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Sample records for demonstrate latitudinal shift-related

  1. Morphological disparity opposes latitudinal diversity gradient in lacertid lizards.

    PubMed

    Hipsley, Christy A; Miles, Donald B; Müller, Johannes

    2014-05-01

    While global variation in taxonomic diversity is strongly linked to latitude, the extent to which morphological disparity follows geographical gradients is less well known. We estimated patterns of lineage diversification, morphological disparity and rates of phenotypic evolution in the Old World lizard family Lacertidae, which displays a nearly inverse latitudinal diversity gradient with decreasing species richness towards the tropics. We found that lacertids exhibit relatively constant rates of lineage accumulation over time, although the majority of morphological variation appears to have originated during recent divergence events, resulting in increased partitioning of disparity within subclades. Among subclades, tropical arboreal taxa exhibited the fastest rates of shape change while temperate European taxa were the slowest, resulting in an inverse relationship between latitudinal diversity and rates of phenotypic evolution. This pattern demonstrates a compelling counterexample to the ecological opportunity theory of diversification, suggesting an uncoupling of the processes generating species diversity and morphological differentiation across spatial scales. PMID:24806424

  2. Temporal dynamics within a contemporary latitudinal diversity gradient.

    PubMed

    Fisher, Jonathan A D; Frank, Kenneth T; Petrie, Brian; Leggett, William C; Shackell, Nancy L

    2008-09-01

    Poleward declines in species diversity [latitudinal diversity gradients (LDG)] remain among the oldest and most widespread of macroecological patterns. However, their contemporary dynamics remain largely unexplored even though changing ecological conditions, including global change, may modify LDG and their respective ecosystems. Here, we examine temporal variation within a temperate Northwest Atlantic LDG using 31 years of annual fisheries-independent surveys and explore its dynamics in relation to a dominant climate signal [the wintertime North Atlantic Oscillation (NAO)] that varies interannually and alters the latitudinal gradient of Northwest Atlantic continental shelf bottom water temperatures. We found that the slopes of the annual LDG vary dramatically due to changes in geographic distributions of 100+ species, variations that are concealed within the cumulative, static LDG. These changes are strongly associated with changes in NAO sign and strength. This is the first illustration of temporal dynamics in a contemporary LDG and the first demonstration of the speed at which local environmental variations can alter an LDG. Our findings underscore the need to investigate factors that modify LDG separately from those that contribute to their origins. PMID:18616548

  3. Latitudinal TEC gradients over polar ionosphere using high latitude GPS measurements

    NASA Astrophysics Data System (ADS)

    Shagimuratov, Irk; Cherniak, Iurii; Zakharenkova, Irina; Tepenitsyna, Nadezhda; Yakimova, Galina; Ephishov, I. I.

    The GPS observations of Greenland network were used to analyze the latitudinal variations of TEC at the high-latitudes ionosphere. This network provides unique opportunity to monitor TEC variability in polar ionosphere on a regular base. GPS stations are arranged along the latitude over the range 60-83°N (65°-87° Corrected Geomagnetic Latitude) near of 30°-40° longitudes. More than 20 GPS stations are located closely with one another along latitude. The distance between stations is about 1°-2°.Such spatial resolution provides the possibility to analyze the detailed structure of latitudinal TEC profiles. The standard procedure of processing GPS observations was used for TEC estimation. On this base it was obtained the diurnal TEC variations over all Greenland stations. The TEC data is used to form latitudinal profiles (TEC section) covered subauroral, auroral and polar ionosphere. In the report the observations of TEC for quiet and disturbed ionosphere during several geomagnetic storms occurred in September 2011 are presented. During quiet conditions in the night-time TEC profiles demonstrated invariable values about of 4-6 TECU in latitudinal region of 60°-75°N; then it presented THE increase towards the higher latitude and reached the value of 10 TECU near 80°N. The daytime profiles revealed TEC decrease toward high latitude in keeping with 0.8 TECU/degree. During storm the structure of latitudinal TEC profiles was essentially changed with agreement to the development of geomagnetic storm. The positive effect was observed at subauroral and auroral latitudes, negative effect was prevailed at the polar region. During the night time the ionospheric trough can be observed. In the report features of the behavior of latitudinal profiles at high-latitude ionosphere for September 2011 events were discussed.

  4. The Effect of Latitudinal Variation on Shrimp Reproductive Strategies.

    PubMed

    van de Kerk, Madelon; Jones Littles, Chanda; Saucedo, Omar; Lorenzen, Kai

    2016-01-01

    Reproductive strategies comprise the timing and frequency of reproductive events and the number of offspring per reproductive event, depending on factors such as climate conditions. Therefore, species that exhibit plasticity in the allocation of reproductive effort can alter their behavior in response to climate change. Studying how the reproductive strategy of species varies along the latitudinal gradient can help us understand and predict how they will respond to climate change. We investigated the effects of the temporal allocation of reproductive effort on the population size of brown shrimp (Farfantepenaeus aztecus) along a latitudinal gradient. Multiple shrimp species exhibit variation in their reproductive strategies, and given the economic importance of brown shrimp to the commercial fishing sector of the Unites States, changes in the timing of their reproduction could have significant economic and social consequences. We used a stage-based, density-dependent matrix population model tailored to the life history of brown shrimp. Shrimp growth rates and environmental carrying capacity were varied based on the seasonal climate conditions at different latitudes, and we estimated the population size at equilibrium. The length of the growing season increased with decreasing latitude and the reproductive strategy leading to the highest population size changed from one annual birth pulse with high reproductive output to continuous low-output reproduction. Hence, our model confirms the classical paradigm of continuous reproduction at low latitudes, with increased seasonality of the breeding period towards the poles. Our results also demonstrate the potential for variation in climate to affect the optimal reproductive strategy for achieving maximum population sizes. Certainly, understanding these dynamics may inform more comprehensive management strategies for commercially important species like brown shrimp.

  5. The Effect of Latitudinal Variation on Shrimp Reproductive Strategies

    PubMed Central

    van de Kerk, Madelon; Jones Littles, Chanda; Saucedo, Omar; Lorenzen, Kai

    2016-01-01

    Reproductive strategies comprise the timing and frequency of reproductive events and the number of offspring per reproductive event, depending on factors such as climate conditions. Therefore, species that exhibit plasticity in the allocation of reproductive effort can alter their behavior in response to climate change. Studying how the reproductive strategy of species varies along the latitudinal gradient can help us understand and predict how they will respond to climate change. We investigated the effects of the temporal allocation of reproductive effort on the population size of brown shrimp (Farfantepenaeus aztecus) along a latitudinal gradient. Multiple shrimp species exhibit variation in their reproductive strategies, and given the economic importance of brown shrimp to the commercial fishing sector of the Unites States, changes in the timing of their reproduction could have significant economic and social consequences. We used a stage-based, density-dependent matrix population model tailored to the life history of brown shrimp. Shrimp growth rates and environmental carrying capacity were varied based on the seasonal climate conditions at different latitudes, and we estimated the population size at equilibrium. The length of the growing season increased with decreasing latitude and the reproductive strategy leading to the highest population size changed from one annual birth pulse with high reproductive output to continuous low-output reproduction. Hence, our model confirms the classical paradigm of continuous reproduction at low latitudes, with increased seasonality of the breeding period towards the poles. Our results also demonstrate the potential for variation in climate to affect the optimal reproductive strategy for achieving maximum population sizes. Certainly, understanding these dynamics may inform more comprehensive management strategies for commercially important species like brown shrimp. PMID:27158895

  6. The latitudinal biodiversity gradient through deep time.

    PubMed

    Mannion, Philip D; Upchurch, Paul; Benson, Roger B J; Goswami, Anjali

    2014-01-01

    Today, biodiversity decreases from equatorial to polar regions. This is a fundamental pattern governing the distribution of extant organisms, the understanding of which is critical to predicting climatically driven biodiversity loss. However, its causes remain unresolved. The fossil record offers a unique perspective on the evolution of this latitudinal biodiversity gradient (LBG), providing a dynamic system in which to explore spatiotemporal diversity fluctuations. Deep-time studies indicate that a tropical peak and poleward decline in species diversity has not been a persistent pattern throughout the Phanerozoic, but is restricted to intervals of the Palaeozoic and the past 30 million years. A tropical peak might characterise cold icehouse climatic regimes, whereas warmer greenhouse regimes display temperate diversity peaks or flattened gradients. PMID:24139126

  7. Latitudinal dependence of solar wind speed

    NASA Technical Reports Server (NTRS)

    Fry, C. D.; Akasofu, S.-I.

    1987-01-01

    The data of King (1979, 1983) and of Hoeksema et al. (1982, 1983) are used to investigate the solar-cycle evolution of solar wind bulk speed as a function of source magnetic field strength. The effects of solar transient events are removed. The data suggest that the latitudinal gradient in background solar wind speed is steepest at solar minimum and broadest at solar maximum. The lowest and highest background speeds are found to remain fairly constant throughout the solar cycle. A function developed for the background solar wind speed is inserted into the improved kinematic code of Hakamada and Akasofu (1982), and solar wind speed and IMF are simulated for two periods in the solar cycle. The observed parameters for specific coronal hole passage are well reproduced by the analysis.

  8. Latitudinal Variation of Solar Wind Velocity

    NASA Astrophysics Data System (ADS)

    Ananthakrishnan, S.; Balasubramanian, V.; Janardhan, P.

    1995-04-01

    Single station solar wind velocity measurements using the Ooty Radio Telescope (ORT) in India (operating at 327 MHz) are reported for the period August 1992 to August 1993. Interplanetary scintillation (IPS) observations on a large number of compact radio sources covering a latitudinal range of ±80° were used to derive solar wind velocities using the method of fitting a power law model to the observed IPS spectra. The data shows a velocity versus heliographic latitude pattern which is similar to that reported by Rickett and Coles (1991) for the 1981 1982 period. However, the average of the measured equatorial velocities are higher, being about 470 km s-1 compared to their value of 400 km s-1. The distribution of electron density variations (ΔN e ) between 50R⊙ and 90R⊙ was also determined and it was found that ΔN e was about 30% less at the poles as compared to the equator.

  9. Latitudinal distribution of the recent Arctic warming

    SciTech Connect

    Chylek, Petr; Lesins, Glen K; Wang, Muyin

    2010-12-08

    Increasing Arctic temperature, disappearance of Arctic sea ice, melting of the Greenland ice sheet, sea level rise, increasing strength of Atlantic hurricanes are these impending climate catastrophes supported by observations? Are the recent data really unprecedented during the observational records? Our analysis of Arctic temperature records shows that the Arctic and temperatures in the 1930s and 1940s were almost as high as they are today. We argue that the current warming of the Arctic region is affected more by the multi-decadal climate variability than by an increasing concentration of carbon dioxide. Unfortunately, none of the existing coupled Atmosphere-Ocean General Circulation Models used in the IPCC 2007 cIimate change assessment is able to reproduce neither the observed 20th century Arctic cIimate variability nor the latitudinal distribution of the warming.

  10. The latitudinal gradient of the NO peak density

    SciTech Connect

    Fesen, C.G.; Rusch, D.W. ); Gerard, J.C. )

    1990-11-01

    The latitudinal gradients of the maximum nitric oxide densities near 110 km are presented for solstice and equinox periods from 1982 through 1985 as observed by the Solar Mesosphere Explorer satellite. The data indicate that the response of the maximum NO densities to the declining level of solar activity is latitudinally and seasonally dependent: the polar regions exhibit little sensitivity to solar activity, while the low latitude NO responds strongly. The data also reveal marked asymmetries in the latitudinal structure of the two hemispheres for each season. During June solstice periods, the latitudinal distribution is fairly flat, unlike December solstice periods which tend to show a definite minimum near 30{degree}N. Similarly, March data show very little latitudinal variation in the NO peak density between about {plus minus} 40{degree}, while the September data show marked gradients for the later years. The SME data further indicate that the nitric oxide densities vary considerably from day to day, even during very quiet geomagnetic periods, suggesting that the concept of an average distribution is of limited usefulness in understanding nitric oxide. A two-dimensional model is used to simualte the June solar cycle minimum data. The latitudinally averaged magnitudes of the observed NO peak densities are reproduced reasonably well by the model, but the shape of the latitudinal variation is not.

  11. Short Periodicities in Latitudinal Variation of Sunspots

    NASA Astrophysics Data System (ADS)

    Kim, Bang-Yeop; Chang, Heon-Young

    2011-06-01

    The latitudinal variation of sunspots appearing during the period from 1874 to 2009 has been studied in terms of centerof- latitude (COL). The butterfly diagram has been used to study the evolution of the magnetic field and the dynamics at the bottom of the solar convection zone. Short-term periodicities have been of particular interest, in that they are somehow related to the structure and dynamics of the solar interior. We thus have focused our investigation on shortterm periodicities. We first calculated COL by averaging the latitude of sunspots with the weight function in area. Then, we analyzed the time series of COL using the wavelet transform technique. We found that a periodicity of ~5 years is the most dominant feature in the time series of COL, with the exception of the ~11 year solar cycle itself. This periodicity can be easily understood by considering small humps between the minima in the area-weighted butterfly diagram. However, we find that periodicities of ~1.3 (0.064), ~1.5 (0.056), or ~1.8 (0.046) years ( 1/ month ), which have been previously suggested as evidence of links between the changing structure of the sunspot zone and the tachocline rotation rate oscillations, are insignificant and inconsistent. We therefore conclude that the only existing short-term periodicity is of ~5 years, and that periodicities of ~1.3, ~1.5, or ~1.8 years are likely to be artifacts due to random noise of small sunspots.

  12. Extinction as a driver of avian latitudinal diversity gradients.

    PubMed

    Pulido-Santacruz, Paola; Weir, Jason T

    2016-04-01

    The role of historical factors in driving latitudinal diversity gradients is poorly understood. Here, we used an updated global phylogeny of terrestrial birds to test the role of three key historical factors-speciation, extinction, and dispersal rates-in generating latitudinal diversity gradients for eight major clades. We fit a model that allows speciation, extinction, and dispersal rates to differ, both with latitude and between the New and Old World. Our results consistently support extinction (all clades had lowest extinction where species richness was highest) as a key driver of species richness gradients across each of eight major clades. In contrast, speciation and dispersal rates showed no consistent latitudinal patterns across replicate bird clades, and thus are unlikely to represent general underlying drivers of latitudinal diversity gradients. PMID:26940812

  13. Latitudinal Libration in a Triaxial Ellipsoid

    NASA Astrophysics Data System (ADS)

    Cebron, D.; Vantieghem, S.; Noir, J.

    2014-12-01

    As a consequence of gravitational coupling with their orbital partners, the rotational dynamics of planets and moons exhibits periodic variations in time, such as precession, libration and nutation. Moreover, most planets are subject to tidal forces, which in combination with the planet's rotation, result in a departure from a purely spherically symmetric object. In this theoretical-numerical study, we investigate the flows driven by latitudinal libration (i.e. an oscillation of the figure axis with respect to the mean rotation axis) within liquid cores of triaxial ellipsoidal shape. We first derive a uniform-vorticity solution for the equations of motion, and find that it can resonate with the spin-over inertial mode. Using a reduced model of viscosity (J. Noir and D. Cébron, J. Fluid Mech., vol. 737 (2013)), we deduce that the amplitude of the flow at resonance diverges as the inverse square-root of the Ekman number. Our results are consistent with previous studies in a spheroidal geometry (K. Zhang et al., J. Fluid Mech., vol. 696 (2012)). In a following step, we address the dynamical stability of this uniform-vorticity flow. We show that it is prone to inertial instabilities arising from a parametric resonance between two free inertial modes and the base flow. We also show that the vigor of the instability is governed by the frequency and two parameters that capture the dependence on the libration amplitude and geometry. The resonant nature of these phenomena suggests that libration in latitude, despite its small amplitude, may drive strong flows within planetary cores with possibly major implications for heat transport, dissipation and magnetic field generation/induction. This is discussed at planetary settings for the cores of the Moon, Io and Mercury, and the ancient lunar core.

  14. Latitudinal Gradients in Degradation of Marine Dissolved Organic Carbon

    PubMed Central

    Arnosti, Carol; Steen, Andrew D.; Ziervogel, Kai; Ghobrial, Sherif; Jeffrey, Wade H.

    2011-01-01

    Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO2 reservoir, such a change could profoundly affect the global carbon cycle. PMID:22216139

  15. Soil organic nitrogen mineralization across a global latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Jones, D. L.; Kielland, K.; Sinclair, F. L.; Dahlgren, R. A.; Newsham, K. K.; Farrar, J. F.; Murphy, D. V.

    2009-03-01

    Understanding and accurately predicting the fate of carbon and nitrogen in the terrestrial biosphere remains a central goal in ecosystem science. Amino acids represent a key pool of C and N in soil, and their availability to plants and microorganisms has been implicated as a major driver in regulating ecosystem functioning. Because of potential differences in biological diversity and litter quality, it has been thought that soils from different latitudes and plant communities may possess intrinsically different capacities to perform key functions such as the turnover of amino acids. In this study we measured the soil solution concentration and microbial mineralization of amino acids in soils collected from 40 latitudinal points from the Arctic through to Antarctica. Our results showed that soil solution amino acid concentrations were relatively similar between sites and not strongly related to latitude. In addition, when constraints of temperature and moisture were removed, we demonstrate that soils worldwide possess a similar innate capacity to rapidly mineralize amino acids. Similarly, we show that the internal partitioning of amino acid-C into catabolic and anabolic processes is conservative in microbial communities and independent of global position. This supports the view that the conversion of high molecular weight (MW) organic matter to low MW compounds is the rate limiting step in organic matter breakdown in most ecosystems.

  16. Coral reefs. Limited scope for latitudinal extension of reef corals.

    PubMed

    Muir, Paul R; Wallace, Carden C; Done, Terence; Aguirre, J David

    2015-06-01

    An analysis of present-day global depth distributions of reef-building corals and underlying environmental drivers contradicts a commonly held belief that ocean warming will promote tropical coral expansion into temperate latitudes. Using a global data set of a major group of reef corals, we found that corals were confined to shallower depths at higher latitudes (up to 0.6 meters of predicted shallowing per additional degree of latitude). Latitudinal attenuation of the most important driver of this phenomenon-the dose of photosynthetically available radiation over winter-would severely constrain latitudinal coral range extension in response to ocean warming. Latitudinal gradients in species richness for the group also suggest that higher winter irradiance at depth in low latitudes allowed a deep-water fauna that was not viable at higher latitudes. PMID:26045436

  17. Coral reefs. Limited scope for latitudinal extension of reef corals.

    PubMed

    Muir, Paul R; Wallace, Carden C; Done, Terence; Aguirre, J David

    2015-06-01

    An analysis of present-day global depth distributions of reef-building corals and underlying environmental drivers contradicts a commonly held belief that ocean warming will promote tropical coral expansion into temperate latitudes. Using a global data set of a major group of reef corals, we found that corals were confined to shallower depths at higher latitudes (up to 0.6 meters of predicted shallowing per additional degree of latitude). Latitudinal attenuation of the most important driver of this phenomenon-the dose of photosynthetically available radiation over winter-would severely constrain latitudinal coral range extension in response to ocean warming. Latitudinal gradients in species richness for the group also suggest that higher winter irradiance at depth in low latitudes allowed a deep-water fauna that was not viable at higher latitudes.

  18. Latitudinal clines: an evolutionary view on biological rhythms†,‡

    PubMed Central

    Hut, Roelof A.; Paolucci, Silvia; Dor, Roi; Kyriacou, Charalambos P.; Daan, Serge

    2013-01-01

    Properties of the circadian and annual timing systems are expected to vary systematically with latitude on the basis of different annual light and temperature patterns at higher latitudes, creating specific selection pressures. We review literature with respect to latitudinal clines in circadian phenotypes as well as in polymorphisms of circadian clock genes and their possible association with annual timing. The use of latitudinal (and altitudinal) clines in identifying selective forces acting on biological rhythms is discussed, and we evaluate how these studies can reveal novel molecular and physiological components of these rhythms. PMID:23825204

  19. Simulation of Rapoport's rule for latitudinal species spread.

    PubMed

    Stauffer, Dietrich; Rohde, Klaus

    2006-08-01

    Rapoport's rule claims that latitudinal ranges of plant and animal species are generally smaller at low than at high latitudes. However, doubts as to the generality of the rule have been expressed, because studies providing evidence against the rule are more numerous than those in support of it. In groups for which support has been provided, the trend of increasing latitudinal ranges with latitude is restricted to or at least most distinct at high latitudes, suggesting that the effect may be a local phenomenon, for example the result of glaciations. Here we test the rule using two models, a simple one-dimensional one with a fixed number of animals expanding in a northern or southerly direction only, and the evolutionary/ecological Chowdhury model using birth, ageing, death, mutation, speciation, prey-predator relations and food levels. Simulations with both models gave results contradicting Rapoport's rule. In the first, latitudinal ranges were roughly independent of latitude, in the second, latitudinal ranges were greatest at low latitudes, as also shown empirically for some well-studied groups of animals.

  20. Shifting latitudinal clines in avian body size correlate with global warming in Australian passerines.

    PubMed

    Gardner, Janet L; Heinsohn, Robert; Joseph, Leo

    2009-11-01

    Intraspecific latitudinal clines in the body size of terrestrial vertebrates, where members of the same species are larger at higher latitudes, are widely interpreted as evidence for natural selection and adaptation to local climate. These clines are predicted to shift in response to climate change. We used museum specimens to measure changes in the body size of eight passerine bird species from south-eastern Australia over approximately the last 100 years. Four species showed significant decreases in body size (1.8-3.6% of wing length) and a shift in latitudinal cline over that period, and a meta-analysis demonstrated a consistent trend across all eight species. Southern high-latitude populations now display the body sizes typical of more northern populations pre-1950, equivalent to a 7 degrees shift in latitude. Using ptilochronology, we found no evidence that these morphological changes were a plastic response to changes in nutrition, a likely non-genetic mechanism for the pattern observed. Our results demonstrate a generalized response by eight avian species to some major environmental change over the last 100 years or so, probably global warming.

  1. Mid-Paleozoic latitudinal predation gradient: Distribution of brachiopod ornamentation reflects shifting Carboniferous climate

    NASA Astrophysics Data System (ADS)

    Dietl, Gregory P.; Kelley, Patricia H.

    2001-02-01

    Shell ornamentation in modern oceans increases toward the tropics in conjunction with an equatorward increase in shell-breaking predation. Latitudinal gradients in antipredatory ornamentation were previously documented for Devonian brachiopods. We examined the latitudinal distribution of shell ornamentation in Tournaisian, Visean, and Namurian articulate brachiopods to test the hypothesis that the latitudinal gradient in antipredatory ornamentation was present in the Carboniferous. We found a statistically significant latitudinal ornamentation gradient, which was most pronounced in the Tournaisian, when the latitudinal temperature gradient was most steep. These results support the hypothesis that a latitudinal gradient in defensive morphology occurred as a result of the mid-Paleozoic increase in predation. Although the mid-Paleozoic and late Mesozoic intervals of predator-prey escalation may have differed in dynamics and intensity, both episodes produced adaptations in prey morphology that varied along a latitudinal gradient.

  2. Sources of Controversy Surrounding Latitudinal Patterns in Herbivory and Defense.

    PubMed

    Anstett, Daniel N; Nunes, Krystal A; Baskett, Carina; Kotanen, Peter M

    2016-10-01

    Both herbivory and plant defenses against herbivores have been predicted to increase toward tropical regions. Early tests of this latitudinal herbivory-defense hypothesis (LHDH) were supportive, but accumulating evidence has been mixed. We argue that the lack of clarity might be due to heterogeneity in methodology and problems with study design and interpretation. We suggest possible solutions. Latitudinal studies need to carefully consider spatial and phylogenetic scale, to link plant defense measurements to herbivore performance, and to incorporate additional concepts from plant defense theory such as tolerance and induced defense. In addition, we call for consistent measures of herbivory to standardize comparisons across biomes. Improving methodology in future studies of LHDH should resolve much of the current controversy. PMID:27545844

  3. Optimal programmable unambiguous discriminator between two unknown latitudinal states

    NASA Astrophysics Data System (ADS)

    Sunian, XiaoBing; Li, YuWei; Zhou, Tao

    2016-10-01

    Two unknown states can be unambiguously distinguished by a universal programmable discriminator, which has been widely discussed in previous works and the optimal solution has also been obtained. In this paper, we investigate the programmable unambiguous discriminator between two unknown "latitudinal" states, which lie in a subspace of the total state space. By equivalence of unknown pure states to known average mixed states, the optimal solution for this problem is systematically derived, and the analytical success probabilities for the optimal unambiguous discrimination are obtained. It is beyond one's expectation that the optimal setting for the programmable unambiguous discrimination between two unknown "latitudinal" states is the same as that for the universal ones. The results in this work can be used for the realization of the programmable discriminator in laboratory.

  4. Population divergence in plant species reflects latitudinal biodiversity gradients.

    PubMed

    Eo, Soo Hyung; Wares, John P; Carroll, John P

    2008-08-23

    The trend for increasing biodiversity from the poles to the tropics is one of the best-known patterns in nature. This latitudinal biodiversity gradient has primarily been documented so far with extant species as the measure of biodiversity. Here, we evaluate the global pattern in biodiversity across latitudes based on the magnitude of genetic population divergence within plant species, using a robust spatial design to compare published allozyme datasets. Like the pattern of plant species richness across latitudes, we expected the divergence among populations of current plant species would have a similar pattern and direction. We found that lower latitudinal populations showed greater genetic differentiation within species after controlling for geographical distance. Our analyses are consistent with previous population-level studies in animals, suggesting a high possibility of tropical peaks in speciation rates associated with observed levels of species richness.

  5. Sources of Controversy Surrounding Latitudinal Patterns in Herbivory and Defense.

    PubMed

    Anstett, Daniel N; Nunes, Krystal A; Baskett, Carina; Kotanen, Peter M

    2016-10-01

    Both herbivory and plant defenses against herbivores have been predicted to increase toward tropical regions. Early tests of this latitudinal herbivory-defense hypothesis (LHDH) were supportive, but accumulating evidence has been mixed. We argue that the lack of clarity might be due to heterogeneity in methodology and problems with study design and interpretation. We suggest possible solutions. Latitudinal studies need to carefully consider spatial and phylogenetic scale, to link plant defense measurements to herbivore performance, and to incorporate additional concepts from plant defense theory such as tolerance and induced defense. In addition, we call for consistent measures of herbivory to standardize comparisons across biomes. Improving methodology in future studies of LHDH should resolve much of the current controversy.

  6. Radial and latitudinal gradients of anomalous oxygen during 1977 - 1985

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Cummings, A. C.; Stone, E. C.

    1985-01-01

    It is found that the radial gradient of anomalous O remains during 1977 to 1985 at approx. 10% to 15%/AU although the intensity changes by more than a factor of 100. These results can be used to deduce that most of the modulation of the intensities of these particles is occurring beyond 27 AU. Evidence is also found for a latitudinal gradient of approx. +3%/degree at low energies (7.1 to 10.6 MeV/nuc).

  7. Widespread range expansions shape latitudinal variation in insect thermal limits

    NASA Astrophysics Data System (ADS)

    Lancaster, Lesley T.

    2016-06-01

    Current anthropogenic impacts, including habitat modification and climate change, may contribute to a sixth mass extinction. To mitigate these impacts and slow further losses of biodiversity, we need to understand which species are most at risk and identify the factors contributing to current and future declines. Such information is often obtained through large-scale, comparative and biogeographic analysis of lineages or traits that are potentially sensitive to ongoing anthropogenic change--for instance to predict which regions are most susceptible to climate change-induced biodiversity loss. However, for this approach to be generally successful, the underlying causes of identified geographical trends need to be carefully considered. Here, I augment and reanalyse a global data set of insect thermal tolerances, evaluating the contribution of recent and contemporary range expansions to latitudinal variation in thermal niche breadth. Previous indications that high-latitude ectotherms exhibit broad thermal niches and high warming tolerances held only for species undergoing range expansions or invasions. In contrast, species with stable or declining geographic ranges exhibit latitudinally decreasing absolute thermal tolerances and no latitudinal variation in tolerance breadths. Thus, non-range-expanding species, particularly insular or endemic species, which are often of highest conservation priority, are unlikely to tolerate future climatic warming at high latitudes.

  8. Latitudinal variation in population structure of wintering Pacific Black Brant

    USGS Publications Warehouse

    Schamber, J.L.; Sedinger, J.S.; Ward, D.H.; Hagmeier, K.R.

    2007-01-01

    Latitudinal variation in population structure during the winter has been reported in many migratory birds, but has been documented in few species of waterfowl. Variation in environmental and social conditions at wintering sites can potentially influence the population dynamics of differential migrants. We examined latitudinal variation in sex and age classes of wintering Pacific Black Brant (Branta bernicla nigricans). Brant are distributed along a wide latitudinal gradient from Alaska to Mexico during the winter. Accordingly, migration distances for brant using different wintering locations are highly variable and winter settlement patterns are likely associated with a spatially variable food resource. We used resightings of brant banded in southwestern Alaska to examine sex and age ratios of birds wintering at Boundary Bay in British Columbia, and at San Quintin Bay, Ojo de Liebre Lagoon, and San Ignacio Lagoon in Baja California from 1998 to 2000. Sex ratios were similar among wintering locations for adults and were consistent with the mating strategy of geese. The distribution of juveniles varied among wintering areas, with greater proportions of juveniles observed at northern (San Quintin Bay and Ojo de Liebre Lagoon) than at southern (San Ignacio Lagoon) locations in Baja California. We suggest that age-related variation in the winter distribution of Pacific Black Brant is mediated by variation in productivity among individuals at different wintering locations and by social interactions among wintering family groups.

  9. Local adaptation at range edges: comparing elevation and latitudinal gradients.

    PubMed

    Halbritter, A H; Billeter, R; Edwards, P J; Alexander, J M

    2015-10-01

    Local adaptation at range edges influences species' distributions and how they respond to environmental change. However, the factors that affect adaptation, including gene flow and local selection pressures, are likely to vary across different types of range edge. We performed a reciprocal transplant experiment to investigate local adaptation in populations of Plantago lanceolata and P. major from central locations in their European range and from their latitudinal and elevation range edges (in northern Scandinavia and Swiss Alps, respectively). We also characterized patterns of genetic diversity and differentiation in populations using molecular markers. Range-centre plants of P. major were adapted to conditions at the range centre, but performed similarly to range-edge plants when grown at the range edges. There was no evidence for local adaptation when comparing central and edge populations of P. lanceolata. However, plants of both species from high elevation were locally adapted when compared with plants from high latitude, although the reverse was not true. This asymmetry was associated with greater genetic diversity and less genetic differentiation over the elevation gradient than over the latitudinal gradient. Our results suggest that adaptation in some range-edge populations could increase their performance following climate change. However, responses are likely to differ along elevation and latitudinal gradients, with adaptation more likely at high-elevation. Furthermore, based upon these results, we suggest that gene flow is unlikely to constrain adaptation in range-edge populations of these species.

  10. Structure of Benthic Communities along the Taiwan Latitudinal Gradient.

    PubMed

    Ribas-Deulofeu, Lauriane; Denis, Vianney; De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

  11. Structure of Benthic Communities along the Taiwan Latitudinal Gradient

    PubMed Central

    De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

  12. Structure of Benthic Communities along the Taiwan Latitudinal Gradient.

    PubMed

    Ribas-Deulofeu, Lauriane; Denis, Vianney; De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed.

  13. Local adaptation at range edges: comparing elevation and latitudinal gradients.

    PubMed

    Halbritter, A H; Billeter, R; Edwards, P J; Alexander, J M

    2015-10-01

    Local adaptation at range edges influences species' distributions and how they respond to environmental change. However, the factors that affect adaptation, including gene flow and local selection pressures, are likely to vary across different types of range edge. We performed a reciprocal transplant experiment to investigate local adaptation in populations of Plantago lanceolata and P. major from central locations in their European range and from their latitudinal and elevation range edges (in northern Scandinavia and Swiss Alps, respectively). We also characterized patterns of genetic diversity and differentiation in populations using molecular markers. Range-centre plants of P. major were adapted to conditions at the range centre, but performed similarly to range-edge plants when grown at the range edges. There was no evidence for local adaptation when comparing central and edge populations of P. lanceolata. However, plants of both species from high elevation were locally adapted when compared with plants from high latitude, although the reverse was not true. This asymmetry was associated with greater genetic diversity and less genetic differentiation over the elevation gradient than over the latitudinal gradient. Our results suggest that adaptation in some range-edge populations could increase their performance following climate change. However, responses are likely to differ along elevation and latitudinal gradients, with adaptation more likely at high-elevation. Furthermore, based upon these results, we suggest that gene flow is unlikely to constrain adaptation in range-edge populations of these species. PMID:26201435

  14. New sources for the hot oxygen geocorona: Solar cycle, seasonal, latitudinal, and diurnal variations

    SciTech Connect

    Hickey, M.P.; Richards, P.G.; Torr, D.G.

    1995-09-01

    This paper demonstrates the variability of thermospheric sources of hot oxygen atoms. Numerical calculations were performed for day and night, high and low solar activity, summer and winter, and low- and middle-latitude conditions. Under most conditions, reactions involving metastable species are more important hot {Omicron} sources than previously considered dissociative recombination of {Omicron}{sub 2}{sup +} and NO{sup +}. All the hot {Omicron} sources are an order of magnitude lower at midnight than at noon. At night, dissociative recombination of O{sub 2}{sup +} and NO{sup +} are the most important sources. Quenching of vibrationally excited N{sub 2} (N{sub 2}{sup *}) by {Omicron} is the most important metastable source at night. Above 300 km, hot {Omicron} kinetic energy is greater during winter than during summer, indicating a dominance of cooler hot {Omicron} sources during summer. The N{sub 2}{sup *} source dominates at low altitudes. At high altitudes it is almost negligible at solar minimum, but increases to become the dominant source at solar maximum. Atomic oxygen quenching of N({sup 2}D) is a large source at solar minimum and is still important at solar maximum. Overall, seasonal variations are small compared to solar cycle, diurnal and latitudinal variations. While quenching of metastable species if more important at midlatitudes than at low latitudes, there is little latitudinal variation in hot {Omicron} production due to dissociative recombination of NO{sup +} and O{sub 2}{sup +}. 37 refs., 9 figs., 1 tab.

  15. Revisiting Jablonski (1993): cladogenesis and range expansion explain latitudinal variation in taxonomic richness.

    PubMed

    Martin, P R; Bonier, F; Tewksbury, J J

    2007-05-01

    The increase in diversity towards the equator arises from latitudinal variation in rates of cladogenesis, extinction, immigration and/or emigration of taxa. We tested the relative contribution of all four processes to the latitudinal gradient in 26 marine invertebrate orders with extensive fossil records, examined previously by David Jablonski. Coupling Jablonski's estimates of latitudinal variation in cladogenesis with new data on patterns of extinction and current distributions, we show that the present-day gradient in diversity is caused by higher rates of cladogenesis and subsequent range expansion (immigration) at lower latitudes. In contrast, extinction and emigration were not important in the creation of the latitudinal gradient in ordinal richness. This work represents one of the first simultaneous tests of the role of all four processes in the creation of the latitudinal gradient in taxonomic richness, and suggests that low tropical extinction rates are not essential to the creation of latitudinal diversity gradients.

  16. Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes.

    PubMed

    Pennings, Steven C; Ho, Chuan-Kai; Salgado, Cristiano S; Wieski, Kazimierz; Davé, Nilam; Kunza, Amy E; Wason, Elizabeth L

    2009-01-01

    Despite long-standing interest in latitudinal variation in ecological patterns and processes, there is to date weak and conflicting evidence that herbivore pressure varies with latitude. We used three approaches to examine latitudinal variation in herbivore pressure in Atlantic Coast salt marshes, focusing on five abundant plant taxa: the grass Spartina alterniflora, the congeneric rushes Juncus gerardii and J. roemerianus, the forb Solidago sempervirens, and the shrubs Iva frutescens and Baccharis halimifolia. Herbivore counts indicated that chewing and gall-making herbivores were typically > or = 10 times more abundant at low-latitude sites than at high-latitude sites, but sucking herbivores did not show a clear pattern. For two herbivore taxa (snails and tettigoniid grasshoppers), correctly interpreting latitudinal patterns required an understanding of the feeding ecology of the species, because the species common at high latitudes did not feed heavily on plant leaves whereas the related species common at low latitudes did. Damage to plants from chewing herbivores was 2-10 times greater at low-latitude sites than at high-latitude sites. Damage to transplanted "phytometer" plants was 100 times greater for plants transplanted to low- than to high-latitude sites, and two to three times greater for plants originating from high- vs. low-latitude sites. Taken together, these results provide compelling evidence that pressure from chewing and gall-making herbivores is greater at low vs. high latitudes in Atlantic Coast salt marshes. Sucking herbivores do not show this pattern and deserve greater study. Selective pressure due to greater herbivore damage at low latitudes is likely to partially explain documented patterns of low plant palatability to chewing herbivores and greater plant defenses at low latitudes, but other factors may also play a role in mediating these geographic patterns.

  17. Latitudinal gradients in ecosystem engineering by oysters vary across habitats.

    PubMed

    McAfee, Dominic; Cole, Victoria J; Bishop, Melanie J

    2016-04-01

    Ecological theory predicts that positive interactions among organisms will increase across gradients of increasing abiotic stress or consumer pressure. This theory has been supported by empirical studies examining the magnitude of ecosystem engineering across environmental gradients and between habitat settings at local scale. Predictions that habitat setting, by modifying both biotic and abiotic factors, will determine large-scale gradients in ecosystem engineering have not been tested, however. A combination of manipulative experiments and field surveys assessed whether along the east Australian coastline: (1) facilitation of invertebrates by the oyster Saccostrea glomerata increased across a latitudinal gradient in temperature; and (2) the magnitude of this effect varied between intertidal rocky shores and mangrove forests. It was expected that on rocky shores, where oysters are the primary ecosystem engineer, they would play a greater role in ameliorating latitudinal gradients in temperature than in mangroves, where they are a secondary ecosystem engineer living under the mangrove canopy. On rocky shores, the enhancement of invertebrate abundance in oysters as compared to bare microhabitat decreased with latitude, as the maximum temperatures experienced by intertidal organisms diminished. By contrast, in mangrove forests, where the mangrove canopy resulted in maximum temperatures that were cooler and of greater humidity than on rocky shores, we found no evidence of latitudinal gradients of oyster effects on invertebrate abundance. Contrary to predictions, the magnitude by which oysters enhanced biodiversity was in many instances similar between mangroves and rocky shores. Whether habitat-context modifies patterns of spatial variation in the effects of ecosystem engineers on community structure will depend, in part, on the extent to which the environmental amelioration provided by an ecosystem engineer replicates that of other co-occurring ecosystem engineers.

  18. Latitudinal gradients in ecosystem engineering by oysters vary across habitats.

    PubMed

    McAfee, Dominic; Cole, Victoria J; Bishop, Melanie J

    2016-04-01

    Ecological theory predicts that positive interactions among organisms will increase across gradients of increasing abiotic stress or consumer pressure. This theory has been supported by empirical studies examining the magnitude of ecosystem engineering across environmental gradients and between habitat settings at local scale. Predictions that habitat setting, by modifying both biotic and abiotic factors, will determine large-scale gradients in ecosystem engineering have not been tested, however. A combination of manipulative experiments and field surveys assessed whether along the east Australian coastline: (1) facilitation of invertebrates by the oyster Saccostrea glomerata increased across a latitudinal gradient in temperature; and (2) the magnitude of this effect varied between intertidal rocky shores and mangrove forests. It was expected that on rocky shores, where oysters are the primary ecosystem engineer, they would play a greater role in ameliorating latitudinal gradients in temperature than in mangroves, where they are a secondary ecosystem engineer living under the mangrove canopy. On rocky shores, the enhancement of invertebrate abundance in oysters as compared to bare microhabitat decreased with latitude, as the maximum temperatures experienced by intertidal organisms diminished. By contrast, in mangrove forests, where the mangrove canopy resulted in maximum temperatures that were cooler and of greater humidity than on rocky shores, we found no evidence of latitudinal gradients of oyster effects on invertebrate abundance. Contrary to predictions, the magnitude by which oysters enhanced biodiversity was in many instances similar between mangroves and rocky shores. Whether habitat-context modifies patterns of spatial variation in the effects of ecosystem engineers on community structure will depend, in part, on the extent to which the environmental amelioration provided by an ecosystem engineer replicates that of other co-occurring ecosystem engineers

  19. Latitudinal gradients in marine diatom and coccolithophore diversity

    NASA Astrophysics Data System (ADS)

    O'Brien, Colleen; Vogt, Meike; Leblanc, Karine; Gruber, Nicolas

    2013-04-01

    Latitudinal gradients in biodiversity have long been recognised in terrestrial ecosystems, with the highest diversity of many groups occurring in the tropics and declining towards the poles. For marine phytoplankton, a latitudinal gradient has been observed in dinoflagellates, and there seems to be some consensus that coccolithophore diversity also follows the typical pattern of highest diversity at low latitudes. Mixed results have so far been reported for marine diatoms. We use the new MAREDAT (Marine Ecosystem DATa) diatom and coccolithophore datasets to investigate global patterns in species diversity. This database contains global biomass and abundance observations for 10 plankton functional groups, including 91 704 samples of diatom abundance and biomass and 11 703 for coccolithophores. We find evidence for a poleward decline in species richness and diversity for both groups, with total observed species richness per 5 degree latitudinal band declining by approximately 75% between the equator and 60°. Mean station diversity is measured using both species richness and the Shannon diversity index. For the diatoms, species richness per station declines from a mean of 25 between 20°S and 20°N to values less than 10 for stations above 60°S and N. For the coccolithophores, the trend is less clear: mean station richness reaches a maximum of 22 between 10 and 15°N and shows a clear northward decline, with only one species per station reported north of 60°N. Mean coccolithophore richness per station is, however, relatively low at the equator, with highest richness per station in the Southern Hemisphere observed between 20 and 40°S. Highest richness and diversity of both groups is associated with low group-specific biomass and low total chlorophyll, with higher productivity regions typically dominated by one or few species.

