispersal timing and their interactions with water-diversion structure operations. Therefore, the aim of this study was to describe and compare the ontogeny and allometry of larval green and white sturgeon swimming capacities until completion of metamorphosis into juveniles. Despite the faster growth rates and eventual larger size of larval white sturgeon, green sturgeon critical swimming velocities remained consistently, though modestly, greater than those of white sturgeon throughout the larval life stage. Although behavioural interactions with water-diversion structures are also important considerations, regarding swimming capacity, Sacramento–San Joaquin sturgeons are most vulnerable to entrainment in February–May, when white sturgeon early larvae are in the middle Sacramento River, and April–May, when green sturgeon early larvae are in the upper river. Green sturgeon migrating downstream to the estuary and bays in October–November are also susceptible to entrainment due to their movements combined with seasonal declines in their swimming capacity. An additional inter-species comparison of the allometric relationship between critical swimming velocities and total length with several sturgeon species found throughout the world suggests a similar ontogeny of swimming capacity with growth. Therefore, although dispersal and behaviour differ among river systems and sturgeon species, similar recommendations are applicable for managers seeking to balance water demands with restoration and conservation of sturgeons worldwide. PMID:27293652

Inter-class competition in stage-structured populations: effects of adult density on life-history traits of adult and juvenile common lizards.

PubMed

San-Jose, Luis M; Peñalver-Alcázar, Miguel; Huyghe, Katleen; Breedveld, Merel C; Fitze, Patrick S

2016-12-01

Ecological and evolutionary processes in natural populations are largely influenced by the population's stage-structure. Commonly, different classes have different competitive abilities, e.g., due to differences in body size, suggesting that inter-class competition may be important and largely asymmetric. However, experimental evidence states that inter-class competition, which is important, is rare and restricted to marine fish. Here, we manipulated the adult density in six semi-natural populations of the European common lizard, Zootoca vivipara, while holding juvenile density constant. Adult density affected juveniles, but not adults, in line with inter-class competition. High adult density led to lower juvenile survival and growth before hibernation. In contrast, juvenile survival after hibernation was higher in populations with high adult density, pointing to relaxed inter-class competition. As a result, annual survival was not affected by adult density, showing that differences in pre- and post-hibernation survival balanced each other out. The intensity of inter-class competition affected reproduction, performance, and body size in juveniles. Path analyses unravelled direct treatment effects on early growth (pre-hibernation) and no direct treatment effects on the parameters measured after hibernation. This points to allometry of treatment-induced differences in early growth, and it suggests that inter-class competition mainly affects the early growth of the competitively inferior class and thereby their future performance and reproduction. These results are in contrast with previous findings and, together with results in marine fish, suggest that the strength and direction of density dependence may depend on the degree of inter-class competition, and thus on the availability of resources used by the competing classes.

Global patterns and clines in the growth of common carp Cyprinus carpio.

PubMed

Vilizzi, L; Copp, G H

2017-07-01

This review provides a meta-analytical assessment of the global patterns and clines in the growth of Cyprinus carpio as measured by length-at-age (L t ) or von Bertalanffy growth function (VBGF) parameters, mass-length relationship (W-L t ) and condition factor, based on literature data. In total, 284 studies were retrieved spanning 91 years of research and carried out on 381 waterbodies-locations in 50 countries in all five continents. Although native C. carpio achieved larger (asymptotic) size relative to its non-native counterpart, the latter grew faster during the first 7 years of life. Lentic populations (especially in natural lakes) also achieved larger sizes relative to lotic ones and the same was true for populations in cold and temperate v. arid climates. Unlike previous studies (on much more restricted datasets), only weak latitudinal clines in instantaneous growth rate, L t at age 3 and mortality were observed globally and this was probably due to the presence of counter-gradient growth variation at all representative age classes (i.e. 1-10 years). Slightly negative allometry was revealed by the W-L t and the related form factor tended to distinguish the more elongated and torpedo-shaped body typical of the wild form from the deeper body of feral-domesticated C. carpio. Existing population dynamics models for C. carpio will benefit from the comprehensive range of waterbody type × climate class-specific VBGF parameters provided in the present study; whereas, more studies are needed on the species' growth in tropical regions and to unravel the possibility of confounding effects on age estimation due to both historical and methodological reasons. © 2017 The Fisheries Society of the British Isles.

Allometries of maximum growth rate versus body mass at maximum growth indicate that non-avian dinosaurs had growth rates typical of fast growing ectothermic sauropsids.

PubMed

Werner, Jan; Griebeler, Eva Maria

2014-01-01

We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case's study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either of the two thermoregulation strategies for studied dinosaurs.

Allometries of Maximum Growth Rate versus Body Mass at Maximum Growth Indicate That Non-Avian Dinosaurs Had Growth Rates Typical of Fast Growing Ectothermic Sauropsids

PubMed Central

Werner, Jan; Griebeler, Eva Maria

2014-01-01

We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case’s study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either of the two thermoregulation strategies for studied dinosaurs. PMID:24586409

Formal comment on: Myhrvold (2016) Dinosaur metabolism and the allometry of maximum growth rate. PLoS ONE; 11(11): e0163205

PubMed Central

Werner, Jan

2018-01-01

In his 2016 paper, Myhrvold criticized ours from 2014 on maximum growth rates (Gmax, maximum gain in body mass observed within a time unit throughout an individual’s ontogeny) and thermoregulation strategies (ectothermy, endothermy) of 17 dinosaurs. In our paper, we showed that Gmax values of similar-sized extant ectothermic and endothermic vertebrates overlap. This strongly questions a correct assignment of a thermoregulation strategy to a dinosaur only based on its Gmax and (adult) body mass (M). Contrary, Gmax separated similar-sized extant reptiles and birds (Sauropsida) and Gmax values of our studied dinosaurs were similar to those seen in extant similar-sized (if necessary scaled-up) fast growing ectothermic reptiles. Myhrvold examined two hypotheses (H1 and H2) regarding our study. However, we did neither infer dinosaurian thermoregulation strategies from group-wide averages (H1) nor were our results based on that Gmax and metabolic rate (MR) are related (H2). In order to assess whether single dinosaurian Gmax values fit to those of extant endotherms (birds) or of ectotherms (reptiles), we already used a method suggested by Myhrvold to avoid H1, and we only discussed pros and cons of a relation between Gmax and MR and did not apply it (H2). We appreciate Myhrvold’s efforts in eliminating the correlation between Gmax and M in order to statistically improve vertebrate scaling regressions on maximum gain in body mass. However, we show here that his mass-specific maximum growth rate (kC) replacing Gmax (= MkC) does not model the expected higher mass gain in larger than in smaller species for any set of species. We also comment on, why we considered extant reptiles and birds as reference models for extinct dinosaurs and why we used phylogenetically-informed regression analysis throughout our study. Finally, we question several arguments given in Myhrvold in order to support his results. PMID:29489816

A Macroecological Analysis of SERA Derived Forest Heights and Implications for Forest Volume Remote Sensing

PubMed Central

Brolly, Matthew; Woodhouse, Iain H.; Niklas, Karl J.; Hammond, Sean T.