  20. Latitudinal variability of arsine, germane and phosphine in Jupiter's troposphere

    NASA Astrophysics Data System (ADS)

    Giles, Rohini Sara; Fletcher, Leigh N.; Irwin, Patrick Gerard Joseph

    2016-10-01

    High-resolution 5-μm observations of Jupiter from the CRIRES instrument at the Very Large Telescope are used to measure latitudinal variability in AsH3, GeH4 and PH3. The 5-micron region is a spectral window allowing us to probe down to Jupiter's middle troposphere (4-8 bar). CRIRES observations in 2012 and 2013 provide high-resolution (R=96,000) latitudinally-resolved spectra in the 4.7-5.2 μm region. In the middle troposphere, AsH3, GeH4and PH3 are disequilibrium species that are only present because of rapid upwelling from deeper regions of the planet. Their observed abundances depend on the chemical lifetimes, the strength of the vertical mixing and the rate of photolytic destruction, and are therefore likely to vary with latitude. We analyse the CRIRES observations using the NEMESIS radiative transfer code and retrieval algorithm in order to search for any latitudinal variability in the disequilibrium species. We find that there is a significant degeneracy between the retrieved gaseous abundances and the cloud structure – specifically, the scattering properties of the main tropospheric cloud deck, and the presence/absence of an additional deep cloud. Because of these degeneracies, there is no clear evidence for any variability in GeH4. However, for AsH3 and PH3, there are significant latitudinal differences in the observed lineshape that cannot be accounted for by clouds. We conclude that both of these gases show an enhancement at high latitudes. In the case of AsH3, the retrieved abundance varies from subsolar in the equatorial regions (as seen in previous studies) to supersolar in the polar regions. Our findings are in contrast with the theoretical simulations of Wang et al. (2016, doi:10.1016/j.icarus.2016.04.027), which predict that AsH3 and PH3 should not vary with latitude, and that GeH4 should decrease in abundance at high latitudes.

  1. Temporal latitudinal-gradient dynamics and tropical instability of deep-sea species diversity

    USGS Publications Warehouse

    Yasuhara, Moriaki; Hunt, G.; Cronin, T. M.; Okahashi, H.

    2009-01-01

    A benthic microfaunal record from the equatorial Atlantic Ocean over the past four glacial-interglacial cycles was investigated to understand temporal dynamics of deep-sea latitudinal species diversity gradients (LSDGs). The results demonstrate unexpected instability and high amplitude fluctuations of species diversity in the tropical deep ocean that are correlated with orbital-scale oscillations in global climate: Species diversity is low during glacial and high during interglacial periods. This implies that climate severely influences deep-sea diversity, even at tropical latitudes, and that deep-sea LSDGs, while generally present for the last 36 million years, were weakened or absent during glacial periods. Temporally dynamic LSDGs and unstable tropical diversity require reconsideration of current ecological hypotheses about the generation and maintenance of biodiversity as they apply to the deep sea, and underscore the potential vulnerability and conservation importance of tropical deep-sea ecosystems.

  2. Latitudinal clines in alternative life histories in a geometrid moth.

    PubMed

    Välimäki, P; Kivelä, S M; Mäenpää, M I; Tammaru, T

    2013-01-01

    The relative roles of genetic differentiation and developmental plasticity in generating latitudinal gradients in life histories remain insufficiently understood. In particular, this applies to determination of voltinism (annual number of generations) in short-lived ectotherms, and the associated trait values. We studied different components of variation in development of Chiasmia clathrata (Lepidoptera: Geometridae) larvae that originated from populations expressing univoltine, partially bivoltine or bivoltine phenology along a latitudinal gradient of season length. Indicative of population-level genetic differentiation, larval period became longer while growth rate decreased with increasing season length within a particular phenology, but saw-tooth clines emerged across the phenologies. Indicative of phenotypic plasticity, individuals that developed directly into reproductive adults had shorter development times and higher growth rates than those entering diapause. The most marked differences between the alternative developmental pathways were found in the bivoltine region suggesting that the adaptive correlates of the direct development evolve if exposed to selection. Pupal mass followed a complex cline without clear reference to the shift in voltinism or developmental pathway probably due to varying interplay between the responses in development time and growth rate. The results highlight the multidimensionality of evolutionary trajectories of life-history traits, which either facilitate or constrain the evolution of integrated traits in alternative phenotypes.

  3. Latitudinal differences in the hibernation characteristics of woodchucks (Marmota monax).

    PubMed

    Zervanos, Stam M; Maher, Christine R; Waldvogel, Jerry A; Florant, Gregory L

    2010-01-01

    There is little information on the phenotypic flexibility of hibernation characteristics within species. To address this issue, we observed differences in hibernation characteristics of three free-ranging populations of woodchucks (Marmota monax) distributed along a latitudinal gradient from Maine to South Carolina. Data from free-ranging animals exhibited a direct relationship between latitude and length of the hibernation season. As expected, woodchucks in the northern latitudes hibernated longer than those in the southern latitudes. Also, the length of interbout arousals decreased with increase in latitude, whereas the length of torpor bouts and the number of arousals increased. Thus, we observed phenotypic plasticity in hibernation characteristics based primarily on latitudinal temperature differences in each population. Further analysis revealed a direct relationship between latitude and total time spent in torpor. Maine animals spent 68% more time in torpor than South Carolina animals. However, total time spent euthermic did not differ among the three populations. The "cost-benefit" hypothesis of hibernation may help to explain these results. It assumes that hibernators avoid the physiological stress of torpor by staying euthermic as much as possible. Woodchucks in each population maximized time spent euthermic, utilizing torpor only at the level needed to survive winter hibernation and to commence reproduction in the spring.

  4. Latitudinal clines in alternative life histories in a geometrid moth.

    PubMed

    Välimäki, P; Kivelä, S M; Mäenpää, M I; Tammaru, T

    2013-01-01

    The relative roles of genetic differentiation and developmental plasticity in generating latitudinal gradients in life histories remain insufficiently understood. In particular, this applies to determination of voltinism (annual number of generations) in short-lived ectotherms, and the associated trait values. We studied different components of variation in development of Chiasmia clathrata (Lepidoptera: Geometridae) larvae that originated from populations expressing univoltine, partially bivoltine or bivoltine phenology along a latitudinal gradient of season length. Indicative of population-level genetic differentiation, larval period became longer while growth rate decreased with increasing season length within a particular phenology, but saw-tooth clines emerged across the phenologies. Indicative of phenotypic plasticity, individuals that developed directly into reproductive adults had shorter development times and higher growth rates than those entering diapause. The most marked differences between the alternative developmental pathways were found in the bivoltine region suggesting that the adaptive correlates of the direct development evolve if exposed to selection. Pupal mass followed a complex cline without clear reference to the shift in voltinism or developmental pathway probably due to varying interplay between the responses in development time and growth rate. The results highlight the multidimensionality of evolutionary trajectories of life-history traits, which either facilitate or constrain the evolution of integrated traits in alternative phenotypes. PMID:23193976

  5. Latitudinal gradients in tertiary molluscan faunas of the Pacific coast

    USGS Publications Warehouse

    Addicott, W.O.

    1970-01-01

    Tertiary molluscan faunas of the middle latitudes of the marginal eastern North Pacific are characterized by warm-water taxa whose descendants now live in more southerly latitudes. A series of profiles in which cumulative percentages of warm-water faunal elements are plotted against latitude show progressive northward decreases in the percentage of these elements in the faunas of Pacific coast Tertiary stages. Systematic changes in the relative position of these latitudinal gradients during the Middle and Late Tertiary are related to climatic change in the Pacific Basin. Widespread tropical marine climate in the middle latitudes of the eastern North Pacific during the Eocene is indicated by widespread faunal units characterized by high levels of taxonomic diversity. Succeeding Early Oligocene faunas are less diverse, suggesting cooler climatic conditions. Unusually low representations of warm-water genera characterize the molluscan faunas of the Acila shumardi Zone in central California (latitude 34??-37??N). The anomalously cool-water aspect of these faunas may record the occurrence of upwelling along a bold linear segment of the Pacific coast. During the Late Oligocene or the Early Miocene, they are replaced by faunas of unusually warm-water aspect resulting in positive anomalies in Miocene latitudinal faunal gradients in central California. The Miocene anomalies seem to result from the development of an irregular Neogene coastline with extensive, newly established shallow-water embayments. ?? 1970.

  6. Comment on "Disentangling the drivers of β diversity along latitudinal and elevational gradients".

    PubMed

    Tuomisto, Hanna; Ruokolainen, Kalle

    2012-03-30

    Kraft et al. (Report, 23 September 2011, p. 1755) argued that the latitudinal trend in β diversity is spurious and just reflects a trend in γ diversity. Their results depend on the idiosyncrasies of their data, especially the latitudinally varying degree of undersampling and a local sampling setup that is not suitable for analyzing drivers of β diversity.

  7. Global Latitudinal Differences of Molecular Absorption on Jupiter

    NASA Astrophysics Data System (ADS)

    Tejfel, V. G.

    2002-09-01

    In the future planetary monitoring from the groundbased observatories or space telescopes the selection of a number of planetary state indices will be necessary to obtain homogeneous temporal series of numerical planetary characteristics. In 1999 special observations of latitude-longitudinal distribution of absorption in the methane bands on Jupiter were carried out. CCD-spectra of the central meridian of Jupiter were recorded in each 3 minutes that corresponded a turning of Jupiter by 1.8 degrees. All the longitudes of the planet were twice covered and full number of spectrograms was 388. A comparison of the latitudinal dependence of absorption in the different absorption bands has revealed some noticeable global, longitudinally independent differences in the character of latitudinal variations of absorption. So, equatorial depression of absorption is well expressed in the bands at 725 and 887 nm, but it is absent in the band at 619 nm. It is interesting that for the band 798 nm, which is a combination of the methane and ammonia absorption, the similar depression is displaced significantly northward from the equator (minimum of the absorption take place at the latitude about +15 deg) in contrast with the depression observed for the band CH4 887 nm. Very small northward displacement is noticeable also for the CH4 725 nm equatorial depression. There is no determined relationship between the value of molecular absorption and visible albedo of the cloud belts. Standard deviations calculated at the longitudinally averaging of the central meridian profiles of the band central depths R are small and no more than 1-2 per cent of mean value. Thus the latitudinal differences are more clearly expressed than longitudinal variations and the global, longitudinally averaged N-S profiles of the absorption variations may be considered as one of characteristics of the current state of Jupiter (as well as of Saturn). There may be not significant mistake if the individual profiles R

  8. Spatial frequencies associated with the latitudinal structures of ionospheric currents seen by CHAMP satellite

    NASA Astrophysics Data System (ADS)

    Thomas, Neethal; Vichare, Geeta; Sinha, A. K.

    2016-07-01

    The CHAMP magnetic field variations during international quiet days of low solar activity period 2008-2009 are investigated. The present paper reports the existence of frequency peaks ≤20 mHz in the compressional component of the magnetic field in almost all CHAMP passes. The magnetic field variations associated with these frequencies have amplitude of a few tens of nT during the daytime. The geomagnetic activity and interplanetary magnetic field parameters were observed to be low during the period of study. The spectral powers of the observed frequencies show no dependence on solar wind velocity and cone angle; hence, the reported frequencies are not related to the geomagnetic pulsations. For frequency-peaks ≤15 mHz, strong local time dependence is observed with maximum power near noon and minimum at night. The longitudinal and seasonal variation of the powers of these frequency peaks match well with those of the equator-to-middle latitude ionospheric currents derived by the earlier studies. As a polar Low Earth Orbiting (LEO) satellite spans the entire range of latitudes within few minutes, it monitors the geomagnetic field variations caused by the quiet-time ionospheric currents flowing at different latitudes. This can result in certain frequencies in the magnetic field recorded by LEO satellites. We demonstrate that the frequencies <10 mHz are mainly due to the latitudinal structure of the equatorial electrojet. The observed frequencies in CHAMP data are therefore attributed to the latitudinal structures of the ionospheric currents that are monitored only by the polar LEO satellites and are found to alter the observations of geomagnetic pulsations (Pc4-5 and Pi2) significantly.

  9. Bimodality of Latitudinal Gradients in Marine Species Richness.

    PubMed

    Chaudhary, Chhaya; Saeedi, Hanieh; Costello, Mark J

    2016-09-01

    The paradigm for the latitudinal gradient in species richness is that it is unimodal with a tropical peak. For 27 published studies, and global datasets of 65 000 recent and 50 000 fossil marine species, we found that almost all datasets were significantly bimodal with a dip in species richness near the equator. The locations of mid-latitude peaks varied between taxa and were higher in the northern hemisphere where the continental shelf is greatest. Our findings support hypotheses of tropical species evolving in response to temperature variation near the edges of the tropics and available high-productivity habitat. They suggest that the equator may already be too hot for some species and that the modes may move further apart due to climate warming.

  10. Bimodality of Latitudinal Gradients in Marine Species Richness.

    PubMed

    Chaudhary, Chhaya; Saeedi, Hanieh; Costello, Mark J

    2016-09-01

    The paradigm for the latitudinal gradient in species richness is that it is unimodal with a tropical peak. For 27 published studies, and global datasets of 65 000 recent and 50 000 fossil marine species, we found that almost all datasets were significantly bimodal with a dip in species richness near the equator. The locations of mid-latitude peaks varied between taxa and were higher in the northern hemisphere where the continental shelf is greatest. Our findings support hypotheses of tropical species evolving in response to temperature variation near the edges of the tropics and available high-productivity habitat. They suggest that the equator may already be too hot for some species and that the modes may move further apart due to climate warming. PMID:27372733

  11. Origination and Immigration Drive Latitudinal Gradients in Marine Functional Diversity

    PubMed Central

    Berke, Sarah K.; Jablonski, David; Krug, Andrew Z.; Valentine, James W.

    2014-01-01

    Global patterns in the functional attributes of organisms are critical to understanding biodiversity trends and predicting biotic responses to environmental change. In the first global marine analysis, we find a strong decrease in functional richness, but a strong increase in functional evenness, with increasing latitude using intertidal-to-outer-shelf bivalves as a model system (N = 5571 species). These patterns appear to be driven by the interplay between variation in origination rates among functional groups, and latitudinal patterns in origination and range expansion, as documented by the rich fossil record of the group. The data suggest that (i) accumulation of taxa in spatial bins and functional categories has not impeded continued diversification in the tropics, and (ii) extinctions will influence ecosystem function differentially across latitudes. PMID:25036112

  12. Latitudinal and altitudinal controls of Titan's dune field morphometry

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Hayes, A. G.; Ewing, R.; Janssen, M. A.; Radebaugh, J.; Savage, C.; Encrenaz, P.; the Cassini Radar Team

    2012-01-01

    Dune fields dominate ˜13% of Titan's surface and represent an important sink of carbon in the methane cycle. Herein, we discuss correlations in dune morphometry with altitude and latitude. These correlations, which have important implications in terms of geological processes and climate on Titan, are investigated through the microwave electromagnetic signatures of dune fields using Cassini radar and radiometry observations. The backscatter and emissivity from Titan's dune terrains are primarily controlled by the amount of interdune area within the radar footprint and are also expected to vary with the degree of the interdunal sand cover. Using SAR-derived topography, we find that Titan's main dune fields (Shangri-La, Fensal, Belet and Aztlan) tend to occupy the lowest elevation areas in Equatorial regions occurring at mean elevations between ˜-400 and ˜0 m (relative to the geoid). In elevated dune terrains, we show a definite trend towards a smaller dune to interdune ratio and possibly a thinner sand cover in the interdune areas. A similar correlation is observed with latitude, suggesting that the quantity of windblown sand in the dune fields tends to decrease as one moves farther north. The altitudinal trend among Titan's sand seas is consistent with the idea that sediment source zones most probably occur in lowlands, which would reduce the sand supply toward elevated regions. The latitudinal preference could result from a gradual increase in dampness with latitude due to the asymmetric seasonal forcing associated with Titan's current orbital configuration unless it is indicative of a latitudinal preference in the sand source distribution or wind transport capacity.

  13. Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

    PubMed Central

    Pittera, Justine; Humily, Florian; Thorel, Maxine; Grulois, Daphné; Garczarek, Laurence; Six, Christophe

    2014-01-01

    Marine Synechococcus cyanobacteria constitute a monophyletic group that displays a wide latitudinal distribution, ranging from the equator to the polar fronts. Whether these organisms are all physiologically adapted to stand a large temperature gradient or stenotherms with narrow growth temperature ranges has so far remained unexplored. We submitted a panel of six strains, isolated along a gradient of latitude in the North Atlantic Ocean, to long- and short-term variations of temperature. Upon a downward shift of temperature, the strains showed strikingly distinct resistance, seemingly related to their latitude of isolation, with tropical strains collapsing while northern strains were capable of growing. This behaviour was associated to differential photosynthetic performances. In the tropical strains, the rapid photosystem II inactivation and the decrease of the antioxydant β-carotene relative to chl a suggested a strong induction of oxidative stress. These different responses were related to the thermal preferenda of the strains. The northern strains could grow at 10 °C while the other strains preferred higher temperatures. In addition, we pointed out a correspondence between strain isolation temperature and phylogeny. In particular, clades I and IV laboratory strains were all collected in the coldest waters of the distribution area of marine Synechococus. We, however, show that clade I Synechococcus exhibit different levels of adaptation, which apparently reflect their location on the latitudinal temperature gradient. This study reveals the existence of lineages of marine Synechococcus physiologically specialised in different thermal niches, therefore suggesting the existence of temperature ecotypes within the marine Synechococcus radiation. PMID:24401861

  14. Temporal and latitudinal distributions of stratospheric N2O isotopomers

    NASA Astrophysics Data System (ADS)

    Toyoda, Sakae; Yoshida, Naohiro; Urabe, Taichiro; Nakayama, Yusuke; Suzuki, Takeshi; Tsuji, Kazuhide; Shibuya, Kazuhiko; Aoki, Shuji; Nakazawa, Takakiyo; Ishidoya, Shigeyuki; Ishijima, Kentaro; Sugawara, Satoshi; Machida, Toshinobu; Hashida, Gen; Morimoto, Shinji; Honda, Hideyuki

    2004-04-01

    Temporal and latitudinal variations of vertical profiles of N2O isotopomers were observed in the stratosphere over Japan (39°N, 142°E), Sweden (68°N, 20°E), and Antarctica (69°N, 40°E) during the period between 1990 and 2001. Samples were collected with a balloon-borne cryogenic sampler and analyzed by mass spectrometry in the laboratory. Observed enrichment factors for heavier isotopomers (15N14N16O, 14N15N16O, and 14N14N18O) relative to 14N14N16O were nearly constant in the lower stratosphere (less than ˜22 km) but increased at higher altitudes (˜22-35 km) while showing seasonal and latitudinal differences. Enrichment factors during the photolysis and photo-oxidation of N2O were also obtained in laboratory experiments and compared with those observed. We found that in the higher-altitude region (1) fractionation of the isotopomers is mainly determined by photolysis, but is also affected by physical processes, (2) subsidence of air masses in the winter polar vortex induces the intrusion of an upper stratospheric air mass depleted in N2O, and (3) decay of the vortex in the local spring leads to rapid horizontal advection of midlatitude air masses. At lower altitudes, isotopomer ratios are determined by photolysis, photo-oxidation, and the mixing of air masses within the stratosphere or between the stratosphere and the troposphere. Secular trend of isotopomer profiles was not detectable over Japan during 11 years. Assuming that the lower stratospheric air over midlatitudes is exchanged with the troposphere, isotopomer ratios of the N2O "back-flux" from the stratosphere were estimated. These values can be used in the isotopomeric mass balance model to constrain the global N2O budget.

  15. Climate and Biological Controls of Carbon Fluxes along latitudinal gradients

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Yuan, J.; Niu, S.

    2012-12-01

    It has not been carefully examined whether relative importance of climate and biological controls of carbon fluxes is similar among various ecosystem types along latitudinal gradients from the tropical to polar region. We hypothesize that except tropical regions, there is a consistent pattern of climate and biological controls of carbon fluxes across all the other ecosystems. We tested the hypothesis by analyzing data of net ecosystem exchange (NEE) from nearly 200 eddy-flux towers distributed worldwide and simulated gross primary production (GPP) from the Australian Community Atmosphere Land Exchange (CABLE) model. Specifically, we estimated yearly NEE (i.e., NEP), carbon uptake period (CUP) and seasonal maximum of NEE (NEE¬_max) from eddy-flux data. Similarly, we estimated CUP, GPP_max, seasonal maximum leaf area index (LAI_max), and Vcmax from the model across the globe. Our regression analysis indicates that NEP is very tightly correlated with the product of CUP and NEE_max cross all sites. Similarly, simulated GPP is highly correlated with the product of CUP and GPP_max over the globe in the CABLE model. CUP is related to phenology and represents climate control of carbon fluxes while NEE_max or GPP_max is determined by biological processes and thus represents biological control of carbon processes. We further analyzed relationships of GPP_max with LAI_max and Vcmax individually or in combination. GPP_max is highly correlated with them. This talk will present results of our analysis and explain our hypothesis test regarding relative importance of biological and climate controls of carbon fluxes along the latitudinal gradients.

  16. Antipredator defenses along a latitudinal gradient in Rana temporaria.

    PubMed

    Laurila, Anssi; Lindgren, Beatrice; Laugen, Ane T

    2008-05-01

    Antipredator defenses are expected to decrease toward higher latitudes because predation rates are predicted to decrease with latitude. However, latitudinal variation in predator avoidance and defense mechanisms has seldom been studied. We studied tadpole antipredator defenses in seven Rana temporaria populations collected along a 1500-km latitudinal gradient across Sweden, along which previous studies have found increasing tadpole growth and development rates. In a laboratory common garden experiment, we measured behavioral and morphological defenses by raising tadpoles in the presence and absence of a predator (Aeshna dragonfly larva) in two temperature treatments. We also estimated tadpole survival in the presence of free-ranging predators and compared predator densities between R. temporaria breeding ponds situated at low and high latitudes. Activity and foraging were generally positively correlated with latitude in the common garden experiment. While all populations responded to predator presence by decreasing activity and foraging, high-latitude populations maintained higher activity levels in the presence of the predator. All populations exhibited defensive morphology in body and tail shape. However, whereas tail depth tended to increase with latitude in the presence of predator, it did not change with latitude in the absence of the predator. Predator presence generally increased larval period and decreased growth rate. In the southern populations, predator presence tended to have a negative effect on metamorphic size, whereas in the northern populations predators had little or a positive effect on size. Latitude of origin had a strong effect on survival in the presence of a free-ranging predator, with high-latitude tadpoles experiencing higher mortality than those from the low latitudes. In the wild, predator densities were significantly lower in high-latitude than in mid-latitude breeding ponds. Although the higher activity level in the northern

  17. Mangrove pore water exchange across a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Tait, Douglas R.; Maher, Damien T.; Macklin, Paul A.; Santos, Isaac R.

    2016-04-01

    We combined observations of the natural tracer radon (222Rn) with hydrodynamic models across a broad latitudinal gradient covering several climate zones to estimate pore water exchange rates in mangroves. Pore water exchange ranged from 2.1 to 35.5 cm d-1 from temperate to tropical regions and averaged 16.3 ± 5.1 cm d-1. If upscaled to the global weighted mangrove area, pore water exchange in mangroves would recirculate the entire volume of water overlying the continental shelf in less than 153 years. Although pore water exchange (recirculated seawater) and river discharge represent different pathways for water entering the coastal ocean, the estimated global mangrove pore water exchange would be equal to approximately one third of annual global river discharge to the ocean (3.84 × 1013 m3 yr-1). Because biogeochemical processes in mangroves are largely dependent on pore water exchange, these large exchange rates have major implications for coastal nutrient, carbon, and greenhouse gas cycling in tropical marine systems.

  18. Functional trait space and the latitudinal diversity gradient

    PubMed Central

    Lamanna, Christine; Blonder, Benjamin; Violle, Cyrille; Kraft, Nathan J. B.; Sandel, Brody; Šímová, Irena; Donoghue, John C.; Svenning, Jens-Christian; McGill, Brian J.; Boyle, Brad; Buzzard, Vanessa; Dolins, Steven; Jørgensen, Peter M.; Marcuse-Kubitza, Aaron; Morueta-Holme, Naia; Peet, Robert K.; Piel, William H.; Regetz, James; Schildhauer, Mark; Spencer, Nick; Thiers, Barbara; Wiser, Susan K.; Enquist, Brian J.

    2014-01-01

    The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory. PMID:25225365

  19. Disease Ecology, Biodiversity, and the Latitudinal Gradient in Income

    PubMed Central

    Bonds, Matthew H.; Dobson, Andrew P.; Keenan, Donald C.

    2012-01-01

    While most of the world is thought to be on long-term economic growth paths, more than one-sixth of the world is roughly as poor today as their ancestors were hundreds of years ago. The majority of the extremely poor live in the tropics. The latitudinal gradient in income is highly suggestive of underlying biophysical drivers, of which disease conditions are an especially salient example. However, conclusions have been confounded by the simultaneous causality between income and disease, in addition to potentially spurious relationships. We use a simultaneous equations model to estimate the relative effects of vector-borne and parasitic diseases (VBPDs) and income on each other, controlling for other factors. Our statistical model indicates that VBPDs have systematically affected economic development, evident in contemporary levels of per capita income. The burden of VBDPs is, in turn, determined by underlying ecological conditions. In particular, the model predicts it to rise as biodiversity falls. Through these positive effects on human health, the model thus identifies measurable economic benefits of biodiversity. PMID:23300379

  20. Latitudinal variation in reproductive strategies by the migratory Louisiana Waterthrush

    USGS Publications Warehouse

    Mattsson, B.J.; Latta, S.C.; Cooper, R.J.; Mulvihill, R.S.

    2011-01-01

    We evaluated hypotheses that seek to explain breeding strategies of the Louisiana Waterthrush (Parkesia motacilla) that vary across a latitudinal gradient. On the basis of data from 418 nests of color-banded individuals in southwestern Pennsylvania and 700 km south in the Georgia Piedmont, we found that clutch size in replacement nests and probability of renesting were significantly greater in Pennsylvania (clutch size 4.4; renesting probability 0.66) than in Georgia (clutch size 3.8; renesting probability 0.54). Contrasts of the remaining measures of breeding were not statistically significant, and, in particular, mean daily nest survival in the two study areas was nearly identical (0.974 in Pennsylvania; 0.975 in Georgia). An individual-based model of fecundity (i.e., number of fledged young per adult female), predicted that approximately half of the females in both Pennsylvania and Georgia fledge at least one young, and mean values for fecundity in Pennsylvania and Georgia were 2.28 and 1.91, respectively. On the basis of greater support for the food-limitation hypothesis than for the season-length hypothesis, the trade-off between breeding in a region with more food but making a longer migration may be greater for waterthrushes breeding farther north than for those breeding farther south. ?? The Cooper Ornithological Society 2011.

  1. Functional trait space and the latitudinal diversity gradient.

    PubMed

    Lamanna, Christine; Blonder, Benjamin; Violle, Cyrille; Kraft, Nathan J B; Sandel, Brody; Šímová, Irena; Donoghue, John C; Svenning, Jens-Christian; McGill, Brian J; Boyle, Brad; Buzzard, Vanessa; Dolins, Steven; Jørgensen, Peter M; Marcuse-Kubitza, Aaron; Morueta-Holme, Naia; Peet, Robert K; Piel, William H; Regetz, James; Schildhauer, Mark; Spencer, Nick; Thiers, Barbara; Wiser, Susan K; Enquist, Brian J

    2014-09-23

    The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory. PMID:25225365

  2. Latitudinal dependence of variations in stratospheric NO2 content

    NASA Astrophysics Data System (ADS)

    Gruzdev, A. N.

    2008-06-01

    Diurnal and annual variations in the NO2 total content (TC), the effect of its decrease owing to the products of the eruption of Mt. Pinatubo, its variations during an 11-year cycle of solar activity, and its linear trends are analyzed on the basis of data obtained from the ground-based spectrometric measurements of the NO2 TC in stratospheric vertical columns over the stations of the Network for the Detection of Atmospheric Composition Change. Latitudinal dependence of the indicated variations and trends is revealed. The annual estimates of the linear trends of the NO2 TC are found to be mostly positive for the middle and low latitudes of the Southern Hemisphere and negative for the middle and low latitudes of the Northern Hemisphere. The maximum values of the positive and negative trends amount to ˜10% per ten years. In the high and polar latitudes of both hemispheres, the annual trend estimates are statistically insignificant. Seasonal estimates of the trends may differ from their annual estimates. The trends and solar-activity effect in the NO2 TC, which were estimated by using the two-dimensional model SOCRATES, as well as the analytical estimates of a zonal mean trend of the NO2 TC, on the whole, significantly differ from the estimates obtained from the measurements.

  3. Charge sign dependent latitudinal gradients of galactic cosmic

    NASA Astrophysics Data System (ADS)

    Heber, Bernd; Gieseler, Jan; Gomez-Herrero, Raul; Klassen, Andreas; Müller-Mellin, Reinhold; Dunzlaff, Phillip; Labrenz, Johannes; Mewaldt, R. A.; Ferreira, Stefan; Potgieter, Marius

    We study the spatial gradients of galactic cosmic ray helium, protons and electrons in the inner heliosphere using data from the Kiel Electron Telescope (KET) aboard Ulysses, the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE), and the Electron Proton Helium Instrument aboard SOHO for the time period from 1997 to 2008. This covers the solar minimum in the A>0-solar magnetic epoch, the solar magnetic reversal to an A<0-magnetic epoch at solar maximum and the declining phase of solar cycle 23. In order to calculate the galactic cosmic ray intensity distribution in the inner heliosphere we used the 34 to 69 MeV/n, 69 - 106 MeV/n, and 125-250 MeV/nuc helium channel from KET and a combination of helium and carbon channels from the EPHIN and CRIS instruments. Our analysis results in a radial and latitudinal intensity gradient Gr of about 4%/AU and Gθ of about 0

  4. Disease ecology, biodiversity, and the latitudinal gradient in income.

    PubMed

    Bonds, Matthew H; Dobson, Andrew P; Keenan, Donald C

    2012-01-01

    While most of the world is thought to be on long-term economic growth paths, more than one-sixth of the world is roughly as poor today as their ancestors were hundreds of years ago. The majority of the extremely poor live in the tropics. The latitudinal gradient in income is highly suggestive of underlying biophysical drivers, of which disease conditions are an especially salient example. However, conclusions have been confounded by the simultaneous causality between income and disease, in addition to potentially spurious relationships. We use a simultaneous equations model to estimate the relative effects of vector-borne and parasitic diseases (VBPDs) and income on each other, controlling for other factors. Our statistical model indicates that VBPDs have systematically affected economic development, evident in contemporary levels of per capita income. The burden of VBDPs is, in turn, determined by underlying ecological conditions. In particular, the model predicts it to rise as biodiversity falls. Through these positive effects on human health, the model thus identifies measurable economic benefits of biodiversity.

  5. Effects of predation risk across a latitudinal temperature gradient.

    PubMed

    Matassa, Catherine M; Trussell, Geoffrey C

    2015-03-01

    The nonconsumptive effects (NCEs) of predators on prey behavior and physiology can influence the structure and function of ecological communities. However, the strength of NCEs should depend on the physiological and environmental contexts in which prey must choose between food and safety. For ectotherms, temperature effects on metabolism and foraging rates may shape these choices, thereby altering NCE strength. We examined NCEs in a rocky intertidal food chain across a latitudinal sea surface temperature gradient within the Gulf of Maine. The NCEs of green crabs (Carcinus maenas) on the foraging, growth, and growth efficiency of prey snails (Nucella lapillus) were consistent across a broad (~8.5 °C) temperature range, even though snails that were transplanted south consumed twice as many mussels (Mytilus edulis) and grew twice as much as snails that were transplanted north. The positive effects of warmer temperatures in the south allowed snails under high risk to perform similarly to or better than snails under low risk at cooler temperatures. Our results suggest that for prey populations residing at temperatures below their thermal optimum, the positive effects of future warming may offset the negative effects of predation risk. Such effects may be favorable to prey populations facing increased predation rates due to warmer temperatures associated with climate change. Attention to the direct and indirect effects of temperature on species interactions should improve our ability to predict the effects of climate change on ecological communities. PMID:25433694

  6. Latitudinal Dependence of the Radial IMF Component - Interplanetary Imprint

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Smith, E. J.; Phillips, J.; Goldstein, B. E.; Nerney, S.

    1996-01-01

    Ulysses measurements have confirmed that there is no significant gradient with respect to heliomagnetic latitude in the radial component, B(sub r,), of the interplanetary magnetic field. There are two processes responsible for this observation. In the corona, the plasma beta is much less than 1, except directly above streamers, so both longitudinal and latitudinal (meridional) gradients in field strength will relax, due to the transverse magnetic pressure gradient force, as the solar wind carries magnetic flux away from the Sun. This happens so quickly that the field is essentially uniform by 5 solar radius. Beyond 10 solar radius, beta is greater than 1 and it is possible for a meridional thermal pressure gradient to redistribute magnetic flux - an effect apparently absent in Ulysses and earlier ICE and Interplanetary Magnetic Physics (IMP) data. We discuss this second effect here, showing that its absence is mainly due to the perpendicular part of the anisotropic thermal pressure gradient in the interplanetary medium being too small to drive significant meridional transport between the Sun and approx. 4 AU. This is done using a linear analytic estimate of meridional transport. The first effect was discussed in an earlier paper.

  7. No Latitudinal Trends in Body Size of Foraminifera

    NASA Astrophysics Data System (ADS)

    Liao, Z.; Payne, J.; Seixas, G.

    2012-12-01

    Many organisms, such as penguins and polar bears, follow Bergmann's rule, which states that body size of animals tends to increase as temperature decreases, and thus as latitude increases toward to poles. A study of marine mollusk bivalves across a latitudinal gradient found no correlation between body size and latitude along the North American Pacific Coast, suggesting that the body size of marine bivalves might be controlled by other factors. This posed the question: Is there a lack of correlation between latitude and body size for all marine invertebrates or is it unique to marine bivalves? In this study, we examined four suborders of benthic foraminifera, Lagenina, Miliolina, Rotaliina, and Textulariina, a diverse phylum of amoeboid protists, to determine the relationship between body size and latitude within and across suborders at the global scale. We measured the shell (test) dimensions of foraminifera from a compilation of monograph images of type specimens. The mean test size as well as the maximum body size of those foraminifera suborders does not vary with increasing latitude. Our results show that foraminifera do not follow Bergmann's rule, consistent with the body size distribution pattern observed in marine bivalves. Different biological and environmental factors that vary between foraminifera suborders, such as life habitats, behaviors, and physiology, might have a greater influence on body size distributions.

  8. Latitudinal and Seasonal Investigations of Storm-Time TEC Variation

    NASA Astrophysics Data System (ADS)

    Adimula, I. A.; Oladipo, O. A.; Adebiyi, S. J.

    2016-07-01

    The ionosphere responds markedly and unpredictably to varying magnetospheric energy inputs caused by solar disturbances on the geospace. Knowledge of the impact of the space weather events on the ionosphere is important to assess the environmental effect on the operations of ground- and space-based technologies. Thus, global positioning system (GPS) measurements from the international GNSS service (IGS) database were used to investigate the ionospheric response to 56 geomagnetic storm events at six different latitudes comprising the northern and southern hemispheres in the Afro-European sector. Statistical distributions of total electron content (TEC) response show that during the main phase of the storms, enhancement of TEC is more pronounced in most of the seasons, regardless of the latitude and hemisphere. However, a strong seasonal dependence appears in the TEC response during the recovery phase. Depletion of TEC is majorly observed at the high latitude stations, and its appearance at lower latitudes is seasonally dependent. In summer hemisphere, the depletion of TEC is more pronounced in nearly all the latitudinal bands. In winter hemisphere, enhancement as well as depletion of TEC is observed over the high latitude, while enhancement is majorly observed over the mid and low latitudes. In equinoxes, the storm-time TEC distribution shows a fairly consistent characteristic with the summer distribution, particularly in the northern hemisphere.

  9. Effect of continental sources and sinks on the seasonal and latitudinal gradient of atmospheric carbon dioxide over East Asia

    NASA Astrophysics Data System (ADS)

    Shim, Changsub; Lee, Jeongsoon; Wang, Yuxuan

    2013-11-01

    Here we demonstrate the sharp seasonal and latitudinal gradient of atmospheric CO2 over East Asia, where there are relatively few ground-based observations. The Greenhouse gases Observing SATellite (GOSAT) column-averaged dry air CO2 mole fraction (xCO2) retrieved by NASA's Atmospheric CO2 Observations from Space (ACOS) (2009-2011) program and GEOS-Chem nested-grid CO2 results are used. The strong anthropogenic emissions mainly from China and intensive vegetation uptake from northeastern Asia lead to a clear seasonal change of the xCO2 between spring maximum and summer minimum (>10 ppm). In particular, the steep latitudinal gradient of summer time xCO2 by 3-5 ppm in the vicinity of the Korean Peninsula (32°N-44°N) is likely attributed to the large difference in CO2 fluxes among industry/cities, northeastern forests and the northwest Pacific region. This study represents the current progress to understand sub-continental scale atmospheric CO2 variabilities with recent satellite retrievals and nested-grid modeling.

  10. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1984-01-01

    Procedures for two demonstrations are presented. The first is a demonstration of chemiluminescence. The second is a demonstration using a secondary battery constructed from common household articles. (JN)

  11. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1978-01-01

    Presents the following chemistry lecture demonstrations and experiments: (1) a versatile kinetic demonstration; (2) the Bakelite Demonstration; (3) applying Beer's law; and (4) entropy calculations. (HM)

  12. Zooplankton grazing in the Atlantic Ocean: A latitudinal study

    NASA Astrophysics Data System (ADS)

    Calbet, Albert; Atienza, Dacha; Henriksen, Casper I.; Saiz, Enric; Adey, Timothy R.

    2009-07-01

    Mesozooplankton and 63-200 μm net-collected microzooplankton grazing on phytoplankton and protozoans was evaluated by 24-h incubations on a latitudinal transect in the Atlantic Ocean, from 35°N to 38°S (AMT-15; September-October 2004). The sampling area comprised contrasting ecosystems, including upwelling zones and oligotrophic subtropical gyres. Grazing impacts of mesozooplankton and 63-200 μm microzooplankton on total chlorophyll a (Chl a), >5 μm Chl a, ciliates, and dinoflagellates were low for both zooplankton size fractions, always removing<1.5% of the standing stocks of these groups. Grazing had a slightly greater impact upon primary production (up to 10% of primary production consumed daily), although on most occasions grazing removed<1% of primary production per day. To account for the reduction of micrograzers by predators in the experimental bottles and the consequent reduction of grazing pressure, the data were corrected with knowledge on the decrease of microzooplankton during incubations and global estimates of microzooplankton grazing. The corrected grazing rates for mesozooplankton ranged from 4% to 28% of the primary production consumed daily, and from 1% to 2% of the standing stock of Chl a removed every day. The 63-200 μm microzooplankton corrected grazing impact was always<5% of the primary production and standing stock consumed per day. The corrected grazing activity of 63-200 μm microzooplankton and mesozooplankton rendered daily rations ranging from 3% to 38% of the body carbon consumed daily, not sufficient for basal metabolism in most of the areas studied. Finally, the data on mesozooplankton grazing on primary production confirm the recent hypothesis of a decline of the relative importance of mesozooplankton grazing on primary producers with increasing primary production [Calbet, A., 2001. Mesozooplankton grazing effect on primary production: a global comparative analysis in marine ecosystems. Limnology and Oceanography 46, 1824-1830].

  13. Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics.

    PubMed

    Mainwaring, Mark C; Deeming, D Charles; Jones, Chris I; Hartley, Ian R

    2014-03-01

    Nest construction is taxonomically widespread, yet our understanding of adaptive intraspecific variation in nest design remains poor. Nest characteristics are expected to vary adaptively in response to predictable variation in spring temperatures over large spatial scales, yet such variation in nest design remains largely overlooked, particularly amongst open-cup-nesting birds. Here, we systematically examined the effects of latitudinal variation in spring temperatures and precipitation on the morphology, volume, composition, and insulatory properties of open-cup-nesting Common Blackbirds' Turdus merula nests to test the hypothesis that birds living in cooler environments at more northerly latitudes would build better insulated nests than conspecifics living in warmer environments at more southerly latitudes. As spring temperatures increased with decreasing latitude, the external diameter of nests decreased. However, as nest wall thickness also decreased, there was no variation in the diameter of the internal nest cups. Only the mass of dry grasses within nests decreased with warmer temperatures at lower latitudes. The insulatory properties of nests declined with warmer temperatures at lower latitudes and nests containing greater amounts of dry grasses had higher insulatory properties. The insulatory properties of nests decreased with warmer temperatures at lower latitudes, via changes in morphology (wall thickness) and composition (dry grasses). Meanwhile, spring precipitation did not vary with latitude, and none of the nest characteristics varied with spring precipitation. This suggests that Common Blackbirds nesting at higher latitudes were building nests with thicker walls in order to counteract the cooler temperatures. We have provided evidence that the nest construction behavior of open-cup-nesting birds systematically varies in response to large-scale spatial variation in spring temperatures. PMID:24683466

  14. Regularized GRACE monthly solutions by constraining the difference between the longitudinal and latitudinal gravity variations

    NASA Astrophysics Data System (ADS)

    Chen, Qiujie; Chen, Wu; Shen, Yunzhong; Zhang, Xingfu; Hsu, Houze

    2016-04-01

    The existing unconstrained Gravity Recovery and Climate Experiment (GRACE) monthly solutions i.e. CSR RL05 from Center for Space Research (CSR), GFZ RL05a from GeoForschungsZentrum (GFZ), JPL RL05 from Jet Propulsion Laboratory (JPL), DMT-1 from Delft Institute of Earth Observation and Space Systems (DEOS), AIUB from Bern University, and Tongji-GRACE01 as well as Tongji-GRACE02 from Tongji University, are dominated by correlated noise (such as north-south stripe errors) in high degree coefficients. To suppress the correlated noise of the unconstrained GRACE solutions, one typical option is to use post-processing filters such as decorrelation filtering and Gaussian smoothing , which are quite effective to reduce the noise and convenient to be implemented. Unlike these post-processing methods, the CNES/GRGS monthly GRACE solutions from Centre National d'Etudes Spatiales (CNES) were developed by using regularization with Kaula rule, whose correlated noise are reduced to such a great extent that no decorrelation filtering is required. Actually, the previous studies demonstrated that the north-south stripes in the GRACE solutions are due to the poor sensitivity of gravity variation in east-west direction. In other words, the longitudinal sampling of GRACE mission is very sparse but the latitudinal sampling of GRACE mission is quite dense, indicating that the recoverability of the longitudinal gravity variation is poor or unstable, leading to the ill-conditioned monthly GRACE solutions. To stabilize the monthly solutions, we constructed the regularization matrices by minimizing the difference between the longitudinal and latitudinal gravity variations and applied them to derive a time series of regularized GRACE monthly solutions named RegTongji RL01 for the period Jan. 2003 to Aug. 2011 in this paper. The signal powers and noise level of RegTongji RL01 were analyzed in this paper, which shows that: (1) No smoothing or decorrelation filtering is required for RegTongji RL

  15. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    Details three demonstrations for use in chemistry classrooms. Includes: "A Demonstration of Corrosion by Differential Aeration"; "A Simple Demonstration of the Activation Energy Concept"; and "A Boiling Demonstration at Room Temperature." Each description includes equipment, materials, and methods. (CW)

  16. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    Describes two chemistry demonstrations including a demonstration of chemical inhibition and "The Rayleigh Fountain" which demonstrates the polarity of the water molecule. Provides instructions and explanations for each demonstration. (CW)

  17. The mossy north: an inverse latitudinal diversity gradient in European bryophytes.

    PubMed

    Mateo, Rubén G; Broennimann, Olivier; Normand, Signe; Petitpierre, Blaise; Araújo, Miguel B; Svenning, Jens-C; Baselga, Andrés; Fernández-González, Federico; Gómez-Rubio, Virgilio; Muñoz, Jesús; Suarez, Guillermo M; Luoto, Miska; Guisan, Antoine; Vanderpoorten, Alain

    2016-01-01

    It remains hotly debated whether latitudinal diversity gradients are common across taxonomic groups and whether a single mechanism can explain such gradients. Investigating species richness (SR) patterns of European land plants, we determine whether SR increases with decreasing latitude, as predicted by theory, and whether the assembly mechanisms differ among taxonomic groups. SR increases towards the south in spermatophytes, but towards the north in ferns and bryophytes. SR patterns in spermatophytes are consistent with their patterns of beta diversity, with high levels of nestedness and turnover in the north and in the south, respectively, indicating species exclusion towards the north and increased opportunities for speciation in the south. Liverworts exhibit the highest levels of nestedness, suggesting that they represent the most sensitive group to the impact of past climate change. Nevertheless, although the extent of liverwort species turnover in the south is substantially and significantly lower than in spermatophytes, liverworts share with the latter a higher nestedness in the north and a higher turn-over in the south, in contrast to mosses and ferns. The extent to which the similarity in the patterns displayed by spermatophytes and liverworts reflects a similar assembly mechanism remains, however, to be demonstrated. PMID:27151094

  18. Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

    PubMed

    Gaitán-Espitia, Juan Diego; Bacigalupe, Leonardo D; Opitz, Tania; Lagos, Nelson A; Timmermann, Tania; Lardies, Marco A

    2014-12-15

    Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions. Our study found that populations of P. violaceus show no differences in the limits of their thermal performance curves and demonstrate a negative correlation of their optimal temperatures with latitude. Additionally, our findings show that high-latitude populations of P. violaceus exhibit broader thermal tolerances, which is consistent with the climatic variability hypothesis. Interestingly, under a future scenario of warming oceans, the thermal safety margins of P. violaceus indicate that lower latitude populations can physiologically tolerate the ocean-warming scenarios projected by the IPCC for the end of the twenty-first century.