2012-01-01

Individual trees have been shown to exhibit strong relationships between DBH, height and volume. Often such studies are cited as justification for forest volume or standing biomass estimation through remote sensing. With resolution of common satellite remote sensing systems generally too low to resolve individuals, and a need for larger coverage, these systems rely on descriptive heights, which account for tree collections in forests. For remote sensing and allometric applications, this height is not entirely understood in terms of its location. Here, a forest growth model (SERA) analyzes forest canopy height relationships with forest wood volume. Maximum height, mean, H100, and Lorey's height are examined for variability under plant number density, resource and species. Our findings, shown to be allometrically consistent with empirical measurements for forested communities world-wide, are analyzed for implications to forest remote sensing techniques such as LiDAR and RADAR. Traditional forestry measures of maximum height, and to a lesser extent H100 and Lorey's, exhibit little consistent correlation with forest volume across modeled conditions. The implication is that using forest height to infer volume or biomass from remote sensing requires species and community behavioral information to infer accurate estimates using height alone. SERA predicts mean height to provide the most consistent relationship with volume of the height classifications studied and overall across forest variations. This prediction agrees with empirical data collected from conifer and angiosperm forests with plant densities ranging between 102–106 plants/hectare and heights 6–49 m. Height classifications investigated are potentially linked to radar scattering centers with implications for allometry. These findings may be used to advance forest biomass estimation accuracy through remote sensing. Furthermore, Lorey's height with its specific relationship to remote sensing physics is recommended as a more universal indicator of volume when using remote sensing than achieved using either maximum height or H100. PMID:22457800

Urban forest ecosystem analysis using fused airborne hyperspectral and lidar data

NASA Astrophysics Data System (ADS)

Alonzo, Mike Gerard

Urban trees are strategically important in a city's effort to mitigate their carbon footprint, heat island effects, air pollution, and stormwater runoff. Currently, the most common method for quantifying urban forest structure and ecosystem function is through field plot sampling. However, taking intensive structural measurements on private properties throughout a city is difficult, and the outputs from sample inventories are not spatially explicit. The overarching goal of this dissertation is to develop methods for mapping urban forest structure and function using fused hyperspectral imagery and waveform lidar data at the individual tree crown scale. Urban forest ecosystem services estimated using the USDA Forest Service's i-Tree Eco (formerly UFORE) model are based largely on tree species and leaf area index (LAI). Accordingly, tree species were mapped in my Santa Barbara, California study area for 29 species comprising >80% of canopy. Crown-scale discriminant analysis methods were introduced for fusing Airborne Visible Infrared Imaging Spectrometry (AVIRIS) data with a suite of lidar structural metrics (e.g., tree height, crown porosity) to maximize classification accuracy in a complex environment. AVIRIS imagery was critical to achieving an overall species-level accuracy of 83.4% while lidar data was most useful for improving the discrimination of small and morphologically unique species. LAI was estimated at both the field-plot scale using laser penetration metrics and at the crown scale using allometry. Agreement of the former with photographic estimates of gap fraction and the latter with allometric estimates based on field measurements was examined. Results indicate that lidar may be used reasonably to measure LAI in an urban environment lacking in continuous canopy and characterized by high species diversity. Finally, urban ecosystem services such as carbon storage and building energy-use modification were analyzed through combination of aforementioned methods and the i-Tree Eco modeling framework. The remote sensing methods developed in this dissertation will allow researchers to more precisely constrain urban ecosystem spatial analyses and equip cities to better manage their urban forest resource.

Interaction between Orobanche crenata and its Host Legumes: Unsuccessful Haustorial Penetration and Necrosis of the Developing Parasite

PubMed Central

PÉREZ-DE-LUQUE, A.; RUBIALES, D.; CUBERO, J. I.; PRESS, M. C.; SCHOLES, J.; YONEYAMA, K.; TAKEUCHI, Y.; PLAKHINE, D.; JOEL, D. M.

2005-01-01

• Background and Aims Orobanche species represent major constraints to crop production in many parts of the world as they reduce yield and alter root/shoot allometry. Although much is known about the histology and effect of Orobanche spp. on susceptible hosts, less is known about the basis of host resistance to these parasites. In this work, histological aspects related to the resistance of some legumes to Orobanche crenata have been investigated in order to determine which types of resistance responses are involved in the unsuccessful penetration of O. crenata. • Methods Samples of resistance reactions against O. crenata on different genotypes of resistant legumes were collected. The samples were fixed, sectioned and stained using different procedures. Sections were observed using a transmission light microscope and by epi-fluorescence. • Key Results Lignification of endodermal and pericycle host cells seems to prevent parasite intrusion into the root vascular cylinder at early infection stages. But in other cases, established tubercles became necrotic and died. Contrary to some previous studies, it was found that darkening at the infection site in these latter cases does not correspond to death of host tissues, but to the secretion of substances that fill the apoplast in the host–parasite interface and in much of the infected host tissues. The secretions block neighbouring host vessels. This may interfere with the nutrient flux between host and parasite, and may lead to necrosis and death of the developing parasite. • Conclusions The unsuccessful penetration of O. crenata seedlings into legume roots cannot be attributed to cell death in the host. It seems to be associated with lignification of host endodermis and pericycle cells at the penetration site. The accumulation of secretions at the infection site, may lead to the activation of xylem occlusion, another defence mechanism, which may cause further necrosis of established tubercles. PMID:15749751

Variability in echolocation call intensity in a community of horseshoe bats: a role for resource partitioning or communication?

PubMed

Schuchmann, Maike; Siemers, Björn M

2010-09-17

Only recently data on bat echolocation call intensities is starting to accumulate. Yet, intensity is an ecologically crucial parameter, as it determines the extent of the bats' perceptual space and, specifically, prey detection distance. Interspecifically, we thus asked whether sympatric, congeneric bat species differ in call intensities and whether differences play a role for niche differentiation. Specifically, we investigated whether R. mehelyi that calls at a frequency clearly above what is predicted by allometry, compensates for frequency-dependent loss in detection distance by using elevated call intensity. Maximum echolocation call intensities might depend on body size or condition and thus be used as an honest signal of quality for intraspecific communication. We for the first time investigated whether a size-intensity relation is present in echolocating bats. We measured maximum call intensities and frequencies for all five European horseshoe bat species. Maximum intensity differed among species largely due to R. euryale. Furthermore, we found no compensation for frequency-dependent loss in detection distance in R. mehelyi. Intraspecifically, there is a negative correlation between forearm lengths and intensity in R. euryale and a trend for a negative correlation between body condition index and intensity in R. ferrumequinum. In R. hipposideros, females had 8 dB higher intensities than males. There were no correlations with body size or sex differences and intensity for the other species. Based on call intensity and frequency measurements, we estimated echolocation ranges for our study community. These suggest that intensity differences result in different prey detection distances and thus likely play some role for resource access. It is interesting and at first glance counter-intuitive that, where a correlation was found, smaller bats called louder than large individuals. Such negative relationship between size or condition and vocal amplitude may indicate an as yet unknown physiological or sexual selection pressure.

Phylogenetic and functional implications of the ear region anatomy of Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina

NASA Astrophysics Data System (ADS)

Boscaini, Alberto; Iurino, Dawid A.; Billet, Guillaume; Hautier, Lionel; Sardella, Raffaele; Tirao, German; Gaudin, Timothy J.; Pujos, François

2018-04-01

Several detailed studies of the external morphology of the ear region in extinct sloths have been published in the past few decades, and this anatomical region has proved extremely helpful in elucidating the phylogenetic relationships among the members of this mammalian clade. Few studies of the inner ear anatomy in these peculiar animals were conducted historically, but these are increasing in number in recent years, in both the extinct and extant representatives, due to wider access to CT-scanning facilities, which allow non-destructive access to internal morphologies. In the present study, we analyze the extinct ground sloth Glossotherium robustum and provide a description of the external features of the ear region and the endocranial side of the petrosal bone, coupled with the first data on the anatomy of the bony labyrinth. Some features observable in the ear region of G. robustum (e.g., the shape and size of the entotympanic bone and the morphology of the posteromedial surface of the petrosal) are highly variable, both intraspecifically and intraindividually. The form of the bony labyrinth of G. robustum is also described, providing the first data from this anatomical region for the family Mylodontidae. The anatomy of the bony labyrinth of the genus Glossotherium is here compared at the level of the superorder Xenarthra, including all available extant and extinct representatives, using geometric morphometric methods. In light of the new data, we discuss the evolution of inner ear anatomy in the xenarthran clade, and most particularly in sloths, considering the influence of phylogeny, allometry, and physiology on the shape of this highly informative region of the skull. These analyses show that the inner ear of Glossotherium more closely resembles that of the extant anteaters, and to a lesser extent those of the giant ground sloth Megatherium and euphractine armadillos, than those of the extant sloths Bradypus and Choloepus, further demonstrating the striking morphological convergence between the two extant sloth genera.

The Price of Precision: Large-Scale Mapping of Forest Structure and Biomass Using Airborne Lidar

NASA Astrophysics Data System (ADS)

Dubayah, R.

2015-12-01

Lidar remote sensing provides one of the best means for acquiring detailed information on forest structure. However, its application over large areas has been limited largely because of its expense. Nonetheless, extant data exist over many states in the U.S., funded largely by state and federal consortia and mainly for infrastructure, emergency response, flood plain and coastal mapping. These lidar data are almost always acquired in leaf-off seasons, and until recently, usually with low point count densities. Even with these limitations, they provide unprecedented wall-to-wall mappings that enable development of appropriate methodologies for large-scale deployment of lidar. In this talk we summarize our research and lessons learned in deriving forest structure over regional areas as part of NASA's Carbon Monitoring System (CMS). We focus on two areas: the entire state of Maryland and Sonoma County, California. The Maryland effort used low density, leaf-off data acquired by each county in varying epochs, while the on-going Sonoma work employs state-of-the-art, high density, wall-to-wall, leaf-on lidar data. In each area we combine these lidar coverages with high-resolution multispectral imagery from the National Agricultural Imagery Program (NAIP) and in situ plot data to produce maps of canopy height, tree cover and biomass, and compare our results against FIA plot data and national biomass maps. Our work demonstrates that large-scale mapping of forest structure at high spatial resolution is achievable but products may be complex to produce and validate over large areas. Furthermore, fundamental issues involving statistical approaches, plot types and sizes, geolocation, modeling scales, allometry, and even the definitions of "forest" and "non-forest" must be approached carefully. Ultimately, determining the "price of precision", that is, does the value of wall-to-wall forest structure data justify their expense, should consider not only carbon market applications, but the other ways the underlying lidar data may be used.

The scaling of postcranial muscles in cats (Felidae) I: forelimb, cervical, and thoracic muscles.