  19. Scots pine fine roots adjust along a 2000-km latitudinal climatic gradient.

    PubMed

    Zadworny, Marcin; McCormack, M Luke; Mucha, Joanna; Reich, Peter B; Oleksyn, Jacek

    2016-10-01

    Patterns of plant biomass allocation and functional adjustments along climatic gradients are poorly understood, particularly belowground. Generally, low temperatures suppress nutrient release and uptake, and forests under such conditions have a greater proportion of their biomass in roots. However, it is not clear whether 'more roots' means better capacity to acquire soil resources. Herein we quantified patterns of fine-root anatomy and their biomass distribution across Scots pine (Pinus sylvestris) populations both along a 2000-km latitudinal gradient and within a common garden experiment with a similar range of populations. We found that with decreasing mean temperature, a greater percentage of Scots pine root biomass was allocated to roots with higher potential absorptive capacity. Similar results were seen in the common experimental site, where cold-adapted populations produced roots with greater absorptive capacity than populations originating from warmer climates. These results demonstrate that plants growing in or originated from colder climates have more acquisitive roots, a trait that is likely adaptive in the face of the low resource availability typical of cold soils. PMID:27301778

  20. Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

    PubMed

    Gaitán-Espitia, Juan Diego; Bacigalupe, Leonardo D; Opitz, Tania; Lagos, Nelson A; Timmermann, Tania; Lardies, Marco A

    2014-12-15

    Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions. Our study found that populations of P. violaceus show no differences in the limits of their thermal performance curves and demonstrate a negative correlation of their optimal temperatures with latitude. Additionally, our findings show that high-latitude populations of P. violaceus exhibit broader thermal tolerances, which is consistent with the climatic variability hypothesis. Interestingly, under a future scenario of warming oceans, the thermal safety margins of P. violaceus indicate that lower latitude populations can physiologically tolerate the ocean-warming scenarios projected by the IPCC for the end of the twenty-first century. PMID:25394627

  1. The mossy north: an inverse latitudinal diversity gradient in European bryophytes.

    PubMed

    Mateo, Rubén G; Broennimann, Olivier; Normand, Signe; Petitpierre, Blaise; Araújo, Miguel B; Svenning, Jens-C; Baselga, Andrés; Fernández-González, Federico; Gómez-Rubio, Virgilio; Muñoz, Jesús; Suarez, Guillermo M; Luoto, Miska; Guisan, Antoine; Vanderpoorten, Alain

    2016-05-06

    It remains hotly debated whether latitudinal diversity gradients are common across taxonomic groups and whether a single mechanism can explain such gradients. Investigating species richness (SR) patterns of European land plants, we determine whether SR increases with decreasing latitude, as predicted by theory, and whether the assembly mechanisms differ among taxonomic groups. SR increases towards the south in spermatophytes, but towards the north in ferns and bryophytes. SR patterns in spermatophytes are consistent with their patterns of beta diversity, with high levels of nestedness and turnover in the north and in the south, respectively, indicating species exclusion towards the north and increased opportunities for speciation in the south. Liverworts exhibit the highest levels of nestedness, suggesting that they represent the most sensitive group to the impact of past climate change. Nevertheless, although the extent of liverwort species turnover in the south is substantially and significantly lower than in spermatophytes, liverworts share with the latter a higher nestedness in the north and a higher turn-over in the south, in contrast to mosses and ferns. The extent to which the similarity in the patterns displayed by spermatophytes and liverworts reflects a similar assembly mechanism remains, however, to be demonstrated.

  2. The mossy north: an inverse latitudinal diversity gradient in European bryophytes

    NASA Astrophysics Data System (ADS)

    Mateo, Rubén G.; Broennimann, Olivier; Normand, Signe; Petitpierre, Blaise; Araújo, Miguel B.; Svenning, Jens-C.; Baselga, Andrés; Fernández-González, Federico; Gómez-Rubio, Virgilio; Muñoz, Jesús; Suarez, Guillermo M.; Luoto, Miska; Guisan, Antoine; Vanderpoorten, Alain

    2016-05-01

    It remains hotly debated whether latitudinal diversity gradients are common across taxonomic groups and whether a single mechanism can explain such gradients. Investigating species richness (SR) patterns of European land plants, we determine whether SR increases with decreasing latitude, as predicted by theory, and whether the assembly mechanisms differ among taxonomic groups. SR increases towards the south in spermatophytes, but towards the north in ferns and bryophytes. SR patterns in spermatophytes are consistent with their patterns of beta diversity, with high levels of nestedness and turnover in the north and in the south, respectively, indicating species exclusion towards the north and increased opportunities for speciation in the south. Liverworts exhibit the highest levels of nestedness, suggesting that they represent the most sensitive group to the impact of past climate change. Nevertheless, although the extent of liverwort species turnover in the south is substantially and significantly lower than in spermatophytes, liverworts share with the latter a higher nestedness in the north and a higher turn-over in the south, in contrast to mosses and ferns. The extent to which the similarity in the patterns displayed by spermatophytes and liverworts reflects a similar assembly mechanism remains, however, to be demonstrated.

  3. The mossy north: an inverse latitudinal diversity gradient in European bryophytes

    PubMed Central

    Mateo, Rubén G.; Broennimann, Olivier; Normand, Signe; Petitpierre, Blaise; Araújo, Miguel B.; Svenning, Jens-C.; Baselga, Andrés; Fernández-González, Federico; Gómez-Rubio, Virgilio; Muñoz, Jesús; Suarez, Guillermo M.; Luoto, Miska; Guisan, Antoine; Vanderpoorten, Alain

    2016-01-01

    It remains hotly debated whether latitudinal diversity gradients are common across taxonomic groups and whether a single mechanism can explain such gradients. Investigating species richness (SR) patterns of European land plants, we determine whether SR increases with decreasing latitude, as predicted by theory, and whether the assembly mechanisms differ among taxonomic groups. SR increases towards the south in spermatophytes, but towards the north in ferns and bryophytes. SR patterns in spermatophytes are consistent with their patterns of beta diversity, with high levels of nestedness and turnover in the north and in the south, respectively, indicating species exclusion towards the north and increased opportunities for speciation in the south. Liverworts exhibit the highest levels of nestedness, suggesting that they represent the most sensitive group to the impact of past climate change. Nevertheless, although the extent of liverwort species turnover in the south is substantially and significantly lower than in spermatophytes, liverworts share with the latter a higher nestedness in the north and a higher turn-over in the south, in contrast to mosses and ferns. The extent to which the similarity in the patterns displayed by spermatophytes and liverworts reflects a similar assembly mechanism remains, however, to be demonstrated. PMID:27151094

  4. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    Describes three flame test demonstrations including "Student-Presented Demonstrations on the Colors of Transition Metal Complexes,""A Flame Test Demonstration Device," and "Vivid Flame Tests." Preparation and procedures are discussed. Included in the first demonstration is an evaluation scheme for grading student demonstrations. (CW)

  5. Latitudinal concordance between biogeographic regionalization, community structure, and richness patterns: a study on the reptiles of China.

    PubMed

    Chen, Youhua; Srivastava, Diane S

    2015-02-01

    Latitudinal patterns in species richness may be affected by both continuous variations in macroecological factors as well as discrete change between biogeographic regions. We examined whether latitudinal reptilian richness and community structure in China were best explained by three macroecological patterns (mid-domain effects, Rapoport's rule effects, or environmental correlates) within or across the ranges of biogeographic realms. The results showed that (1) there was a weak mid-domain effect within the Oriental Realm. However, the mid-domain effect was detected neither at the overall regional scale nor in the Palaearctic Realm. (2) Rapoport's rule was only weakly supported for reptilian fauna in China at lower latitudinal areas. (3) Environmental variables were more strongly correlated with species' latitudinal community structure and richness patterns at the scale of biogeographic realms. Based on the faunal similarity of reptilian community across latitudinal bands, we proposed a latitudinal delineation scheme at 34° N for dividing East Asia into Oriental and Palaearctic biogeographic realms. At last, at the functional group level, we also evaluated the relevant ecological patterns for lizard and snake species across different latitudinal bins, showing that the distributions of lizards presented strong mid-domain effects at the latitudinal ranges within the Oriental Realm and over the whole range but did not support Rapoport's rule. In comparison, snake species supported Rapoport's rule at low latitudinal zones but did not present any remarkable mid-domain effects at any spatial extents. In conclusion, biogeographic realms are an appropriate scale for studying macroecological patterns. Reptilian latitudinal richness patterns of China were explained by a combination of environmental factors and geometric constraints, while the latitudinal community structure patterns were greatly affected by environmental gradients. Functional guilds present differentiated

  6. Latitudinal concordance between biogeographic regionalization, community structure, and richness patterns: a study on the reptiles of China

    NASA Astrophysics Data System (ADS)

    Chen, Youhua; Srivastava, Diane S.

    2015-02-01

    Latitudinal patterns in species richness may be affected by both continuous variations in macroecological factors as well as discrete change between biogeographic regions. We examined whether latitudinal reptilian richness and community structure in China were best explained by three macroecological patterns (mid-domain effects, Rapoport's rule effects, or environmental correlates) within or across the ranges of biogeographic realms. The results showed that (1) there was a weak mid-domain effect within the Oriental Realm. However, the mid-domain effect was detected neither at the overall regional scale nor in the Palaearctic Realm. (2) Rapoport's rule was only weakly supported for reptilian fauna in China at lower latitudinal areas. (3) Environmental variables were more strongly correlated with species' latitudinal community structure and richness patterns at the scale of biogeographic realms. Based on the faunal similarity of reptilian community across latitudinal bands, we proposed a latitudinal delineation scheme at 34° N for dividing East Asia into Oriental and Palaearctic biogeographic realms. At last, at the functional group level, we also evaluated the relevant ecological patterns for lizard and snake species across different latitudinal bins, showing that the distributions of lizards presented strong mid-domain effects at the latitudinal ranges within the Oriental Realm and over the whole range but did not support Rapoport's rule. In comparison, snake species supported Rapoport's rule at low latitudinal zones but did not present any remarkable mid-domain effects at any spatial extents. In conclusion, biogeographic realms are an appropriate scale for studying macroecological patterns. Reptilian latitudinal richness patterns of China were explained by a combination of environmental factors and geometric constraints, while the latitudinal community structure patterns were greatly affected by environmental gradients. Functional guilds present differentiated

  7. Latitudinal distribution of prokaryotic picoplankton populations in the Atlantic Ocean.

    PubMed

    Schattenhofer, Martha; Fuchs, Bernhard M; Amann, Rudolf; Zubkov, Mikhail V; Tarran, Glen A; Pernthaler, Jakob

    2009-08-01

    Members of the prokaryotic picoplankton are the main drivers of the biogeochemical cycles over large areas of the world's oceans. In order to ascertain changes in picoplankton composition in the euphotic and twilight zones at an ocean basin scale we determined the distribution of 11 marine bacterial and archaeal phyla in three different water layers along a transect across the Atlantic Ocean from South Africa (32.9 degrees S) to the UK (46.4 degrees N) during boreal spring. Depth profiles down to 500 m at 65 stations were analysed by catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and automated epifluorescence microscopy. There was no obvious overall difference in microbial community composition between the surface water layer and the deep chlorophyll maximum (DCM) layer. There were, however, significant differences between the two photic water layers and the mesopelagic zone. SAR11 (35 +/- 9%) and Prochlorococcus (12 +/- 8%) together dominated the surface waters, whereas SAR11 and Crenarchaeota of the marine group I formed equal proportions of the picoplankton community below the DCM (both approximately 15%). However, due to their small cell sizes Crenarchaeota contributed distinctly less to total microbial biomass than SAR11 in this mesopelagic water layer. Bacteria from the uncultured Chloroflexi-related clade SAR202 occurred preferentially below the DCM (4-6%). Distinct latitudinal distribution patterns were found both in the photic zone and in the mesopelagic waters: in the photic zone, SAR11 was more abundant in the Northern Atlantic Ocean (up to 45%) than in the Southern Atlantic gyre (approximately 25%), the biomass of Prochlorococcus peaked in the tropical Atlantic Ocean, and Bacteroidetes and Gammaproteobacteria bloomed in the nutrient-rich northern temperate waters and in the Benguela upwelling. In mesopelagic waters, higher proportions of SAR202 were present in both central gyre regions, whereas Crenarchaeota were clearly

  8. Pluto's Insolation History: Latitudinal Variations and Effects on Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.

    2014-11-01

    Since previous insolation modeling in the early 1990’s, new atmospheric pressure data, increased computational power, and the upcoming flyby of the Pluto system by NASA’s New Horizons spacecraft have generated new motivation and increased capabilities for the study of Pluto’s complex long-term (million-years) insolation history. The two primary topics of interest in studying Pluto’s insolation history are the variations in insolation patterns when integrated over different intervals and the evolution of diurnal insolation patterns over the last several decades. We find latitudinal dichotomies when comparing average insolation over timescales of days, decades, centuries, and millennia. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. For any single rotation of Pluto there is a latitude that receives more insolation relative to the others. Often this is the sub-subsolar latitude but it can also be an arctic circle latitude when near-polar regions of Pluto experience the "midnight sun". We define the amount of that greatest insolation value over the course of one rotation as the "maximum diurnal insolation" (MDI). We find that MDI is driven to its highest values when Pluto’s obliquity creates a long arctic summer (or “midnight sun”) beginning just after perihelion. Pluto’s atmospheric pressure, as measured through stellar occultation observations during the past three decades, appears to correlate with Pluto's currently occurring midnight sun as quantified by the MDI parameter. If insolation (as parameterized by the MDI value) is the single dominant factor driving Pluto's atmospheric pressure, this “Midnight Sun Model” predicts that Pluto's maximum atmospheric pressure will be reached in 2017 followed by a steady decline. Pluto's maximum diurnal insolation value begins dropping after 2017 due to two factors: Pluto’s sub-solar point

  9. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1982-01-01

    Three chemistry demonstrations are described: (1) partition coefficients; (2) Rutherford simulation experiment; and (3) demonstration of the powerful oxidizing property of dimanganeseheptoxide. Background information, materials needed, and procedures are provided for each demonstration. (JN)

  10. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Presented are three demonstrations for chemical education. The activities include: (1) demonstration of vapor pressure; (2) a multicolored luminol-based chemiluminescence demonstration; and (3) a Charles's Law/Vapor pressure apparatus. (RH)

  11. Reflectance Demonstration.

    ERIC Educational Resources Information Center

    Kowalski, Frank

    1993-01-01

    Presents a demonstration in which a mirror "disappears" upon rotation. The author has used the demonstration with students from fourth grade up through college. Suggestions are given for making the demonstration into a permanent hallway display. (MVL)

  12. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1981-01-01

    Provides procedures for demonstrations: (1) the ferrioxalate actinometer, which demonstrates a photochemical reaction; and (2) the silver mirror, which demonstrates the reduction of a metal salt to the metal and/or the reducing power of sugars. (CS)

  13. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    This article details two demonstrations involving color changes. Included are "Manganese Color Reactions" and "Flame Colors Demonstration." Include a list of materials needed, procedures, cautions, and results. (CW)

  14. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1985-01-01

    Background information (including chemical reactions) and procedures used are provided for (1) three buffer demonstrations and (2) a demonstration of phase transfer catalysis and carbanion formation. (JN)

  15. Tested Demonstrations

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1977-01-01

    Three demonstrations are described: paramagnetic properties of Fe(11) and Fe(111), the preparation of polyurethane foam: a lecture demonstration and the electrolysis of water-fuel cell reactions. A small discussion of the concepts demonstrated is included in each demonstration's description. (MR)

  16. Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics.

    PubMed

    Martinez-Bakker, Micaela; Bakker, Kevin M; King, Aaron A; Rohani, Pejman

    2014-05-22

    More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infected-recovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity. PMID:24695423

  17. Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

    PubMed Central

    Martinez-Bakker, Micaela; Bakker, Kevin M.; King, Aaron A.; Rohani, Pejman

    2014-01-01

    More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infected-recovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity. PMID:24695423

  18. Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics.

    PubMed

    Martinez-Bakker, Micaela; Bakker, Kevin M; King, Aaron A; Rohani, Pejman

    2014-05-22

    More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infected-recovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity.

  19. Global-scale latitudinal patterns of species diversity in the deep-sea benthos

    NASA Astrophysics Data System (ADS)

    Rex, Michael A.; Stuart, Carol T.; Hessler, Robert R.; Allen, John A.; Sanders, Howard L.; Wilson, George D. F.

    1993-10-01

    LATITUDINAL gradients of species diversity are ubiquitous features of terrestrial and coastal marine biotas, and they have inspired the development of theoretical ecology1-3. Since the discovery of high species diversity in the deep-sea benthos4, much has been learned about local5,6and regional7-9patterns of diversity. Variation in diversity on larger scales remains poorly described. Latitudinal gradients of diversity were unexpected because it was assumed that the environmental gradients that cause large-scale patterns in surface environments could not affect communities living at great depths10. Here we report that deep-sea bivalves, gastropods and isopods show clear latitudinal diversity gradients in the North Atlantic, and strong interregional variation in the South Atlantic. Many seemingly incompatible mechanisms have been proposed to explain deep-sea species diversity11. The existence of regular global patterns suggests that these mechanisms operate at different spatial and temporal scales.

  20. Average latitudinal variation in ultraviolet radiation at the earth's surface. [biological sensitivity and dosage

    NASA Technical Reports Server (NTRS)

    Johnson, F. S.; Mo, T.; Green, A. E. S.

    1976-01-01

    Tabulated values are presented for ultraviolet radiation at the earth's surface as a function of wavelength, latitude, and season, for clear sky and seasonally and latitudinally averaged ozone amounts. These tabulations can be combined with any biological sensitivity function in order to obtain the seasonal and latitudinal variation of the corresponding effective doses. The integrated dosages, based on the erythemal sensitivity curve and on the Robertson-Berger sunburn-meter sensitivity curve, have also been calculated, and these are found to vary with latitude and season in very nearly the same way as 307 and 314 nm radiation, respectively.

  1. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    Describes two demonstrations for college level chemistry courses including: "Electrochemical Cells Using Sodium Silicate" and "A Simple, Vivid Demonstration of Selective Precipitation." Lists materials, preparation, procedures, and precautions. (CW)

  2. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1981-01-01

    Two demonstrations are described: (1) red cabbage and electrolysis of water to bring together acid/base and electrochemical concepts; and (2) a model to demonstrate acid/base conjugate pairs utilizing magnets. (SK)

  3. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1981-01-01

    Presents: (1) a simple demonstration which illustrates the driving force of entropy using the familiar effects of the negative thermal expansion coefficient of rubber; and (2) a demonstration of tetrahedral bonding using soap films. (CS)

  4. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1989-01-01

    Presented are two demonstrations including a variation of the iodine clock reaction, and a simple demonstration of refractive index. The materials, procedures, and a discussion of probable results are given for each. (CW)

  5. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1990-01-01

    Presented are two demonstrations; "Heat of Solution and Colligative Properties: An Illustration of Enthalpy and Entropy," and "A Vapor Pressure Demonstration." Included are lists of materials and experimental procedures. Apparatus needed are illustrated. (CW)

  6. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1978-01-01

    Presents two demonstrations; one on Boyle's Law, to illustrate the gas law and serve as a challenging problem for the students; the other is a modified Color Blind Traffic Light demonstration in which the oscillating reactions were speeded up. (GA)

  7. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Provides instructions on conducting four demonstrations for the chemistry classroom. Outlines procedures for demonstrations dealing with coupled oscillations, the evaporation of liquids, thioxanthone sulfone radical anion, and the control of variables and conservation of matter. (TW)

  8. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1978-01-01

    Two demonstrations are described which are suitable for introductory chemistry classes. The first involves the precipitation of silver, and the second is a demonstration of the relationship between rate constants and equilibrium constants using water and beakers. (BB)

  9. Demonstrating Diffusion

    ERIC Educational Resources Information Center

    Foy, Barry G.

    1977-01-01

    Two demonstrations are described. Materials and instructions for demonstrating movement of molecules into cytoplasm using agar blocks, phenolphthalein, and sodium hydroxide are given. A simple method for demonstrating that the rate of diffusion of a gas is inversely proportional to its molecular weight is also presented. (AJ)

  10. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Describes a demonstration involving the controlled combustion of a mixture of metals with black and smokeless powder in a small Erlenmeyer flask. Also describes demonstrations using a device that precludes breathing of hazardous vapors during class demonstrations; the device is easy to transport and use in rooms without sinks. (JN)

  11. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Describes two demonstrations used in laboratory chemistry courses. Discusses a "pH-activated" display used to chemically and visually supplement lecture demonstrations. Outlines another demonstration designed to show that copper(II) chloride is made of two ions, blue and yellow, which are combined to produce green. (TW)

  12. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Sands, Robert; And Others

    1982-01-01

    Procedures for two demonstrations are provided. The solubility of ammonia gas in water is demonstrated by introducing water into a closed can filled with the gas, collapsing the can. The second demonstration relates scale of standard reduction potentials to observed behavior of metals in reactions with hydrogen to produce hydrogen gas. (Author/JN)

  13. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Describes two classroom chemistry demonstrations which focus on the descriptive chemistry of bromine and iodine. Outlines the chemicals and equipment needed, experimental procedures, and discussion of one demonstration of the oxidation states of bromine and iodine, and another demonstration of the oxidation states of iodine. (TW)

  14. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1985-01-01

    List of materials needed, procedures used, and results obtained are provided for two demonstrations. The first is an inexpensive and quick method for demonstrating column chromatography of plant pigments of spinach extract. The second is a demonstration of cathodic protection by impressed current. (JN)

  15. Latitudinal variation in virus-induced mortality of phytoplankton across the North Atlantic Ocean.

    PubMed

    Mojica, Kristina D A; Huisman, Jef; Wilhelm, Steven W; Brussaard, Corina P D

    2016-02-01

    Viral lysis of phytoplankton constrains marine primary production, food web dynamics and biogeochemical cycles in the ocean. Yet, little is known about the biogeographical distribution of viral lysis rates across the global ocean. To address this, we investigated phytoplankton group-specific viral lysis rates along a latitudinal gradient within the North Atlantic Ocean. The data show large-scale distribution patterns of different virus groups across the North Atlantic that are associated with the biogeographical distributions of their potential microbial hosts. Average virus-mediated lysis rates of the picocyanobacteria Prochlorococcus and Synechococcus were lower than those of the picoeukaryotic and nanoeukaryotic phytoplankton (that is, 0.14 per day compared with 0.19 and 0.23 per day, respectively). Total phytoplankton mortality (virus plus grazer-mediated) was comparable to the gross growth rate, demonstrating high turnover rates of phytoplankton populations. Virus-induced mortality was an important loss process at low and mid latitudes, whereas phytoplankton mortality was dominated by microzooplankton grazing at higher latitudes (>56°N). This shift from a viral-lysis-dominated to a grazing-dominated phytoplankton community was associated with a decrease in temperature and salinity, and the decrease in viral lysis rates was also associated with increased vertical mixing at higher latitudes. Ocean-climate models predict that surface warming will lead to an expansion of the stratified and oligotrophic regions of the world's oceans. Our findings suggest that these future shifts in the regional climate of the ocean surface layer are likely to increase the contribution of viral lysis to phytoplankton mortality in the higher-latitude waters of the North Atlantic, which may potentially reduce transfer of matter and energy up the food chain and thus affect the capacity of the northern North Atlantic to act as a long-term sink for CO2. PMID:26262815

  16. Functional microarray analysis of nitrogen and carbon cycling genes across an Antarctic latitudinal transect.

    PubMed

    Yergeau, Etienne; Kang, Sanghoon; He, Zhili; Zhou, Jizhong; Kowalchuk, George A

    2007-06-01

    Soil-borne microbial communities were examined via a functional gene microarray approach across a southern polar latitudinal gradient to gain insight into the environmental factors steering soil N- and C-cycling in terrestrial Antarctic ecosystems. The abundance and diversity of functional gene families were studied for soil-borne microbial communities inhabiting a range of environments from 51 degrees S (cool temperate-Falkland Islands) to 72 degrees S (cold rock desert-Coal Nunatak). The recently designed functional gene array used contains 24,243 oligonucleotide probes and covers >10,000 genes in >150 functional groups involved in nitrogen, carbon, sulfur and phosphorus cycling, metal reduction and resistance and organic contaminant degradation (He et al. 2007). The detected N- and C-cycle genes were significantly different across different sampling locations and vegetation types. A number of significant trends were observed regarding the distribution of key gene families across the environments examined. For example, the relative detection of cellulose degradation genes was correlated with temperature, and microbial C-fixation genes were more present in plots principally lacking vegetation. With respect to the N-cycle, denitrification genes were linked to higher soil temperatures, and N2-fixation genes were linked to plots mainly vegetated by lichens. These microarray-based results were confirmed for a number of gene families using specific real-time PCR, enzymatic assays and process rate measurements. The results presented demonstrate the utility of an integrated functional gene microarray approach in detecting shifts in functional community properties in environmental samples and provide insight into the forces driving important processes of terrestrial Antarctic nutrient cycling. PMID:18043626

  17. Latitudinal Variation of a Defensive Symbiosis in the Bugula neritina (Bryozoa) Sibling Species Complex

    PubMed Central

    Linneman, Jonathan; Paulus, Darcy; Lim-Fong, Grace; Lopanik, Nicole B.

    2014-01-01

    Mutualistic relationships are beneficial for both partners and are often studied within a single environment. However, when the range of the partners is large, geographical differences in selective pressure may shift the relationship outcome from positive to negative. The marine bryozoan Bugula neritina is a colonial invertebrate common in temperate waters worldwide. It is the source of bioactive polyketide metabolites, the bryostatins. Evidence suggests that an uncultured vertically transmitted symbiont, “Candidatus Endobugula sertula”, hosted by B. neritina produces the bryostatins, which protect the vulnerable larvae from predation. Studies of B. neritina along the North American Atlantic coast revealed a complex of two morphologically similar sibling species separated by an apparent biogeographic barrier: the Type S sibling species was found below Cape Hatteras, North Carolina, while Type N was found above. Interestingly, the Type N colonies lack “Ca. Endobugula sertula” and, subsequently, defensive bryostatins; their documented northern distribution was consistent with traditional biogeographical paradigms of latitudinal variation in predation pressure. Upon further sampling of B. neritina populations, we found that both host types occur in wider distribution, with Type N colonies living south of Cape Hatteras, and Type S to the north. Distribution of the symbiont, however, was not restricted to Type S hosts. Genetic and microscopic evidence demonstrates the presence of the symbiont in some Type N colonies, and larvae from these colonies are endowed with defensive bryostatins and contain “Ca. Endobugula sertula”. Molecular analysis of the symbiont from Type N colonies suggests an evolutionarily recent acquisition, which is remarkable for a symbiont thought to be transmitted only vertically. Furthermore, most Type S colonies found at higher latitudes lack the symbiont, suggesting that this host-symbiont relationship is more flexible than previously

  18. Latitudinal variation in virus-induced mortality of phytoplankton across the North Atlantic Ocean.

    PubMed

    Mojica, Kristina D A; Huisman, Jef; Wilhelm, Steven W; Brussaard, Corina P D

    2016-02-01

    Viral lysis of phytoplankton constrains marine primary production, food web dynamics and biogeochemical cycles in the ocean. Yet, little is known about the biogeographical distribution of viral lysis rates across the global ocean. To address this, we investigated phytoplankton group-specific viral lysis rates along a latitudinal gradient within the North Atlantic Ocean. The data show large-scale distribution patterns of different virus groups across the North Atlantic that are associated with the biogeographical distributions of their potential microbial hosts. Average virus-mediated lysis rates of the picocyanobacteria Prochlorococcus and Synechococcus were lower than those of the picoeukaryotic and nanoeukaryotic phytoplankton (that is, 0.14 per day compared with 0.19 and 0.23 per day, respectively). Total phytoplankton mortality (virus plus grazer-mediated) was comparable to the gross growth rate, demonstrating high turnover rates of phytoplankton populations. Virus-induced mortality was an important loss process at low and mid latitudes, whereas phytoplankton mortality was dominated by microzooplankton grazing at higher latitudes (>56°N). This shift from a viral-lysis-dominated to a grazing-dominated phytoplankton community was associated with a decrease in temperature and salinity, and the decrease in viral lysis rates was also associated with increased vertical mixing at higher latitudes. Ocean-climate models predict that surface warming will lead to an expansion of the stratified and oligotrophic regions of the world's oceans. Our findings suggest that these future shifts in the regional climate of the ocean surface layer are likely to increase the contribution of viral lysis to phytoplankton mortality in the higher-latitude waters of the North Atlantic, which may potentially reduce transfer of matter and energy up the food chain and thus affect the capacity of the northern North Atlantic to act as a long-term sink for CO2.

  19. Functional microarray analysis of nitrogen and carbon cycling genes across an Antarctic latitudinal transect.

    PubMed

    Yergeau, Etienne; Kang, Sanghoon; He, Zhili; Zhou, Jizhong; Kowalchuk, George A

    2007-06-01

    Soil-borne microbial communities were examined via a functional gene microarray approach across a southern polar latitudinal gradient to gain insight into the environmental factors steering soil N- and C-cycling in terrestrial Antarctic ecosystems. The abundance and diversity of functional gene families were studied for soil-borne microbial communities inhabiting a range of environments from 51 degrees S (cool temperate-Falkland Islands) to 72 degrees S (cold rock desert-Coal Nunatak). The recently designed functional gene array used contains 24,243 oligonucleotide probes and covers >10,000 genes in >150 functional groups involved in nitrogen, carbon, sulfur and phosphorus cycling, metal reduction and resistance and organic contaminant degradation (He et al. 2007). The detected N- and C-cycle genes were significantly different across different sampling locations and vegetation types. A number of significant trends were observed regarding the distribution of key gene families across the environments examined. For example, the relative detection of cellulose degradation genes was correlated with temperature, and microbial C-fixation genes were more present in plots principally lacking vegetation. With respect to the N-cycle, denitrification genes were linked to higher soil temperatures, and N2-fixation genes were linked to plots mainly vegetated by lichens. These microarray-based results were confirmed for a number of gene families using specific real-time PCR, enzymatic assays and process rate measurements. The results presented demonstrate the utility of an integrated functional gene microarray approach in detecting shifts in functional community properties in environmental samples and provide insight into the forces driving important processes of terrestrial Antarctic nutrient cycling.

  20. Latitudinal variation of a defensive symbiosis in the Bugula neritina (Bryozoa) sibling species complex.

    PubMed

    Linneman, Jonathan; Paulus, Darcy; Lim-Fong, Grace; Lopanik, Nicole B

    2014-01-01

    Mutualistic relationships are beneficial for both partners and are often studied within a single environment. However, when the range of the partners is large, geographical differences in selective pressure may shift the relationship outcome from positive to negative. The marine bryozoan Bugula neritina is a colonial invertebrate common in temperate waters worldwide. It is the source of bioactive polyketide metabolites, the bryostatins. Evidence suggests that an uncultured vertically transmitted symbiont, "Candidatus Endobugula sertula", hosted by B. neritina produces the bryostatins, which protect the vulnerable larvae from predation. Studies of B. neritina along the North American Atlantic coast revealed a complex of two morphologically similar sibling species separated by an apparent biogeographic barrier: the Type S sibling species was found below Cape Hatteras, North Carolina, while Type N was found above. Interestingly, the Type N colonies lack "Ca. Endobugula sertula" and, subsequently, defensive bryostatins; their documented northern distribution was consistent with traditional biogeographical paradigms of latitudinal variation in predation pressure. Upon further sampling of B. neritina populations, we found that both host types occur in wider distribution, with Type N colonies living south of Cape Hatteras, and Type S to the north. Distribution of the symbiont, however, was not restricted to Type S hosts. Genetic and microscopic evidence demonstrates the presence of the symbiont in some Type N colonies, and larvae from these colonies are endowed with defensive bryostatins and contain "Ca. Endobugula sertula". Molecular analysis of the symbiont from Type N colonies suggests an evolutionarily recent acquisition, which is remarkable for a symbiont thought to be transmitted only vertically. Furthermore, most Type S colonies found at higher latitudes lack the symbiont, suggesting that this host-symbiont relationship is more flexible than previously thought. Our

  1. Latitudinal variation of a defensive symbiosis in the Bugula neritina (Bryozoa) sibling species complex.

    PubMed

    Linneman, Jonathan; Paulus, Darcy; Lim-Fong, Grace; Lopanik, Nicole B

    2014-01-01

    Mutualistic relationships are beneficial for both partners and are often studied within a single environment. However, when the range of the partners is large, geographical differences in selective pressure may shift the relationship outcome from positive to negative. The marine bryozoan Bugula neritina is a colonial invertebrate common in temperate waters worldwide. It is the source of bioactive polyketide metabolites, the bryostatins. Evidence suggests that an uncultured vertically transmitted symbiont, "Candidatus Endobugula sertula", hosted by B. neritina produces the bryostatins, which protect the vulnerable larvae from predation. Studies of B. neritina along the North American Atlantic coast revealed a complex of two morphologically similar sibling species separated by an apparent biogeographic barrier: the Type S sibling species was found below Cape Hatteras, North Carolina, while Type N was found above. Interestingly, the Type N colonies lack "Ca. Endobugula sertula" and, subsequently, defensive bryostatins; their documented northern distribution was consistent with traditional biogeographical paradigms of latitudinal variation in predation pressure. Upon further sampling of B. neritina populations, we found that both host types occur in wider distribution, with Type N colonies living south of Cape Hatteras, and Type S to the north. Distribution of the symbiont, however, was not restricted to Type S hosts. Genetic and microscopic evidence demonstrates the presence of the symbiont in some Type N colonies, and larvae from these colonies are endowed with defensive bryostatins and contain "Ca. Endobugula sertula". Molecular analysis of the symbiont from Type N colonies suggests an evolutionarily recent acquisition, which is remarkable for a symbiont thought to be transmitted only vertically. Furthermore, most Type S colonies found at higher latitudes lack the symbiont, suggesting that this host-symbiont relationship is more flexible than previously thought. Our

  2. Ecological Genomics of Anopheles gambiae Along a Latitudinal Cline: A Population-Resequencing Approach

    PubMed Central

    Cheng, Changde; White, Bradley J.; Kamdem, Colince; Mockaitis, Keithanne; Costantini, Carlo; Hahn, Matthew W.; Besansky, Nora J.

    2012-01-01

    The association between fitness-related phenotypic traits and an environmental gradient offers one of the best opportunities to study the interplay between natural selection and migration. In cases in which specific genetic variants also show such clinal patterns, it may be possible to uncover the mutations responsible for local adaptation. The malaria vector, Anopheles gambiae, is associated with a latitudinal cline in aridity in Cameroon; a large inversion on chromosome 2L of this mosquito shows large differences in frequency along this cline, with high frequencies of the inverted karyotype present in northern, more arid populations and an almost complete absence of the inverted arrangement in southern populations. Here we use a genome resequencing approach to investigate patterns of population divergence along the cline. By sequencing pools of individuals from both ends of the cline as well as in the center of the cline—where the inversion is present in intermediate frequency—we demonstrate almost complete panmixia across collinear parts of the genome and high levels of differentiation in inverted parts of the genome. Sequencing of separate pools of each inversion arrangement in the center of the cline reveals large amounts of gene flux (i.e., gene conversion and double crossovers) even within inverted regions, especially away from the inversion breakpoints. The interplay between natural selection, migration, and gene flux allows us to identify several candidate genes responsible for the match between inversion frequency and environmental variables. These results, coupled with similar conclusions from studies of clinal variation in Drosophila, point to a number of important biological functions associated with local environmental adaptation. PMID:22209907

  3. Herbivory Differentially Affects Plant Fitness in Three Populations of the Perennial Herb Lythrum salicaria along a Latitudinal Gradient.

    PubMed

    Lehndal, Lina; Ågren, Jon

    2015-01-01

    Herbivory can negatively and selectively affect plant fitness by reducing growth, survival and reproductive output, thereby influencing plant population dynamics and evolution. Latitudinal variation in intensity of herbivory is common, but the extent to which it translates into corresponding variation in effects on plant performance is still poorly known. We tested the hypothesis that variation in the fitness-consequences of herbivory mirror differences in intensity of herbivory among three natural populations of the perennial herb Lythrum salicaria along a latitudinal gradient from southern to northernmost Sweden. We documented intensity of herbivory and examined its effect on survival, growth and reproductive output over two years by experimentally removing herbivores with insecticide. The intensity of herbivory and the effects of herbivory on plant fitness were strongest in the southern population, intermediate in the central population and weakest in the northern population. The mean proportion of the leaf area removed ranged from 11% in the southern to 3% in the northern population. Herbivore removal increased plant height 1.5-fold in the southern and 1.2-fold in the central population, the proportion plants flowering 4-fold in the southern and 2-fold in the central population, and seed production per flower 1.6-fold in the southern and 1.2-fold in the central population, but did not affect plant fitness in the northern population. Herbivore removal thus affected the relative fecundity of plants in the three populations: In the control, seed output per plant was 8.6 times higher in the northern population compared to the southern population, whereas after herbivore removal it was 2.5 times higher in the southern population. The results demonstrate that native herbivores may strongly affect the demographic structure of L. salicaria populations and thereby shape geographic patterns of seed production. They further suggest that the strength of herbivore

  4. Kangaroo tooth enamel oxygen and carbon isotope variation on a latitudinal transect in southern Australia: implications for palaeoenvironmental reconstruction.

    PubMed

    Brookman, Tom H; Ambrose, Stanley H

    2013-02-01

    Tooth enamel apatite carbonate carbon and oxygen isotope ratios of modern kangaroos (Macropus spp.) collected on a 900-km latitudinal transect spanning a C(3)-C(4) transition zone were analysed to create a reference set for palaeoenvironmental reconstruction in southern Australia. The carbon isotope composition of enamel carbonate reflects the proportional intake of C(3) and C(4) vegetation, and its oxygen isotope composition reflects that of ingested water. Tooth enamel forms incrementally, recording dietary and environmental changes during mineralisation. Analyses show only weak correlations between climate records and latitudinal changes in δ(13)C and δ(18)O. No species achieved the δ(13)C values (~-1.0 ‰) expected for 100 % C(4) grazing diets; kangaroos at low latitudes that are classified as feeding primarily on C(4) grasses (grazers) have δ(13)C of up to -3.5 ‰. In these areas, δ(13)C below -12 ‰ suggests a 100 % C(3) grass and/or leafy plant (browse) diet while animals from higher latitude have lower δ(13)C. Animals from semi-arid areas have δ(18)O of 34-40 ‰, while grazers from temperate areas have lower values (~28-30 ‰). Three patterns with implications for palaeoenvironmental reconstruction emerge: (1) all species in semi-arid areas regularly browse to supplement limited grass resources; (2) all species within an environmental zone have similar carbon and oxygen isotope compositions, meaning data from different kangaroo species can be pooled for palaeoenvironmental investigations; (3) relatively small regional environmental differences can be distinguished when δ(13)C and δ(18)O data are used together. These data demonstrate that diet-isotope and climate-isotope relationships should be evaluated in modern ecosystems before application to the regional fossil record.

  5. Herbivory Differentially Affects Plant Fitness in Three Populations of the Perennial Herb Lythrum salicaria along a Latitudinal Gradient

    PubMed Central

    Lehndal, Lina; Ågren, Jon

    2015-01-01

    Herbivory can negatively and selectively affect plant fitness by reducing growth, survival and reproductive output, thereby influencing plant population dynamics and evolution. Latitudinal variation in intensity of herbivory is common, but the extent to which it translates into corresponding variation in effects on plant performance is still poorly known. We tested the hypothesis that variation in the fitness-consequences of herbivory mirror differences in intensity of herbivory among three natural populations of the perennial herb Lythrum salicaria along a latitudinal gradient from southern to northernmost Sweden. We documented intensity of herbivory and examined its effect on survival, growth and reproductive output over two years by experimentally removing herbivores with insecticide. The intensity of herbivory and the effects of herbivory on plant fitness were strongest in the southern population, intermediate in the central population and weakest in the northern population. The mean proportion of the leaf area removed ranged from 11% in the southern to 3% in the northern population. Herbivore removal increased plant height 1.5-fold in the southern and 1.2-fold in the central population, the proportion plants flowering 4-fold in the southern and 2-fold in the central population, and seed production per flower 1.6-fold in the southern and 1.2-fold in the central population, but did not affect plant fitness in the northern population. Herbivore removal thus affected the relative fecundity of plants in the three populations: In the control, seed output per plant was 8.6 times higher in the northern population compared to the southern population, whereas after herbivore removal it was 2.5 times higher in the southern population. The results demonstrate that native herbivores may strongly affect the demographic structure of L. salicaria populations and thereby shape geographic patterns of seed production. They further suggest that the strength of herbivore

  6. Latitudinal gradients in tree ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon System

    NASA Astrophysics Data System (ADS)

    Szejner, Paul; Wright, William E.; Babst, Flurin; Belmecheri, Soumaya; Trouet, Valerie; Leavitt, Steven W.; Ehleringer, James R.; Monson, Russell K.