PubMed

Cuff, Andrew R; Sparkes, Emily L; Randau, Marcela; Pierce, Stephanie E; Kitchener, Andrew C; Goswami, Anjali; Hutchinson, John R

2016-07-01

The body masses of cats (Mammalia, Carnivora, Felidae) span a ~300-fold range from the smallest to largest species. Despite this range, felid musculoskeletal anatomy remains remarkably conservative, including the maintenance of a crouched limb posture at unusually large sizes. The forelimbs in felids are important for body support and other aspects of locomotion, as well as climbing and prey capture, with the assistance of the vertebral (and hindlimb) muscles. Here, we examine the scaling of the anterior postcranial musculature across felids to assess scaling patterns between different species spanning the range of felid body sizes. The muscle architecture (lengths and masses of the muscle-tendon unit components) for the forelimb, cervical and thoracic muscles was quantified to analyse how the muscles scale with body mass. Our results demonstrate that physiological cross-sectional areas of the forelimb muscles scale positively with increasing body mass (i.e. becoming relatively larger). Many significantly allometric variables pertain to shoulder support, whereas the rest of the limb muscles become relatively weaker in larger felid species. However, when phylogenetic relationships were corrected for, most of these significant relationships disappeared, leaving no significantly allometric muscle metrics. The majority of cervical and thoracic muscle metrics are not significantly allometric, despite there being many allometric skeletal elements in these regions. When forelimb muscle data were considered in isolation or in combination with those of the vertebral muscles in principal components analyses and MANOVAs, there was no significant discrimination among species by either size or locomotory mode. Our results support the inference that larger felid species have relatively weaker anterior postcranial musculature compared with smaller species, due to an absence of significant positive allometry of forelimb or vertebral muscle architecture. This difference in strength is consistent with behavioural changes in larger felids, such as a reduction of maximal speed and other aspects of locomotor abilities. © 2016 Anatomical Society.

Unusual Ratio between Free Thyroxine and Free Triiodothyronine in a Long-Lived Mole-Rat Species with Bimodal Ageing

PubMed Central

Henning, Yoshiyuki; Vole, Christiane; Begall, Sabine; Bens, Martin; Broecker-Preuss, Martina; Sahm, Arne; Szafranski, Karol; Burda, Hynek; Dammann, Philip

2014-01-01

Ansell's mole-rats (Fukomys anselli) are subterranean, long-lived rodents, which live in eusocial families, where the maximum lifespan of breeders is twice as long as that of non-breeders. Their metabolic rate is significantly lower than expected based on allometry, and their retinae show a high density of S-cone opsins. Both features may indicate naturally low thyroid hormone levels. In the present study, we sequenced several major components of the thyroid hormone pathways and analyzed free and total thyroxine and triiodothyronine in serum samples of breeding and non-breeding F. anselli to examine whether a) their thyroid hormone system shows any peculiarities on the genetic level, b) these animals have lower hormone levels compared to euthyroid rodents (rats and guinea pigs), and c) reproductive status, lifespan and free hormone levels are correlated. Genetic analyses confirmed that Ansell's mole-rats have a conserved thyroid hormone system as known from other mammalian species. Interspecific comparisons revealed that free thyroxine levels of F. anselli were about ten times lower than of guinea pigs and rats, whereas the free triiodothyronine levels, the main biologically active form, did not differ significantly amongst species. The resulting fT4:fT3 ratio is unusual for a mammal and potentially represents a case of natural hypothyroxinemia. Comparisons with total thyroxine levels suggest that mole-rats seem to possess two distinct mechanisms that work hand in hand to downregulate fT4 levels reliably. We could not find any correlation between free hormone levels and reproductive status, gender or weight. Free thyroxine may slightly increase with age, based on sub-significant evidence. Hence, thyroid hormones do not seem to explain the different ageing rates of breeders and non-breeders. Further research is required to investigate the regulatory mechanisms responsible for the unusual proportion of free thyroxine and free triiodothyronine. PMID:25409169

Growth of the eye lens: II. Allometric studies

PubMed Central

2014-01-01

Purpose The purpose of this study was to examine the ontogeny and phylogeny of lens growth in a variety of species using allometry. Methods Data on the accumulation of wet and/or dry lens weight as a function of bodyweight were obtained for 40 species and subjected to allometric analysis to examine ontogenic growth and compaction. Allometric analysis was also used to compare the maximum adult lens weights for 147 species with the maximum adult bodyweight and to compare lens volumes calculated from wet and dry weights with eye volumes calculated from axial length. Results Linear allometric relationships were obtained for the comparison of ontogenic lens and bodyweight accumulation. The body mass exponent (BME) decreased with increasing animal size from around 1.0 in small rodents to 0.4 in large ungulates for both wet and dry weights. Compaction constants for the ontogenic growth ranged from 1.00 in birds and reptiles up to 1.30 in mammals. Allometric comparison of maximum lens wet and dry weights with maximum bodyweights also yielded linear plots with a BME of 0.504 for all warm blooded species except primates which had a BME of 0.25. When lens volumes were compared with eye volumes, all species yielded a scaling constant of 0.75 but the proportionality constants for primates and birds were lower. Conclusions Ontogenic lens growth is fastest, relative to body growth, in small animals and slowest in large animals. Fiber cell compaction takes place throughout life in most species, but not in birds and reptiles. Maximum adult lens size scales with eye size with the same exponent in all species, but birds and primates have smaller lenses relative to eye size than other species. Optical properties of the lens are generated through the combination of variations in the rate of growth, rate of compaction, shape and size. PMID:24715759

Climate and Edaphic Controls on Humid Tropical Forest Tree Height

NASA Astrophysics Data System (ADS)

Yang, Y.; Saatchi, S. S.; Xu, L.

2014-12-01

Uncertainty in the magnitude and spatial variations of forest carbon density in tropical regions is due to under sampling of forest structure from inventory plots and the lack of regional allometry to estimate the carbon density from structure. Here we quantify the variation of tropical forest structure by using more than 2.5 million measurements of canopy height from systematic sampling of Geoscience Laser Altimeter System (GLAS) satellite observations between 2004 to 2008 and examine the climate and edaphic variables influencing the variations. We used top canopy height of GLAS footprints (~ 0.25 ha) to grid the statistical mean and 90 percentile of samples at 0.5 degrees to capture the regional variability of large trees in tropics. GLAS heights were also aggregated based on a stratification of tropical regions using soil, elevation, and forest types. Both approaches provided consistent patterns of statistically dominant large trees and the least heterogeneity, both as strong drivers of distribution of high biomass forests. Statistical models accounting for spatial autocorrelation suggest that climate, soil and spatial features together can explain more than 60% of the variations in observed tree height information, while climate-only variables explains about one third of the first-order changes in tree height. Soil basics, including physical compositions such as clay and sand contents, chemical properties such as PH values and cation-exchange capacity, as well as biological variables such as organic matters, all present independent but statistically significant relationships to tree height variations. The results confirm other landscape and regional studies that soil fertility, geology and climate may jointly control a majority of the regional variations of forest structure in pan-tropics and influencing both biomass stocks and dynamics. Consequently, other factors such as biotic and disturbance regimes, not included in this study, may have less influence on regional variations but strongly mediate landscape and small-scale forest structure and dynamics.

An allometric approach to quantify the extinction vulnerability of birds and mammals.

PubMed

Hilbers, J P; Schipper, A M; Hendriks, A J; Verones, F; Pereira, H M; Huijbregts, M A J

2016-03-01

Methods to quantify the vulnerability of species to extinction are typically limited by the availability of species-specific input data pertaining to life-history characteristics and population dynamics. This lack of data hampers global biodiversity assessments and conservation planning. Here, we developed a new framework that systematically quantifies extinction risk based on allometric relationships between various wildlife demographic parameters and body size. These allometric relationships have a solid theoretical and ecological foundation. Extinction risk indicators included are (1) the probability of extinction, (2) the mean time to extinction, and (3) the critical patch size. We applied our framework to assess the global extinction vulnerability of terrestrial carnivorous and non-carnivorous birds and mammals. Irrespective of the indicator used, large-bodied species were found to be more vulnerable to extinction than their smaller counterparts. The patterns with body size were confirmed for all species groups by a comparison with IUCN data on the proportion of extant threatened species: the models correctly predicted a multimodal distribution with body size for carnivorous birds and a monotonic distribution for mammals and non-carnivorous birds. Carnivorous mammals were found to have higher extinction risks than non-carnivores, while birds were more prone to extinction than mammals. These results are explained by the allometric relationships, predicting the vulnerable species groups to have lower intrinsic population growth rates, smaller population sizes, lower carrying capacities, or larger dispersal distances, which, in turn, increase the importance of losses due to environmental stochastic effects and dispersal activities. Our study is the first to integrate population viability analysis and allometry into a novel, process-based framework that is able to quantify extinction risk of a large number of species without requiring data-intensive, species-specific information. The framework facilitates the estimation of extinction vulnerabilities of data-deficient species. It may be applied to forecast extinction vulnerability in response to a changing environment, by incorporating quantitative relationships between wildlife demographic parameters and environmental drivers like habitat alteration, climate change, or hunting.

Can Foraging Ecology Drive the Evolution of Body Size in a Diving Endotherm?

PubMed Central

Cook, Timothée R.; Lescroël, Amélie; Cherel, Yves; Kato, Akiko; Bost, Charles-André

2013-01-01

Within a single animal species, different morphs can allow for differential exploitation of foraging niches between populations, while sexual size dimorphism can provide each sex with access to different resources. Despite being potentially important agents of evolution, resource polymorphisms, and the way they operate in wild populations, remain poorly understood. In this study, we examine how trophic factors can select for different body sizes between populations and sexes in a diving endotherm. Dive depth and duration are positively related to body size in diving birds and mammals, a relationship explained by a lower mass-specific metabolic rate and greater oxygen stores in larger individuals. Based on this allometry, we predict that selection for exploiting resources situated at different depths can drive the evolution of body size in species of diving endotherms at the population and sexual level. To test this prediction, we studied the foraging ecology of Blue-eyed Shags, a group of cormorants with male-biased sexual size dimorphism from across the Southern Ocean. We found that mean body mass and relative difference in body mass between sexes varied by up to 77% and 107% between neighbouring colonies, respectively. Birds from colonies with larger individuals dived deeper than birds from colonies with smaller individuals, when accounting for sex. In parallel, males dived further offshore and deeper than females and the sexual difference in dive depth reflected the level of sexual size dimorphism at each colony. We argue that body size in this group of birds is under intense selection for diving to depths of profitable benthic prey patches and that, locally, sexual niche divergence selection can exaggerate the sexual size dimorphism of Blue-eyed Shags initially set up by sexual selection. Our findings suggest that trophic resources can select for important geographic micro-variability in body size between populations and sexes. PMID:23409169

Formal comment on: Myhrvold (2016) Dinosaur metabolism and the allometry of maximum growth rate. PLoS ONE; 11(11): e0163205.

PubMed

Griebeler, Eva Maria; Werner, Jan

2018-01-01

In his 2016 paper, Myhrvold criticized ours from 2014 on maximum growth rates (Gmax, maximum gain in body mass observed within a time unit throughout an individual's ontogeny) and thermoregulation strategies (ectothermy, endothermy) of 17 dinosaurs. In our paper, we showed that Gmax values of similar-sized extant ectothermic and endothermic vertebrates overlap. This strongly questions a correct assignment of a thermoregulation strategy to a dinosaur only based on its Gmax and (adult) body mass (M). Contrary, Gmax separated similar-sized extant reptiles and birds (Sauropsida) and Gmax values of our studied dinosaurs were similar to those seen in extant similar-sized (if necessary scaled-up) fast growing ectothermic reptiles. Myhrvold examined two hypotheses (H1 and H2) regarding our study. However, we did neither infer dinosaurian thermoregulation strategies from group-wide averages (H1) nor were our results based on that Gmax and metabolic rate (MR) are related (H2). In order to assess whether single dinosaurian Gmax values fit to those of extant endotherms (birds) or of ectotherms (reptiles), we already used a method suggested by Myhrvold to avoid H1, and we only discussed pros and cons of a relation between Gmax and MR and did not apply it (H2). We appreciate Myhrvold's efforts in eliminating the correlation between Gmax and M in order to statistically improve vertebrate scaling regressions on maximum gain in body mass. However, we show here that his mass-specific maximum growth rate (kC) replacing Gmax (= MkC) does not model the expected higher mass gain in larger than in smaller species for any set of species. We also comment on, why we considered extant reptiles and birds as reference models for extinct dinosaurs and why we used phylogenetically-informed regression analysis throughout our study. Finally, we question several arguments given in Myhrvold in order to support his results.

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure

PubMed Central

Miquelajauregui, Yosune; Cumming, Steven G.; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity. PMID:26919456

The 'temporal effect' in hominids: Reinvestigating the nature of support for a chimp-human clade in bone morphology.