    2016-07-01

    The arrival of the North American Monsoon System (NAMS) terminates a presummer hyperarid period in the southwestern United States (U.S.), providing summer moisture that is favorable for forest growth. Montane forests in this region rely on winter snowpack to drive much of their growth; the extent to which they use NAMS moisture is uncertain. We addressed this by studying stable carbon and oxygen isotopes in earlywood and latewood from 11 sites along a latitudinal gradient extending from Arizona and New Mexico to Utah. This study provides the first regional perspective on the relative roles of winter versus summer precipitation as an ecophysiological resource. Here we present evidence that Ponderosa pine uses NAMS moisture differentially across this gradient. 13C/12C ratios suggest that photosynthetic water use efficiency during latewood formation is more sensitive to summer precipitation at the northern than at the southern sites. This is likely due to the fact that NAMS moisture provides sufficiently favorable conditions for tree photosynthesis and growth during most years in the southern sites, whereas the northern sites experience larger summer moisture variability, which in some years is limiting growth. Cellulose δ18O and δ13C values revealed that photoassimilates in the southern sites were produced under higher vapor pressure deficit conditions during spring compared to summer, demonstrating a previously underappreciated effect of seasonal differences in atmospheric humidity on tree ring isotope ratios. Our findings suggest that future changes in NAMS will potentially alter productivity and photosynthetic water use dynamics differentially along latitudinal gradients in southwestern U.S. montane forests.

  7. Influence of the Latitudinal Temperature Gradient on Soil Dust Concentration and Deposition in Greenland

    NASA Technical Reports Server (NTRS)

    Tegen, Ina; Rind, David

    2000-01-01

    To investigate the effects of changes in the latitudinal temperature gradient and the global mean temperature on dust concentration in the Northern Hemisphere, experiments with the GISS GCM (Goddard Institute for Space Studies General Circulation Model) are performed. The dust concentration over Greenland is calculated from sources in central and eastern Asia, which are integrated on-line in the model. The results show that an increase in the latitudinal temperature gradient increases both the Asian dust source strength and the concentration over Greenland. The source increase is the result of increased surface winds, and to a minor extent, the increase in Greenland dust is also associated with increased northward transport. Cooling the climate in addition to this increased gradient leads to a decrease in precipitation scavenging, which helps produce a further (slight) increase in Greenland dust in this experiment. Reducing the latitudinal gradient reduces the surface wind and hence the dust source, with a subsequent reduction in Greenland dust concentrations. Warming the climate in addition to this reduced gradient leads to a further reduction in Greenland dust due to enhanced precipitation scavenging. These results can be used to evaluate the relationship of Greenland ice core temperature changes to changes in the latitudinal and global temperatures.

  8. Influence of the Latitudinal Temperature Gradient on Soil Dust Concentration and Deposition in Greenland

    NASA Technical Reports Server (NTRS)

    Tegen, Ina; Rind, David

    2000-01-01

    To investigate the effects of changes in the latitudinal temperature gradient and the global mean temperature on dust concentration in the Northern Hemisphere, experiments with the Goddard Institute for Space Studies General Circulation Model (GISS GCM) are performed. The dust concentration over Greenland is calculated from sources in central and eastern Asia, which are integrated on-line in the model. The results show that an increase in the latitudinal temperature gradient increases both the Asian dust source strength and the concentration over Greenland. The source increase is the result of increased surface winds, and to a minor extent, the increase in Greenland dust is also associated with increased northward transport. Cooling the climate in addition to this increased gradient leads to a decrease in precipitation scavenging, which helps produce a further (slight) increase in Greenland dust in this experiment. Reducing the latitudinal gradient reduces the surface wind and hence the dust source, with a subsequent reduction in Greenland dust concentrations. Warming the climate in addition to this reduced gradient leads to a further reduction in Greenland dust due to enhanced precipitation scavenging. These results can be used to evaluate the relationship of Greenland ice core temperature changes to changes in the latitudinal and global temperatures.

  9. Explaining the sawtooth: latitudinal periodicity in a circadian gene correlates with shifts in generation number.

    PubMed

    Levy, R C; Kozak, G M; Wadsworth, C B; Coates, B S; Dopman, E B

    2015-01-01

    Many temperate insects take advantage of longer growing seasons at lower latitudes by increasing their generation number or voltinism. In some insects, development time abruptly decreases when additional generations are fit into the season. Consequently, latitudinal 'sawtooth' clines associated with shifts in voltinism are seen for phenotypes correlated with development time, like body size. However, latitudinal variation in voltinism has not been linked to genetic variation at specific loci. Here, we show a pattern in allele frequency among voltinism ecotypes of the European corn borer moth (Ostrinia nubilalis) that is reminiscent of a sawtooth cline. We characterized 145 autosomal and sex-linked SNPs and found that period, a circadian gene that is genetically linked to a major QTL determining variation in post-diapause development time, shows cyclical variation between voltinism ecotypes. Allele frequencies at an unlinked circadian clock gene cryptochrome1 were correlated with period. These results suggest that selection on development time to 'fit' complete life cycles into a latitudinally varying growing season produces oscillations in alleles associated with voltinism, primarily through changes at loci underlying the duration of transitions between diapause and other life history phases. Correlations among clock loci suggest possible coupling between the circadian clock and the circannual rhythms for synchronizing seasonal life history. We anticipate that latitudinal oscillations in allele frequency will represent signatures of adaptation to seasonal environments in other insects and may be critical to understanding the ecological and evolutionary consequences of variable environments, including response to global climate change. PMID:25430782

  10. ESTIMATING THE EFFECTS OF SCALE ON LATITUDINAL DIVERSITY GRADIENTS IN COASTAL ESTUARIES

    EPA Science Inventory

    Garza, Corey. 2003. Estimating the Effects of Scale on Latitudinal Diversity Gradients in Coastal Estuaries (Abstract). Presented at the 84th Annual Meeting of the Western Society of Naturalists, 7-10 November 2003, Long Beach, CA. 1 p. (ERL,GB R967).

    In this study the ef...

  11. Explaining the sawtooth: Latitudinal periodicity in a circadian gene correlates with shifts in generation number

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many species in temperate climates show latitudinal variation in life-cycle corresponding to synchronization with seasonal fluctuations in resources. In particular, insects often vary clinally in voltinism (the number of generations per year) which is determined by the timing of diapause terminatio...

  12. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1983-01-01

    Free radical chlorination of methane is used in organic chemistry to introduce free radical/chain reactions. In spite of its common occurrence, demonstrations of the reaction are uncommon. Therefore, such a demonstration is provided, including background information, preparation of reactants/reaction vessel, introduction of reactants, irradiation,…

  13. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Provides three descriptions of demonstrations used in various chemistry courses. Includes the use of a simple demonstration model to illustrate principles of chromatography, techniques for using balloons to teach about the behavior of gases, and the use of small concentrations of synthetic polyelectrolytes to induce the flocculation hydrophobic…

  14. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Outlines a simple, inexpensive way of demonstrating electroplating using the reaction between nickel ions and copper metal. Explains how to conduct a demonstration of the electrolysis of water by using a colored Na2SO4 solution as the electrolyte so that students can observe the pH changes. (TW)

  15. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1990-01-01

    Presented are three demonstrations: "The Construction and Use of Commercial Voltaic Cell Displays in Freshman Chemistry"; Dramatizing Isotopes: Deuterated Ice Cubes Sink"; and "A Simple Apparatus to Demonstrate Differing Gas Diffusion Rates (Graham's Law)." Materials, procedures, and safety considerations are discussed. (CW)

  16. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1980-01-01

    Described is a demonstration utilized to measure the heat of vaporization using the Clausius-Clapeyron equation. Explained is that when measurement is made as part of a demonstration, it raises student's consciousness that chemistry is experimentally based. (Author/DS)

  17. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1982-01-01

    Three chemistry demonstrations are described: (1) modification of copper catalysis demonstration apparatus; (2) experiments in gas-liquid chromatography with simple gas chromatography at room temperature; and (3) equilibria in silver arsenate-arsenic acid and silver phosphate-phosphoric acid systems. Procedures and materials needed are provided.…

  18. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1989-01-01

    Presented are two chemistry demonstrations: (1) an alternative method for the demonstration of the properties of alkali metals, water is added to small amounts of metal; (2) an exploration of the properties of hydrogen, helium, propane, and carbon dioxide using an open trough and candle. (MVL)

  19. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1990-01-01

    Described are demonstrations designed to reveal the important "nonsolvent" properties of water through its interaction with a toy called "Magic Sand" and other synthetic silica derivatives, especially those bonded with organic moities. The procedures for seven demonstrations along with a discussion of the effects are presented. (CW)

  20. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1980-01-01

    Two demonstrations are described: (1) a variant of preparing purple benzene by phase transfer catalysis with quaternary ammonium salts and potassium permanganate in which crown ethers are used; (2) a corridor or "hallway" demonstration in which unknown molecular models are displayed and prizes awarded to students correctly identifying the…

  1. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1983-01-01

    Describes a lecture demonstration of a solid state phase transition using a thermodynamic material which changes state at room temperature. Also describes a demonstration on kinetics using a "Big Bang" (trade mark) calcium carbide cannon. Indicates that the cannon is safe to use. (JN)

  2. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1983-01-01

    Provides directions for setup and performance of two demonstrations. The first demonstrates the principles of Raoult's Law; using a simple apparatus designed to measure vapor pressure. The second illustrates the energy available from alcohol combustion (includes safety precautions) using an alcohol-fueled missile. (JM)

  3. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1979-01-01

    Presents two demonstrations for classroom use related to precipitation of ferrous hydroxide and to variation of vapor pressure with temperature. The former demonstration is simple and useful when discussing solubility of ionic compounds electrode potential of transition elements, and mixed valence compounds. (Author/SA)

  4. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1983-01-01

    Discusses a supplement to the "water to rose" demonstration in which a pink color is produced. Also discusses blood buffer demonstrations, including hydrolysis of sodium bicarbonate, simulated blood buffer, metabolic acidosis, natural compensation of metabolic acidosis, metabolic alkalosis, acidosis treatment, and alkalosis treatment. Procedures…

  5. Complete Demonstration.

    ERIC Educational Resources Information Center

    Yelon, Stephen; Maddocks, Peg

    1986-01-01

    Describes four-step approach to educational demonstration: tell learners they will have to perform; what they should notice; describe each step before doing it; and require memorization of steps. Examples illustrate use of this process to demonstrate a general mental strategy, and industrial design, supervisory, fine motor, and specific…

  6. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Describes two laboratory demonstrations in chemistry. One uses dry ice, freon, and freezer bags to demonstrate volume changes, vapor-liquid equilibrium, a simulation of a rain forest, and vaporization. The other uses the clock reaction technique to illustrate fast reactions and kinetic problems in releasing carbon dioxide during respiration. (TW)

  7. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1984-01-01

    Background information and procedures are provided for a second part to the dichromate volcano demonstration. The green ash produced during the demonstration is reduced to metal using aluminothermy (Goldschmide process). Also describes suitable light sources and spectroscopes for student observation of emission spectra in lecture halls. (JN)

  8. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Describes two demonstrations designed to help chemistry students visualize certain chemical properties. One experiment uses balloons to illustrate the behavior of gases under varying temperatures and pressures. The other uses a makeshift pea shooter and a commercial model to demonstrate atomic structure and the behavior of high-speed particles.…

  9. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1989-01-01

    Provided are two demonstrations for an introductory course in chemistry. The first one emphasizes the observation and the interpretation of facts to form hypotheses during the heating of a beaker of water. The second demonstration shows the liquid phase of carbon dioxide using dry ice and a pressure gauge. (YP)

  10. Latitudinal and Energy Dependence of Energetic Neutral Atom Spectral Indices Measured by the Interstellar Boundary Explorer

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Allegrini, F.; Dayeh, M. A.; Funsten, H.; Heerikhuisen, J.; McComas, D. J.; Fuselier, S. A.; Pogorelov, N.; Schwadron, N. A.; Zank, G. P.; Zirnstein, E. J.

    2015-04-01

    We investigate the latitudinal and energy dependence of the globally distributed 0.5-6 keV energetic neutral atom (ENA) spectra measured by the Interstellar Boundary Explorer (IBEX) during the first 3 yrs of the mission. Our results are: (1) the ENA spectral indices at the two lowest energies (0.89 and 1.47 keV) exhibit no clear trend with ecliptic latitude θ, while those at ˜2.29 and ˜3.41 keV exhibit a clear latitudinal pattern; flatter spectra occur above 60° latitude and steeper spectra occur ±30° of the equator. (2) The latitudinal dependence of the spectral indices at different energies can be represented by the cosine function γ ={{a}0}+{{a}1}cos ({{a}2}θ ) with unique offsets, amplitudes, and phase angles; the higher energy ENA indices transition to successively larger amplitudes within ±45° of the equator. Our results confirm the previously reported latitudinal organization of the ENA spectra and their remarkable similarity to that of the solar wind (SW) speed observed by Ulysses in the inner heliosphere. While earlier studies showed that the ˜0.5-6 keV globally distributed ENA spectral indices could be represented as single power laws over much of the sky, our new results indicate that this is an over-simplification because the spectral indices have an energy and latitude dependence. This dependence is an important factor that must be taken into consideration by models and simulations that seek to map the IBEX ENA observations back to the latitudinal profile of the SW speed structure observed in the inner heliosphere.

  11. Distribution of dominant zooplankton species along a latitudinal gradient in China sea during spring

    NASA Astrophysics Data System (ADS)

    Xu, Jiayi; Xu, Zhaoli; Gao, Qian

    2016-06-01

    Dominant species of zooplankton community vary with latitude. Though China possesses a vast coastal area in northwestern Pacific, studies on the latitudinal dominant species gradient are rare. We collected zooplankton samples from Haizhou Bay (34.56°-35.19°N, 119.51°-120.30°E), Yueqing Bay (28.14°-28.38°N, 121.10°-121.21°E) and Dongshan Bay (23.65°-23.90°N, 117.45°-117.60°E) in May 2012 and May 2013 to preliminarily characterize the latitudinal dominant species distribution. All the samples were collected vertically using a 0.505 mm mesh plankton net with 0.8 m in mouth diameter from bottom to surface. Calanus sinicus, Aidanosagitta crassa, Labidocera euchaeta, Zonosagitta nagae, Acartia pacifica and Paracalanus parvus were found to be dominant. C. sinicus was the most dominant species and the unique one occurred in all three bays. With latitude decreasing, both the abundance and proportion of C. sinicus declined sharply. Cluster analysis showed that the 6 dominant species could be divided into 3 groups, based on their occurrences in the three bays. Our results suggested that the distribution of dominant species along the coast of China has a significant latitudinal gradient. C. sinicus which widely distributes in the coastal water of the northwestern Pacific can well adapt to the temperature at different latitudes. The high abundance in Haizhou Bay indicated that C. sinicus was an exemplary warm-temperate species, and more commonly occurs in the north of China seas. The ecological characteristics of dominant species change from warm-temperate type in high-latitudinal bays to warm water type in low-latitudinal bays.

  12. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1979-01-01

    Presents a recipe for the Nylon Rope Trick, which is considered to be one of the most spectacular demonstrations in chemistry. Materials for growing the polymer and some safety precautions are given. (SA)

  13. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L.

    1990-01-01

    Included are three demonstrations that include the phase change of ice when under pressure, viscoelasticity and colloid systems, and flame tests for metal ions. The materials, procedures, probable results, and applications to real life situations are included. (KR)

  14. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Describes two demonstrations suitable for chemistry instruction. One involves fractal structures obtained by electrodeposition of silver at an air-water interface and the other deals with molecular weights and music. (TW)

  15. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1986-01-01

    Background information, list of materials needed, and procedures used are provided for a demonstration involving the transformation of a hydrophobic liquid to a partially hydrophobic semisolid. Safety considerations are noted. (JN)

  16. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Roffia, Sergio; And Others

    1988-01-01

    Reports two electrochemical demonstrations. Uses a hydrogen-oxygen fuel cell to power a clock. Includes description of methods and materials. Investigates the "potato clock" used with different fruits. Lists emf and current for various fruit and electrode combinations. (ML)

  17. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1980-01-01

    Presented is a Corridor Demonstration which can be set up in readily accessible areas such as hallways or lobbies. Equipment is listed for a display of three cells (solar cells, fuel cells, and storage cells) which develop electrical energy. (CS)

  18. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Rehfeld, D. W.; And Others

    1988-01-01

    Describes two demonstrations (1) a dust explosion using a coffee can, candle, rubber tubing, and cornstarch and (2) forming a silicate-polyvinyl alcohol polymer which can be pressed into plastic sheets or molded. Gives specific instructions. (MVL)

  19. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1979-01-01

    Two demonstrations are presented: a verification of the discontinuity of matter based on the law of definite proportions, and a series of consecutive chemical reactions featuring reversible equilibria. (BB)

  20. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Presents three demonstrations suitable for undergraduate chemistry classes. Focuses on experiments with calcium carbide, the induction by iron of the oxidation of iodide by dichromate, and the classical iodine clock reaction. (ML)

  1. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L.

    1982-01-01

    Two demonstrations are described: (1) a sunset effect using a gooseneck lamp and 20 sheets of paper and (2) the preparation and determination of structural features of dimethyl sulfoxide (DMSO) by infrared spectroscopy. (SK)

  2. Tested Demonstrations

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1977-01-01

    Describes a room-temperature method for demonstrating phosphorescence by including samples in a polymer matrix. Also discusses the Old Nassau Reaction, a clock reaction which turns orange then black. (MLH)

  3. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1988-01-01

    Describes two demonstrations for use in college chemistry classes. Includes "Spectroscopy in Large Lecture Halls" and "The Endothermic Dissolution of Ammonium Nitrate." Gives materials lists and procedures as well as a discussion of the results. (CW)

  4. Defense pattern of Chinese cork oak across latitudinal gradients: influences of ontogeny, herbivory, climate and soil nutrients.

    PubMed

    Wang, Xiao-Fei; Liu, Jian-Feng; Gao, Wen-Qiang; Deng, Yun-Peng; Ni, Yan-Yan; Xiao, Yi-Hua; Kang, Feng-Feng; Wang, Qi; Lei, Jing-Pin; Jiang, Ze-Ping

    2016-06-02

    Knowledge of latitudinal patterns in plant defense and herbivory is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. Using a widely distributed species in East Asia, Quercus variabilis, we aim to reveal defense patterns of trees with respect to ontogeny along latitudinal gradients. Six leaf chemical (total phenolics and total condensed tannin concentrations) and physical (cellulose, hemicellulose, lignin and dry mass concentration) defensive traits as well as leaf herbivory (% leaf area loss) were investigated in natural Chinese cork oak (Q. variabilis) forests across two ontogenetic stages (juvenile and mature trees) along a ~14°-latitudinal gradient. Our results showed that juveniles had higher herbivory values and a higher concentration of leaf chemical defense substances compared with mature trees across the latitudinal gradient. In addition, chemical defense and herbivory in both ontogenetic stages decreased with increasing latitude, which supports the latitudinal herbivory-defense hypothesis and optimal defense theory. The identified trade-offs between chemical and physical defense were primarily determined by environmental variation associated with the latitudinal gradient, with the climatic factors (annual precipitation, minimum temperature of the coldest month) largely contributing to the latitudinal defense pattern in both juvenile and mature oak trees.

  5. Defense pattern of Chinese cork oak across latitudinal gradients: influences of ontogeny, herbivory, climate and soil nutrients

    PubMed Central

    Wang, Xiao-Fei; Liu, Jian-Feng; Gao, Wen-Qiang; Deng, Yun-Peng; Ni, Yan-Yan; Xiao, Yi-Hua; Kang, Feng-Feng; Wang, Qi; Lei, Jing-Pin; Jiang, Ze-Ping

    2016-01-01

    Knowledge of latitudinal patterns in plant defense and herbivory is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. Using a widely distributed species in East Asia, Quercus variabilis, we aim to reveal defense patterns of trees with respect to ontogeny along latitudinal gradients. Six leaf chemical (total phenolics and total condensed tannin concentrations) and physical (cellulose, hemicellulose, lignin and dry mass concentration) defensive traits as well as leaf herbivory (% leaf area loss) were investigated in natural Chinese cork oak (Q. variabilis) forests across two ontogenetic stages (juvenile and mature trees) along a ~14°-latitudinal gradient. Our results showed that juveniles had higher herbivory values and a higher concentration of leaf chemical defense substances compared with mature trees across the latitudinal gradient. In addition, chemical defense and herbivory in both ontogenetic stages decreased with increasing latitude, which supports the latitudinal herbivory-defense hypothesis and optimal defense theory. The identified trade-offs between chemical and physical defense were primarily determined by environmental variation associated with the latitudinal gradient, with the climatic factors (annual precipitation, minimum temperature of the coldest month) largely contributing to the latitudinal defense pattern in both juvenile and mature oak trees. PMID:27252112

  6. Is there metabolic cold adaptation in terrestrial ectotherms? Exploring latitudinal compensation in the invasive snail Cornu aspersum.

    PubMed

    Gaitán-Espitia, Juan Diego; Nespolo, Roberto

    2014-07-01

    Lower temperatures, extreme seasonality and shorter growing seasons at higher latitudes are expected to cause a decline in metabolic rates and annual growth rates of ectotherms. If a reduction in the rates of these biological processes involves a reduction in fitness, then organisms may evolve compensatory responses for the constraints imposed by high-latitude habitats. To test the existence of a latitudinal compensation in ectotherms, we used a common-garden experiment to investigate the extent to which the level of energy turnover (measured as standard metabolic rate, SMR) and the energy budget (energy allocation to growth) are affected by climatic constraints in three populations of the land snail Cornu aspersum, distributed across a latitudinal gradient of 1300 km in Chile. Our results did not support the existence of a latitudinal compensation in metabolic rates (metabolic cold adaptation). However, there was a countergradient variation (CnGV) for growth rate in which the highest latitudinal population exhibited greater growth rates than their counterparts from lower latitudes. Surprisingly, this CnGV pattern was accompanied by a lower apparent dry-matter digestibility, which could highlight a differential assimilation of ingested nutrients into somatic tissue, revealing enhanced growth efficiency in snails from the highest latitudinal habitat. Our evidence highlights that adjustments in energy allocation to the digestive machinery and to protein storage could act as a latitudinal compensation for enhanced growth efficiency in snails from the highest latitudinal population.

  7. Defense pattern of Chinese cork oak across latitudinal gradients: influences of ontogeny, herbivory, climate and soil nutrients.

    PubMed

    Wang, Xiao-Fei; Liu, Jian-Feng; Gao, Wen-Qiang; Deng, Yun-Peng; Ni, Yan-Yan; Xiao, Yi-Hua; Kang, Feng-Feng; Wang, Qi; Lei, Jing-Pin; Jiang, Ze-Ping

    2016-01-01

    Knowledge of latitudinal patterns in plant defense and herbivory is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. Using a widely distributed species in East Asia, Quercus variabilis, we aim to reveal defense patterns of trees with respect to ontogeny along latitudinal gradients. Six leaf chemical (total phenolics and total condensed tannin concentrations) and physical (cellulose, hemicellulose, lignin and dry mass concentration) defensive traits as well as leaf herbivory (% leaf area loss) were investigated in natural Chinese cork oak (Q. variabilis) forests across two ontogenetic stages (juvenile and mature trees) along a ~14°-latitudinal gradient. Our results showed that juveniles had higher herbivory values and a higher concentration of leaf chemical defense substances compared with mature trees across the latitudinal gradient. In addition, chemical defense and herbivory in both ontogenetic stages decreased with increasing latitude, which supports the latitudinal herbivory-defense hypothesis and optimal defense theory. The identified trade-offs between chemical and physical defense were primarily determined by environmental variation associated with the latitudinal gradient, with the climatic factors (annual precipitation, minimum temperature of the coldest month) largely contributing to the latitudinal defense pattern in both juvenile and mature oak trees. PMID:27252112

  8. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Describes two demonstrations for use in chemistry instruction. The first illustrates the preparation of a less common oxide of iron, showing why this oxide is rare. The second is an explosion reaction of hydrogen and oxygen that is recommended for use as an attention-getting device. (TW)

  9. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1981-01-01

    Provides instructions and a list of materials needed to demonstrate: (1) a model of the quantum mechanical atom; (2) principles involved in metal corrosion and in the prevention of this destructive process by electrochemical means; and (3) a Thermit reaction, modified to make it more dramatic and interesting for students. (SK)

  10. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1985-01-01

    Background information, procedures, and typical results obtained are provided for two demonstrations. The first involves the colorful complexes of copper(II). The second involves reverse-phase separation of Food, Drug, and Cosmetic (FD & C) dyes using a solvent gradient. (JN)

  11. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Cliche, Jean-Marie; And Others

    1988-01-01

    Describes two demonstrations: 1) the effect of polarity on solubility using sodium dichromate, TTE, ligroin, and water to form nonpolar-polar-nonpolar layers with the polar layer being colored; 2) determination of egg whites to be yellow by determining the content of yellow colored riboflavin in the egg white. (MVL)

  12. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1987-01-01

    Describes two demonstrations to illustrate characteristics of substances. Outlines a method to detect the changes in pH levels during the electrolysis of water. Uses water pistols, one filled with methane gas and the other filled with water, to illustrate the differences in these two substances. (TW)

  13. Tested Demonstrations

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1976-01-01

    Describes two demonstrations: one that illustrates the attainment of equilibrium in first-order reactions by changing the volumes of two beakers of water at a specified rate, and another that illustrates the role of indicators in showing pH changes in buffer solutions. (MLH)

  14. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1985-01-01

    Describes two demonstrations that require almost no preparation time, are visually stimulating, and present a variety of material for class discussion (with sample questions provided). The first involves a sodium bicarbonate hydrochloric acid volcano; the second involves a dissolving polystyrene cup. Procedures used and information on…

  15. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L.

    1983-01-01

    An apparatus is described in which effects of pressure, volume, and temperature changes on a gas can be observed simultaneously. Includes use of the apparatus in demonstrating Boyle's, Gay-Lussac's, and Charles' Laws, attractive forces, Dalton's Law of Partial pressures, and in illustrating measurable vapor pressures of liquids and some solids.…

  16. Tested Demonstrations.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1984-01-01

    Two demonstrations are described. The first shows the effect of polarity on solubility. The second is based on the unexpected formation of a precipitate of barium nitrate when barium carbonate or barium phosphate is treated with dilute nitric acid. List of materials needed and procedures used are included. (JN)

  17. Latitudinal gradients of cosmic rays and the polarity reversal of the heliospheric magnetic field: A preliminary evaluation

    NASA Technical Reports Server (NTRS)

    Newkirk, G., Jr.; Lockwood, J. A.; Garcia-Munoz, M.; Simpson, J. A.

    1985-01-01

    Within the statistical limits imposed by the currently available data and the noise inherent in the determination of the latitudinal gradient, no evidence for the expected change in the latitudinal gradient from pre-1980 to post-1980 epochs can be found. In addition, the rigidity dependence of the gradient appears to be the same in the two epochs. Thus, no evidence is found for a sensitivity of the latitudinal gradient to the polarity of the largescale heliospheric magnetic field such as has been predicted by models incorporating particle drifts.

  18. Latitudinal Controls on Topography: The Role of Precipitation and Fluvial Erosion

    NASA Astrophysics Data System (ADS)

    Sorensen, C.; Yanites, B.

    2014-12-01

    Observations from the North and South American Cordillera show that mean and maximum elevations decrease with increasing latitude. The trend in elevation follows the latitudinal dependence of snowline altitudes. This correlation between elevation and snowline altitude has been the impetus behind the glacial 'buzzsaw' hypothesis, which states that glaciers limit the elevation of mountain peaks. Underlying this hypothesis is an assumption that elevations prior to glaciation were either uniform, randomly distributed, or followed a pattern that is no longer present. However, there may be other factors that are responsible for these patterns, such as latitudinal trends in precipitation. Here, we address this assumption and the necessity of glacial erosion in explaining the latitudinal trend in elevation. We use the CHILD landscape evolution model parameterized by modern precipitation data along a latitudinal gradient in the Andes to predict the topography in the absence of glaciation. Using NCEP/NCAR Reanalysis precipitation data from 1981-2010, we derive storm duration, intensity, and frequency statistics for a series of locations along the Andean orogen. For each location, we run a model using a sequence of storms generated from these statistics. Erodibility and rock-uplift are held constant between the different locations and the models are run until topographic steady-state is achieved. We also present runs exploring the role of a threshold for bedrock detachment in the modeled results. For each run, we track the maximum and mean elevation as well as the time to steady-state. Preliminary results for all cases show that fluvial processes alone are sufficient to account for the latitudinal dependence of topography. For example, landscapes produced with precipitation statistics similar to the dry central Andes are more than an order of magnitude higher than landscapes from the southern, wetter, part of the orogen. Future analysis will use precipitation data from

  19. Phylogenetic niche conservatism explains an inverse latitudinal diversity gradient in freshwater arthropods.

    PubMed

    Morinière, Jérôme; Van Dam, Matthew H; Hawlitschek, Oliver; Bergsten, Johannes; Michat, Mariano C; Hendrich, Lars; Ribera, Ignacio; Toussaint, Emmanuel F A; Balke, Michael

    2016-01-01

    The underlying mechanisms responsible for the general increase in species richness from temperate regions to the tropics remain equivocal. Many hypotheses have been proposed to explain this astonishing pattern but additional empirical studies are needed to shed light on the drivers at work. Here we reconstruct the evolutionary history of the cosmopolitan diving beetle subfamily Colymbetinae, the majority of which are found in the Northern hemisphere, hence exhibiting an inversed latitudinal diversity gradient. We reconstructed a dated phylogeny using 12 genes, to investigate the biogeographical history and diversification dynamics in the Colymbetinae. We aimed to identify the role that phylogenetic niche conservatism plays in the inversed diversification pattern seen in this group. Our results suggest that Colymbetinae originated in temperate climates, which supports the hypothesis that their distribution is the result of an ancestral adaptation to temperate environmental conditions rather than tropical origins, and that temperate niche conservatism can generate and/or maintain inverse latitudinal diversity gradients. PMID:27215956

  20. Coupling of soil prokaryotic diversity and plant diversity across latitudinal forest ecosystems

    PubMed Central

    Wang, Jun-Tao; Zheng, Yuan-Ming; Hu, Hang-Wei; Li, Jing; Zhang, Li-Mei; Chen, Bao-Dong; Chen, Wei-Ping; He, Ji-Zheng

    2016-01-01

    The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Yet, the nature of how soil prokaryotic diversity co-varies with aboveground plant diversity along a latitudinal gradient remains elusive. By establishing three hundred 400-m2 quadrats from tropical rainforest to boreal forest in a large-scale parallel study on both belowground soil prokaryote and aboveground tree and herb communities, we found that soil prokaryotic diversity couples with the diversity of herbs rather than trees. The diversity of prokaryotes and herbs responds similarly to environmental factors along the latitudinal gradient. These findings revealed that herbs provide a good predictor of belowground biodiversity in forest ecosystems, and provide new perspective on the aboveground and belowground interactions in forest ecosystems. PMID:26781165

  1. Chatanika observations of the latitudinal structure of electric fields and particle precipitation on November 21, 1975

    NASA Technical Reports Server (NTRS)

    Wedde, T.; Doupnik, J. R.; Banks, P. M.

    1977-01-01

    By using a new multiposition experimental procedure the incoherent scatter radar facility of Chatanika, Alaska, has been used to obtain detailed latitudinal structure of ion velocities and electric fields in the afternoon and midnight sectors during a period of moderate magnetic disturbance. In particular, the latitudinal and local time structure of the Harang discontinuity has been investigated. In agreement with other observations it is found that the convection flow direction changes from westward through south to eastward over a fairly wide local time range (1-2 hours), the highest latitudes displaying the widest region. The Harang discontinuity encounter is accompanied by an abrupt increase in electron precipitation, the most intense part being located slightly east of the center of the discontinuity. It is suggested that this injection is due to processes closely connected with the discontinuity region itself, rather than to a substorm-related energization.

  2. Phylogenetic niche conservatism explains an inverse latitudinal diversity gradient in freshwater arthropods

    PubMed Central

    Morinière, Jérôme; Van Dam, Matthew H.; Hawlitschek, Oliver; Bergsten, Johannes; Michat, Mariano C.; Hendrich, Lars; Ribera, Ignacio; Toussaint, Emmanuel F.A.; Balke, Michael

    2016-01-01

    The underlying mechanisms responsible for the general increase in species richness from temperate regions to the tropics remain equivocal. Many hypotheses have been proposed to explain this astonishing pattern but additional empirical studies are needed to shed light on the drivers at work. Here we reconstruct the evolutionary history of the cosmopolitan diving beetle subfamily Colymbetinae, the majority of which are found in the Northern hemisphere, hence exhibiting an inversed latitudinal diversity gradient. We reconstructed a dated phylogeny using 12 genes, to investigate the biogeographical history and diversification dynamics in the Colymbetinae. We aimed to identify the role that phylogenetic niche conservatism plays in the inversed diversification pattern seen in this group. Our results suggest that Colymbetinae originated in temperate climates, which supports the hypothesis that their distribution is the result of an ancestral adaptation to temperate environmental conditions rather than tropical origins, and that temperate niche conservatism can generate and/or maintain inverse latitudinal diversity gradients. PMID:27215956

  3. Species richness and the analytic geometry of latitudinal and altitudinal gradients.

    PubMed

    Gorelick, Root

    2008-09-01

    Extensive empirical work has shown that species richness decreases roughly exponentially or quadratically with latitude. What appears to be a latitudinal gradient in fact may simply be a negative correlation of latitude with area at that latitude, due to convergence of lines of meridian at the poles. There is simply less area at high latitudes, which means fewer niches and fewer opportunities for speciation, hence diminished biodiversity at high latitudes. Similarly, analytic geometry of a cone shows that species number should decrease linearly with altitude on a conical mountain. Here, I provide an explicit mathematical model of the area hypothesis of species richness along latitude and altitude gradients. I re-analyze a previously published latitudinal gradient dataset and show that species number is a linear function of the predicted area and that species number is more fully explained by predicted area than by a quadratic function of latitude. However, analytic geometry is not needed if precise measures of area are known.

  4. Phylogenetic niche conservatism explains an inverse latitudinal diversity gradient in freshwater arthropods

    NASA Astrophysics Data System (ADS)

    Morinière, Jérôme; van Dam, Matthew H.; Hawlitschek, Oliver; Bergsten, Johannes; Michat, Mariano C.; Hendrich, Lars; Ribera, Ignacio; Toussaint, Emmanuel F. A.; Balke, Michael

    2016-05-01

    The underlying mechanisms responsible for the general increase in species richness from temperate regions to the tropics remain equivocal. Many hypotheses have been proposed to explain this astonishing pattern but additional empirical studies are needed to shed light on the drivers at work. Here we reconstruct the evolutionary history of the cosmopolitan diving beetle subfamily Colymbetinae, the majority of which are found in the Northern hemisphere, hence exhibiting an inversed latitudinal diversity gradient. We reconstructed a dated phylogeny using 12 genes, to investigate the biogeographical history and diversification dynamics in the Colymbetinae. We aimed to identify the role that phylogenetic niche conservatism plays in the inversed diversification pattern seen in this group. Our results suggest that Colymbetinae originated in temperate climates, which supports the hypothesis that their distribution is the result of an ancestral adaptation to temperate environmental conditions rather than tropical origins, and that temperate niche conservatism can generate and/or maintain inverse latitudinal diversity gradients.

  5. Global-scale latitudinal patterns of plant fine-root nitrogen and phosphorus.

    PubMed

    Yuan, Z Y; Chen, Han Y H; Reich, Peter B

    2011-01-01

    Most water and essential soil nutrient uptake is carried out by fine roots in plants. It is therefore important to understand the global geographic patterns of fine-root nitrogen and phosphorus cycling. Here, by compiling plant root data from 211 studies in 51 countries, we show that live fine roots have low nitrogen (N) and phosphorus (P), but similar N:P ratios when compared with green leaves. The fine-root N:P ratio differs between biomes and declines exponentially with latitude in roots of all diameter classes. This is in contrast to previous reports of a linear latitudinal decline in green leaf N:P, but consistent with nonlinear declines in leaf litter N:P. Whereas the latitudinal N:P decline in both roots and leaves reflects collective influences of climate, soil age and weathering, differences in the shape of the response function may be a result of their different N and P use strategies. PMID:21673665

  6. Global-scale latitudinal patterns of plant fine-root nitrogen and phosphorus.

    PubMed

    Yuan, Z Y; Chen, Han Y H; Reich, Peter B

    2011-06-14

    Most water and essential soil nutrient uptake is carried out by fine roots in plants. It is therefore important to understand the global geographic patterns of fine-root nitrogen and phosphorus cycling. Here, by compiling plant root data from 211 studies in 51 countries, we show that live fine roots have low nitrogen (N) and phosphorus (P), but similar N:P ratios when compared with green leaves. The fine-root N:P ratio differs between biomes and declines exponentially with latitude in roots of all diameter classes. This is in contrast to previous reports of a linear latitudinal decline in green leaf N:P, but consistent with nonlinear declines in leaf litter N:P. Whereas the latitudinal N:P decline in both roots and leaves reflects collective influences of climate, soil age and weathering, differences in the shape of the response function may be a result of their different N and P use strategies.

  7. Inferred calcification rate of a temperate azooxanthellate caryophylliid coral along a wide latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Caroselli, E.; Brambilla, V.; Ricci, F.; Mattioli, G.; Levy, O.; Falini, G.; Dubinsky, Z.; Goffredo, S.

    2016-09-01

    Correlations between environmental parameters (depth temperature and solar radiation) and growth parameters (bulk skeletal density, linear extension rate and net calcification rate) of the solitary azooxanthellate coral, Caryophyllia inornata, were investigated along an 8° latitudinal gradient on the western Italian coasts. Net calcification rate correlated positively with both bulk skeletal density and linear extension rate, showing that C. inornata allocates calcification resources evenly to thickening the skeleton and increasing linear growth. Overall, the three growth parameters did not follow gradients in the two environmental parameters, showing a different trend compared to most studies on zooxanthellate corals. However, the results are in agreement with the only previous analysis of an azooxanthellate coral, Leptopsammia pruvoti, studied along the same latitudinal gradient. In a comparison of the response to temperature of all Mediterranean species whose growth has been investigated to date, azooxanthellate corals were more tolerant to temperature increases than zooxanthellate corals.

  8. Seasonal and latitudinal variations of gravity wave-driven fluctuations in OH nightglow

    NASA Technical Reports Server (NTRS)

    Hickey, M. P.; Schubert, G.; Walterscheid, R. L.

    1992-01-01

    A model which incorporates extended OH-layer emission and gravity-wave dynamics with eddy diffusivities is set forth to analyze seasonal and latitudinal variations in the OH nightglow. The 2D analysis is aimed at determining the nature of the relationship between the oscillation in intensity about a mean intensity and the oscillation in temperature of the emission region about a mean temperature. Competing eddy diffusivities modify the local values and altitudes of maximum wave amplitude, so long-period characterization of the relationship is imprecise. Seasonal trends in the relationship are noted for periods of several hrs or less that are primarily related to seasonal changes in the mesopause undisturbed temperature. Latitudinal trends are shown to be less pronounced, and trends that exist at intermediate periods are difficult to isolate due to interference effects.

  9. The tropics: cradle, museum or casino? A dynamic null model for latitudinal gradients of species diversity.

    PubMed

    Arita, Héctor T; Vázquez-Domínguez, Ella

    2008-07-01

    Several ecological and evolutionary hypotheses have been proposed to explain the latitudinal diversity gradient (LDG), but a general model for this conspicuous pattern remains elusive. Mid-domain effect (MDE) models generate gradients of species diversity by randomly placing the geographic ranges of species in one- or two-dimensional spaces, thus excluding both evolutionary processes and the effect of contemporary climate. Traditional MDE models are statistical and static because they determine the size of ranges either randomly or based on empirical frequency distributions. Here we present a simple dynamic null model for the LDG that simulates stochastic processes of range shifts, extinction and speciation. The model predicts higher species diversity and higher extinction and speciation rates in the tropics, and a strong influence of range movements in shaping the LDG. These null expectations should be taken into consideration in studies aimed at understanding the many factors that generate latitudinal diversity gradients.

  10. Coupling of soil prokaryotic diversity and plant diversity across latitudinal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Tao; Zheng, Yuan-Ming; Hu, Hang-Wei; Li, Jing; Zhang, Li-Mei; Chen, Bao-Dong; Chen, Wei-Ping; He, Ji-Zheng

    2016-01-01

    The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Yet, the nature of how soil prokaryotic diversity co-varies with aboveground plant diversity along a latitudinal gradient remains elusive. By establishing three hundred 400-m2 quadrats from tropical rainforest to boreal forest in a large-scale parallel study on both belowground soil prokaryote and aboveground tree and herb communities, we found that soil prokaryotic diversity couples with the diversity of herbs rather than trees. The diversity of prokaryotes and herbs responds similarly to environmental factors along the latitudinal gradient. These findings revealed that herbs provide a good predictor of belowground biodiversity in forest ecosystems, and provide new perspective on the aboveground and belowground interactions in forest ecosystems.

  11. [Latitudinal Changes in Plant Stoichiometric and Soil C, N, P Stoichiometry in Loess Plateau].