PubMed

Pearson, Alannah; Groves, Colin; Cardini, Andrea

2015-11-01

In 2004, an analysis by Lockwood and colleagues of hard-tissue morphology, using geometric morphometrics on the temporal bone, succeeded in recovering the correct phylogeny of living hominids without resorting to potentially problematic methods for transforming continuous shape variables into meristic characters. That work has increased hope that by using modern analytical methods and phylogenetically informative anatomical data we might one day be able to accurately infer the relationships of hominins, including the closest extinct relatives of modern humans. In the present study, using 3D virtually generated models of the hominid temporal bone and a larger suite of geometric morphometric and comparative techniques, we have re-examined the evidence for a Pan-Homo clade. Despite differences in samples, as well as the type of raw data, the effect of measurement error (and especially landmark digitization by a different operator), but also a broader perspective brought in by our diverse set of approaches, our reanalysis largely supports Lockwood and colleagues' original results. However, by focusing not only mainly on shape (as in the original 2004 analysis) but also on size and 'size-corrected' (non-allometric) shape, we demonstrate that the strong phylogenetic signal in the temporal bone is largely related to similarities in size. Thus, with this study, we are not suggesting the use of a single 'character', such as size, for phylogenetic inference, but we do challenge the common view that shape, with its highly complex and multivariate nature, is necessarily more phylogenetically informative than size and that actually size and size-related shape variation (i.e., allometry) confound phylogenetic inference based on morphology. This perspective may in fact be less generalizable than often believed. Thus, while we confirm the original findings by Lockwood et al., we provide a deep reinterpretation of their nature and potential implications for hominid phylogenetics and we show how crucial it is not to overlook size in geometric morphometric analyses. Copyright © 2015 Elsevier Ltd. All rights reserved.

Canopy structural complexity as a continental predictor of primary production: Using NEON to transform understanding of forest structure-function

NASA Astrophysics Data System (ADS)

Atkins, J. W.; Fahey, R. T.; Gough, C. M.; Hardiman, B. S.

2016-12-01

Ecosystem structure-function relationships represent a long-standing research area for ecosystem science. Relationships between canopy structural complexity (CSC) and net primary productivity (NPP), have been characterized for a limited number of sites, yet whether these relationships are conserved across eco-climatic boundaries remains unknown. We hypothesize an underlying mechanistic basis for global NPP-CSC linkages to include improved resource-use efficiency as CSC increases, examined here by correlating CSC with measures of light-use efficiency and nitrogen-use efficiency. Here we present a broad, continental scale analysis of CSC-NPP linkages. We are using multiple NEON sites coupled with other sites across a diverse array of temperate forest types spanning six eco-climatic domains of the continental United States to examine CSC-NPP relationships. Portable canopy LiDAR (PCL) data were used to calculate a suite of CSC metrics at the plot-level within each site. Ongoing work compares CSC to co-located measurements of wood net primary production estimated from the incremental change in woody biomass calculated using tree allometries. Results to date show CSC is highly variable across forest sites and may provide additional explanatory power for predicting NPP that is independent of other commonly used forest structural attributes such as leaf area index. CSC metrics such as rugosity vary widely across sites—ranging from high values (30 - 35) in complex canopies such as the Great Smoky Mountains to low values in open, savanna systems like North-Central Florida (< 0.5 - 2). NPP, and light- and nitrogen-use calculations are underway and will be paired with site-level CSC, with the expectation that CSC, resource-use efficiency, and NPP are positively correlated. Advancing understanding of how and why CSC affects forest NPP across a broad spatial dimension could transform mechanistic understanding of ecosystem structure-carbon cycling relationships, and greatly improve carbon cycling models and remote sensing applications, while providing a crucial linkage between the two.

Phylogenetic and functional implications of the ear region anatomy of Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina.

PubMed

Boscaini, Alberto; Iurino, Dawid A; Billet, Guillaume; Hautier, Lionel; Sardella, Raffaele; Tirao, German; Gaudin, Timothy J; Pujos, François

2018-03-27

Several detailed studies of the external morphology of the ear region in extinct sloths have been published in the past few decades, and this anatomical region has proved extremely helpful in elucidating the phylogenetic relationships among the members of this mammalian clade. Few studies of the inner ear anatomy in these peculiar animals were conducted historically, but these are increasing in number in recent years, in both the extinct and extant representatives, due to wider access to CT-scanning facilities, which allow non-destructive access to internal morphologies. In the present study, we analyze the extinct ground sloth Glossotherium robustum and provide a description of the external features of the ear region and the endocranial side of the petrosal bone, coupled with the first data on the anatomy of the bony labyrinth. Some features observable in the ear region of G. robustum (e.g., the shape and size of the entotympanic bone and the morphology of the posteromedial surface of the petrosal) are highly variable, both intraspecifically and intraindividually. The form of the bony labyrinth of G. robustum is also described, providing the first data from this anatomical region for the family Mylodontidae. The anatomy of the bony labyrinth of the genus Glossotherium is here compared at the level of the superorder Xenarthra, including all available extant and extinct representatives, using geometric morphometric methods. In light of the new data, we discuss the evolution of inner ear anatomy in the xenarthran clade, and most particularly in sloths, considering the influence of phylogeny, allometry, and physiology on the shape of this highly informative region of the skull. These analyses show that the inner ear of Glossotherium more closely resembles that of the extant anteaters, and to a lesser extent those of the giant ground sloth Megatherium and euphractine armadillos, than those of the extant sloths Bradypus and Choloepus, further demonstrating the striking morphological convergence between the two extant sloth genera.

A new approach for the analysis of facial growth and age estimation: Iris ratio

PubMed Central

Machado, Carlos Eduardo Palhares; Flores, Marta Regina Pinheiro; Lima, Laíse Nascimento Correia; Tinoco, Rachel Lima Ribeiro; Bezerra, Ana Cristina Barreto; Evison, Martin Paul; Guimarães, Marco Aurélio

2017-01-01

The study of facial growth is explored in many fields of science, including anatomy, genetics, and forensics. In the field of forensics, it acts as a valuable tool for combating child pornography. The present research proposes a new method, based on relative measurements and fixed references of the human face—specifically considering measurements of the diameter of the iris (iris ratio)—for the analysis of facial growth in association with age in children and sub-adults. The experimental sample consisted of digital photographs of 1000 Brazilian subjects, aged between 6 and 22 years, distributed equally by sex and divided into five specific age groups (6, 10, 14, 18, and 22 year olds ± one month). The software package SAFF-2D® (Forensic Facial Analysis System, Brazilian Federal Police, Brazil) was used for positioning 11 landmarks on the images. Ten measurements were calculated and used as fixed references to evaluate the growth of the other measurements for each age group, as well the accumulated growth (6–22 years old). The Intraclass Correlation Coefficient (ICC) was applied for the evaluation of intra-examiner and inter-examiner reliability within a specific set of images. Pearson’s Correlation Coefficient was used to assess the association between each measurement taken and the respective age groups. ANOVA and Post-hoc Tukey tests were used to search for statistical differences between the age groups. The outcomes indicated that facial structures grow with different timing in children and adolescents. Moreover, the growth allometry expressed in this study may be used to understand what structures have more or less proportional variation in function for the age ranges studied. The diameter of the iris was found to be the most stable measurement compared to the others and represented the best cephalometric measurement as a fixed reference for facial growth ratios (or indices). The method described shows promising potential for forensic applications, especially as part of the armamentarium against crimes involving child pornography and child abuse. PMID:28686631

[Effects of selective cutting on the carbon density and net primary productivity of a mixed broadleaved-Korean pine forest in Northeast China].