    PubMed

    Li, Ting; Deng, Qiang; Yuan, Zhi-you; Jiao, Feng

    2015-08-01

    Field investigations and sampling were conducted in Loess Plateau, including Fu County, Ganquan County, Ansai County, Jingbian County and Hengshan County and Yuyang District. Our objective was to examine changes of leaf and soil stoichiometry characteristics along latitudinal gradient in Loess Plateau, and to provide references for the prediction of soil nutrient status of the ecosystem and constraints of plant nutrition elements in Loess Plateau. The results showed that (1) Across the 35.95 degrees-38.36 degrees N latitude gradient, leaf C, N and P stoichiometry were ranging from 336.95 to 477.38 mg x g(-1) for C, from 18.09 to 33.173 mg x g(-1) for N and from 1.07 to 1.73 mg x g(-1) for P, the arithmetic means were 442.9 mg x g(-1), 25.79 mg x g(-1) and 1.37 mg x g(-1), separately, the variation coefficients were 11.9%, 17.4% and 13.3%. There were obvious correlation between leaf C, N, P and latitude, leaf C, C : N ratio and C: P ratio significantly decreased with the increasing latitude, while leaf N and P significantly increased with the increasing latitude. The relationship between N: P ratio and latitude was not significant. (2) The content of soil organic C and soil total N decreased with increasing latitude and soil layer. In contrast, with the increase of latitude, soil P increased and then decreased. In the 0-10 cm, 10-20 cm soil layers, soil C: N ratio did not change significantly with latitude, while in the 20-40 cm layer, C: N ratio decreased obviously, but soil C: P and N: P ratios decreased with the increasing latitude in all soil layers. (3) Leaf C, C: N and C: P ratios were correlated to soil organic C, soil total N and soil total P in all soil layers, leaf N and P were correlated to soil organic C and soil total N, while leaf N: P ratio was not correlated to soil organic C, soil total N and soil total P. There was a certain correlation between the leaf C, N, P and latitude, however, the correlations between leaf and soil C, N, P were inconsistent

  12. Temperature-Stress Resistance and Tolerance along a Latitudinal Cline in North American Arabidopsis lyrata

    PubMed Central

    Wos, Guillaume; Willi, Yvonne

    2015-01-01

    The study of latitudinal gradients can yield important insights into adaptation to temperature stress. Two strategies are available: resistance by limiting damage, or tolerance by reducing the fitness consequences of damage. Here we studied latitudinal variation in resistance and tolerance to frost and heat and tested the prediction of a trade-off between the two strategies and their costliness. We raised plants of replicate maternal seed families from eight populations of North American Arabidopsis lyrata collected along a latitudinal gradient in climate chambers and exposed them repeatedly to either frost or heat stress, while a set of control plants grew under standard conditions. When control plants reached maximum rosette size, leaf samples were exposed to frost and heat stress, and electrolyte leakage (PEL) was measured and treated as an estimate of resistance. Difference in maximum rosette size between stressed and control plants was used as an estimate of tolerance. Northern populations were more frost resistant, and less heat resistant and less heat tolerant, but—unexpectedly—they were also less frost tolerant. Negative genetic correlations between resistance and tolerance to the same and different thermal stress were generally not significant, indicating only weak trade-offs. However, tolerance to frost was consistently accompanied by small size under control conditions, which may explain the non-adaptive latitudinal pattern for frost tolerance. Our results suggest that adaptation to frost and heat is not constrained by trade-offs between them. But the cost of frost tolerance in terms of plant size reduction may be important for the limits of species distributions and climate niches. PMID:26110428

  13. Determination of galactic cosmic ray latitudinal gradient using Earth based detectors

    NASA Technical Reports Server (NTRS)

    BADRUDDIN; Yadav, R. S.

    1985-01-01

    Using cosmic ray intensity data from the Deep River Neutron monitor and the relation between solar wind velocity and heliomagnetic latitude, an attempt is made to evaluate quantitatively the latitudinal gradient of cosmic ray intensity during the periods dominated by a two sector pattern. Assuming a constant orientation of the heliospheric current sheet on a time scale of the order of a year, a relationship is determined between cosmic ray intensity and heliomagnetic latitude.

  14. Latitudinal gradient of energetic particles in the outer heliosphere during 1985-1986

    SciTech Connect

    Decker, R.B.; Krimigis, S.M.; Venkatesan, D.

    1987-04-01

    We report a measurement of a sustained latitudinal gradient of 70-MeV galactic cosmic ray protons using data from the interplanetary probes Voyager 1 and 2 and the earth-orbiting satellite IMP 8 during a 1-year period from mid-1985 to mid-1986. Starting in early 1985 the intensity of cosmic rays at Voyager 2 began increasing faster than that at Voyager 1. By mid- 1985 the intensity at Voyager 2 (helioradius 17 AU, heliolatitude --0/sup 0/) exceeded and remained higher than that at Voyager 1 (helioradius 24 AU, heliolatitude --26/sup 0/) for at least 14 solar rotations. Using the Voyager 2-IMP 8 data to correct for the radial gradient, we determine an average latitudinal gradient during this period of (-0.53 +- 0.10)% deg/sup -1/ or (-0.38 +- 0.11)% deg/sup -1/ (i.e., intensity decreasing northward of the solar equatorial plane), assuming either a constant radial gradient or one that decreased at an average rate of -0.025% AU/sup -1/ AU/sup -1/, as was the case during 1984, respectively. In addition, we present Voyager data at very low (approx. >30 keV) ion energies which are associated with acceleration at corotating shocks. These ions also exhibit a latitudinal gradient (---3% deg/sup -1/), with lower intensities at higher latitudes, and serve to highlight changes that occurred in the interplanetary medium in early 1985. Copyright American Geophysical Union 1987.

  15. Unifying latitudinal gradients in range size and richness across marine and terrestrial systems.

    PubMed

    Tomašových, Adam; Kennedy, Jonathan D; Betzner, Tristan J; Kuehnle, Nicole Bitler; Edie, Stewart; Kim, Sora; Supriya, K; White, Alexander E; Rahbek, Carsten; Huang, Shan; Price, Trevor D; Jablonski, David

    2016-05-11

    Many marine and terrestrial clades show similar latitudinal gradients in species richness, but opposite gradients in range size-on land, ranges are the smallest in the tropics, whereas in the sea, ranges are the largest in the tropics. Therefore, richness gradients in marine and terrestrial systems do not arise from a shared latitudinal arrangement of species range sizes. Comparing terrestrial birds and marine bivalves, we find that gradients in range size are concordant at the level of genera. Here, both groups show a nested pattern in which narrow-ranging genera are confined to the tropics and broad-ranging genera extend across much of the gradient. We find that (i) genus range size and its variation with latitude is closely associated with per-genus species richness and (ii) broad-ranging genera contain more species both within and outside of the tropics when compared with tropical- or temperate-only genera. Within-genus species diversification thus promotes genus expansion to novel latitudes. Despite underlying differences in the species range-size gradients, species-rich genera are more likely to produce a descendant that extends its range relative to the ancestor's range. These results unify species richness gradients with those of genera, implying that birds and bivalves share similar latitudinal dynamics in net species diversification. PMID:27147094

  16. Latitudinal Clines of the Human Vitamin D Receptor and Skin Color Genes.

    PubMed

    Tiosano, Dov; Audi, Laura; Climer, Sharlee; Zhang, Weixiong; Templeton, Alan R; Fernández-Cancio, Monica; Gershoni-Baruch, Ruth; Sánchez-Muro, José Miguel; El Kholy, Mohamed; Hochberg, Zèev

    2016-05-03

    The well-documented latitudinal clines of genes affecting human skin color presumably arise from the need for protection from intense ultraviolet radiation (UVR) vs. the need to use UVR for vitamin D synthesis. Sampling 751 subjects from a broad range of latitudes and skin colors, we investigated possible multilocus correlated adaptation of skin color genes with the vitamin D receptor gene (VDR), using a vector correlation metric and network method called BlocBuster. We discovered two multilocus networks involving VDR promoter and skin color genes that display strong latitudinal clines as multilocus networks, even though many of their single gene components do not. Considered one by one, the VDR components of these networks show diverse patterns: no cline, a weak declining latitudinal cline outside of Africa, and a strong in- vs. out-of-Africa frequency pattern. We confirmed these results with independent data from HapMap. Standard linkage disequilibrium analyses did not detect these networks. We applied BlocBuster across the entire genome, showing that our networks are significant outliers for interchromosomal disequilibrium that overlap with environmental variation relevant to the genes' functions. These results suggest that these multilocus correlations most likely arose from a combination of parallel selective responses to a common environmental variable and coadaptation, given the known Mendelian epistasis among VDR and the skin color genes.

  17. Latitudinal Clines of the Human Vitamin D Receptor and Skin Color Genes

    PubMed Central

    Tiosano, Dov; Audi, Laura; Climer, Sharlee; Zhang, Weixiong; Templeton, Alan R.; Fernández-Cancio, Monica; Gershoni-Baruch, Ruth; Sánchez-Muro, José Miguel; El Kholy, Mohamed; Hochberg, Zèev

    2016-01-01

    The well-documented latitudinal clines of genes affecting human skin color presumably arise from the need for protection from intense ultraviolet radiation (UVR) vs. the need to use UVR for vitamin D synthesis. Sampling 751 subjects from a broad range of latitudes and skin colors, we investigated possible multilocus correlated adaptation of skin color genes with the vitamin D receptor gene (VDR), using a vector correlation metric and network method called BlocBuster. We discovered two multilocus networks involving VDR promoter and skin color genes that display strong latitudinal clines as multilocus networks, even though many of their single gene components do not. Considered one by one, the VDR components of these networks show diverse patterns: no cline, a weak declining latitudinal cline outside of Africa, and a strong in- vs. out-of-Africa frequency pattern. We confirmed these results with independent data from HapMap. Standard linkage disequilibrium analyses did not detect these networks. We applied BlocBuster across the entire genome, showing that our networks are significant outliers for interchromosomal disequilibrium that overlap with environmental variation relevant to the genes’ functions. These results suggest that these multilocus correlations most likely arose from a combination of parallel selective responses to a common environmental variable and coadaptation, given the known Mendelian epistasis among VDR and the skin color genes. PMID:26921301

  18. Links between viruses and prokaryotes throughout the water column along a North Atlantic latitudinal transect.

    PubMed

    De Corte, Daniele; Sintes, Eva; Yokokawa, Taichi; Reinthaler, Thomas; Herndl, Gerhard J

    2012-08-01

    Viruses are an abundant, diverse and dynamic component of marine ecosystems and have a key role in the biogeochemical processes of the ocean by controlling prokaryotic and phytoplankton abundance and diversity. However, most of the studies on virus-prokaryote interactions in marine environments have been performed in nearshore waters. To assess potential variations in the relation between viruses and prokaryotes in different oceanographic provinces, we determined viral and prokaryotic abundance and production throughout the water column along a latitudinal transect in the North Atlantic. Depth-related trends in prokaryotic and viral abundance (both decreasing by one order of magnitude from epi- to abyssopelagic waters), and prokaryotic production (decreasing by three orders of magnitude) were observed along the latitudinal transect. The virus-to-prokaryote ratio (VPR) increased from ~19 in epipelagic to ~53 in the bathy- and abyssopelagic waters. Although the lytic viral production decreased significantly with depth, the lysogenic viral production did not vary with depth. In bathypelagic waters, pronounced differences in prokaryotic and viral abundance were found among different oceanic provinces with lower leucine incorporation rates and higher VPRs in the North Atlantic Gyre province than in the provinces further north and south. The percentage of lysogeny increased from subpolar regions toward the more oligotrophic lower latitudes. Based on the observed trends over this latitudinal transect, we conclude that the viral-host interactions significantly change among different oceanic provinces in response to changes in the biotic and abiotic variables. PMID:22258100

  19. Global latitudinal-asymmetric vegetation growth trends and their driving mechanisms: 1982-2009

    SciTech Connect

    Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E; Hoffman, Forrest M; Zhu, Zaichun; Myneni, Ranga B.

    2013-01-01

    Using a recent Leaf Area Index (LAI) dataset and the Community Land Model version 4 (CLM4), we investigate percent changes and controlling factors of global vegetation growth for the period 1982 to 2009. Over that 28-year period, both the remote-sensing estimate and model simulation show a significant increasing trend in annual vegetation growth. Latitudinal asymmetry appeared in both products, with small increases in the Southern Hemisphere (SH) and larger increases at high latitudes in the Northern Hemisphere (NH). The south-to-north asymmetric land surface warming was assessed to be the principal driver of this latitudinal asymmetry of LAI trend. Heterogeneous precipitation functioned to decrease this latitudinal LAI gradient, and considerably regulated the local LAI change. CO2 fertilization during the last three decades, was simulated to be the dominant cause for the enhanced vegetation growth. Our study, though limited by observational and modeling uncertainties, adds further insight into vegetation growth trends and environmental correlations. These validation exercises also provide new quantitative and objective metrics for evaluation of land ecosystem process models at multiple spatio-temporal scales.

  20. Factors Affecting the Latitudinal Location of the Intertropical Convergence Zone in a GCM

    NASA Technical Reports Server (NTRS)

    Chao, Winston C.; Chen, Baode

    2002-01-01

    The dominant role of the latitudinal peak of the sea surface temperature (SST) in determining the latitudinal location of the intertropical convergence zone (ITCZ) is well-known. However, the roles of the other factors are less well-known and are the topic of this study. These other factors include the inertial stability, the interaction between convection and surface fluxes and the interaction between convection and radiation. Since these interactions involve convection, in a model they involve the cumulus parameterization scheme. These factors are studied with a general circulation model with uniform SST and solar angle. Under the aforementioned model settings, the latitudinal location of the ITCZ is the latitude where the balance of two types of attraction on the ITCZ, both due to earth's rotation, exists. Directly related to the Coriolis parameter, the first type pulls the ITCZ toward the equator and is not sensitive to model design changes. Related to the convective circulation, the second type pulls the ITCZ poleward and is sensitive to model design changes. Due to the shape and the magnitude of the attractors, the balance of the two types of attractions is reached either at the equator or more than 10 degrees away from the equator. The former case results in a single ITCZ over the equator and the latter case a double ITCZ straddling the equator.

  1. Unifying latitudinal gradients in range size and richness across marine and terrestrial systems.

    PubMed

    Tomašových, Adam; Kennedy, Jonathan D; Betzner, Tristan J; Kuehnle, Nicole Bitler; Edie, Stewart; Kim, Sora; Supriya, K; White, Alexander E; Rahbek, Carsten; Huang, Shan; Price, Trevor D; Jablonski, David

    2016-05-11

    Many marine and terrestrial clades show similar latitudinal gradients in species richness, but opposite gradients in range size-on land, ranges are the smallest in the tropics, whereas in the sea, ranges are the largest in the tropics. Therefore, richness gradients in marine and terrestrial systems do not arise from a shared latitudinal arrangement of species range sizes. Comparing terrestrial birds and marine bivalves, we find that gradients in range size are concordant at the level of genera. Here, both groups show a nested pattern in which narrow-ranging genera are confined to the tropics and broad-ranging genera extend across much of the gradient. We find that (i) genus range size and its variation with latitude is closely associated with per-genus species richness and (ii) broad-ranging genera contain more species both within and outside of the tropics when compared with tropical- or temperate-only genera. Within-genus species diversification thus promotes genus expansion to novel latitudes. Despite underlying differences in the species range-size gradients, species-rich genera are more likely to produce a descendant that extends its range relative to the ancestor's range. These results unify species richness gradients with those of genera, implying that birds and bivalves share similar latitudinal dynamics in net species diversification.

  2. Can Rapoport's rule be rescued? Modeling causes of the latitudinal gradient in species richness

    SciTech Connect

    Taylor, P.H.; Gaines, S.D.

    1999-12-01

    The latitudinal gradient in species richness, wherein species richness peaks near the equator and declines toward the poles, is a widely recognized phenomenon that holds true for many taxa in all habitat types. Understanding the causative mechanism of mechanisms that generate the latitudinal gradient in species richness (LGSR) has been a major challenge, and the gradient remains unexplained. A different latitudinal trend (named Rapoport's rule), in which the mean size of species geographical ranges tends to decline toward the equator, has been hypothesized by G.C. Stevens to play a key role in generating the LGSR when coupled with a version of the rescue effect, in which local populations toward the fringes of geographical ranges are sustained by immigration. The Stevens hypothesis is now commonly cited as a potential explanation for the LGSR and has provoked numerous empirical studies in macroecology and biogeography. However, important aspects of the hypothesis are not obvious in Steven's verbal model and may go unrecognized, despite their major implications for empirical work related to large-scale ecological and evolutionary processes. Here the authors present mathematical simulation models that test the logical structure of the Stevens hypothesis, examine effects on global patterns of species richness produced by the mechanisms (Rapoport's rule and the rescue effect) explicitly identified by Stevens, and investigate the additional effect of competition.

  3. Phosgene in the UTLS: seasonal and latitudinal variations from MIPAS observations

    NASA Astrophysics Data System (ADS)

    Valeri, Massimo; Carlotti, Massimo; Flaud, Jean-Marie; Raspollini, Piera; Ridolfi, Marco; Dinelli, Bianca Maria

    2016-09-01

    The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a Fourier transform spectrometer that measured mid-infrared atmospheric limb emission spectra from July 2002 to April 2012 on board the polar-orbiting satellite ENVISAT. We have used MIPAS data to study the latitudinal variations of phosgene (COCl2 or carbonyl chloride) and, for the first time, its seasonal variation in the upper troposphere/lower stratosphere region (UTLS). Retrievals of phosgene were made using the 830-860 cm-1 region, corresponding to the ν5 bands of COCl2. Unfortunately, in that region, the ν4 band of CFC-11, which is much stronger than COCl2 ν5, hides the phosgene emission. In order to evaluate seasonality and latitudinal distribution of phosgene we have analysed all the measurements made by MIPAS on days 18 and 20 of each month of 2008 with the optimized retrieval model (ORM) recently upgraded with the multi-target retrieval technique and with the optimal estimation functionality to apply external constraints to the state vector. Average seasonal profiles of phosgene show an evident latitudinal variability with the largest values observed in the tropical regions (maximum ≈ 35 parts per trillion by volume (pptv) at about 300 hPa). In the midlatitude and polar regions, the volume mixing ratio (VMR) values do not exceed 30 pptv and the vertical distributions are less peaked. Our analysis highlights that COCl2 seasonal variability is fairly low, apart from the polar regions.

  4. Predicting competitive shifts and responses to climate change based on latitudinal distributions of species assemblages.

    PubMed

    Lord, Joshua; Whitlatch, Robert

    2015-05-01

    Many terrestrial plant and marine benthic communities involve intense competition for space as a means to survive and reproduce. Superior competitors can dominate other species numerically with high reproductive rates, indirectly with high growth rates that facilitate space acquisition, or directly with competitive overgrowth. To assess how climate change could affect competitive interactions, we examined latitudinal patterns in growth rates and overgrowth competition via field surveys and experiments with marine epibenthic communities. Epibenthic fouling communities are dominated by invasive tunicates, bryozoans, and other species that grow on docks, boats, and other artificial structures. Fouling communities are space limited, so growth rate and overgrowth competition play an important role in shaping abundance patterns. We experimentally assessed temperature-dependent growth rates of several tunicates and bryozoans in eight regions spanning the U.S. east and west coasts. Several species displayed positive growth responses to warmer temperature in the northern portions of their latitudinal ranges, and vice versa. We used photo surveys of floating docks in at least 16 harbors in each region to compare communities and overgrowth competition. There was a strong correlation across species and regions between growth rate and competitive ability, indicating that growth plays an important role in competitive outcomes. Because growth rates are typically temperature dependent for organisms that compete for space, including terrestrial plants, fungi, algae, bacteria, and sessile benthic organisms, global warming could affect competitive outcomes. Our results suggest that these competitive shifts can be predicted by species' relative growth rates and latitudinal ranges.

  5. Predicting competitive shifts and responses to climate change based on latitudinal distributions of species assemblages.

    PubMed

    Lord, Joshua; Whitlatch, Robert

    2015-05-01

    Many terrestrial plant and marine benthic communities involve intense competition for space as a means to survive and reproduce. Superior competitors can dominate other species numerically with high reproductive rates, indirectly with high growth rates that facilitate space acquisition, or directly with competitive overgrowth. To assess how climate change could affect competitive interactions, we examined latitudinal patterns in growth rates and overgrowth competition via field surveys and experiments with marine epibenthic communities. Epibenthic fouling communities are dominated by invasive tunicates, bryozoans, and other species that grow on docks, boats, and other artificial structures. Fouling communities are space limited, so growth rate and overgrowth competition play an important role in shaping abundance patterns. We experimentally assessed temperature-dependent growth rates of several tunicates and bryozoans in eight regions spanning the U.S. east and west coasts. Several species displayed positive growth responses to warmer temperature in the northern portions of their latitudinal ranges, and vice versa. We used photo surveys of floating docks in at least 16 harbors in each region to compare communities and overgrowth competition. There was a strong correlation across species and regions between growth rate and competitive ability, indicating that growth plays an important role in competitive outcomes. Because growth rates are typically temperature dependent for organisms that compete for space, including terrestrial plants, fungi, algae, bacteria, and sessile benthic organisms, global warming could affect competitive outcomes. Our results suggest that these competitive shifts can be predicted by species' relative growth rates and latitudinal ranges. PMID:26236840

  6. Nitrogen fixation strategies can explain the latitudinal shift in nitrogen-fixing tree abundance.

    PubMed

    Menge, Duncan N L; Lichstein, Jeremy W; Angeles-Pérez, Gregorio

    2014-08-01

    The rarity of symbiotic nitrogen-fixing trees in higher-latitude compared to lower-latitude forests is paradoxical because higher-latitude soils are relatively N poor. Using national-scale forest inventories from the United States and Mexico, we show that the latitudinal abundance distribution of N-fixing trees (more than 10 times less abundant poleward of 35 degrees N) coincides with a latitudinal transition in symbiotic N-fixation type: rhizobial N-fixing trees (which are typically facultative, regulating fixation to meet nutritional demand) dominate equatorward of 35 degrees N, whereas actinorhizal N-fixing trees (typically obligate, maintaining fixation regardless of soil nutrition) dominate to the north. We then use theoretical and statistical models to show that a latitudinal shift in N-fixation strategy (facultative vs. obligate) near 35 degrees N can explain the observed change in N-fixing tree abundance, even if N availability is lower at higher latitudes, because facultative fixation leads to much higher landscape-scale N-fixing tree abundance than obligate fixation.

  7. Different Planctomycetes diversity patterns in latitudinal surface seawater of the open sea and in sediment.

    PubMed

    Shu, Qinglong; Jiao, Nianzhi

    2008-04-01

    The 16S rRNA gene approach was applied to investigate the diversity of Planctomycetes in latitudinal surface seawater of the Western Pacific Ocean. The results revealed that the Pirellula-Rhodopirellula-Blastopirellula clade dominated the Planctomycetes community at all surface seawater sites while the minority genera Gemmata and Planctomyces were only found at sites H5 and H2 respectively. Although the clone frequency of the PRB clade seemed stable (between 83.3% and 94.1%) for all surface seawater sites, the retrieved Pirellula-Rhodopirellula-Blastopirellula clade presented unexpected diversity. Interestingly, low latitude seawater appeared to have higher diversity than mid-latitudes. integral-LIBSHUFF software analysis revealed significantly different diversity patterns between in latitudinal surface seawater and in the sediment of South China Sea station M2896. Our data suggested that different hydrological and geographic features contributed to the shift of Planctomycetes diversity in marine environments. This is, to our knowledge, the first systematic assessment of Planctomycetes in latitudinal surface seawater of the open sea and the first comparison of diversity pattern between surface seawater and sediments and has broadened our understanding of Planctomycetes diversity in marine environments.

  8. Proximate causes of adaptive growth rates: growth efficiency variation among latitudinal populations of Rana temporaria.

    PubMed

    Lindgren, B; Laurila, A

    2005-07-01

    In ectothermic organisms, declining season length and lower temperature towards higher latitudes often select for latitudinal variation in growth and development. However, the energetic mechanisms underlying this adaptive variation are largely unknown. We investigated growth, food intake and growth efficiency of Rana temporaria tadpoles from eight populations along a 1500 km latitudinal gradient across Sweden. To gain an insight into the mechanisms of adaptation at organ level, we also examined variation in tadpole gut length. The tadpoles were raised at two temperatures (16 and 20 degrees C) in a laboratory common garden experiment. We found increased growth rate towards higher latitudes, regardless of temperature treatment. This increase in growth was not because of a higher food intake rate, but populations from higher latitudes had higher growth efficiency, i.e. they were more efficient at converting ingested food into body mass. Low temperature reduced growth efficiency most strongly in southern populations. Relative gut length increased with latitude, and tadpoles at low temperature tended to have longer guts. However, variation in gut length was not the sole adaptive explanation for increased growth efficiency as latitude and body length still explained significant amounts of variation in growth efficiency. Hence, additional energetic adaptations are probably involved in growth efficiency variation along the latitudinal gradient.

  9. Mississippian coral latitudinal diversity gradients (western interior United States): Testing the limits of high resolution diversity data

    USGS Publications Warehouse

    Webb, G.E.; Sando, W.J.; Raymond, A.

    1997-01-01

    Analysis of high resolution diversity data for Mississippian corals in the western interior United States yielded mild latitudinal diversity gradients despite the small geographic area covered by samples and a large influence on diversity patterns by geographic sampling intensity (sample bias). Three competing plate tectonic reconstructions were tested using the diversity patterns. Although none could be forcefully rejected, one reconstruction proved less consistent with diversity patterns than the other two and additional coral diversity data from farther north in Canada would better discriminate the two equivalent reconstructions. Despite the relatively high sampling intensity represented by the analyzed database, diversity patterns were greatly affected by sample abundance and distribution. Hence, some effort at recognizing and accounting for sample bias should be undertaken in any study of latitudinal diversity gradients. Small-scale geographic lumping of sample localities had only small effects on geographic diversity patterns. However, large-scale (e.g., regional) geographic lumping of diversity data may not yield latitudinally sensitive diversity patterns. Temporal changes in coral diversity in this region reflect changes in eustacy, local tectonism, and terrigenous sediment flux, far more than they do shifting latitude. Highest regional diversity occurred during the interval when the studied region occupied the highest latitude. Therefore, diversity data from different regions may not be comparable, in terms of latitudinal inference. Small-scale stratigraphic lumping of the data caused a nearly complete loss of the latitudinal diversity patterns apparent prior to lumping. Hence, the narrowest possible stratigraphic resolution should be maintained in analyzing latitudinal diversity gradients.

  10. GASIS demonstration

    SciTech Connect

    Vidas, E.H.

    1995-04-01

    A prototype of the GASIS database and retrieval software has been developed and is the subject of this poster session and computer demonstration. The prototype consists of test or preliminary versions of the GASIS Reservoir Data System and Source Directory datasets and the software for query and retrieval. The prototype reservoir database covers the Rocky Mountain region and contains the full GASIS data matrix (all GASIS data elements) that will eventually be included on the CD-ROM. It is populated for development purposes primarily by the information included in the Rocky Mountain Gas Atlas. The software has been developed specifically for GASIS using Foxpro for Windows. The application is an executable file that does not require Foxpro to run. The reservoir database software includes query and retrieval, screen display, report generation, and data export functions. Basic queries by state, basin, or field name will be assisted by scrolling selection lists. A detailed query screen will allow record selection on the basis of any data field, such as depth, cumulative production, or geological age. Logical operators can be applied to any-numeric data element or combination of elements. Screen display includes a {open_quotes}browse{close_quotes} display with one record per row and a detailed single record display. Datasets can be exported in standard formats for manipulation with other software packages. The Source Directory software will allow record retrieval by database type or subject area.

  11. Unimodal latitudinal pattern of land-snail species richness across northern Eurasian lowlands.

    PubMed

    Horsák, Michal; Chytrý, Milan

    2014-01-01

    Large-scale patterns of species richness and their causes are still poorly understood for most terrestrial invertebrates, although invertebrates can add important insights into the mechanisms that generate regional and global biodiversity patterns. Here we explore the general plausibility of the climate-based "water-energy dynamics" hypothesis using the latitudinal pattern of land-snail species richness across extensive topographically homogeneous lowlands of northern Eurasia. We established a 1480-km long latitudinal transect across the Western Siberian Plain (Russia) from the Russia-Kazakhstan border (54.5°N) to the Arctic Ocean (67.5°N), crossing eight latitudinal vegetation zones: steppe, forest-steppe, subtaiga, southern, middle and northern taiga, forest-tundra, and tundra. We sampled snails in forests and open habitats each half-degree of latitude and used generalized linear models to relate snail species richness to climatic variables and soil calcium content measured in situ. Contrary to the classical prediction of latitudinal biodiversity decrease, we found a striking unimodal pattern of snail species richness peaking in the subtaiga and southern-taiga zones between 57 and 59°N. The main south-to-north interchange of the two principal diversity constraints, i.e. drought stress vs. cold stress, explained most of the variance in the latitudinal diversity pattern. Water balance, calculated as annual precipitation minus potential evapotranspiration, was a single variable that could explain 81.7% of the variance in species richness. Our data suggest that the "water-energy dynamics" hypothesis can apply not only at the global scale but also at subcontinental scales of higher latitudes, as water availability was found to be the primary limiting factor also in this extratropical region with summer-warm and dry climate. A narrow zone with a sharp south-to-north switch in the two main diversity constraints seems to constitute the dominant and general pattern of

  12. Unimodal Latitudinal Pattern of Land-Snail Species Richness across Northern Eurasian Lowlands

    PubMed Central

    Horsák, Michal; Chytrý, Milan

    2014-01-01

    Large-scale patterns of species richness and their causes are still poorly understood for most terrestrial invertebrates, although invertebrates can add important insights into the mechanisms that generate regional and global biodiversity patterns. Here we explore the general plausibility of the climate-based “water-energy dynamics” hypothesis using the latitudinal pattern of land-snail species richness across extensive topographically homogeneous lowlands of northern Eurasia. We established a 1480-km long latitudinal transect across the Western Siberian Plain (Russia) from the Russia-Kazakhstan border (54.5°N) to the Arctic Ocean (67.5°N), crossing eight latitudinal vegetation zones: steppe, forest-steppe, subtaiga, southern, middle and northern taiga, forest-tundra, and tundra. We sampled snails in forests and open habitats each half-degree of latitude and used generalized linear models to relate snail species richness to climatic variables and soil calcium content measured in situ. Contrary to the classical prediction of latitudinal biodiversity decrease, we found a striking unimodal pattern of snail species richness peaking in the subtaiga and southern-taiga zones between 57 and 59°N. The main south-to-north interchange of the two principal diversity constraints, i.e. drought stress vs. cold stress, explained most of the variance in the latitudinal diversity pattern. Water balance, calculated as annual precipitation minus potential evapotranspiration, was a single variable that could explain 81.7% of the variance in species richness. Our data suggest that the “water-energy dynamics” hypothesis can apply not only at the global scale but also at subcontinental scales of higher latitudes, as water availability was found to be the primary limiting factor also in this extratropical region with summer-warm and dry climate. A narrow zone with a sharp south-to-north switch in the two main diversity constraints seems to constitute the dominant and general

  13. Unimodal latitudinal pattern of land-snail species richness across northern Eurasian lowlands.

    PubMed

    Horsák, Michal; Chytrý, Milan

    2014-01-01

    Large-scale patterns of species richness and their causes are still poorly understood for most terrestrial invertebrates, although invertebrates can add important insights into the mechanisms that generate regional and global biodiversity patterns. Here we explore the general plausibility of the climate-based "water-energy dynamics" hypothesis using the latitudinal pattern of land-snail species richness across extensive topographically homogeneous lowlands of northern Eurasia. We established a 1480-km long latitudinal transect across the Western Siberian Plain (Russia) from the Russia-Kazakhstan border (54.5°N) to the Arctic Ocean (67.5°N), crossing eight latitudinal vegetation zones: steppe, forest-steppe, subtaiga, southern, middle and northern taiga, forest-tundra, and tundra. We sampled snails in forests and open habitats each half-degree of latitude and used generalized linear models to relate snail species richness to climatic variables and soil calcium content measured in situ. Contrary to the classical prediction of latitudinal biodiversity decrease, we found a striking unimodal pattern of snail species richness peaking in the subtaiga and southern-taiga zones between 57 and 59°N. The main south-to-north interchange of the two principal diversity constraints, i.e. drought stress vs. cold stress, explained most of the variance in the latitudinal diversity pattern. Water balance, calculated as annual precipitation minus potential evapotranspiration, was a single variable that could explain 81.7% of the variance in species richness. Our data suggest that the "water-energy dynamics" hypothesis can apply not only at the global scale but also at subcontinental scales of higher latitudes, as water availability was found to be the primary limiting factor also in this extratropical region with summer-warm and dry climate. A narrow zone with a sharp south-to-north switch in the two main diversity constraints seems to constitute the dominant and general pattern of

  14. Mechanisms controlling the number and latitudinal spacing of jets-streams on multiple jet planets: from terrestrial planets to gas giants

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Chemke, Rei

    2015-11-01

    Zonal jets dominate the atmospheric dynamics of a wide range of planetary systems as observed in all Solar System planetary atmospheres and even observed on exoplanets. Specifically, when the ratio between the eddy length scale and the planetary scale becomes small these planetary atmospheres develop multiple jets. In this study we use an idealized general circulation model to demonstrate how such multiple-jets are formed and what controls their latitudinal width and spacing. We find that for each latitude, over a wide range of parameters, the jet spacing scales with the Rhines scale. The simulations show the presence of a critical latitude, where poleward (equatorward) of this latitude the Rhines scale is larger (smaller) than the Rossby deformation radius. Poleward of this latitude, a classic geostrophic turbulence picture appears with a -5/3 spectral slope of inverse energy cascade from the deformation radius up to the Rhines scale. A shallower slope than the classic -3 slope of forward cascade is found from the deformation radius down to the viscosity scale, due to the broad input of baroclinic eddy kinetic energy. At these latitudes, eddy-eddy interactions transfer barotropic eddy kinetic energy from the input scales of baroclinic eddy kinetic energy up to the jet scale and down to smaller scales. We provide scaling laws for the number of eddy driven jets, their latitudinal width and speed as a function of a broad range of planetary parameters.

  15. Effects of particle drift on cosmic ray transport. II - Analytical solution to the modulation problem with no latitudinal diffusion

    NASA Technical Reports Server (NTRS)

    Isenberg, P. A.; Jokipii, J. R.

    1978-01-01

    An analytical solution to a model of the modulation of galactic cosmic rays in the presence of particle drifts is presented and discussed. The solution assumes an energy-independent radial diffusion coefficient proportional to distance and no latitudinal diffusion, and includes energy-independent particle drift velocities similar to those expected in a Parker spiral magnetic field with an equatorial current sheet. The solutions clearly demonstrate the large effects of drifts on the modulated cosmic-ray intensity. For values of the radial diffusion coefficient and particle drift velocity which are plausible for 1-GV-rigidity protons, the logarithmic radial gradient in the inner solar system is reduced by more than a factor of 5 over the value calculated in the absence of drifts. It is found that even for much smaller values of particle drift velocity and radial diffusion coefficient, such as might be expected for protons with energies of the order of 10 MeV, the effects of the drifts can be substantial.

  16. Latitudinal species diversity gradient of mushroom corals off eastern Australia: a baseline from the 1970s

    NASA Astrophysics Data System (ADS)

    Hoeksema, Bert W.

    2015-11-01

    Based on a study of mushroom coral species of eastern Australia, a decrease in species richness can be discerned from north to south. Eastern Australia, including the Great Barrier Reef (GBR), is one of only few coral reef areas suitable for studies on large-scale latitudinal biodiversity patterns. Such patterns may help to recognize biogeographic boundaries and factors regulating biodiversity. Owing to the eastern Australian long coastline, such studies are a logistic challenge unless reliable distribution data are already available, as in museum collections. A large coral collection predominantly sampled from this area in the 1970s is present in the Museum of Tropical Queensland (MTQ). The scleractinian family Fungiidae (mushroom corals), representing about 10% of Indo-Pacific reef coral species, was selected as proxy. It was represented by 1289 specimens belonging to 34 species with latitudinal ranges between 09°09‧S and 31°28‧S. The fauna of the northernmost reefs in the Gulf of Papua and the Torres Strait, and north of the Great Barrier Reef Marine Park (GBRMP), was represented by a maximum of 30 fungiids. From here a southward decline in species number was observed, down to Lord Howe Island with only one species. Together with previous records, the mushroom coral fauna of eastern Australia consists of 37 species, which is more diverse than hitherto known and similar to numbers found in the Coral Triangle. Future field surveys in the GBR should specifically target rarely known species, which are mainly small and found at depths >25 m. In the light of global climate change, they may also show whether previously recorded species are still present and whether their latitudinal ranges have shifted, using the 1970s records as a baseline.

  17. Ecosystem-wide morphological structure of leaf-litter ant communities along a tropical latitudinal gradient.

    PubMed

    Silva, Rogério R; Brandão, Carlos Roberto F

    2014-01-01

    General principles that shape community structure can be described based on a functional trait approach grounded on predictive models; increased attention has been paid to factors accounting for the functional diversity of species assemblages and its association with species richness along environmental gradients. We analyze here the interaction between leaf-litter ant species richness, the local communities' morphological structure and fundamental niche within the context of a northeast-southeast latitudinal gradient in one of the world's most species-rich ecosystems, the Atlantic Forest, representing 2,700 km of tropical rainforest along almost 20° of latitude in eastern Brazil. Our results are consistent with an ecosystem-wide pattern in communities' structure, with relatively high species turnover but functionally analogous leaf-litter ant communities' organization. Our results suggest directional shifts in the morphological space along the environmental gradient from overdispersed to aggregated (from North to South), suggesting that primary productivity and environmental heterogeneity (altitude, temperature and precipitation in the case) determine the distribution of traits and regulate the assembly rules, shaping local leaf-litter ant communities. Contrary to the expected and most common pattern along latitudinal gradients, the Atlantic Forest leaf litter ant communities show an inverse pattern in richness, that is, richer communities in higher than in lower latitudes. The morphological specialization of communities showed more morphologically distinct communities at low latitudes and species redundancy at high latitudes. We claim that an inverse latitudinal gradient in primary productivity and environmental heterogeneity across the Atlantic forest may affect morphological diversity and species richness, enhancing species coexistence mechanisms, and producing thus the observed patterns. We suggest that a functional framework based on flexible enough traits

  18. Ecosystem-wide morphological structure of leaf-litter ant communities along a tropical latitudinal gradient.

    PubMed

    Silva, Rogério R; Brandão, Carlos Roberto F

    2014-01-01

    General principles that shape community structure can be described based on a functional trait approach grounded on predictive models; increased attention has been paid to factors accounting for the functional diversity of species assemblages and its association with species richness along environmental gradients. We analyze here the interaction between leaf-litter ant species richness, the local communities' morphological structure and fundamental niche within the context of a northeast-southeast latitudinal gradient in one of the world's most species-rich ecosystems, the Atlantic Forest, representing 2,700 km of tropical rainforest along almost 20° of latitude in eastern Brazil. Our results are consistent with an ecosystem-wide pattern in communities' structure, with relatively high species turnover but functionally analogous leaf-litter ant communities' organization. Our results suggest directional shifts in the morphological space along the environmental gradient from overdispersed to aggregated (from North to South), suggesting that primary productivity and environmental heterogeneity (altitude, temperature and precipitation in the case) determine the distribution of traits and regulate the assembly rules, shaping local leaf-litter ant communities. Contrary to the expected and most common pattern along latitudinal gradients, the Atlantic Forest leaf litter ant communities show an inverse pattern in richness, that is, richer communities in higher than in lower latitudes. The morphological specialization of communities showed more morphologically distinct communities at low latitudes and species redundancy at high latitudes. We claim that an inverse latitudinal gradient in primary productivity and environmental heterogeneity across the Atlantic forest may affect morphological diversity and species richness, enhancing species coexistence mechanisms, and producing thus the observed patterns. We suggest that a functional framework based on flexible enough traits

  19. Leaf Caloric Value from Tropical to Cold-Temperate Forests: Latitudinal Patterns and Linkage to Productivity

    PubMed Central

    Song, Guangyan; Hou, Jihua; Li, Ying; Zhang, Jiahui; He, Nianpeng

    2016-01-01

    Leaf caloric value (LCV) reflects the capacity of a leaf to fix and accumulate solar energy through photosynthesis. We systematically investigated the LCV of 745 plant species in 9 forests, representing a range of tropical to cold-temperate forests along the 4700-km North-South Transect of Eastern China. The goals were to explore the latitudinal patterns of LCV at the levels of species, plant functional group, and community and to establish the relationship between LCV and gross primary productivity (GPP). Our results showed that LCV for all species ranged from 12.85 to 22.15 KJ g–1 with an average of 18.46 KJ g–1. Plant functional groups had a significant influence on LCV, with trees > shrubs > herbs, conifers > broadleaved trees, and evergreens > deciduous trees. The different values of LCV represented the long-term evolution and adaptation of plant species to different environments. Unexpectedly, no apparent latitudinal trends of LCV at community level were observed, although LCV at the species level clearly decreased with increasing latitude. Use efficiency of LCV (CUE, gC KJ–1), defined as the ratio of GPP to total LCV at the community level, varied quadratic with latitude and was lower in the middle latitudes. Climate (temperature and precipitation) may explain 52.9% of the variation in spatial patterns of CUE, which was positively correlated with aridity. Our findings are the first large-scale report of the latitudinal patterns of LCV in forests at the species, plant functional group, and community levels and provide new insights into the relationship between LCV and ecosystem functions in forest communities. PMID:27341474

  20. An evaluation of the latitudinal gradient of chlorophyll in the California Current

    NASA Astrophysics Data System (ADS)

    Dietrich, W.; Broughton, J.; Kudela, R. M.

    2013-12-01

    Tracking of spatial and temporal trends in phytoplankton abundance and distribution is an important step toward understanding large-scale macroecological processes in the ocean. Measurements of ocean radiance from satellite-borne sensors, such as SeaWiFS and MODIS, can be used to estimate surface chlorophyll concentration, which is a good indicator of phytoplankton biomass. The primary goal of this study was to evaluate the latitudinal gradient in chlorophyll concentration within the California Current first reported by Ware and Thomson (2005). They found that average chlorophyll concentration tended to increase steadily from 32-48°N latitude. This concentration gradient was reevaluated using a longer dataset and an algorithm refined for the region. Radiance data from the MODIS-Aqua instrument were obtained for every year from 2002 through 2013. Data included annual averages of remote sensing radiance as well as monthly averages for February, April, and August. These months were chosen to represent each of the three oceanographic seasons present in the California Current. Estimates of chlorophyll concentration were derived from these data using the CALFIT algorithm developed by Kahru et al. (2012). The resulting maps of chlorophyll concentration were processed in MATLAB and linear regressions were performed using SYSTAT 13 software. A statistically significant (p < 0.05) latitudinal trend in chlorophyll was observed in the annual averaged data as well as in the averaged seasonal data from February and August. No significant trend was observed in the averaged April data. Chlorophyll concentration was positively correlated with latitude in every instance, except in April 2003 and April 2005, where a negative correlation was observed. The positive latitudinal trend was strongest during August and weakest during April. Strong peaks in chlorophyll were observed near San Francisco Bay and the mouth of the Columbia River, suggesting that river-borne nutrient input may be

  1. Latitudinal variation in seasonal activity and mortality in ratsnakes (Elaphe obsoleta).

    PubMed

    Sperry, Jinelle H; Blouin-Demers, Gabriel; Carfagno, Gerardo L F; Weatherhead, Patrick J

    2010-06-01

    The ecology of ectotherms should be particularly affected by latitude because so much of their biology is temperature dependent. Current latitudinal patterns should also be informative about how ectotherms will have to modify their behavior in response to climate change. We used data from a total of 175 adult black ratsnakes (Elaphe obsoleta) radio-tracked in Ontario, Illinois, and Texas, a latitudinal distance of >1500 km, to test predictions about how seasonal patterns of activity and mortality should vary with latitude. Despite pronounced differences in temperatures among study locations, and despite ratsnakes in Texas not hibernating and switching from diurnal to nocturnal activity in the summer, seasonal patterns of snake activity were remarkably similar during the months that snakes in all populations were active. Rather than being a function of temperature, activity may be driven by the timing of reproduction, which appears similar among populations. Contrary to the prediction that mortality should be highest in the most active population, overall mortality did not follow a clinal pattern. Winter mortality did increase with latitude, however, consistent with temperature limiting the northern distribution of ratsnakes. This result was opposite that found in the only previous study of latitudinal variation in winter mortality in reptiles, which may be a consequence of whether or not the animals exhibit true hibernation. Collectively, these results suggest that, at least in the northern part of their range, ratsnakes should be able to adjust easily to, and may benefit from, a warmer climate, although climate-based changes to the snakes' prey or habitat, for example, could alter that prediction. PMID:20583726

  2. Leaf Caloric Value from Tropical to Cold-Temperate Forests: Latitudinal Patterns and Linkage to Productivity.

    PubMed

    Song, Guangyan; Hou, Jihua; Li, Ying; Zhang, Jiahui; He, Nianpeng

    2016-01-01

    Leaf caloric value (LCV) reflects the capacity of a leaf to fix and accumulate solar energy through photosynthesis. We systematically investigated the LCV of 745 plant species in 9 forests, representing a range of tropical to cold-temperate forests along the 4700-km North-South Transect of Eastern China. The goals were to explore the latitudinal patterns of LCV at the levels of species, plant functional group, and community and to establish the relationship between LCV and gross primary productivity (GPP). Our results showed that LCV for all species ranged from 12.85 to 22.15 KJ g-1 with an average of 18.46 KJ g-1. Plant functional groups had a significant influence on LCV, with trees > shrubs > herbs, conifers > broadleaved trees, and evergreens > deciduous trees. The different values of LCV represented the long-term evolution and adaptation of plant species to different environments. Unexpectedly, no apparent latitudinal trends of LCV at community level were observed, although LCV at the species level clearly decreased with increasing latitude. Use efficiency of LCV (CUE, gC KJ-1), defined as the ratio of GPP to total LCV at the community level, varied quadratic with latitude and was lower in the middle latitudes. Climate (temperature and precipitation) may explain 52.9% of the variation in spatial patterns of CUE, which was positively correlated with aridity. Our findings are the first large-scale report of the latitudinal patterns of LCV in forests at the species, plant functional group, and community levels and provide new insights into the relationship between LCV and ecosystem functions in forest communities.