PubMed

Liu, Qi; Cai, Hui-Ying; Jin, Guang-Ze

2013-10-01

To accurately quantify forest carbon density and net primary productivity (NPP) is of great significance in estimating the role of forest ecosystems in global carbon cycle. By using the forest inventory and allometry approaches, this paper measured the carbon density and NPP of the virgin broadleaved-Korean pine (Pinus koraiensis) forest and of the broadleaved-Korean pine forest after 34 years selective-cutting (the cutting intensity was 30%, and the cutting trees were in large diameter class). The total carbon density of the virgin and selective-cutting broadleaved-Korean pine forests was (397.95 +/- 93.82) and (355.61 +/- 59.37) t C x hm(-2), respectively. In the virgin forest, the carbon density of the vegetation, debris, and soil accounted for 31.0%, 3.1%, and 65.9% of the total carbon pool, respectively; in the selective-cutting forest, the corresponding values were 31.7%, 2.9%, and 65.4%, respectively. No significant differences were observed in the total carbon density and the carbon density of each component between the two forests. The total NPP of the virgin and selective-cutting forests was (36.27 +/- 0.36) and (6.35 +/- 0.70) t C x hm(-2) x a(-1), among which, the NPP of overstory, understory, and fine roots in virgin forest and selective-cutting forest accounted for 60.3%, 2.0%, and 37.7%, and 66.1%, 2.0%, and 31.2%, respectively. No significant differences were observed in the total NPP and the contribution rate of each component between the two forests. However, the ratios of the needle and broadleaf NPPs of the virgin and selective-cutting forests were 47.24:52.76 and 20.48:79.52, respectively, with a significant difference. The results indicated that the carbon density and NPP of the broadleaved-Korean pine forest after 34 years selective-cutting recovered to the levels of the virgin broadleaved-Korean pine forest.

Growth but Not Photosynthesis Response of a Host Plant to Infection by a Holoparasitic Plant Depends on Nitrogen Supply

PubMed Central

Shen, Hao; Xu, Shu-Jun; Hong, Lan; Wang, Zhang-Ming; Ye, Wan-Hui

2013-01-01

Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources transferred to the parasite at low than at high nitrate levels. PMID:24116055

Unusual ratio between free thyroxine and free triiodothyronine in a long-lived mole-rat species with bimodal ageing.

PubMed

Henning, Yoshiyuki; Vole, Christiane; Begall, Sabine; Bens, Martin; Broecker-Preuss, Martina; Sahm, Arne; Szafranski, Karol; Burda, Hynek; Dammann, Philip

2014-01-01

Ansell's mole-rats (Fukomys anselli) are subterranean, long-lived rodents, which live in eusocial families, where the maximum lifespan of breeders is twice as long as that of non-breeders. Their metabolic rate is significantly lower than expected based on allometry, and their retinae show a high density of S-cone opsins. Both features may indicate naturally low thyroid hormone levels. In the present study, we sequenced several major components of the thyroid hormone pathways and analyzed free and total thyroxine and triiodothyronine in serum samples of breeding and non-breeding F. anselli to examine whether a) their thyroid hormone system shows any peculiarities on the genetic level, b) these animals have lower hormone levels compared to euthyroid rodents (rats and guinea pigs), and c) reproductive status, lifespan and free hormone levels are correlated. Genetic analyses confirmed that Ansell's mole-rats have a conserved thyroid hormone system as known from other mammalian species. Interspecific comparisons revealed that free thyroxine levels of F. anselli were about ten times lower than of guinea pigs and rats, whereas the free triiodothyronine levels, the main biologically active form, did not differ significantly amongst species. The resulting fT4:fT3 ratio is unusual for a mammal and potentially represents a case of natural hypothyroxinemia. Comparisons with total thyroxine levels suggest that mole-rats seem to possess two distinct mechanisms that work hand in hand to downregulate fT4 levels reliably. We could not find any correlation between free hormone levels and reproductive status, gender or weight. Free thyroxine may slightly increase with age, based on sub-significant evidence. Hence, thyroid hormones do not seem to explain the different ageing rates of breeders and non-breeders. Further research is required to investigate the regulatory mechanisms responsible for the unusual proportion of free thyroxine and free triiodothyronine.

State-dependent behavior alters endocrine–energy relationship: Implications for conservation and management

USGS Publications Warehouse

Jesmer, Brett R.; Goheen, Jacob R.; Monteith, Kevin L.; Kauffman, Matthew J.

2017-01-01

Glucocorticoids (GC) and triiodothyronine (T3) are two endocrine markers commonly used to quantify resource limitation, yet the relationships between these markers and the energetic state of animals has been studied primarily in small-bodied species in captivity. Free-ranging animals, however, adjust energy intake in accordance with their energy reserves, a behavior known as state-dependent foraging. Further, links between life-history strategies and metabolic allometries cause energy intake and energy reserves to be more strongly coupled in small animals relative to large animals. Because GC and T3 may reflect energy intake or energy reserves, state-dependent foraging and body size may cause endocrine–energy relationships to vary among taxa and environments. To extend the utility of endocrine markers to large-bodied, free-ranging animals, we evaluated how state-dependent foraging, energy reserves, and energy intake influenced fecal GC and fecal T3 concentrations in free-ranging moose (Alces alces). Compared with individuals possessing abundant energy reserves, individuals with few energy reserves had higher energy intake and high fecal T3 concentrations, thereby supporting state-dependent foraging. Although fecal GC did not vary strongly with energy reserves, individuals with higher fecal GC tended to have fewer energy reserves and substantially greater energy intake than those with low fecal GC. Consequently, individuals with greater energy intake had both high fecal T3 and high fecal GC concentrations, a pattern inconsistent with previous documentation from captive animal studies. We posit that a positive relationship between GC and T3 may be expected in animals exhibiting state-dependent foraging if GC is associated with increased foraging and energy intake. Thus, we recommend that additional investigations of GC– and T3–energy relationships be conducted in free-ranging animals across a diversity of body size and life-history strategies before these endocrine markers are applied broadly to wildlife conservation and management.