  3. Faster speciation and reduced extinction in the tropics contribute to the Mammalian latitudinal diversity gradient.

    PubMed

    Rolland, Jonathan; Condamine, Fabien L; Jiguet, Frederic; Morlon, Hélène

    2014-01-01

    The increase in species richness from the poles to the tropics, referred to as the latitudinal diversity gradient, is one of the most ubiquitous biodiversity patterns in the natural world. Although understanding how rates of speciation and extinction vary with latitude is central to explaining this pattern, such analyses have been impeded by the difficulty of estimating diversification rates associated with specific geographic locations. Here, we use a powerful phylogenetic approach and a nearly complete phylogeny of mammals to estimate speciation, extinction, and dispersal rates associated with the tropical and temperate biomes. Overall, speciation rates are higher, and extinction rates lower, in the tropics than in temperate regions. The diversity of the eight most species-rich mammalian orders (covering 92% of all mammals) peaks in the tropics, except that of the Lagomorpha (hares, rabbits, and pikas) reaching a maxima in northern-temperate regions. Latitudinal patterns in diversification rates are strikingly consistent with these diversity patterns, with peaks in species richness associated with low extinction rates (Primates and Lagomorpha), high speciation rates (Diprotodontia, Artiodactyla, and Soricomorpha), or both (Chiroptera and Rodentia). Rates of range expansion were typically higher from the tropics to the temperate regions than in the other direction, supporting the "out of the tropics" hypothesis whereby species originate in the tropics and disperse into higher latitudes. Overall, these results suggest that differences in diversification rates have played a major role in shaping the modern latitudinal diversity gradient in mammals, and illustrate the usefulness of recently developed phylogenetic approaches for understanding this famous yet mysterious pattern.

  4. Leaf Caloric Value from Tropical to Cold-Temperate Forests: Latitudinal Patterns and Linkage to Productivity.

    PubMed

    Song, Guangyan; Hou, Jihua; Li, Ying; Zhang, Jiahui; He, Nianpeng

    2016-01-01

    Leaf caloric value (LCV) reflects the capacity of a leaf to fix and accumulate solar energy through photosynthesis. We systematically investigated the LCV of 745 plant species in 9 forests, representing a range of tropical to cold-temperate forests along the 4700-km North-South Transect of Eastern China. The goals were to explore the latitudinal patterns of LCV at the levels of species, plant functional group, and community and to establish the relationship between LCV and gross primary productivity (GPP). Our results showed that LCV for all species ranged from 12.85 to 22.15 KJ g-1 with an average of 18.46 KJ g-1. Plant functional groups had a significant influence on LCV, with trees > shrubs > herbs, conifers > broadleaved trees, and evergreens > deciduous trees. The different values of LCV represented the long-term evolution and adaptation of plant species to different environments. Unexpectedly, no apparent latitudinal trends of LCV at community level were observed, although LCV at the species level clearly decreased with increasing latitude. Use efficiency of LCV (CUE, gC KJ-1), defined as the ratio of GPP to total LCV at the community level, varied quadratic with latitude and was lower in the middle latitudes. Climate (temperature and precipitation) may explain 52.9% of the variation in spatial patterns of CUE, which was positively correlated with aridity. Our findings are the first large-scale report of the latitudinal patterns of LCV in forests at the species, plant functional group, and community levels and provide new insights into the relationship between LCV and ecosystem functions in forest communities. PMID:27341474

  5. Large-scale phytogeographical patterns in eastern Asia in relation to latitudinal and climatic gradients

    USGS Publications Warehouse

    Qian, H.; Song, J.-S.; Krestov, P.; Guo, Q.; Wu, Z.; Shen, X.; Guo, X.

    2003-01-01

    This paper aims at determining how different floristic elements (e.g. cosmopolitan, tropical, and temperate) change with latitude and major climate factors, and how latitude affects the floristic relationships between East Asia and the other parts of the world. The large-scale patterns of phytogeography in East Asia are strongly related to latitude, which covaries with several climatic variables such as temperature. Evolutionary processes such as the adaptation of plants to cold climates and current and past land connections are likely responsible for the observed latitudinal patterns.

  6. Latitudinal Discontinuity in Thermal Conditions along the Nearshore of Central-Northern Chile

    PubMed Central

    Tapia, Fabian J.; Largier, John L.; Castillo, Manuel; Wieters, Evie A.; Navarrete, Sergio A.

    2014-01-01

    Over the past decade, evidence of abrupt latitudinal changes in the dynamics, structure and genetic variability of intertidal and subtidal benthic communities along central-northern Chile has been found consistently at 30–32°S. Changes in the advective and thermal environment in nearshore waters have been inferred from ecological patterns, since analyses of in situ physical data have thus far been missing. Here we analyze a unique set of shoreline temperature data, gathered over 4–10 years at 15 sites between 28–35°S, and combine it with satellite-derived winds and sea surface temperatures to investigate the latitudinal transition in nearshore oceanographic conditions suggested by recent ecological studies. Our results show a marked transition in thermal conditions at 30–31°S, superimposed on a broad latitudinal trend, and small-scale structures associated with cape-and-bay topography. The seasonal cycle dominated temperature variability throughout the region, but its relative importance decreased abruptly south of 30–31°S, as variability at synoptic and intra-seasonal scales became more important. The response of shoreline temperatures to meridional wind stress also changed abruptly at the transition, leading to a sharp drop in the occurrence of low-temperature waters at northern sites, and a concurrent decrease in corticated algal biomass. Together, these results suggest a limitation of nitrate availability in nearshore waters north of the transition. The localized alongshore change results from the interaction of latitudinal trends (e.g., wind stress, surface warming, inertial period) with a major headland-bay system (Punta Lengua de Vaca at 30.25°S), which juxtaposes a southern stretch of coast characterized by upwelling with a northern stretch of coast characterized by warm surface waters and stratification. This transition likely generates a number of latitude-dependent controls on ecological processes in the nearshore that can explain species

  7. Latitudinal variations in Titan's methane and haze from Cassini VIMS observations

    USGS Publications Warehouse

    Penteado, P.F.; Griffith, C.A.; Tomasko, M.G.; Engel, S.; See, C.; Doose, L.; Baines, K.H.; Brown, R.H.; Buratti, B.J.; Clark, R.; Nicholson, P.; Sotin, C.

    2010-01-01

    We analyze observations taken with Cassini's Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60??S and 40??N. The methane variation was measured primarily from its absorption band at 0.61 ??m, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan's 0.4-1.6 ??m spectra, which sample Titan's atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20??S and 10??S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60??S and 40??N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27??S and 19??N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan's visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane

  8. Assessment of tannin variation in Tamarisk foliage across a latitudinal gradient

    USGS Publications Warehouse

    Hussey, A.M.; Kimball, B.A.; Friedman, J.M.

    2011-01-01

    Certain phenotypic traits of plants vary with latitude of origin. To understand if tannin concentration varies among populations of tamarisk (Tamarix spp.) according to a latitudinal gradient, an analytical method was adapted from an enological tannin assay. The tannin content (wet basis) of tamarisk foliage collected from 160 plants grown in a common garden ranged from 8.26 to 62.36 mg/g and was not correlated with the latitude of the original North American plant collection site. Tannins do not contribute to observed differences in herbivory observed among these tamarisk populations.

  9. Fluxes of Dissolved Organic Carbon within Soils across a Boreal Forest Ecosystem Latitudinal Transect

    NASA Astrophysics Data System (ADS)

    Bowering, K.; Edwards, K.; Billings, S. A.; Skinner, A.; Warren, J.; Ziegler, S. E.

    2013-12-01

    The movement of dissolved organic carbon (DOC) can represent a significant flux of C within soils, and may be a critical flux of C from the terrestrial into the aquatic environment. Further, these fluxes can represent an important source of C to deeper mineral horizons where stabilization mechanisms may exist. However the quantity and quality of this C flux is largely unknown, and regulating factors that are influenced by climate and land-use change are poorly understood. This movement of C is of particular interest in the boreal forest, where large soil C stocks are vulnerable to the impacts of climate change. Laboratory experiments have demonstrated that warming, in the absence of moisture limitation, can increase the rate of production of DOC in soils directly through increased decomposition rates; however, this has been difficult to test under field conditions where seasonality, intact soil, and hydrological systems influence DOC production and movement. To assess the impact of climate warming on DOC fluxes occurring through the organic soil layer of the eastern North American boreal forest, we sampled passive lysimeters installed at 3 sites along a latitudinal transect in Newfoundland and Labrador, Canada. Separated by just over 5° latitude, mean annual temperature at these sites were 4°C, 2.1°C, and -0.5°C from lowest to highest latitude. Six lysimeters were sampled from each site and collections were made at least three times annually for two consecutive years (2011-2013). Soils tend to freeze over-winter in the high-latitude site whereas they rarely freeze in the low-latitude site. The low-latitude site also experiences more variable precipitation, with a longer snow-free season and more precipitation falling during single events. Rates of DOC flux increased with decreasing latitude, indicating greater DOC transport through soils in forests experiencing a warmer climate. DOC fluxes calculated over different seasonal time periods ranged from 4.6 to 20

  10. Clock polymorphism in Pacific salmon: evidence for variable selection along a latitudinal gradient.

    PubMed

    O'Malley, Kathleen G; Ford, Michael J; Hard, Jeffrey J

    2010-12-22

    Seasonal timing of life-history events is often under strong natural selection. The Clock gene is a central component of an endogenous circadian clock that senses changes in photoperiod (day length) and mediates seasonal behaviours. Among Pacific salmonids (Oncorhynchus spp.), seasonal timing of migration and breeding is influenced by photoperiod. To expand a study of 42 North American Chinook salmon (Oncorhynchus tshawytscha) populations, we tested whether duplicated Clock genes contribute to population differences in reproductive timing. Specifically, we examined geographical variation along a similar latitudinal gradient in the polyglutamine domain (PolyQ) of OtsClock1a and OtsClock1b among 53 populations of three species: chum (Oncorhynchus keta), coho (Oncorhynchus kisutch) and pink salmon (Oncorhynchus gorbuscha). We found evidence for variable selection on OtsClock1b that corresponds to latitudinal variation in reproductive timing among these species. We evaluated the contribution of day length and a freshwater migration index to OtsClock1b PolyQ domain variation using regression trees and found that day length at spawning explains much of the variation in OtsClock1b allele frequency among chum and Chinook, but not coho and pink salmon populations. Our findings suggest that OtsClock1b mediates seasonal adaptation and influences geographical variation in reproductive timing in some of these highly migratory species.

  11. Direct observation of the latitudinal extent of a high-speed stream in the solar wind

    NASA Technical Reports Server (NTRS)

    Schwenn, R.; Montgomery, M. D.; Rosenbauer, H.; Miggenrieder, H.; Muehlhaeuser, K. H.; Bame, S. J.; Feldman, W. C.; Hansen, R. T.

    1978-01-01

    The latitudinal boundaries of stationary fast solar wind streams emerging from equatorward extensions of the sun's polar coronal holes are studied. Simultaneous data from the Helios 1 and Imp spacecraft at different heliographic latitudes are compared. The measured latitudinal speed gradient of 30 km/s/deg shows that large angular speed gradients occur at the leading edges of fast streams and also with respect to latitude. The data indicate that longitudinal speed gradients are steeper near 0.3 AU than at 1.0 AU. Generally, regions with large angular speed gradients are observed to separate fast streams from the surrounding slower plasma. This suggests the existence of mechanisms which diminish longitudinal speed gradients as the plasma travels toward 1.0 AU. It also seems that the distribution of solar wind speeds on a near-sun spherical surface has large mesalike high-speed regions. Comparisons of Helios 1 and Imp data with corona observations supports the hypothesis that high-speed solar wind streams emerge from coronal holes.

  12. Increased temperatures negatively affect Juniperus communis seeds: evidence from transplant experiments along a latitudinal gradient.

    PubMed

    Gruwez, R; De Frenne, P; Vander Mijnsbrugge, K; Vangansbeke, P; Verheyen, K

    2016-05-01

    With a distribution range that covers most of the Northern hemisphere, common juniper (Juniperus communis) has one of the largest ranges of all vascular plant species. In several regions in Europe, however, populations are decreasing in size and number due to failing recruitment. One of the main causes for this failure is low seed viability. Observational evidence suggests that this is partly induced by climate warming, but our mechanistic understanding of this effect remains incomplete. Here, we experimentally assess the influence of temperature on two key developmental phases during sexual reproduction, i.e. gametogenesis and fertilisation (seed phase two, SP2) and embryo development (seed phase three, SP3). Along a latitudinal gradient from southern France to central Sweden, we installed a transplant experiment with shrubs originating from Belgium, a region with unusually low juniper seed viability. Seeds of both seed phases were sampled during three consecutive years, and seed viability assessed. Warming temperatures negatively affected the seed viability of both SP2 and SP3 seeds along the latitudinal gradient. Interestingly, the effect on embryo development (SP3) only occurred in the third year, i.e. when the gametogenesis and fertilisation also took place in warmer conditions. We found strong indications that this negative influence mostly acts via disrupting growth of the pollen tube, the development of the female gametophyte and fertilisation (SP2). This, in turn, can lead to failing embryo development, for example, due to nutritional problems. Our results confirm that climate warming can negatively affect seed viability of juniper.

  13. Clonality-Climate Relationships along Latitudinal Gradient across China: Adaptation of Clonality to Environments

    PubMed Central

    Ye, Duo; Hu, Yukun; Song, Minghua; Pan, Xu; Xie, Xiufang; Liu, Guofang; Ye, Xuehua; Dong, Ming

    2014-01-01

    Plant clonality, the ability of a plant species to reproduce itself vegetatively through ramets (shoot-root units), occurs in many plant species and is considered to be more frequent in cold or wet environments. However, a deeper understanding on the clonality-climate relationships along large geographic gradients is still scarce. In this study we revealed the clonality-climate relationships along latitudinal gradient of entire China spanning from tropics to temperate zones using clonality data for 4015 vascular plant species in 545 terrestrial communities. Structural equation modeling (SEM) showed that, in general, the preponderance of clonality increased along the latitudinal gradient towards cold, dry or very wet environments. However, the distribution of clonality in China was significantly but only weakly correlated with latitude and four climatic factors (mean annual temperature, temperature seasonality, mean annual precipitation, precipitation seasonality). Clonality of woody and herbaceous species had opposite responses to climatic variables. More precisely, woody clonality showed higher frequency in wet or climatically stable environments, while herbaceous clonality preferred cold, dry or climatically instable environments. Unexplained variation in clonality may be owed to the influences of other environmental conditions and to different clonal strategies and underlying traits adopted by different growth forms and phylogenetic lineages. Therefore, in-depth research in terms of more detailed clonal growth form, phylogeny and additional environmental variables are encouraged to further understand plant clonality response to climatic and/or edaphic conditions. PMID:24709992

  14. A Latitudinal Diversity Gradient in Terrestrial Bacteria of the Genus Streptomyces

    PubMed Central

    Andam, Cheryl P.; Doroghazi, James R.; Campbell, Ashley N.; Kelly, Peter J.; Choudoir, Mallory J.

    2016-01-01

    ABSTRACT We show that Streptomyces biogeography in soils across North America is influenced by the regional diversification of microorganisms due to dispersal limitation and genetic drift. Streptomyces spp. form desiccation-resistant spores, which can be dispersed on the wind, allowing for a strong test of whether dispersal limitation governs patterns of terrestrial microbial diversity. We employed an approach that has high sensitivity for determining the effects of genetic drift. Specifically, we examined the genetic diversity and phylogeography of physiologically similar Streptomyces strains isolated from geographically distributed yet ecologically similar habitats. We found that Streptomyces beta diversity scales with geographic distance and both beta diversity and phylogenetic diversity manifest in a latitudinal diversity gradient. This pattern of Streptomyces biogeography resembles patterns seen for diverse species of plants and animals, and we therefore evaluated these data in the context of ecological and evolutionary hypotheses proposed to explain latitudinal diversity gradients. The data are consistent with the hypothesis that niche conservatism limits dispersal, and historical patterns of glaciation have limited the time for speciation in higher-latitude sites. Most notably, higher-latitude sites have lower phylogenetic diversity, higher phylogenetic clustering, and evidence of range expansion from lower latitudes. In addition, patterns of beta diversity partition with respect to the glacial history of sites. Hence, the data support the hypothesis that extant patterns of Streptomyces biogeography have been driven by historical patterns of glaciation and are the result of demographic range expansion, dispersal limitation, and regional diversification due to drift. PMID:27073097

  15. Latitudinal patterns in phenotypic plasticity: the case of seasonal flexibility in lizards' fat body size.

    PubMed

    Aguilar-Kirigin, Álvaro J; Naya, Daniel E

    2013-11-01

    Several studies published over the last years suggest that the ability of many species to cope with global change will be closely related to the current amount of plasticity for fitness-related traits. Thus, disentangling general patterns in phenotypic flexibility, which could be then included in models aimed to predict changes in species distribution, represent a central goal in the current ecological agenda. The climatic variability hypothesis (CVH) could be considered a timely and promising hypothesis since it provides an explicit link between climatic and geographic variables and phenotypic plasticity. Specifically, the CVH states that as the range of climatic fluctuation experienced by terrestrial animals increases with latitude, individuals at higher latitudes should present greater levels of phenotypic flexibility. Within this framework, here we evaluate the existence of latitudinal patterns in fat body size flexibility--estimated as the difference between maximum and minimum fat body size values observed throughout a year--for 59 lizard species, comprising the first evaluation of the CVH for a trait, other than thermic or metabolic characters, in ectothermic species. Conventional and phylogenetic analyses indicated a positive relationship between fat body size flexibility and latitude, and also between flexibility and temperature variability indexes. Together with previous findings our results suggest that: (1) latitudinal pattern for fitness-related traits, other than thermal characters, are beginning to emerge; (2) latitude is usually a better predictor of phenotypic plasticity than putative climatic variables; (3) hemispheric differences in climatic variability appears to be correlated with hemispheric differences in phenotypic plasticity.

  16. Present wind activity on Mars - Relation to large latitudinally zoned sediment deposits

    NASA Technical Reports Server (NTRS)

    Thomas, P.

    1982-01-01

    The relation of present Martian winds to large latitudinally zoned sediment deposits has been investigated using global wind streak data and mapping of large sand and dust deposits. Dune sand deposits occur primarily in three latitude belts: north polar (74-85 degrees North), low latitude (5 degrees North-20 degrees South), and south polar (40-80 degrees South). Comparison with wind streak data shows the high-latitude dunes to be in areas of seasonally reversing winds. The present winds can form latitudinal dune belts from a variety of initial dune distributions, including uniform distribution and a polar source. The presence of dune sand within the polar layered deposits, the erosional state of the deposits, and the present surface wind flow away from the poles indicate that both polar dune concentrations have been derived from erosion of the layered deposits. The low-latitude dunes are topographically confined in canyons and craters; they are probably subject to long-term reversal of orientations with climate cycles.

  17. Comparative population genomics of latitudinal variation in Drosophila simulans and Drosophila melanogaster.

    PubMed

    Machado, Heather E; Bergland, Alan O; O'Brien, Katherine R; Behrman, Emily L; Schmidt, Paul S; Petrov, Dmitri A

    2016-02-01

    Examples of clinal variation in phenotypes and genotypes across latitudinal transects have served as important models for understanding how spatially varying selection and demographic forces shape variation within species. Here, we examine the selective and demographic contributions to latitudinal variation through the largest comparative genomic study to date of Drosophila simulans and Drosophila melanogaster, with genomic sequence data from 382 individual fruit flies, collected across a spatial transect of 19 degrees latitude and at multiple time points over 2 years. Consistent with phenotypic studies, we find less clinal variation in D. simulans than D. melanogaster, particularly for the autosomes. Moreover, we find that clinally varying loci in D. simulans are less stable over multiple years than comparable clines in D. melanogaster. D. simulans shows a significantly weaker pattern of isolation by distance than D. melanogaster and we find evidence for a stronger contribution of migration to D. simulans population genetic structure. While population bottlenecks and migration can plausibly explain the differences in stability of clinal variation between the two species, we also observe a significant enrichment of shared clinal genes, suggesting that the selective forces associated with climate are acting on the same genes and phenotypes in D. simulans and D. melanogaster.

  18. Soil bacterial endemism and potential functional redundancy in natural broadleaf forest along a latitudinal gradient

    PubMed Central

    Zhang, Yuguang; Cong, Jing; Lu, Hui; Deng, Ye; Liu, Xiao; Zhou, Jizhong; Li, Diqiang

    2016-01-01

    Microorganisms play key roles in ecosystem processes and biogeochemical cycling, however, the relationship between soil microbial taxa diversity and their function in natural ecosystems is largely unknown. To determine how soil bacteria community and function are linked from the local to regional scale, we studied soil bacteria community composition, potential function and environmental conditions in natural and mature broadleaf forests along a latitudinal gradient in China, using the Illumina 16S rRNA sequencing and GeoChip technologies. The results showed strong biogeographic endemism pattern in soil bacteria were existed, and the spatial distance and climatic variables were the key controlling factors for this pattern. Therefore, dispersal limitation and environmental selection may represent two key processes in generating and maintaining the soil bacterial biogeographic pattern. By contrast, the soil bacterial potential function is highly convergent along the latitudinal gradient and there were highly differing bacterial community compositions, and the soil chemistry may include the main factors active in shaping the soil bacterial potential function. Therefore, the soil bacterial potential function may be affected by local gradients in resource availability, and predicting soil bacterial potential function requires knowledge of abiotic and biotic environmental factors. PMID:27357005

  19. Spatial distribution patterns in macrobenthos along a latitudinal transect at the deep-sea observatory HAUSGARTEN

    NASA Astrophysics Data System (ADS)

    Vedenin, A.; Budaeva, N.; Mokievsky, V.; Pantke, C.; Soltwedel, T.; Gebruk, A.

    2016-08-01

    Spatial distribution patterns of benthic organisms are the focus of various faunal marine studies. However, data on horizontal and bathymetric distribution of the deep-sea macrofauna are still scattered and incomplete, and conclusions are usually based on a low number of samples. Spatial distribution of benthic macrofauna was studied based on the material collected during the RV Polarstern expedition ARK-XXVII/2 in July 2012. Eleven stations along the latitudinal transect at the LTER (Long-Term Ecological Research) observatory HAUSGARTEN in the Fram Strait were taken at depths of about 2.3-2.7 km. Macrofauna was obtained using the box corer. A half core (0.125 m2) was taken at each station and four subcores (0.03 m2) were taken from each core and used for the quantitative analysis. The results suggest that a single, highly variable community with the dominance of polychaetes Galathowenia fragilis and Myriochele heeri inhabits the studied area. No latitudinal gradient in the community was revealed. The prevalence of a spatial variability in the community structure at a scale larger than the full sample per station (0.125 m2) was detected. Several abundant taxa (e.g. the polychaetes Prionospio sp. and Galathowenia fragilis) tend to form patches within a full sample.

  20. Latitudinal variation in sensitivity of flower bud formation to high temperature in Japanese Taraxacum officinale.

    PubMed

    Yoshie, Fumio

    2014-05-01

    Control of flowering time plays a key role in the successful range expansion of plants. Taraxacum officinale has expanded throughout Japan during the 110 years after it was introduced into a cool temperate region. The present study tested a hypothesis that there is a genetic difference in the bud formation time in relation to temperature along latitudinal gradient of T. officinale populations. In Experiment 1, plants from three populations at different latitudes (26, 36, and 43°N) were grown at three temperatures. Time to flower bud appearance did not significantly differ among the three populations when plants were grown at 14 °C, whereas it increased with increasing latitude when grown at 19 and 24 °C. Rosette diameter was not different among the populations, indicating that the variation in bud formation time reflected a difference in genetic control rather than size variation. The latitudinal variation in bud appearance time was confirmed by Experiment 2 in which plants from 17 population were used. In Experiment 3, the size of plants that exhibited late-flowering was studied to test a hypothesis that the variation in flowering time reflects dormancy of vegetative growth, but the late-flowering plants were found to continue growth, indicating that vegetative dormancy was not the cause of the variation. The results clearly indicate that the degree of suppression of flower bud formation at high temperature decreases with latitude from north to south, which is under genetic control.

  1. Soil bacterial endemism and potential functional redundancy in natural broadleaf forest along a latitudinal gradient.

    PubMed

    Zhang, Yuguang; Cong, Jing; Lu, Hui; Deng, Ye; Liu, Xiao; Zhou, Jizhong; Li, Diqiang

    2016-01-01

    Microorganisms play key roles in ecosystem processes and biogeochemical cycling, however, the relationship between soil microbial taxa diversity and their function in natural ecosystems is largely unknown. To determine how soil bacteria community and function are linked from the local to regional scale, we studied soil bacteria community composition, potential function and environmental conditions in natural and mature broadleaf forests along a latitudinal gradient in China, using the Illumina 16S rRNA sequencing and GeoChip technologies. The results showed strong biogeographic endemism pattern in soil bacteria were existed, and the spatial distance and climatic variables were the key controlling factors for this pattern. Therefore, dispersal limitation and environmental selection may represent two key processes in generating and maintaining the soil bacterial biogeographic pattern. By contrast, the soil bacterial potential function is highly convergent along the latitudinal gradient and there were highly differing bacterial community compositions, and the soil chemistry may include the main factors active in shaping the soil bacterial potential function. Therefore, the soil bacterial potential function may be affected by local gradients in resource availability, and predicting soil bacterial potential function requires knowledge of abiotic and biotic environmental factors. PMID:27357005

  2. Southern hospitality: a latitudinal gradient in gene flow in the marine environment.

    PubMed

    Kelly, Ryan P; Eernisse, Douglas J

    2007-03-01

    In recent years population genetics and phylogeographic studies have become increasingly valuable tools for inferring both historical and present-day genetic patterns within marine species. Here, we take a comparative approach to population-level study, analyzing original mitochondrial DNA data from 969 individuals representing 28 chiton (Mollusca: Polyplacophora) species to uncover large-scale genetic patterns along the Pacific coast of North America. The data reveal a distinct latitudinal connectivity gradient among chitons: species that exist at lower latitudes tend to have more isolated populations. This trend appears to be a product of between-species differences; within species, no significant gradient in connectivity is observed. Lower average annual sea surface temperatures are hypothesized to contribute to longer larval duration (and by extension, greater connectivity) among lecithotrophic species, providing a mechanism for the observed positive correlation between gene flow and latitude. Because increased isolation among populations may lead to speciation, a latitudinal trend in gene flow may contribute to the increased species diversity observed at lower latitudes.

  3. Birth seasonality of Cebus apella (Platyrrhini, Cebidae) in Brazilian zoos along a latitudinal gradient.

    PubMed

    Bicca-Marques, Júlio César; Gomes, Daniela Fichtner

    2005-02-01

    Birth seasonality in wild neotropical primates has been suggested to increase with latitude as a response to a stronger divergence in high-quality food availability across the year, and a higher between-year predictability at higher latitudes related to temporal differences in photoperiod. In captivity, however, monkeys are fed foods of similar quality throughout the year, and this consistency of diet should have a releasing effect on the need for birth seasonality. In this paper, we test whether 1) brown capuchin monkeys (Cebus apella) breed seasonally in captivity, and 2) given the consistency of diet in this setting, differences in latitude are reflected in the temporal pattern of birth distribution across the year. Data on the distribution of birth records of C. apella at Brazilian zoos located within three latitudinal zones (Equator perpendicular 8 degrees S, 16 degrees perpendicular 24 degrees S, and 24 degrees perpendicular 32 degrees S) are compared. Captive C. apella showed a birth peak from October to February, despite the consistent provision of food in this setting. In addition, there were no differences in the pattern of birth distribution among the latitudinal zones, which lends no support to the prediction that captive C. apella birth seasonality would increase with latitude. We suggest that if this species is not sensitive to subtle differences in photoperiod, other environmental cues may trigger the onset of reproduction at lower latitudes.

  4. Southern hospitality: a latitudinal gradient in gene flow in the marine environment.

    PubMed

    Kelly, Ryan P; Eernisse, Douglas J

    2007-03-01

    In recent years population genetics and phylogeographic studies have become increasingly valuable tools for inferring both historical and present-day genetic patterns within marine species. Here, we take a comparative approach to population-level study, analyzing original mitochondrial DNA data from 969 individuals representing 28 chiton (Mollusca: Polyplacophora) species to uncover large-scale genetic patterns along the Pacific coast of North America. The data reveal a distinct latitudinal connectivity gradient among chitons: species that exist at lower latitudes tend to have more isolated populations. This trend appears to be a product of between-species differences; within species, no significant gradient in connectivity is observed. Lower average annual sea surface temperatures are hypothesized to contribute to longer larval duration (and by extension, greater connectivity) among lecithotrophic species, providing a mechanism for the observed positive correlation between gene flow and latitude. Because increased isolation among populations may lead to speciation, a latitudinal trend in gene flow may contribute to the increased species diversity observed at lower latitudes. PMID:17348933

  5. Latitudinal Transport of Angular Momentum by Cellular Flows Observed with MDI

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Gilman, Peter A.; Beck, John G.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    We have analyzed Doppler velocity images from the MDI instrument on SOHO to determine the latitudinal transport of angular momentum by the cellular photospheric flows. Doppler velocity images from 60-days in May to July of 1996 were processed to remove the p-mode oscillations, the convective blue shift, the axisymmetric flows, and any instrumental artifacts. The remaining cellular flows were examined for evidence of latitudinal angular momentum transport. Small cells show no evidence of any such transport. Cells the size of supergranules (30,000 km in diameter) show strong evidence for a poleward transport of angular momentum. This would be expected if supergranules are influenced by the Coriolis force, and if the cells are elongated in an east-west direction. We find good evidence for just such an east-west elongation of the supergranules. This elongation may be the result of differential rotation shearing the cellular structures. Data simulations of this effect support the conclusion that elongated supergranules transport angular momentum from the equator toward the poles, Cells somewhat larger than supergranules do not show evidence for this poleward transport. Further analysis of the data is planned to determine if the direction of angular momentum transport reverses for even larger cellular structures. The Sun's rapidly rotating equator must be maintained by such transport somewhere within the convection zone.

  6. Comparative population genomics of latitudinal variation in Drosophila simulans and Drosophila melanogaster

    PubMed Central

    MACHADO, HEATHER E.; BERGLAND, ALAN O.; O’BRIEN, KATHERINE R.; BEHRMAN, EMILY L.; SCHMIDT, PAUL S.; PETROV, DMITRI A.

    2016-01-01

    Examples of clinal variation in phenotypes and genotypes across latitudinal transects have served as important models for understanding how spatially varying selection and demographic forces shape variation within species. Here, we examine the selective and demographic contributions to latitudinal variation through the largest comparative genomic study to date of Drosophila simulans and Drosophila melanogaster, with genomic sequence data from 382 individual fruit flies, collected across a spatial transect of 19 degrees latitude and at multiple time points over 2 years. Consistent with phenotypic studies, we find less clinal variation in D. simulans than D. melanogaster, particularly for the autosomes. Moreover, we find that clinally varying loci in D. simulans are less stable over multiple years than comparable clines in D. melanogaster. D. simulans shows a significantly weaker pattern of isolation by distance than D. melanogaster and we find evidence for a stronger contribution of migration to D. simulans population genetic structure. While population bottlenecks and migration can plausibly explain the differences in stability of clinal variation between the two species, we also observe a significant enrichment of shared clinal genes, suggesting that the selective forces associated with climate are acting on the same genes and phenotypes in D. simulans and D. melanogaster. PMID:26523848

  7. Comparison of the effects of two models for perpendicular diffusion on cosmic-ray latitudinal gradients

    NASA Astrophysics Data System (ADS)

    Minnie, J.; Burger, R. A.; Parhi, S.; Matthaeus, W. H.; Bieber, J. W.

    We compare the effects of two different models for perpendicular diffusion on the latitudinal gradients of galactic cosmic ray protons during solar minimum conditions. These two models correspond to the newly developed non-linear guiding center theory [Matthaeus, W.H., Qin, G., Bieber, J.W., Zank, G.P. Nonlinear collisionless perpendicular diffusion of charged particles. Astrophys. J. Lett., 590 (1), L53 L56, 2003] and the theory based on a velocity correlation function approach [Bieber, J.W., Matthaeus, W.H. Perpendicular diffusion and drift at intermediate cosmic-ray energies. Astrophys. J., 485 (2) 655 659, 1997]. In this ab initio study a steady-state two-dimensional numerical modulation model is used which incorporates a state-of-the-art turbulence model. We show that the non-linear guiding center theory predicts a mean free path that has a rigidity dependence that better accounts for the latitudinal gradients measured by Ulysses during its first fast latitude scan in 1994/1995.

  8. Soil bacterial endemism and potential functional redundancy in natural broadleaf forest along a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Zhang, Yuguang; Cong, Jing; Lu, Hui; Deng, Ye; Liu, Xiao; Zhou, Jizhong; Li, Diqiang

    2016-06-01

    Microorganisms play key roles in ecosystem processes and biogeochemical cycling, however, the relationship between soil microbial taxa diversity and their function in natural ecosystems is largely unknown. To determine how soil bacteria community and function are linked from the local to regional scale, we studied soil bacteria community composition, potential function and environmental conditions in natural and mature broadleaf forests along a latitudinal gradient in China, using the Illumina 16S rRNA sequencing and GeoChip technologies. The results showed strong biogeographic endemism pattern in soil bacteria were existed, and the spatial distance and climatic variables were the key controlling factors for this pattern. Therefore, dispersal limitation and environmental selection may represent two key processes in generating and maintaining the soil bacterial biogeographic pattern. By contrast, the soil bacterial potential function is highly convergent along the latitudinal gradient and there were highly differing bacterial community compositions, and the soil chemistry may include the main factors active in shaping the soil bacterial potential function. Therefore, the soil bacterial potential function may be affected by local gradients in resource availability, and predicting soil bacterial potential function requires knowledge of abiotic and biotic environmental factors.

  9. [Soil microbial biomass in Larix gmelinii forests along a latitudinal gradient during spring soil thawing].

    PubMed

    Ding, Shuang; Wang, Chuan-kuan

    2009-09-01

    The 8-year-old Larix gmelinii forests were transplanted from four sites (Tahe, Songling, Sunwu, and Dailing) comprising a latitudinal gradient across the distribution range of L. gmelinii in Northeastern China, and the soil microbial biomass carbon (Cmic) and nitrogen (Nmic) in spring soil thawing period were measured after 3-year transplanting. Under the similar soil substrates and the same climate conditions, the mean values of soil Cmic and Nmic in the L. gmelinii forests transplanted from the four sites differed significantly, being decreased with increasing latitude and soil depth. The Cmic for Tahe, Songling, Sunwu, and Dailing averaged 554.63, 826.41, 874.81, and 1246.18 mg x kg(-1), and the Nmic averaged 70.63, 96.78, 79.76, and 119.66 mg x kg(-1), respectively. The Cmic and Nmic peaked before soil thawing, declined rapidly at the early stage of soil thawing, and had less change and maintained at a lower level during the period of soil freezing-thawing. By the end of soil thawing, the Cmic for lower latitudinal soils (i.e., Dailing and Sunwu) recovered faster. Soil temperature and moisture content during spring soil thawing affected the temporal patterns of Cmic and Nmic significantly, but the affecting degree depended on the stages of soil thawing. The Cmic and Nmic were negatively correlated to the soil temperature at the early stage of soil thawing, and exponentially related to the soil moisture content during the whole soil thawing period.

  10. Range-wide latitudinal and elevational temperature gradients for the world's terrestrial birds: implications under global climate change.

    PubMed

    La Sorte, Frank A; Butchart, Stuart H M; Jetz, Walter; Böhning-Gaese, Katrin

    2014-01-01

    Species' geographical distributions are tracking latitudinal and elevational surface temperature gradients under global climate change. To evaluate the opportunities to track these gradients across space, we provide a first baseline assessment of the steepness of these gradients for the world's terrestrial birds. Within the breeding ranges of 9,014 bird species, we characterized the spatial gradients in temperature along latitude and elevation for all and a subset of bird species, respectively. We summarized these temperature gradients globally for threatened and non-threatened species and determined how their steepness varied based on species' geography (range size, shape, and orientation) and projected changes in temperature under climate change. Elevational temperature gradients were steepest for species in Africa, western North and South America, and central Asia and shallowest in Australasia, insular IndoMalaya, and the Neotropical lowlands. Latitudinal temperature gradients were steepest for extratropical species, especially in the Northern Hemisphere. Threatened species had shallower elevational gradients whereas latitudinal gradients differed little between threatened and non-threatened species. The strength of elevational gradients was positively correlated with projected changes in temperature. For latitudinal gradients, this relationship only held for extratropical species. The strength of latitudinal gradients was better predicted by species' geography, but primarily for extratropical species. Our findings suggest threatened species are associated with shallower elevational temperature gradients, whereas steep latitudinal gradients are most prevalent outside the tropics where fewer bird species occur year-round. Future modeling and mitigation efforts would benefit from the development of finer grain distributional data to ascertain how these gradients are structured within species' ranges, how and why these gradients vary among species, and the capacity

  11. Total ozone and total NO2 latitudinal distribution derived from measurements in the Atlantic Ocean in May 1988

    NASA Technical Reports Server (NTRS)

    Elokhov, Alexander S.; Gruzdev, Alexander N.

    1994-01-01

    Total ozone and NO2 were measured aboard a ship in the 40S - 40N latitude band in the Atlantic Ocean in the second half of May 1988. The main features of the latitudinal distributions of total NO2 and ozone are similar. There is seen an increase of total ozone and NO2 from the tropical to subtropical latitudes, strongest in the region of the subtropical jet stream. The fine structure has been revealed in the total ozone and NO2 latitudinal distributions, connected most likely with stratosphere-troposphere exchange processes in the tropopause folding zone.

  12. Large-scale phytogeographical patterns in East Asia in relation to latitudinal and climatic gradients

    USGS Publications Warehouse

    Qian, H.; Song, J.-S.; Krestov, P.; Guo, Q.; Wu, Z.; Shen, X.; Guo, X.

    2003-01-01

    Aim: This paper aims at determining how different floristic elements (e.g. cosmopolitan, tropical, and temperate) change with latitude and major climate factors, and how latitude affects the floristic relationships between East Asia and the other parts of the world. Location: East Asia from the Arctic to tropical regions, an area crossing over 50?? of latitudes and covering the eastern part of China, Korea, Japan and the eastern part of Russia. Methods: East Asia is divided into forty-five geographical regions. Based on the similarity of their world-wide distributional patterns, a total of 2808 indigenous genera of seed plants found in East Asia were grouped into fourteen geographical elements, belonging to three major categories (cosmopolitan, tropical and temperate). The 50??-long latitudinal gradient of East Asia was divided into five latitudinal zones, each of c. 10??. Phytogeographical relationships of East Asia to latitude and climatic variables were examined based on the forty-five regional floras. Results: Among all geographical and climatic variables considered, latitude showed the strongest relationship to phytogeographical composition. Tropical genera (with pantropical, amphi-Pacific tropical, palaeotropical, tropical Asia-tropical Australia, tropical Asia-tropical Africa and tropical Asia geographical elements combined) accounted for c. 80% of the total genera at latitude 20??N and for c. 0% at latitude 55-60??N. In contrast, temperate genera (including holarctic, eastern Asia-North America, temperate Eurasia, temperate Asia, Mediterranean, western Asia to central Asia, central Asia and eastern Asia geographical elements) accounted for 15.5% in the southernmost latitude and for 80% at 55-60??N, from where northward the percentage tended to level off. The proportion of cosmopolitan genera increased gradually with latitude from 5% at the southernmost latitude to 21% at 55-60??N, where it levelled off northward. In general, the genera present in a more

  13. Biogeography of Alaska paper birch (Betula neoalaskana): latitudinal patterns in chemical defense and plant architecture.

    PubMed

    Stevens, Michael T; Brown, Sarah C; Bothwell, Helen M; Bryant, John P

    2016-02-01

    The latitudinal herbivory-defense hypothesis (LHDH) predicts that plants near the equator will be more heavily defended against herbivores than are plants at higher latitudes. Although this idea is widely found in the literature, recent studies have called this biogeographic pattern into question. We sought to evaluate the LHDH in a high-latitude terrestrial ecosystem where fire and mammalian herbivores may contribute to selection for higher levels of defensive chemistry. To address this objective, we collected seeds of Alaska paper birch (Betula neoalaskana) from nine locations along two north-south transects between 55 degrees N and 62 degrees N latitudes in western, interior Canada. The birch seeds were planted in pots in a common garden in Madison, Wisconsin, USA. From the resulting seedlings, we determined levels of chemical defense by assessing the density of resin glands, which have been shown to be negatively correlated with browsing. To assess plant architectural traits such as height, mean individual leaf area, and root-to-shoot ratio, we harvested a subset of the birch seedlings. Further, we used these traits to examine growth-defense trade-offs. Contrary to the LHDH, we found a positive correlation between chemical defense and latitude. Investigating relationships with fire, we found a strong positive correlation between resin gland density and percentage of area annually burned (PAAB) around each collection location and also between PAAB and latitude. Additionally, birch seedlings originating from higher latitudes were shorter, smaller-leaved, and rootier than their lower-latitude counterparts. Growth-defense trade-offs were observed in negative correlations between resin gland density and height and leaf size. Seedlings with higher resin gland densities also allocated less biomass to shoots and more to roots. These results further call into question the LHDH and provide specific information about latitudinal trends in plant defense at high, northern

  14. Latitudinal and photic effects on diel foraging and predation risk in freshwater pelagic ecosystems.

    PubMed

    Hansen, Adam G; Beauchamp, David A

    2015-03-01

    Clark & Levy (American Naturalist, 131, 1988, 271-290) described an antipredation window for smaller planktivorous fish during crepuscular periods when light permits feeding on zooplankton, but limits visual detection by piscivores. Yet, how the window is influenced by the interaction between light regime, turbidity and cloud cover over a broad latitudinal gradient remains unexplored. We evaluated how latitudinal and seasonal shifts in diel light regimes alter the foraging-risk environment for visually feeding planktivores and piscivores across a natural range of turbidities and cloud covers. Pairing a model of aquatic visual feeding with a model of sun and moon illuminance, we estimated foraging rates of an idealized planktivore and piscivore over depth and time across factorial combinations of latitude (0-70°), turbidity (0.1-5 NTU) and cloud cover (clear to overcast skies) during the summer solstice and autumnal equinox. We evaluated the foraging-risk environment based on changes in the magnitude, duration and peak timing of the antipredation window. The model scenarios generated up to 10-fold shifts in magnitude, 24-fold shifts in duration and 5.5-h shifts in timing of the peak antipredation window. The size of the window increased with latitude. This pattern was strongest during the solstice. In clear water at low turbidity (0.1-0.5 NTU), peaks in the magnitude and duration of the window formed at 57-60° latitude, before falling to near zero as surface waters became saturated with light under a midnight sun and clear skies at latitudes near 70°. Overcast dampened the midnight sun enough to allow larger windows to form in clear water at high latitudes. Conversely, at turbidities ≥ 2 NTU, greater reductions in the visual range of piscivores than planktivores created a window for long periods at high latitudes. Latitudinal dependencies were essentially lost during the equinox, indicating a progressive compression of the window from early summer into autumn

  15. Salix transect of Europe: latitudinal patterns in willow diversity from Greece to arctic Norway

    PubMed Central

    Ruzzier, Enrico; Belyaeva, Irina; Percy, Diana

    2015-01-01

    Abstract Background Willows (Salix spp.) are ecosystem "foundation species" that are hosts to large numbers of associated insects. Determining their patterns of distribution across Europe is therefore of interest for understanding the spatial distribution of associated fauna. The aim of this study was to record species composition at multiple sites on a long latitudinal gradient (megatransect) across Europe as a baseline for the future detailed analysis of insect fauna at these sites. In this way we used willow stands as comparable mesocosms in which to study floristic and faunistic changes with latitude across Europe. New information To determine spatial patterning of  an ecologically important group on a latitudinal gradient across Europe, we sampled willows at the stand level in 42 sites, approximately 100 km apart, from the Aegean (38.8°N) to the Arctic Ocean (70.6°N), but at a similar longitude (21.2 to 26.1°E). The sites were predominantly lowland (elevations 1 to 556 metres amsl, median = 95 m) and wet (associated with rivers, lakes, drainage ditches or wet meadows). The median number of willow taxa (species and hybrids) per stand was four, and varied from one to nine. There is a progressive increase in willow diversity from south to north with the median number of taxa per stand in southern Europe being three, and in northern Europe six. A total of 20 willow species were recorded, along with 12 hybrids. The most widespread willow in the transect was Salix alba L. (occurring in 20 sites out of 42) followed by S. triandra L. (15 sites), S. caprea L., S. phylicifolia L. (14 sites) and S. myrsinifolia Salisb., Salix ×fragilis L. (13 sites). Voucher specimens from this study are deposited in the herbaria of the Natural History Museum (BM) and the Royal Botanic Gardens Kew (K). These samples provide a "snapshot" of willow diversity along a latitudinal gradient and an indication of the geographically changing taxonomic diversity that is

  16. Latitudinal and photic effects on diel foraging and predation risk in freshwater pelagic ecosystems.

    PubMed

    Hansen, Adam G; Beauchamp, David A

    2015-03-01

    Clark & Levy (American Naturalist, 131, 1988, 271-290) described an antipredation window for smaller planktivorous fish during crepuscular periods when light permits feeding on zooplankton, but limits visual detection by piscivores. Yet, how the window is influenced by the interaction between light regime, turbidity and cloud cover over a broad latitudinal gradient remains unexplored. We evaluated how latitudinal and seasonal shifts in diel light regimes alter the foraging-risk environment for visually feeding planktivores and piscivores across a natural range of turbidities and cloud covers. Pairing a model of aquatic visual feeding with a model of sun and moon illuminance, we estimated foraging rates of an idealized planktivore and piscivore over depth and time across factorial combinations of latitude (0-70°), turbidity (0.1-5 NTU) and cloud cover (clear to overcast skies) during the summer solstice and autumnal equinox. We evaluated the foraging-risk environment based on changes in the magnitude, duration and peak timing of the antipredation window. The model scenarios generated up to 10-fold shifts in magnitude, 24-fold shifts in duration and 5.5-h shifts in timing of the peak antipredation window. The size of the window increased with latitude. This pattern was strongest during the solstice. In clear water at low turbidity (0.1-0.5 NTU), peaks in the magnitude and duration of the window formed at 57-60° latitude, before falling to near zero as surface waters became saturated with light under a midnight sun and clear skies at latitudes near 70°. Overcast dampened the midnight sun enough to allow larger windows to form in clear water at high latitudes. Conversely, at turbidities ≥ 2 NTU, greater reductions in the visual range of piscivores than planktivores created a window for long periods at high latitudes. Latitudinal dependencies were essentially lost during the equinox, indicating a progressive compression of the window from early summer into autumn

  17. Latitudinal and photic effects on diel foraging and predation risk in freshwater pelagic ecosystems

    USGS Publications Warehouse

    Hansen, Adam G.; Beauchamp, David A.

    2014-01-01

    1. Clark & Levy (American Naturalist, 131, 1988, 271–290) described an antipredation window for smaller planktivorous fish during crepuscular periods when light permits feeding on zooplankton, but limits visual detection by piscivores. Yet, how the window is influenced by the interaction between light regime, turbidity and cloud cover over a broad latitudinal gradi- ent remains unexplored. 2. We evaluated how latitudinal and seasonal shifts in diel light regimes alter the foraging- risk environment for visually feeding planktivores and piscivores across a natural range of turbidities and cloud covers. Pairing a model of aquatic visual feeding with a model of sun and moon illuminance, we estimated foraging rates of an idealized planktivore and piscivore over depth and time across factorial combinations of latitude (0–70°), turbidity (01–5 NTU) and cloud cover (clear to overcast skies) during the summer solstice and autumnal equinox. We evaluated the foraging-risk environment based on changes in the magnitude, duration and peak timing of the antipredation window. 3. The model scenarios generated up to 10-fold shifts in magnitude, 24-fold shifts in duration and 55-h shifts in timing of the peak antipredation window. The size of the window increased with latitude. This pattern was strongest during the solstice. In clear water at low turbidity (01–05 NTU), peaks in the magnitude and duration of the window formed at 57–60° latitude, before falling to near zero as surface waters became saturated with light under a midnight sun and clear skies at latitudes near 70°. Overcast dampened the midnight sun enough to allow larger windows to form in clear water at high latitudes. Conversely, at turbidities ≥2 NTU, greater reductions in the visual range of piscivores than planktivores created a window for long periods at high latitudes. Latitudinal dependencies were essentially lost during the equinox, indicating a progressive compression of the window from early

  18. Late Cenozoic onset of the latitudinal diversity gradient of North American mammals

    NASA Astrophysics Data System (ADS)

    Marcot, Jonathan D.; Fox, David L.; Niebuhr, Spencer R.

    2016-06-01

    The decline of species richness from equator to pole, or latitudinal diversity gradient (LDG), is nearly universal among clades of living organisms, yet whether it was such a pervasive pattern in the geologic past remains uncertain. Here, we calculate the strength of the LDG for terrestrial mammals in North America over the past 65 My, using 27,903 fossil occurrences of Cenozoic terrestrial mammals from western North America downloaded from the Paleobiology Database. Accounting for temporal and spatial variation in sampling, the LDG was substantially weaker than it is today for most of the Cenozoic and the robust modern LDG of North American mammals evolved only over the last 4 My. The strength of the LDG correlates negatively with global temperature, suggesting a role of global climate patterns in the establishment and maintenance of the LDG for North American mammals.

  19. What causes latitudinal gradients in species diversity? Evolutionary processes and ecological constraints on swallowtail biodiversity.

    PubMed

    Condamine, Fabien L; Sperling, Felix A H; Wahlberg, Niklas; Rasplus, Jean-Yves; Kergoat, Gael J

    2012-03-01

    The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. Determining the evolutionary causes of this pattern remains a challenging task. To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly. Instead, we use a phylogenetically integrated approach to investigate the ecological and evolutionary processes responsible for the global LDG observed in swallowtail butterflies (Papilionidae). We find evidence for the 'diversification rate hypothesis' with different diversification rates between two similarly aged tropical and temperate clades. We conclude that the LDG is caused by (1) climatically driven changes in both clades based on evidence of responses to cooling and warming events, and (2) distinct biogeographical histories constrained by tropical niche conservatism and niche evolution. This multidisciplinary approach provides new findings that allow better understanding of the factors that shape LDGs.

  20. Latitudinal species diversity gradient of marine zooplankton for the last three million years.

    PubMed

    Yasuhara, Moriaki; Hunt, Gene; Dowsett, Harry J; Robinson, Marci M; Stoll, Danielle K

    2012-10-01

    High tropical and low polar biodiversity is one of the most fundamental patterns characterising marine ecosystems, and the influence of temperature on such marine latitudinal diversity gradients is increasingly well documented. However, the temporal stability of quantitative relationships among diversity, latitude and temperature is largely unknown. Herein we document marine zooplankton species diversity patterns at four time slices [modern, Last Glacial Maximum (18,000 years ago), last interglacial (120,000 years ago), and Pliocene (~3.3-3.0 million years ago)] and show that, although the diversity-latitude relationship has been dynamic, diversity-temperature relationships are remarkably constant over the past three million years. These results suggest that species diversity is rapidly reorganised as species' ranges respond to temperature change on ecological time scales, and that the ecological impact of future human-induced temperature change may be partly predictable from fossil and paleoclimatological records. PMID:22738438

  1. Latitudinal trends in body length distributions of European darkling beetles (Tenebrionidae)

    NASA Astrophysics Data System (ADS)

    Fattorini, Simone; Lo Monaco, Roberto; Di Giulio, Andrea; Ulrich, Werner

    2013-11-01

    The largest species of many invertebrate taxa occur in tropical regions. Nevertheless systematic studies on temperature and latitudinal trends in body size distributions of specific taxa have given inconclusive results and did not unequivocally corroborate existing models of body size evolution. We studied regional body size distributions of tenebrionid beetles across Europe to infer climate dependent trends that could be linked to the postglacial colonization of Europe. Even after correction for sample size effects and phylogenetic relatedness we found an increase in average and maximum body length towards southern Europe. Body size distributions were right skewed and skewness and the width of the distribution decreased significantly with temperature, indicating a more homogeneous species composition with respect to body size at lower latitudes. Our study supports the view that maximum size of heterothermic arthropods is limited by ambient temperature, which triggers the rate of metabolism. Our results contradict models that predict an increase in body size at higher latitudes.

  2. Metagenomic analysis of lacustrine viral diversity along a latitudinal transect of the Antarctic Peninsula.

    PubMed

    Aguirre de Cárcer, Daniel; López-Bueno, Alberto; Alonso-Lobo, Juan M; Quesada, Antonio; Alcamí, Antonio

    2016-06-01

    Environmental viruses constitute the most abundant biological entities on earth, and harbor an enormous genetic diversity. While their strong influence on the ecosystem is widely acknowledged, current knowledge about their diversity and distribution remains limited. Here we present the metagenomic study of viral communities from freshwater bodies located along a transect of the Antarctic Peninsula. These ecosystems were chosen on the basis of environmental and biogeographical variation. The results obtained indicate that the virus assemblages were diverse, and that the larger fraction represented viruses with no close relatives in the databases. Comparisons to existing metaviromes showed that the communities studied were dissimilar to other freshwater viromes including those from the Arctic. Finally, we observed no indication of there being a reduction in either viral richness or diversity estimates with increasing latitude along the studied transect, further adding to the controversy regarding the possible existence of latitudinal gradients of diversity in the microbial world. PMID:27059864

  3. What causes latitudinal gradients in species diversity? Evolutionary processes and ecological constraints on swallowtail biodiversity.

    PubMed

    Condamine, Fabien L; Sperling, Felix A H; Wahlberg, Niklas; Rasplus, Jean-Yves; Kergoat, Gael J

    2012-03-01

    The latitudinal diversity gradient (LDG) is one of the most striking ecological patterns on our planet. Determining the evolutionary causes of this pattern remains a challenging task. To address this issue, previous LDG studies have usually relied on correlations between environmental variables and species richness, only considering evolutionary processes indirectly. Instead, we use a phylogenetically integrated approach to investigate the ecological and evolutionary processes responsible for the global LDG observed in swallowtail butterflies (Papilionidae). We find evidence for the 'diversification rate hypothesis' with different diversification rates between two similarly aged tropical and temperate clades. We conclude that the LDG is caused by (1) climatically driven changes in both clades based on evidence of responses to cooling and warming events, and (2) distinct biogeographical histories constrained by tropical niche conservatism and niche evolution. This multidisciplinary approach provides new findings that allow better understanding of the factors that shape LDGs. PMID:22251895

  4. Disentangling the drivers of β diversity along latitudinal and elevational gradients.

    PubMed

    Kraft, Nathan J B; Comita, Liza S; Chase, Jonathan M; Sanders, Nathan J; Swenson, Nathan G; Crist, Thomas O; Stegen, James C; Vellend, Mark; Boyle, Brad; Anderson, Marti J; Cornell, Howard V; Davies, Kendi F; Freestone, Amy L; Inouye, Brian D; Harrison, Susan P; Myers, Jonathan A

    2011-09-23

    Understanding spatial variation in biodiversity along environmental gradients is a central theme in ecology. Differences in species compositional turnover among sites (β diversity) occurring along gradients are often used to infer variation in the processes structuring communities. Here, we show that sampling alone predicts changes in β diversity caused simply by changes in the sizes of species pools. For example, forest inventories sampled along latitudinal and elevational gradients show the well-documented pattern that β diversity is higher in the tropics and at low elevations. However, after correcting for variation in pooled species richness (γ diversity), these differences in β diversity disappear. Therefore, there is no need to invoke differences in the mechanisms of community assembly in temperate versus tropical systems to explain these global-scale patterns of β diversity.

  5. Solar radiation incident on Mars and the outer planets - Latitudinal, seasonal, and atmospheric effects

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Kraemer, D. R.; Kuhn, W. R.

    1977-01-01

    Calculations of the daily solar radiation incident at the tops of the atmospheres of Mars and the outer planets and its variability with latitude and season are presented in a series of figures and tables. The changes in the latitudinal and seasonal distributions of daily surface insolation during the great Martian dust storm of 1971 (when Martian atmospheric optical depth increased from about tau = 0.1 to 2.0) were significant and dramatically illustrate the effect of atmospheric aerosols on surface insolation; i.e., the mean annual daily insolation at the poles decreased by more than a factor of 100 as tau increased from 0.1 to 2.0.

  6. Late Cenozoic onset of the latitudinal diversity gradient of North American mammals.

    PubMed

    Marcot, Jonathan D; Fox, David L; Niebuhr, Spencer R

    2016-06-28

    The decline of species richness from equator to pole, or latitudinal diversity gradient (LDG), is nearly universal among clades of living organisms, yet whether it was such a pervasive pattern in the geologic past remains uncertain. Here, we calculate the strength of the LDG for terrestrial mammals in North America over the past 65 My, using 27,903 fossil occurrences of Cenozoic terrestrial mammals from western North America downloaded from the Paleobiology Database. Accounting for temporal and spatial variation in sampling, the LDG was substantially weaker than it is today for most of the Cenozoic and the robust modern LDG of North American mammals evolved only over the last 4 My. The strength of the LDG correlates negatively with global temperature, suggesting a role of global climate patterns in the establishment and maintenance of the LDG for North American mammals. PMID:27298355

  7. Late Cenozoic onset of the latitudinal diversity gradient of North American mammals.

    PubMed

    Marcot, Jonathan D; Fox, David L; Niebuhr, Spencer R

    2016-06-28

    The decline of species richness from equator to pole, or latitudinal diversity gradient (LDG), is nearly universal among clades of living organisms, yet whether it was such a pervasive pattern in the geologic past remains uncertain. Here, we calculate the strength of the LDG for terrestrial mammals in North America over the past 65 My, using 27,903 fossil occurrences of Cenozoic terrestrial mammals from western North America downloaded from the Paleobiology Database. Accounting for temporal and spatial variation in sampling, the LDG was substantially weaker than it is today for most of the Cenozoic and the robust modern LDG of North American mammals evolved only over the last 4 My. The strength of the LDG correlates negatively with global temperature, suggesting a role of global climate patterns in the establishment and maintenance of the LDG for North American mammals.

  8. Sulfur isotopic composition of surface snow along a latitudinal transect in East Antarctica

    NASA Astrophysics Data System (ADS)

    Uemura, Ryu; Masaka, Kosuke; Fukui, Kotaro; Iizuka, Yoshinori; Hirabayashi, Motohiro; Motoyama, Hideaki

    2016-06-01

    The sulfur stable isotopic values (δ34S) of sulfate aerosols can be used to assess oxidation pathways and contributions from various sources, such as marine biogenic sulfur, volcanoes, and sea salt. However, because of a lack of observations, the spatial distribution of δ34S values in Antarctic sulfate aerosols remains unclear. Here we present the first sulfur isotopic values from surface snow samples along a latitudinal transect in eastern Dronning Maud Land, East Antarctica. The δ34S values of sulfate showed remarkably uniform values, in the range of 14.8-16.9‰, and no significant decrease toward the inland part of the transect was noted. These results suggest that net isotopic fractionation during long-range transport is insignificant. Thus, the δ34S values can be used to infer source contributions. The δ34S values suggest that marine biogenic sulfur is the dominant source of sulfate aerosols, with a fractional contribution of 84 ± 16%.

  9. Highly consistent effects of plant litter identity and functional traits on decomposition across a latitudinal gradient.

    PubMed

    Makkonen, Marika; Berg, Matty P; Handa, I Tanya; Hättenschwiler, Stephan; van Ruijven, Jasper; van Bodegom, Peter M; Aerts, Rien

    2012-09-01

    Plant litter decomposition is a key process in terrestrial carbon cycling, yet the relative importance of various control factors remains ambiguous at a global scale. A full reciprocal litter transplant study with 16 litter species that varied widely in traits and originated from four forest sites covering a large latitudinal gradient (subarctic to tropics) showed a consistent interspecific ranking of decomposition rates. At a global scale, variation in decomposition was driven by a small subset of litter traits (water saturation capacity and concentrations of magnesium and condensed tannins). These consistent findings, that were largely independent of the varying local decomposer communities, suggest that decomposer communities show little specialisation and high metabolic flexibility in processing plant litter, irrespective of litter origin. Our results provide strong support for using trait-based approaches in modelling the global decomposition component of biosphere-atmosphere carbon fluxes.

  10. Growth rate responses of Missouri and lower Yellowstone river fishes to a latitudinal gradient

    USGS Publications Warehouse

    Pegg, M.A.; Pierce, C.L.

    2001-01-01

    Growth rate coefficients estimated for channel catfish Ictalurus punctatus, emerald shiners Notropis atherinoides, freshwater drums Aplodinotus grunniens, river carpsuckers Carpiodes carpio and saugers Stizostedion canadense collected in 1996-1998 from nine river sections of the Missouri and lower Yellowstone rivers at two life-stages (young-of-the-year and age 1 + years) were significantly different among sections. However, they showed no river-wide latitudinal trend except for age 1 + years emerald shiners that did show a weak negative relation between growth and both latitude and length of growing season. The results suggest growth rates of fishes along the Missouri River system are complex and could be of significance in the management and conservation of fish communities in this altered system. ?? 2001 The Fisheries Society of the British Isles.

  11. Gill's model of the Antarctic Circumpolar Current, revisited: The role of latitudinal variations in wind stress

    NASA Astrophysics Data System (ADS)

    Marshall, David P.; Munday, David R.; Allison, Lesley C.; Hay, Russell J.; Johnson, Helen L.

    2016-01-01

    Gill's (1968) model of the Antarctic Circumpolar Current (ACC) is reinterpreted for a stratified, reduced-gravity ocean, where the barotropic streamfunction is replaced by the pycnocline depth, and the bottom drag coefficient by the Gent and McWilliams eddy diffusivity. The resultant model gives a simple description of the lateral structure of the ACC that is consistent with contemporary descriptions of ACC dynamics. The model is used to investigate and interpret the sensitivity of the ACC to the latitudinal profile of the surface wind stress. A substantial ACC remains when the wind jet is shifted north of the model Drake Passage, even by several thousand kilometers. The integral of the wind stress over the circumpolar streamlines is found to be a useful predictor of the magnitude of the volume transport through the model Drake Passage, although it is necessary to correct for basin-wide zonal pressure gradients in order to obtain good quantitative agreement.

  12. Bivalve network reveals latitudinal selectivity gradient at the end-Cretaceous mass extinction

    PubMed Central

    Vilhena, Daril A.; Harris, Elisha B.; Bergstrom, Carl T.; Maliska, Max E.; Ward, Peter D.; Sidor, Christian A.; Strömberg, Caroline A. E.; Wilson, Gregory P.

    2013-01-01

    Biogeographic patterns of survival help constrain the causal factors responsible for mass extinction. To test whether biogeography influenced end-Cretaceous (K-Pg) extinction patterns, we used a network approach to delimit biogeographic units (BUs) above the species level in a global Maastrichtian database of 329 bivalve genera. Geographic range is thought to buffer taxa from extinction, but the number of BUs a taxon occurred in superseded geographic range as an extinction predictor. Geographically, we found a latitudinal selectivity gradient for geographic range in the K-Pg, such that higher latitude BUs had lower extinction than expected given the geographic ranges of the genera, implying that (i) high latitude BUs were more resistant to extinction, (ii) the intensity of the K-Pg kill mechanism declined with distance from the tropics, or (iii) both. Our results highlight the importance of macroecological structure in constraining causal mechanisms of extinction and estimating extinction risk of taxa.

  13. Altitudinal variation of demographic life-history traits does not mimic latitudinal variation in natterjack toads (Bufo calamita).

    PubMed

    Oromi, Neus; Sanuy, Delfi; Sinsch, Ulrich

    2012-02-01

    In anuran amphibians, age- and size-related life-history traits vary along latitudinal and altiudinal gradients. In the present study, we tested the hypothesis that altitudinal and latitudinal effects cause similar responses by assessing demographic life-history traits in nine Bufo calamita populations inhabiting elevations from sea level to 2270 m. Skeletochronologically determined age at maturity and longevity increased at elevations exceeding 2000 m, but female potential reproductive lifespan (PRLS) did not increase with altitude, as it did with latitude. Integrating the available evidence, it was found that lifetime fecundity of natterjacks decreased at the upper altitudinal range because PRLS was about the same as in lowland populations but females were smaller. In contrast, small size of northern females was compensated for by increased PRLS which minimised latitudinal variation of lifetime fecundity. Thus, this study provides evidence that altitudinal effects on life-history traits do not mimic latitudinal effects. Life-history trait variation along the altitudinal gradient seems to respond directly to the shortening of the annual activity period. As there is no evidence for increasing mortality in highland populations, reduced lifetime fecundity may be the ultimate reason for the natterjacks' inability to colonise elevations exceeding 2500 m.

  14. Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Goldstein, Richard M.

    1994-01-01

    Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling.

  15. Plant species invasions along the latitudinal gradient in the United States

    USGS Publications Warehouse

    Stohlgren, T.J.; Barnett, D.; Flather, C.; Kartesz, J.; Peterjohn, B.

    2005-01-01

    It has been long established that the richness of vascular plant species and many animal taxa decreases with increasing latitude, a pattern that very generally follows declines in actual and potential evapotranspiration, solar radiation, temperature, and thus, total productivity. Using county-level data on vascular plants from the United States (3000 counties in the conterminous 48 states), we used the Akaike Information Criterion (AIC) to evaluate competing models predicting native and nonnative plant species density (number of species per square kilometer in a county) from various combinations of biotic variables (e.g., native bird species density, vegetation carbon, normalized difference vegetation index), environmental/topographic variables (elevation, variation in elevation, the number of land cover classes in the county; radiation, mean precipitation, actual evapotranspiration, and potential evapotranspiration), and human variables (human population density, crop-land, and percentage of disturbed lands in a county). We found no evidence of a latitudinal gradient for the density of native plant species and a significant, slightly positive latitudinal gradient for the density of nonnative plant species. We found stronger evidence of a significant, positive productivity gradient (vegetation carbon) for the density of native plant species and nonnative plant species. We found much stronger significant relationships when biotic, environmental/topographic, and human variables were used to predict native plant species density and nonnative plant species density. Biotic variables generally had far greater influence in multivariate models than human or environmental/topographic variables. Later, we found that the best, single, positive predictor of the density of nonnative plant species in a county was the density of native plant species in a county. While further study is needed, it may be that, while humans facilitate the initial establishment invasions of nonnative

  16. Climate-driven habitat size determines the latitudinal diversity gradient in temporary ponds.

    PubMed

    Kneitel, Jamie M

    2016-04-01

    The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology, typically showing decreasing species diversity with increasing latitude. Studies of these patterns also used different spatial scales and dispersal traits to better understand the underpinning ecological factors. Seasonal freshwater ecosystems are less studied and may exhibit different patterns because they are more sensitive to climatic variation, which result in an inundation-desiccation cycle. In California, precipitation increases and temperature decreases with increasing latitude and thus the LDG pattern may be associated with this climatic gradient. Using collected data and United States Fish and Wildlife Service reports across seven degrees of latitude, analysis of California vernal pool invertebrate community (total richness and richness of passive and active dispersers) was conducted using correlations (Spearman rank and partial). Alpha diversity (total and passive dispersers) increased and beta diversity (passive dispersers) decreased with increasing latitude. Vernal pool surface area was correlated with active disperser alpha and passive disperser beta diversity. This suggests that climate-driven habitat size influences alpha and beta diversity patterns depending on dispersal ability. Active dispersers and predators exhibited higher beta diversity than passive dispersers and prey, respectively. Species composition differed among counties and some of these differences were correlated with pool depth and temperature. These results suggest that seasonal habitats will have diversity patterns strongly associated with local scale characteristics (habitat size and hydroperiod) determined by climate variation along the latitudinal gradient. Understanding these diversity patterns along the gradient will also contribute to management and restoration of these ecosystems with high endemism and diversity. PMID:27220212

  17. Increased temperatures negatively affect Juniperus communis seeds: evidence from transplant experiments along a latitudinal gradient.

    PubMed

    Gruwez, R; De Frenne, P; Vander Mijnsbrugge, K; Vangansbeke, P; Verheyen, K

    2016-05-01

    With a distribution range that covers most of the Northern hemisphere, common juniper (Juniperus communis) has one of the largest ranges of all vascular plant species. In several regions in Europe, however, populations are decreasing in size and number due to failing recruitment. One of the main causes for this failure is low seed viability. Observational evidence suggests that this is partly induced by climate warming, but our mechanistic understanding of this effect remains incomplete. Here, we experimentally assess the influence of temperature on two key developmental phases during sexual reproduction, i.e. gametogenesis and fertilisation (seed phase two, SP2) and embryo development (seed phase three, SP3). Along a latitudinal gradient from southern France to central Sweden, we installed a transplant experiment with shrubs originating from Belgium, a region with unusually low juniper seed viability. Seeds of both seed phases were sampled during three consecutive years, and seed viability assessed. Warming temperatures negatively affected the seed viability of both SP2 and SP3 seeds along the latitudinal gradient. Interestingly, the effect on embryo development (SP3) only occurred in the third year, i.e. when the gametogenesis and fertilisation also took place in warmer conditions. We found strong indications that this negative influence mostly acts via disrupting growth of the pollen tube, the development of the female gametophyte and fertilisation (SP2). This, in turn, can lead to failing embryo development, for example, due to nutritional problems. Our results confirm that climate warming can negatively affect seed viability of juniper. PMID:26465806

  18. On the processes generating latitudinal richness gradients: identifying diagnostic patterns and predictions

    PubMed Central

    Hurlbert, Allen H.; Stegen, James C.

    2014-01-01

    We use a simulation model to examine four of the most common hypotheses for the latitudinal richness gradient and identify patterns that might be diagnostic of those four hypotheses. The hypotheses examined include (1) tropical niche conservatism, or the idea that the tropics are more diverse because a tropical clade origin has allowed more time for diversification in the tropics and has resulted in few species adapted to extra-tropical climates. (2) The ecological limits hypothesis suggests that species richness is limited by the amount of biologically available energy in a region. (3) The speciation rates hypothesis suggests that the latitudinal gradient arises from a gradient in speciation rates. (4) Finally, the tropical stability hypothesis argues that climatic fluctuations and glacial cycles in extratropical regions have led to greater extinction rates and less opportunity for specialization relative to the tropics. We found that tropical niche conservatism can be distinguished from the other three scenarios by phylogenies which are more balanced than expected, no relationship between mean root distance (MRD) and richness across regions, and a homogeneous rate of speciation across clades and through time. The energy gradient, speciation gradient, and disturbance gradient scenarios all produced phylogenies which were more imbalanced than expected, showed a negative relationship between MRD and richness, and diversity-dependence of speciation rate estimates through time. We found that the relationship between speciation rates and latitude could distinguish among these three scenarios, with no relation expected under the ecological limits hypothesis, a negative relationship expected under the speciation rates hypothesis, and a positive relationship expected under the tropical stability hypothesis. We emphasize the importance of considering multiple hypotheses and focusing on diagnostic predictions instead of predictions that are consistent with multiple

  19. The Latitudinal Excursion of Coronal Magnetic Field Lines in Response to Differential Rotation: MHD Simulations

    NASA Technical Reports Server (NTRS)

    Lionello, Roberto; Linker, Jon A.; Mikic, Zoran; Riley, Pete

    2006-01-01

    Solar energetic particles, which are believed to originate from corotating interacting regions (CIRS) at low heliographic latitude, were observed by the Ulysses spacecraft even as it passed over the Sun's poles. One interpretation of this result is that high-latitude field lines intercepted by Ulysses connect to low-latitude CIRs at much larger heliocentric distances. The Fisk model explains the latitudinal excursion of magnetic field lines in the solar corona and heliosphere as the inevitable consequence of the interaction of a tilted dipole in a differentially rotating photosphere with rigidly rotating coronal holes. We use a time-dependent three-dimensional magnetohydrodynamic (MHD) algorithm to follow the evolution of a simple model of the solar corona in response to the differential rotation of the photospheric magnetic flux. We examine the changes of the coronal-hole boundaries, the redistribution of the line-of-sight magnetic field, and the precession of field lines in the corona. Our results confirm the basic idea of the Fisk model, that differential rotation leads to changes in the heliographic latitude of magnetic field lines. However, the latitudinal excursion of magnetic field lines in this simple "tilted dipole" model is too small to explain the Ulysses observations. Although coronal holes in our model rotate more rigidly than do photospheric features (in general agreement with observations), they do not rotate strictly rigidly as assumed by Fisk. This basic difference between our model and Fisk's will be explored in the future by considering more realistic magnetic flux distributions, as observed during Ulysses polar excursions.

  20. Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia

    PubMed Central

    Wild, Birgit; Schnecker, Jörg; Knoltsch, Anna; Takriti, Mounir; Mooshammer, Maria; Gentsch, Norman; Mikutta, Robert; Alves, Ricardo J Eloy; Gittel, Antje; Lashchinskiy, Nikolay; Richter, Andreas

    2015-01-01

    Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using 15N pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67°N) to steppe (54°N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest. Key Points We compared soil N dynamics of seven ecosystems along a latitudinal transectShifts in N dynamics suggest a decrease in microbial N limitation with depthWe found no decrease in microbial N limitation from arctic to temperate zones PMID:26693204

  1. Climate Effects on Methylmercury Bioaccumulation Along a Latitudinal Gradient in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Chetelat, J.; Richardson, M.; MacMillan, G. A.; Amyot, M.; Hintelmann, H.; Crump, D.

    2014-12-01

    Recent evidence indicates that inorganic mercury (Hg) loadings to Arctic lakes decline with latitude. However, monomethylmercury (MMHg) concentrations in fish and their prey do not decline in a similar fashion, suggesting that higher latitude lakes are more vulnerable to Hg inputs. Preliminary results will be presented from a three-year study (2012-2015) of climate effects on MMHg bioaccumulation in lakes of the eastern Canadian Arctic. We have investigated mercury transport and accumulation processes in lakes and ponds from three study regions along a latitudinal gradient in climate-controlled ecosystem types in the Canadian Arctic, specifically sub-Arctic taiga, Arctic tundra and polar desert. In each water body, we measured key aspects of MMHg bioaccumulation—MMHg bioavailability to benthic food webs and organism growth rates—as well as how watershed characteristics affect the transport of Hg and organic carbon to lakes. Novel approaches were incorporated including the use of passive samplers (Diffusive Gradient in Thin Film samplers or DGTs) to estimate sediment bioavailable MMHg concentrations and tissue RNA content to compare organism short-term growth rates. A comparison of Arctic tundra and sub-Arctic taiga lakes showed that surface water concentrations of MMHg were strongly and positively correlated to total Hg concentrations both within and among study regions, implying strong control of inorganic Hg supply. Sediment concentrations of bioavailable MMHg were highly variable among lakes, although average concentrations were similar between study regions. Local environmental conditions appear to have a strong influence on sediment potential for MMHg supply. Lake-dwelling Arctic char from tundra lakes had similar or higher total Hg concentrations compared with brook trout from sub-Arctic lakes that were exposed to higher water MMHg concentrations. Potential environmental drivers of these patterns will be discussed. This latitudinal study will provide new

  2. Differences in beta diversity between exotic and native grasslands vary with scale along a latitudinal gradient.

    PubMed

    Martin, Leanne M; Wilsey, Brian J

    2015-04-01

    Biodiversity can be partitioned into alpha, beta, and gamma components, and beta diversity is not as clearly understood. Biotic homogenization predicts that exotic species should lower beta diversity at global and continental scales, but it is still unclear how exotic species impact beta diversity at smaller scales. Exotic species could theoretically increase or decrease beta diversity relative to natives depending on many factors, including abiotic conditions, community assembly history, management, dispersal rates of species, and connectivity among patches. We sampled plant species abundances in 42 novel, exotic- and native-dominated (remnant) grasslands across a latitudinal gradient in the tallgrass prairie region, and tested whether exotic and native grasslands differed in beta diversity at three scales: across sites within the entire biome, across sites within regions, and across locations within sites. Exotic-dominated grasslands differed from native-dominated grasslands in beta diversity at all scales, but the direction of the difference changed from positive to negative as scales went from large to small. Contrary to expectations, exotic-dominated grasslands had higher beta diversity than native-dominated grasslands at the largest scale considered. This occurred because the identity of dominant exotic species varied across the latitudinal gradient, with many exotic grassland pairs exhibiting zero similarity, whereas native-dominated grasslands differed more gradually with distance. Beta diversity among sites within a region was variable, with exotic-dominated grasslands having 29% higher beta diversity than native grasslands in the south and 33% lower beta diversity in the north. Within sites, beta diversity was 26% lower in exotic-dominated than native grasslands. Our results provide evidence that different regional identities and abundances of exotics, and lack of connectivity in fragmented landscapes can alter beta diversity in unexpected ways across

  3. Differences in beta diversity between exotic and native grasslands vary with scale along a latitudinal gradient.

    PubMed

    Martin, Leanne M; Wilsey, Brian J

    2015-04-01

    Biodiversity can be partitioned into alpha, beta, and gamma components, and beta diversity is not as clearly understood. Biotic homogenization predicts that exotic species should lower beta diversity at global and continental scales, but it is still unclear how exotic species impact beta diversity at smaller scales. Exotic species could theoretically increase or decrease beta diversity relative to natives depending on many factors, including abiotic conditions, community assembly history, management, dispersal rates of species, and connectivity among patches. We sampled plant species abundances in 42 novel, exotic- and native-dominated (remnant) grasslands across a latitudinal gradient in the tallgrass prairie region, and tested whether exotic and native grasslands differed in beta diversity at three scales: across sites within the entire biome, across sites within regions, and across locations within sites. Exotic-dominated grasslands differed from native-dominated grasslands in beta diversity at all scales, but the direction of the difference changed from positive to negative as scales went from large to small. Contrary to expectations, exotic-dominated grasslands had higher beta diversity than native-dominated grasslands at the largest scale considered. This occurred because the identity of dominant exotic species varied across the latitudinal gradient, with many exotic grassland pairs exhibiting zero similarity, whereas native-dominated grasslands differed more gradually with distance. Beta diversity among sites within a region was variable, with exotic-dominated grasslands having 29% higher beta diversity than native grasslands in the south and 33% lower beta diversity in the north. Within sites, beta diversity was 26% lower in exotic-dominated than native grasslands. Our results provide evidence that different regional identities and abundances of exotics, and lack of connectivity in fragmented landscapes can alter beta diversity in unexpected ways across

  4. On the processes generating latitudinal richness gradients: identifying diagnostic patterns and predictions

    SciTech Connect

    Hurlbert, Allen H.; Stegen, James C.

    2014-12-02

    Many processes have been put forward to explain the latitudinal gradient in species richness. Here, we use a simulation model to examine four of the most common hypotheses and identify patterns that might be diagnostic of those four hypotheses. The hypotheses examined include (1) tropical niche conservatism, or the idea that the tropics are more diverse because a tropical clade origin has allowed more time for diversification in the tropics and has resulted in few species adapted to extra-tropical climates. (2) The productivity, or energetic constraints, hypothesis suggests that species richness is limited by the amount of biologically available energy in a region. (3) The tropical stability hypothesis argues that major climatic fluctuations and glacial cycles in extratropical regions have led to greater extinction rates and less opportunity for specialization relative to the tropics. (4) Finally, the speciation rates hypothesis suggests that the latitudinal richness gradient arises from a parallel gradient in rates of speciation. We found that tropical niche conservatism can be distinguished from the other three scenarios by phylogenies which are more balanced than expected, no relationship between mean root distance and richness across regions, and a homogeneous rate of speciation across clades and through time. The energy gradient, speciation gradient, and disturbance gradient scenarios all exhibited phylogenies which were more imbalanced than expected, showed a negative relationship between mean root distance and richness, and diversity-dependence of speciation rate estimates through time. Using Bayesian Analysis of Macroevolutionary Mixtures on the simulated phylogenies, we found that the relationship between speciation rates and latitude could distinguish among these three scenarios. We emphasize the importance of considering multiple hypotheses and focusing on diagnostic predictions instead of predictions that are consistent with more than one hypothesis.

  5. Co-latitudinal Radial Veloctiy Profile Confirmation Via Differential Proper Motion of the Bipolar Egg Nebula

    NASA Astrophysics Data System (ADS)

    Tomasino, Rachael

    2013-10-01

    Requesting the use of ACS/WFC for one orbit to obtain a deep 3rd epoch exposure of the Cygnus Egg Nebula. The proposed observation of the Egg will not only yield multi-epoch snapshots of the circumstellar arcs but also determine the co-latitudinal velocity field that helps break the degeneracy in model fitting. Full 3-D model calculations, done by CoI Kim, have already quantified the co-latitudinal dependence due to the binary orbital motion, relating the orbital speed of the binary stars to the resulting structural pattern in the circumstellar density distributions. We will be able to constrain the orbital properties of the Egg Nebula via a new set of specific model fitting. The duplication of the epoch 2 observation {PI: W. Sparks} is by design and with a baseline between the 2nd and 3rd epoch of more than 11 years, there is a lower limit shift of 1.32 pixels for the slower moving arcs and it will be more than enough to perform a differential proper-motion study. The Cygnus Egg Nebula is a proto-planetary nebula, which means that the circumstellar density structure still retains valuable clues pertaining to the early asymptotic giant branch mass loss history and initial development of their aspherical shell structure. One of the most peculiar characteristics of the circumstellar shell structure of the Egg Nebula is the co-presence of the nebula's signature bipolar lobes and rather circular concentric arcs superposed on top of each other. There is no consensus among researchers on their origins, especially because of the paradox due to the co-presence of the circular arcs and bipolar lobes.

  6. The Latitudinal and Longitudinal Variations of the Thermospheric Density Caused by Aurora Heating

    NASA Astrophysics Data System (ADS)

    Xu, J.; Wang, W.; Smith, A. K.; Jiang, G.; Yuan, W.

    2015-12-01

    We use thermospheric mass densities measured by the accelerometers on satellites of GRACE at ~480 km and CHAMP at ~380 km from 2002-2010 to study the longitudinal and latitudinal distribution of the diurnally averaged thermospheric mass density. The result shows that there are strong longitude variations in the diurnally averaged thermospheric mass density. These variations are global and have the similar characteristics at the two heights under geomagnetically quiet conditions (Ap<10). The largest relative longitudinal changes of the diurnally averaged thermospheric mass density occur at high latitudes from October to February in the Northern Hemisphere and from March to September in the Southern Hemisphere. The positive density peaks locate always near the magnetic poles. The high density regions extend toward lower latitudes and even into the opposite hemisphere. This extension appears to be tilted westward, but mostly is confined to the longitudes where the magnetic poles are located. Thus, the relative longitudinal changes of the diurnally averaged thermospheric mass density have strong seasonal variations and show an annual oscillation at high and middle latitudes but a semiannual oscillation around the equator. Our results suggest that heating of the magnetospheric origin in the auroral region is most likely the cause of these observed longitudinal and latitudinal structures. Our results also show that the relative longitude variation of the diurnally averaged thermospheric mass density is hemispherically asymmetric and more pronounced in the Southern Hemisphere. To check how deep the auroral heating can affect the atmosphere, we analyze the diurnally averaged temperature observed by TIMED/SABER and MIPAS. Results indicate that there are similar structure in the lower thermosphere and the impact of auroral heating on the thermodynamics of the neutral atmosphere can penetrate down to about 105 km under geomagnetically quiet conditions.