Evolutionary morphology in shape and size of haptoral anchors in 14 Ligophorus spp. (Monogenea: Dactylogyridae)

PubMed Central

Rodríguez-González, Abril; Sarabeev, Volodimir; Balbuena, Juan Antonio

2017-01-01

The search for phylogenetic signal in morphological traits using geometric morphometrics represents a powerful approach to estimate the relative weights of convergence and shared evolutionary history in shaping organismal form. We assessed phylogenetic signal in the form of ventral and dorsal haptoral anchors of 14 species of Ligophorus occurring on grey mullets (Osteichthyes: Mugilidae) from the Mediterranean, the Black Sea and the Sea of Azov. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors and two different tests were applied to establish whether the spatial positions in the morphospace were dictated by chance. Overall significant phylogenetic signal was found in the data. Allometric effects on anchor shape were moderate or non-significant in the case of evolutionary allometry. Relatively phylogenetically distant species occurring on the same host differed markedly in anchor morphology indicating little influence of host species on anchor form. Our results suggest that common descent and shared evolutionary history play a major role in determining the shape and, to a lesser degree in the size of haptoral anchors in Ligophorus spp. The present approach allowed tracing paths of morphological evolution in anchor shape. Species with narrow anchors and long shafts were associated predominately with Liza saliens. This morphology was considered to be ancestral relative to anchors of species occurring on Liza haematocheila and M. cephalus possessing shorter shafts and longer roots. Evidence for phylogenetic signal was more compelling for the ventral anchors, than for the dorsal ones, which could reflect different functional roles in attachment to the gills. Although phylogeny and homoplasy may act differently in other monogeneans, the present study delivers a common framework to address effectively the relationships among morphology, phylogeny and other traits, such as host specificity or niche occupancy. PMID:28542570

A new approach for the analysis of facial growth and age estimation: Iris ratio.

PubMed

Machado, Carlos Eduardo Palhares; Flores, Marta Regina Pinheiro; Lima, Laíse Nascimento Correia; Tinoco, Rachel Lima Ribeiro; Franco, Ademir; Bezerra, Ana Cristina Barreto; Evison, Martin Paul; Guimarães, Marco Aurélio

2017-01-01

The study of facial growth is explored in many fields of science, including anatomy, genetics, and forensics. In the field of forensics, it acts as a valuable tool for combating child pornography. The present research proposes a new method, based on relative measurements and fixed references of the human face-specifically considering measurements of the diameter of the iris (iris ratio)-for the analysis of facial growth in association with age in children and sub-adults. The experimental sample consisted of digital photographs of 1000 Brazilian subjects, aged between 6 and 22 years, distributed equally by sex and divided into five specific age groups (6, 10, 14, 18, and 22 year olds ± one month). The software package SAFF-2D® (Forensic Facial Analysis System, Brazilian Federal Police, Brazil) was used for positioning 11 landmarks on the images. Ten measurements were calculated and used as fixed references to evaluate the growth of the other measurements for each age group, as well the accumulated growth (6-22 years old). The Intraclass Correlation Coefficient (ICC) was applied for the evaluation of intra-examiner and inter-examiner reliability within a specific set of images. Pearson's Correlation Coefficient was used to assess the association between each measurement taken and the respective age groups. ANOVA and Post-hoc Tukey tests were used to search for statistical differences between the age groups. The outcomes indicated that facial structures grow with different timing in children and adolescents. Moreover, the growth allometry expressed in this study may be used to understand what structures have more or less proportional variation in function for the age ranges studied. The diameter of the iris was found to be the most stable measurement compared to the others and represented the best cephalometric measurement as a fixed reference for facial growth ratios (or indices). The method described shows promising potential for forensic applications, especially as part of the armamentarium against crimes involving child pornography and child abuse.

Are tree ontogenetic structure and allometric relationship independent of vegetation formation type? A case study with Cordia oncocalyx in the Brazilian caatinga

NASA Astrophysics Data System (ADS)

Silveira, Andréa P.; Martins, Fernando R.; Araújo, Francisca S.

2012-08-01

In temperate and tropical rainforests, ontogenetic structure and allometry during tree ontogeny are often associated with light gradients. Light is not considered a limiting resource in deciduous thorny woodland (DTW), but establishment and growth occur during a short rainy period, when the canopy is fully leaved and light in the understory may be modified. Our aim was to investigate whether the light gradient in DTW and the biomechanical limitations of tree growth would be enough to produce an ontogenetic structure and allometric growth similar to rainforest canopy trees. We investigated the ontogenetic stages and diameter-height relationship of Cordia oncocalyx (Boraginaceae), a dominant canopy tree of the DTW of semiarid northeastern Brazil. We tagged, measured and classified the ontogenetic stages of 2.895 individuals in a 1 ha area (5°6'58.1″S and 40°52'19.4″W). In the rainy season only 4.7% of the light falling on the canopy reached the ground. Initial ontogenetic stages, mainly infant (50.9%) and seedling (42.1%), were predominant in the population, with the remaining 7% distributed among juvenile, immature, virginile and reproductive. The ontogenetic structure was similar to that of rainforest tree species, but the population formed both permanent seed and infant banks in response to long dry periods and erratic rainy spells. Like many other Boraginaceae tree species in tropical rainforests, C. oncocalyx has a Prévost architectural model, but allometric growth was quite different from rainforest trees. C. oncocalyx invested slightly more in diameter at first, then in height and finally invested greatly in diameter and attained an asymptotic height. The continued high investment in diameter growth at late stages and the asymptotic height point to low tree density and more frequent xylem embolism as the main drivers of tree allometric shape in DTW. This indicates that tree ontogenetic structure and allometric relationships depend on vegetation formation type.