  7. Mammalian Biogeography and the Latitudinal Climatic Gradient in Western North America During the Paleocene Evolutionary Radiation of Mammals (Invited)

    NASA Astrophysics Data System (ADS)

    Fox, D. L.; Rose, P.

    2010-12-01

    We use the middle Paleocene (ca. 63-58) mammalian fossil record of western North America to examine the latitudinal gradients in both species richness and body size of mammals during their evolutionary radiation following the Cretaceous-Paleogene mass extinction. Decreasing species richness with latitude is a biogeographic pattern common to most clades today, including mammals, and is linked to climatic gradients; an inverse relationship between body size and environmental temperature (Bergmann’s rule) is well-known both within and among species of living endothermic vertebrates, including diverse clades of mammals. Despite the frequency among mammals of these patterns today, their long-term histories in the fossil record is not well documented. We compiled mammalian taxonomic occurrence data from published literature, online museum collection databases, and the Paleobiology Database for roughly 160 Torrejonian (To, ca. 63-60 Ma) and Tiffanian (Ti, ca. 60-58 Ma) North American Land Mammal Age fossil localities in western North America from Texas to Alberta. These localities were binned into nine geographic regions based on paleolatitude, and the centroids of the regions span ca. 28° of latitude. For the faunas from these regions, we compiled body size data from the literature for 170 Paleocene (Torrejonian and Tiffanian) mammal species, using lower first molar area (m1 LxW) as a proxy for body mass. The phosphate oxygen isotope composition of teeth from species of a single clade of herbivorous mammals (Phenacodontidae) indicates that mid-Paleocene latitudinal climate gradients were broadly similar to modern gradients in the region, so we treat paleolatitude as a proxy for temperature. Slopes of separate least squares linear regressions of rarefied To and Ti species richness on paleolatitude are not significantly different from zero, and the regressions explain only a small fraction of the variances in richness. For all species, m1 area has a statistically

  8. What can multiple phylogenies say about the latitudinal diversity gradient? A new look at the tropical conservatism, out of the tropics, and diversification rate hypotheses.

    PubMed

    Jansson, Roland; Rodríguez-Castañeda, Genoveva; Harding, Larisa E

    2013-06-01

    We reviewed published phylogenies and selected 111 phylogenetic studies representing mammals, birds, insects, and flowering plants. We then mapped the latitudinal range of all taxa to test the relative importance of the tropical conservatism, out of the tropics, and diversification rate hypotheses in generating latitudinal diversity gradients. Most clades originated in the tropics, with diversity peaking in the zone of origin. Transitions of lineages between latitudinal zones occurred at 16-22% of the tree nodes. The most common type of transition was range expansions of tropical lineages to encompass also temperate latitudes. Thus, adaptation to new climatic conditions may not represent a major obstacle for many clades. These results contradict predictions of the tropical conservatism hypothesis (i.e., few clades colonizing extratropical latitudes), but support the out-of-the-tropics model (i.e., tropical originations and subsequent latitudinal range expansions). Our results suggest no difference in diversification between tropical and temperate sister lineages; thus, diversity of tropical clades was not explained by higher diversification rates in this zone. Moreover, lineages with latitudinal stasis diversified more compared to sister lineages entering a new latitudinal zone. This preserved preexisting diversity differences between latitudinal zones and can be considered a new mechanism for why diversity tends to peak in the zone of origin. PMID:23730766

  9. Comparison of Forest Soil Carbon Dynamics at Five Sites Along a Latitudinal Gradient

    SciTech Connect

    Garten Jr, Charles T

    2011-01-01

    Carbon stocks, and C:N ratios, were measured in the forest floor, mineral soil, and two mineral soil fractions (particulate and mineral-associated organic matter, POM and MOM, respectively) at five forest sites, ranging from 60 to 100 years old, along a latitudinal gradient in the eastern United States. Sampling at four sites was replicated over two consecutive years. For many measurements (like forest floor carbon stocks, cumulative soil organic carbon stocks to 20 cm, and the fraction of whole soil carbon in POM), there was no significant difference between years at each site despite the use of somewhat different sampling methods. With one exception, forest floor and mineral soil carbon stocks increased from warm, southern, sites (with fine-textured soils) to northern, cool, sites (with more coarse-textured soils). The exception was a northern site, with less than 10% silt-clay content, that had a soil organic carbon stock similar to those measured at southern sites. Soil carbon at each site was partitioned into two pools (labile and stable) on the basis of carbon measured in the forest floor and POM and MOM fractions from the mineral soil. A two-compartment steady-state model, with randomly varying parameter values, was used in probabilistic calculations to estimate the turnover time of labile soil organic carbon (MRTU) and the annual transfer of labile carbon to stable carbon (k2) at each site in two different years. Based on empirical data, the turnover time of stable soil carbon (MRTS) was determined by mean annual temperature and increased from 30 to 100 years from south to north. Moving from south to north, MRTU increased from approximately 5 to 14 years. Consistent with prior studies, 13C enrichment factors ( ) from the Rayleigh equation, that describe the rate of change in 13C through the soil profile, were an indicator of soil carbon turnover times along the latitudinal gradient. Consistent with its role in stabilization of soil organic carbon, silt

  10. Latitudinal Variations Of The F3 Layer Observed From The SEALION Ionosonde Network

    NASA Astrophysics Data System (ADS)

    Uemoto, J.; Ono, T.; Maruyama, T.; Saito, S.; Iizima, M.; Kumamoto, A.

    2006-12-01

    [INTRODUCTION] The occurrence probability, local time, solar and magnetic activity dependences of the F3 layer have been clarified experimentally from ionosonde observations as well as model calculation, whereas some unexplained problems have remained; It has been reported that the F3 layer was frequently obrved in June solstice season at Fortaleza in Brazil (geographic latitude -4 deg, geographic longitude 322 deg, and dip latitude -5.4 deg) though in this season (local winter season), frequently occurrences of the F3 layer were not predicted from the model calculation with normal values of the E x B drift and meridional neutral wind and seasonal dependence of occurrences at Waltair (17.7 deg, 83.3 deg, 11.5 deg) shows a different tendency from that at Fortaleza. The latter problem seems to result from geographic control or differences of dip latitude between two observation locations, however, its physical mechanism has not been clarified. Then conjugate observations in a magnetic meridional plane are needed. For the purpose of clarifying the mechanism of the F3 layer in more detail, we are analyzing the ionosonde data of the South East Asian Low-latitude IOnosonde Network [SEALION] mainly provided by NiCT which consists of 4 ionosonde stations. In this study, we analyzed ionosonde data observed at Chiang Mai (CMU [18.8 deg, 98.9 deg, 13.0 deg]), Chumphon(CPN [10.7 deg, 99.4 deg, 3.3 deg]) and Kototabang (KTB [-0.2 deg, 100.3 deg, -10.0 deg]). [ANALYSIS] As a result from analyzing ionosonde data on 31st March, 2005, following dip latitudinal differences have been found; At CPN, in the vicinity of the dip equator, the F3 layer moved upward rapidly and disappeared in earlier local time, while at CMU and KTB, in the low dip latitude region, the F3 layer stayed at almost the same altitude and remained to be detectable with longer time duration. [CONCLUSION] From comparing between observation results and the model calculation, it is suggested that such a dip

  11. Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps

    NASA Astrophysics Data System (ADS)

    Scotti, R.; Brardinoni, F.; Crosta, G. B.

    2014-07-01

    The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still matter of debate. To address this question in the Central Italian Alps we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860-1954-1990-2003-2007) along a latitudinal transect that originates north of the continental divide in the Livigno mountains, and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions we examine area change of 111 glaciers. Overall, total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. Average annual decrease (AAD) in glacier area has risen of about an order of magnitude from 1860-1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a-1) to 1990-2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a-1). This ranking changes when considering glaciers <0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a-1). More recent (2007-2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing consistent highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying a transitional behaviour. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends. A decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as well by the higher

  12. Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps

    NASA Astrophysics Data System (ADS)

    Scotti, R.; Brardinoni, F.; Crosta, G. B.

    2014-12-01

    The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860-1954-1990-2003-2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860-1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a-1) to 1990-2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a-1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a-1). More recent (2007-2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in

  13. Evidence of Latitudinal Migration in Tri-colored Bats, Perimyotis subflavus

    PubMed Central

    Fraser, Erin E.; McGuire, Liam P.; Eger, Judith L.; Longstaffe, Fred J.; Fenton, M. Brock

    2012-01-01

    Background Annual movements of tri-colored bats (Perimyotis subflavus) are poorly understood. While this species has been considered a regional migrant, some evidence suggests that it may undertake annual latitudinal migrations, similar to other long distance North American migratory bat species. Methodology/Principal Findings We investigated migration in P. subflavus by conducting stable hydrogen isotope analyses of 184 museum specimen fur samples and comparing these results (δDfur) to published interpolated δD values of collection site growing season precipitation (δDprecip). Results suggest that the male molt period occurred between June 23 and October 16 and 33% of males collected during the presumed non-molt period were south of their location of fur growth. For the same time period, 16% of females were south of their location of fur growth and in general, had not travelled as far as migratory males. There were strong correlations between δDfur from the presumed molt period and both growing season δDprecip (males – r2 = 0.86; p<0.01; females – r2 = 0.75; p<0.01), and latitude of collection (males – r2 = 0.85; p<0.01; females – r2 = 0.73; p<0.01). Most migrants were collected at the northern (>40°N; males and females) and southern (<35°N; males only) extents of the species' range. Conclusions/Significance These results indicate a different pattern of migration for this species than previously documented, suggesting that some P. subflavus engage in annual latitudinal migrations and that migratory tendency varies with latitude and between sexes. We suggest that this species' hibernation ecology makes it particularly susceptible to long winters, making migration from the northern extent of the species' range to more southern hibernacula preferable for some individuals. Fur δD values for some of the northern individuals may indicate an increase in the currently accepted northern range of this species. Sex-biased differences in

  14. Elevational and Latitudinal Gradient Sites Enable Phenology Controls and Climate Change Detection

    NASA Astrophysics Data System (ADS)

    Losleben, M. V.; Weltzin, J. F.; Billick, I.; Jones, D.

    2008-12-01

    Phenology is the study of the timing of recurring biological phases, the causes of their timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different species. Although phenology is a far-reaching component of environmental science, it is poorly understood relative to other ecological patterns and processes. For example, it is unclear how climatic attributes affect the phenology of different organisms, and how those attributes vary in importance on different spatial and temporal scales. We know phenology affects the abundance and diversity of organisms, and their function and interactions in the environment, especially their effects on fluxes in water, energy, and chemical elements at various scales. With sufficient observations and understanding, phenology can be used as a predictor for other processes and variables of importance at local to global scales, and phenology could drive a variety of ecological forecast models with both scientific and practical applications. Integration of spatially-extensive phenological data and models with both short and long-term climatic forecasts offer a powerful agent for human adaptation to ongoing and future climate change. To fully utilize the value of phenology, not only more observations at more locations are needed, but also linkages between climatic factors and phenology must be more firmly established through linked direct observations and remotely sensed (Landscape Phenology or LSP) measurements with climatic factors. Sites along elevational gradients over a range of latitudes provide this opportunity. Elevational gradients present the phenological observational efficiency of compressed ecosystem transitions, and through climatic matching of sites, latitudinal range presents opportunities to control for additional abiotic factors such as day length, seasonal variability, storm track, and atmospheric chemistry. These sites also provide excellent platforms to advance new, and

  15. Declines in both redundant and trace species characterize the latitudinal diversity gradient in tintinnid ciliates.

    PubMed

    Dolan, John R; Yang, Eun Jin; Kang, Sung-Ho; Rhee, Tae Siek

    2016-09-01

    The latitudinal diversity gradient is a well-known biogeographic pattern. However, rarely considered is how a cline in species richness may be reflected in the characteristics of species assemblages. Fewer species may equal fewer distinct ecological types, or declines in redundancy (species functionally similar to one another) or fewer trace species, those occurring in very low concentrations. We focused on tintinnid ciliates of the microzooplankton in which the ciliate cell is housed inside a species-specific lorica or shell. The size of lorica oral aperture, the lorica oral diameter (LOD), is correlated with a preferred prey size and maximum growth rate. Consequently, species of a distinct LOD are distinct in key ecologic characteristics, whereas those of a similar LOD are functionally similar or redundant species. We sampled from East Sea/Sea of Japan to the High Arctic Sea. We determined abundance distributions of biological species and also ecological types by grouping species in LOD size-classes, sets of ecologically similar species. In lower latitudes there are more trace species, more size-classes and the dominant species are accompanied by many apparently ecologically similar species, presumably able to replace the dominant species, at least with regard to the size of prey exploited. Such redundancy appears to decline markedly with latitude in assemblages of tintinnid ciliates. Furthermore, the relatively small species pools of the northern high latitude assemblages suggest a low capacity to adapt to changing conditions. PMID:26990873

  16. The latitudinal distribution of the baseline geomagnetic field during the March 17, 2015 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Alberti, Tommaso; Piersanti, Mirko; Lepreti, Fabio; Vecchio, Antonio; De Michelis, Paola; Villante, Umberto; Carbone, Vincenzo

    2016-04-01

    Geomagnetic storms (GS) are global geomagnetic disturbances that result from the interaction between magnetized plasma that propagates from the Sun and plasma and magnetic fields in the near-Earth space plasma environment. The Dst (Disturbance Storm Time) global Ring Current index is still taken to be the definitive representation for geomagnetic storm and is used widely by researcher. Recent in situ measurements by satellites passing through the ring-current region (i.e. Van Allen probes) and computations with magnetospheric field models showed that there are many other field contributions on the geomagnetic storming time variations at middle and low latitudes. Appling the Empirical Mode Decomposition [Huang et al., 1998] to magnetospheric and ground observations, we detect the different magnetic field contributions during a GS and introduce the concepts of modulated baseline and fluctuations of the geomagnetic field. In this work, we apply this method to study the latitudinal distribution of the baseline geomagnetic field during the St. Patrick's Day Geomagnetic Storm 2015 in order to detect physical informations concerning the differences between high-latitude and equatorial ground measurements.

  17. A latitudinal gradient in climate effects on seabird demography: results from interspecific analyses

    PubMed Central

    SANDVIK, HANNO; COULSON, TIM; SÆTHER, BERNT-ERIK

    2008-01-01

    For an understanding of the effect of climate change on animal population dynamics, it is crucial to be able to identify which climatologic parameters affect which demographic rate, and what the underlying mechanistic links are. An important reason for why the interactions between demography and climate still are poorly understood is that the effects of climate vary both geographically and taxonomically. Here, we analyse interspecifically how different climate variables affect the breeding success of North Atlantic seabird species along latitudinal and longitudinal gradients. By approaching the problem comparatively, we are able to generalize across populations and species. We find a strong interactive effect of climate and latitude on breeding success. Of the climatic variables considered, local sea surface temperatures during the breeding season tend to be more relevant than the North Atlantic Oscillation (NAO). However, the effect of NAO on breeding success shows a clear geographic pattern, changing in sign from positive in the south to negative in the north. If this interaction is taken account of, the model explains more variation than any model with sea surface temperature. This superiority of the NAO index is due to its ability to capture effects of more than one season in a single parameter. Mechanistically, however, several lines of evidence suggest that sea surface temperature is the biologically most relevant explanatory variable.

  18. Thermal acclimation of photosynthesis: a comparison of boreal and temperate tree species along a latitudinal transect.

    PubMed

    Dillaway, Dylan N; Kruger, Eric L

    2010-06-01

    Common gardens were established along a approximately 900 km latitudinal transect to examine factors limiting geographical distributions of boreal and temperate tree species in eastern North America. Boreal representatives were trembling aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.), while temperate species were eastern cottonwood (Populus deltoides Bartr ex. Marsh var. deltoides) and sweetgum (Liquidambar styraciflua L.). The species were compared with respect to adjustments of leaf photosynthetic metabolism along the transect, with emphasis on temperature sensitivities of the maximum rate of ribulose bisphosphate (RuBP) carboxylation (E(V)) and regeneration (E(J)). During leaf development, the average air temperature (T(growth)) differed between the coolest and warmest gardens by 12 degrees C. Evidence of photosynthetic thermal acclimation (metabolic shifts compensating for differences in T(growth)) was generally lacking in all species. Namely, neither E(V) nor E(J) was positively related to T(growth). Correspondingly, the optimum temperature (T(opt)) of ambient photosynthesis (A(sat)) did not vary significantly with T(growth). Modest variation in T(opt) was explained by the combination of E(V) plus the slope and curvature of the parabolic temperature response of mesophyll conductance (g(m)). All in all, species differed little in photosynthetic responses to climate. Furthermore, the adaptive importance of photosynthetic thermal acclimation was overshadowed by g(m)'s influence on A(sat)'s temperature response.

  19. Evidence of latitudinal fractionation of polychlorinated biphenyl congeners along the Baltic Sea region

    SciTech Connect

    Agrell, C.; Okla, L.; Larsson, P.; Backe, C.; Wania, F.

    1999-04-15

    Annual cycles of the atmospheric concentrations of PCBs were determined at 16 (mostly rural) stations around the Baltic Sea between 1990 and 1993. The concentration levels of individual congeners were found to be influenced by their physical-chemical properties, ambient temperature, and geographical location. Median levels of PCBs were similar at all stations except at one urban site near Riga. A latitudinal gradient with higher levels in the south was found for the sum of PCB as well as for individual congeners, and the gradient was more pronounced for the low volatility congeners. As a result, the high volatility congeners increased in relative importance with latitude. Generally, PCB concentrations increased with temperature, but slopes of the partial pressure in air versus reciprocal temperature were different between congeners and between stations. In general, the low volatility congeners were more temperature dependent than the high volatility PCB congeners. Steep slopes at a sampling location indicate that the concentration in air is largely determined by diffusive exchange with soils. Lack of a temperature dependence may be due to the influence of long-range transported air masses at remote sites and due to the episodic or random nature of PCB sources at urban sites.

  20. Latitudinal variation of perturbation electric fields during magnetically disturbed periods - 1986 Sundial observations and model results

    NASA Astrophysics Data System (ADS)

    Fejer, B. G.; Spiro, R. W.; Wolf, R. A.; Foster, J. C.

    1990-06-01

    F-region incoherent scatter radar drift observations from Millstone Hill and Jicamarca, h-prime F observations from Huancayo, and high latitude ground-magnetometer measurements taken during the Sundial 1986 campaign are used to study the relationship between plasmaspheric electric field perturbations and high latitude currents during disturbed periods. The observations are in good agreement with numerical results from a Rice Covection Model run that involved a sharp increase in the polar cap potential drop followed by a subsequent decrease. The zonal disturbance electric field pattern is latitude independent, and the corresponding amplitudes change approximately as L exp n (where n is about 1.5). The meridional electric field patterns and amplitudes have larger latitudinal variations. The mid-, low, and equatorial electric fields from the Rice Convection Model are in good agreement with previous results from the semianalytic, Senior-Blanc (1987) model. Also discussed are three physical mechanisms (over-shielding, fossil winds, and magnetic reconfiguration) that contribute to the long lasting (1-2 h) equatorial zonal electric field perturbations associated with a sudden northward turning of the IMF. It is predicted that the penetration of high latitude electric fields to low latitudes should, in general, be closely related to the rate of motion of the shielding layer and the equatorward edge of the diffuse aurora.

  1. Latitudinal distribution of black carbon soot in the upper troposphere and lower stratosphere

    NASA Technical Reports Server (NTRS)

    Blake, David F.; Kato, Katharine

    1995-01-01

    Black carbon soot from the upper troposphere and lower stratosphere has been systematically collected at latitudes from 90 deg N to 45 deg S. The measured latitudinal distribution of this soot at 10 to 11 km altitude is found to covary with commercial air traffic fuel use, suggesting that aircraft fuel combustion at altitude is the principal source. In addition, at latitudes where the commercial air traffic is high, measured black carbon soot values are high even at 20 km altitude, suggesting that aircraft-generated soot injected just above the tropopause may be transported to higher altitudes. During the volcanically influenced period in which these samples were collected, the number abundances, total mass, and calculated total surface area of black carbon soot are 2-3 orders of magnitude lower than similar measures of sulfuric acid aerosol. During volcanically quiescent periods, the calculated total surface area of black carbon soot aerosol is of the same order of magnitude as that of the background sulfuric acid aerosol. It appears from this comparison that black carbon soot is only capable of influencing lower stratosphere or upper troposphere chemistry during periods when the aerosol budget is not dominated by volcanic activity. It remains to determine the extent to which black carbon soot particles act as nuclei for sulfuric acid aerosol formation. However, mass balance calculations suggest that aircraft soot injected at altitude does not represent a significant source of condensation nuclei for sulfuric acid aerosols.

  2. Susceptibility to a metal under global warming is shaped by thermal adaptation along a latitudinal gradient.

    PubMed

    Dinh Van, Khuong; Janssens, Lizanne; Debecker, Sara; De Jonge, Maarten; Lambret, Philippe; Nilsson-Örtman, Viktor; Bervoets, Lieven; Stoks, Robby

    2013-09-01

    Global warming and contamination represent two major threats to biodiversity that have the potential to interact synergistically. There is the potential for gradual local thermal adaptation and dispersal to higher latitudes to mitigate the susceptibility of organisms to contaminants and global warming at high latitudes. Here, we applied a space-for-time substitution approach to study the thermal dependence of the susceptibility of Ischnura elegans damselfly larvae to zinc in a common garden warming experiment (20 and 24 °C) with replicated populations from three latitudes spanning >1500 km in Europe. We observed a striking latitude-specific effect of temperature on the zinc-induced mortality pattern; local thermal adaptation along the latitudinal gradient made Swedish, but not French, damselfly larvae more susceptible to zinc at 24 °C. Latitude- and temperature-specific differences in zinc susceptibility may be related to the amount of energy available to defend against and repair damage since Swedish larvae showed a much stronger zinc-induced reduction of food intake at 24 °C. The pattern of local thermal adaptation indicates that the predicted temperature increase of 4 °C by 2100 will strongly magnify the impact of a contaminant such as zinc at higher latitudes unless there is thermal evolution and/or migration of lower latitude genotypes. Our results underscore the critical importance of studying the susceptibility to contaminants under realistic warming scenarios taking into account local thermal adaptation across natural temperature gradients. PMID:23640735

  3. Local selection across a latitudinal gradient shapes nucleotide diversity in balsam poplar, Populus balsamifera L.

    PubMed

    Keller, Stephen R; Levsen, Nicholas; Ingvarsson, Pär K; Olson, Matthew S; Tiffin, Peter

    2011-08-01

    Molecular studies of adaptive evolution often focus on detecting selective sweeps driven by positive selection on a species-wide scale; however, much adaptation is local, particularly of ecologically important traits. Here, we look for evidence of range-wide and local adaptation at candidate genes for adaptive phenology in balsam poplar, Populus balsamifera, a widespread forest tree whose range extends across environmental gradients of photoperiod and growing season length. We examined nucleotide diversity of 27 poplar homologs of the flowering-time network-a group of genes that control plant developmental phenology through interactions with environmental cues such as photoperiod and temperature. Only one gene, ZTL2, showed evidence of reduced diversity and an excess of fixed replacement sites, consistent with a species-wide selective sweep. Two other genes, LFY and FRI, harbored high levels of nucleotide diversity and exhibited elevated differentiation between northern and southern accessions, suggesting local adaptation along a latitudinal gradient. Interestingly, FRI has also been identified as a target of local selection between northern and southern accessions of Arabidopsis thaliana, indicating that this gene may be commonly involved in ecological adaptation in distantly related species. Our findings suggest an important role for local selection shaping molecular diversity and reveal limitations of inferring molecular adaptation from analyses designed only to detect species-wide selective sweeps. PMID:21624997

  4. Response of the Morus bombycis growing season to temperature and its latitudinal pattern in Japan.

    PubMed

    Doi, Hideyuki

    2012-09-01

    Changes in leaf phenology lengthen the growing season length (GSL, the days between leaf budburst and leaf fall) under the global warming. GSL and the leaf phenology response to climate change is one of the most important predictors of climate change effect on plants. Empirical evidence of climatic effects on GSL remains scarce, especially at a regional scale and the latitudinal pattern. This study analyzed the datasets of leaf budburst and fall phenology in Morus bombycis (Urticales), which were observed by the agency of the Japan Meteorological Agency (JMA) from 1953 to 2005 over a wide range of latitudes in Japan (31 to 44° N). In the present study, single regression slopes of leaf phenological timing and air temperature across Japan were calculated and their spatial patterns using general linear models were tested. The results showed that the GSL extension was caused mainly by a delay in leaf fall phenology. Relationships between latitude and leaf phenological and GSL responses against air temperature were significantly negative. The response of leaf phenology and GSL to air temperature at lower latitudes was larger than that at higher latitudes. The findings indicate that GSL extension should be considered with regards to latitude and climate change.

  5. The role of freezing in setting the latitudinal limits of mangrove forests.

    PubMed

    Stuart, S A; Choat, B; Martin, K C; Holbrook, N M; Ball, M C

    2007-01-01

    Mangrove trees dominate coastal vegetation in tropical regions, but are completely replaced by herbaceous salt marshes at latitudes above 32 degrees N and 40 degrees S. Because water deficit can increase damage caused by freezing, we hypothesized that mangroves, which experience large deficits as a result of saline substrates, would suffer freeze-induced xylem failure. Vulnerability to freeze-induced xylem embolism was examined in the most poleward mangrove species in North America, in an area where freezing is rare but severe, and in Australia, in an area where freezing is frequent but mild. Percentage loss in hydraulic conductivity was measured following manipulations of xylem tension; xylem sap ion concentration was determined using X-ray microanalysis. Species with wider vessels suffered 60-100% loss of hydraulic conductivity after freezing and thawing under tension, while species with narrower vessels lost as little as 13-40% of conductivity. These results indicate that freeze-induced embolism may play a role in setting the latitudinal limits of distribution in mangroves, either through massive embolism following freezing, or through constraints on water transport as a result of vessel size. PMID:17244052

  6. Cyanobacterial diversity of western European biological soil crusts along a latitudinal gradient.

    PubMed

    Williams, Laura; Loewen-Schneider, Katharina; Maier, Stefanie; Büdel, Burkhard

    2016-10-01

    Cyanobacteria associated with biological soil crusts (BSCs) have important attributes, such as nitrogen fixation and soil stabilisation. However, research on these organisms has been minimal, and their diversity and distribution throughout temperate Europe is currently unknown. The SCIN (Soil Crust International) project is a multidisciplinary research initiative that aims to achieve improved understanding of the BSCs of Europe, one facet being an investigation into the cyanobacterial communities of BSCs across a latitudinal gradient. Cyanobacteria assemblages were analysed by both morphological and molecular analysis. Two treatments were applied prior to DNA extraction, continued sample wetting and a dry sample process, and 16S ribosomal RNA (rRNA) amplicons were processed by Illumina MiSeq sequencing. The results reveal high and variable cyanobacterial diversity with each site showing a unique assemblage. Many common cyanobacterial genera, for example Nostoc and Microcoleus, were found in all sites but the abundances of different genera varied considerably. The polyphasic approach was found to be essential in recording the presence of important cyanobacteria that a single method itself did not highlight. The wet and dry treatments showed some differences in diversity, but mainly in abundance, this may suggest how cyanobacterial composition of BSCs changes with seasonal variability. PMID:27411981

  7. Susceptibility to a metal under global warming is shaped by thermal adaptation along a latitudinal gradient.

    PubMed

    Dinh Van, Khuong; Janssens, Lizanne; Debecker, Sara; De Jonge, Maarten; Lambret, Philippe; Nilsson-Örtman, Viktor; Bervoets, Lieven; Stoks, Robby

    2013-09-01

    Global warming and contamination represent two major threats to biodiversity that have the potential to interact synergistically. There is the potential for gradual local thermal adaptation and dispersal to higher latitudes to mitigate the susceptibility of organisms to contaminants and global warming at high latitudes. Here, we applied a space-for-time substitution approach to study the thermal dependence of the susceptibility of Ischnura elegans damselfly larvae to zinc in a common garden warming experiment (20 and 24 °C) with replicated populations from three latitudes spanning >1500 km in Europe. We observed a striking latitude-specific effect of temperature on the zinc-induced mortality pattern; local thermal adaptation along the latitudinal gradient made Swedish, but not French, damselfly larvae more susceptible to zinc at 24 °C. Latitude- and temperature-specific differences in zinc susceptibility may be related to the amount of energy available to defend against and repair damage since Swedish larvae showed a much stronger zinc-induced reduction of food intake at 24 °C. The pattern of local thermal adaptation indicates that the predicted temperature increase of 4 °C by 2100 will strongly magnify the impact of a contaminant such as zinc at higher latitudes unless there is thermal evolution and/or migration of lower latitude genotypes. Our results underscore the critical importance of studying the susceptibility to contaminants under realistic warming scenarios taking into account local thermal adaptation across natural temperature gradients.

  8. Compensation and climate: Latitudinal variation in ecototherm response to environmental change

    SciTech Connect

    Curtin, C.G.

    1995-06-01

    Thermal preference measured in a laboratory thermal gradient, and field body temperatures in a field enclosure, contrast the fundamental and realized thermal niches of ornate box turtles (Terrapene ornata) from northern, central, and southern locations. The relatively warmer thermal preference of southern turtles appears to result in lower body temperatures and relatively shorter activity periods. Variation in thermal constraints are input into computer simulations of ectotherm response to climate to assess latitudinal variation in turtle response to microclimate cooling (4{degrees} C), current climate (1970-1990), and climatic warming (3-5{degrees} C). Climatic warming is calculated to lead to a northward shift in turtle range and distribution with increases in northern and declines in southern populations. Microclimate cooling is estimated to result in declines in northern areas and in the core of the box turtle range. The local changes in microclimate, such as can result from shifts in land-use, can be greater than those resulting from large scale changes in climate. Suggesting that land managers and conservation biologists need to focus greater attention on the impact of changes in within patch structure of plant associations and its implications for alteration of microclimate and species life history.

  9. The latitudinal distribution of ozone to 35 km altitude from ECC ozonesonde observations, 1982-1990

    NASA Technical Reports Server (NTRS)

    Komhyr, W. D.; Oltmans, S. J.; Lathrop, J. A.; Kerr, J. B.; Matthews, W. A.

    1994-01-01

    Electrochemical concentration cell (ECC) ozone-sonde observations, made in recent years at ten stations whose locations range from the Arctic to Antarctica, have yielded a self-consistent ozone data base from which mean seasonal and annual latitudinal ozone vertical distributions to 35 km have been derived. Ozone measurement uncertainties are estimated, and results are presented in the Bass-Paur (1985) ozone absorption coefficient scale adopted for use with Dobson ozone spectrophotometers January 1, 1992. The data should be useful for comparison with model calculations of the global distribution of atmospheric ozone, for serving as apriori statistical information in deriving ozone vertical distributions from satellite and Umkehr observations, and for improving the satellite and Umkehr ozone inversion algorithms. Attention is drawn to similar results based on a less comprehensive data set published in Ozone in the Atmosphere, Proceedings of the 1988 Quadrennial Ozone Symposium where errors in data tabulations occurred for three of the stations due to inadvertent transposition of ozone partial pressure and air temperature values.

  10. Longitudinal and latitudinal distribution of perfluoroalkyl compounds in the surface water of the Atlantic Ocean.

    PubMed

    Ahrens, Lutz; Barber, Jonathan L; Xie, Zhiyong; Ebinghaus, Ralf

    2009-05-01

    Perfluoroalkyl compounds (PFCs) were determined in 2 L surface water samples collected in the Atlantic Ocean onboard the research vessels Maria S. Merian along the longitudinal gradient from Las Palmas (Spain) to St. Johns (Canada) (15 degrees W to 52 degrees W) and Polarstern along the latitudinal gradient from the Bay of Biscay to the South Atlantic Ocean (46 degrees N to 26 degrees S) in spring and fall 2007, respectively. After filtration the dissolved and particulate phases were extracted separately, and PFC concentrationswere determined using high-performance liquid chromatography interfaced to tandem mass spectrometry. No PFCs were detected in the particulate phase. This study provides the first concentration data of perfluorooctanesulfonamide (FOSA), perfluorohexanoic acid, and perfluoroheptanoic acid from the Atlantic Ocean. Results indicate that trans-Atlantic Ocean currents caused the decreasing concentration gradient from the Bay of Biscay to the South Atlantic Ocean and the concentration drop-off close to the Labrador Sea. Maximum concentrations were found for FOSA, perfluorooctanesulfonate, and perfluorooctanoic acid at 302, 291, and 229 pg L(-1), respectively. However, the concentration of each single compound was usually in the tens of picograms per liter range. South of the equator only FOSA and below 4 degrees S no PFCs could be detected.

  11. Latitudinal Changes of Polar Hiss and Plasmapause Hiss Associated with Magnetospheric Processes

    NASA Astrophysics Data System (ADS)

    Ondoh, T.

    Latitudinal variations of magnetospheric VLF hiss observed at low altitudes reflect dynamical changes of the magnetosphere, since VLF hiss signals at low altitudes are integrated signals of the whistler-mode VLF hiss propagating along geomagnetic field lines from wide-altitude sources in the magnetosphere. Analysis of narrow-band intensity data of ISIS-2 (1400 km) VLF electric field (50 Hz-30 kHz) shows that the broad-band polar hiss occurs at invariant latitudes for 68-85 degrees and the narrow-band plasmapause hiss occurs fro 50-64 degrees in geomagnetic quiet periods, and that the polar hiss region shifts to lower latitudes or inner L-shells and finally joins to the plasmapause hiss region as the substorm develops. The polar hiss is interpreted as the whistler-mode Cerenkov radiations from inverted-V electrons precipitating from the plasmasheet boundary layer and the plasmapause hiss is the whistler-mode emissions due to the electron cyclotron instability around the equatorial plasmapause. The substorm changes of polar hiss and plasmapause hiss regions observed at low altitudes are studied in relation to dynamical changes of inward shift of the plasmasheet horns and of the plasmaspheric plumes as observed by the IMAGE in substorm periods.

  12. Latitudinal Gradient in Otolith Shape among Local Populations of Atlantic Herring (Clupea harengus L.) in Norway

    PubMed Central

    Libungan, Lísa Anne; Slotte, Aril; Husebø, Åse; Godiksen, Jane A.; Pálsson, Snæbjörn

    2015-01-01

    Otolith shape analysis of Atlantic herring (Clupea harengus) in Norwegian waters shows significant differentiation among fjords and a latitudinal gradient along the coast where neighbouring populations are more similar to each other than to those sampled at larger distances. The otolith shape was obtained using quantitative shape analysis, the outlines were transformed with Wavelet and analysed with multivariate methods. The observed morphological differences are likely to reflect environmental differences but indicate low dispersal among the local herring populations. Otolith shape variation suggests also limited exchange between the local populations and their oceanic counterparts, which could be due to differences in spawning behaviour. Herring from the most northerly location (69°N) in Balsfjord, which is genetically more similar to Pacific herring (Clupea pallasii), differed in otolith shape from all the other populations. Our results suggest that the semi-enclosed systems, where the local populations live and breed, are efficient barriers for dispersal. Otolith shape can thus serve as a marker to identify the origin of herring along the coast of Norway. PMID:26101885

  13. Latitudinal and longitudinal clines of phenotypic plasticity in the invasive herb Solidago canadensis in China.

    PubMed

    Li, Junmin; Du, Leshan; Guan, Wenbin; Yu, Fei-Hai; van Kleunen, Mark

    2016-11-01

    Phenotypic plasticity is thought to be important for plants in variable environments. The climatic variability hypothesis poses that populations at higher latitudes, due to the stronger variation in temperature, there should be more plastic in response to temperature than populations at lower latitudes. Similarly, populations at locations with stronger precipitation fluctuations should be more plastic in response to water availability than populations at locations with less variable precipitation. We sampled seven and nine populations of Solidago canadensis, a North American native that is invasive in China, along a latitudinal (temperature variability) and a longitudinal (precipitation variability) gradient, respectively, in China, and grew them under two temperature treatments and two water-availability treatments, respectively. Among the four traits with significant variation in plasticity among populations in response to temperature, plasticity of leaf length-to-width ratio was significantly positively correlated with latitude and temperature seasonality of the populations. In addition, root/shoot ratio and water-use efficiency showed significant variation in plasticity among populations in response to water availability, and plasticities of these two traits were significantly negatively correlated with longitude and positively correlated with precipitation seasonality. The observed geographic clines in plasticity suggest that phenotypic plasticity of S. canadensis may have evolved rapidly in regions with different climatic conditions, and this may have contributed to the spread of this invasive species.

  14. Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples

    PubMed Central

    Ghiglione, Claudio; Alvaro, Maria Chiara; Griffiths, Huw J.; Linse, Katrin; Schiaparelli, Stefano

    2013-01-01

    Abstract Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V “Italica” in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project “BAMBi” (PNRA 2010/A1.10). PMID:24146597

  15. Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples.

    PubMed

    Ghiglione, Claudio; Alvaro, Maria Chiara; Griffiths, Huw J; Linse, Katrin; Schiaparelli, Stefano

    2013-01-01

    Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V "Italica" in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project "BAMBi" (PNRA 2010/A1.10).

  16. Prospecting for ice association: characterization of freeze-thaw selected enrichment cultures from latitudinally distant soils.

    PubMed

    Wilson, Sandra L; Grogan, Paul; Walker, Virginia K

    2012-04-01

    Freeze-thaw stress has previously been shown to alter soil community structure and function. We sought to further investigate this stress on enriched microbial consortia with the aim of identifying microbes with ice-associating adaptations that facilitate survival. Enrichments were established to obtain culturable psychrotolerant microbes from soil samples from the latitudinal extremes of the Canadian Shield plateau. The resulting consortia were subjected to consecutive freeze-thaw cycles, and survivors were putatively identified by their 16S rRNA gene sequences. Even though the northerly site was exposed to longer, colder winters and large spring-time temperature fluctuations, the selective regime similarly affected both enriched consortia. Quantitative PCR and metagenomic sequencing were used to determine the frequency of a subset of the resistant microbes in the original enrichments. The metagenomes showed 22 initial genera, only 6 survived and these were not dominant prior to selection. When survivors were assayed for ice recrystallization inhibition and ice nucleation activities, over 60% had at least one of these properties. These phenotypes were not more prevalent in the northern enrichment, indicating that regarding these adaptations, the enrichment strategy yielded seemingly functionally similar consortia from each site. PMID:22435705

  17. Latitudinal Gradient in Otolith Shape among Local Populations of Atlantic Herring (Clupea harengus L.) in Norway.

    PubMed

    Libungan, Lísa Anne; Slotte, Aril; Husebø, Åse; Godiksen, Jane A; Pálsson, Snæbjörn

    2015-01-01

    Otolith shape analysis of Atlantic herring (Clupea harengus) in Norwegian waters shows significant differentiation among fjords and a latitudinal gradient along the coast where neighbouring populations are more similar to each other than to those sampled at larger distances. The otolith shape was obtained using quantitative shape analysis, the outlines were transformed with Wavelet and analysed with multivariate methods. The observed morphological differences are likely to reflect environmental differences but indicate low dispersal among the local herring populations. Otolith shape variation suggests also limited exchange between the local populations and their oceanic counterparts, which could be due to differences in spawning behaviour. Herring from the most northerly location (69°N) in Balsfjord, which is genetically more similar to Pacific herring (Clupea pallasii), differed in otolith shape from all the other populations. Our results suggest that the semi-enclosed systems, where the local populations live and breed, are efficient barriers for dispersal. Otolith shape can thus serve as a marker to identify the origin of herring along the coast of Norway.

  18. Contrarian clade confirms the ubiquity of spatial origination patterns in the production of latitudinal diversity gradients

    PubMed Central

    Krug, Andrew Z.; Jablonski, David; Valentine, James W.

    2007-01-01

    The latitudinal diversity gradient (LDG), wherein the number of species and higher taxa peaks in the tropics and decreases toward the poles, is the best-documented large-scale diversity pattern on Earth, but hypotheses explaining the standard LDG must also account for rare “contrarian” taxa that show diversity maxima outside of the tropics. For marine bivalves, one of the few groups that provide spatially explicit temporal data on a global scale, we show that a major contrarian group, the Anomalodesmata, unexpectedly exhibits the same large-scale dynamics as related clades having normal LDGs in two key respects. First, maxima in standing genus diversity and genus origination rates coincide spatially. Second, the strength of a clade's present-day LDG is significantly related to the proportion of its living genera that originated in the tropics during the late Cenozoic, with the contrarian gradient strength at both species and genus level predicted quantitatively by the values for the other clades. Geologic age distributions indicate that the anomalous LDG results from origination that is damped in the tropics rather than heightened in the temperate zones. The pervasive role of spatial origination patterns in shaping LDGs, regardless of the position of their diversity maxima, corroborates hypotheses based on clades showing standard gradients and underscores the insights that contrarian groups can provide into general principles of diversity dynamics. PMID:17989214

  19. Observations of Atlantic overturning variability and latitudinal coherence with GRACE time-variable gravity

    NASA Astrophysics Data System (ADS)

    Landerer, Felix; Wiese, David; Bentel, Katrin; Watkins, Michael; Boening, Carmen

    2016-04-01

    The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism of pole-ward planetary heat transport. Concerns about AMOC changes imply the need for a continuous, large-scale observation capability to detect and monitor changes on interannual to decadal time scales. Here we present measurements of AMOC component transport changes directly obtained from time-variable gravity observations of the Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 until now. Recent improvements at JPL of monthly gravity field retrievals allow the detection of AMOC-related interannual bottom pressure anomalies and in turn LNADW transport estimates. In the Atlantic at 26N, these GRACE AMOC estimates are in good agreement with those from the Rapid Climate Change-Meridional Overturning Circulation and Heatflux Array (RAPID/MOCHA) . We extend the GRACE-based estimates of AMOC variability from the Southern Ocean to the Northern sinking branch to assess meridional coherence and discuss challenges of the GRACE observing system. Our results highlight the efficacy and utility of space-gravimetry for observing AMOC variations to evaluate latitudinal coherency and long-term variability.

  20. A distinct latitudinal gradient of diatom diversity is linked to resource supply.

    PubMed

    Passy, Sophia I

    2010-01-01

    For over 200 years, scientists have recognized the nearly ubiquitous poleward decline of species richness, but none of the theories explaining its occurrence has been widely accepted. In this continental study of U.S. running waters, I report an exception to this general pattern, i.e., a U-shaped latitudinal distribution of diatom richness (DR), equally high in subtropical and temperate regions. This gradient is linked unequivocally to corresponding trends in basin and stream properties with impact on resource supply. Specifically, DR distribution was related to wetland area, soil composition, and forest cover in the watershed, which affected iron, manganese, and macronutrient fluxes into streams. These results imply that the large-scale biodiversity patterns of freshwater protists, which are seasonal, highly dispersive, and sheltered by their environment from extreme temperature fluctuations, are resource driven in contrast to more advanced, perennial, and terrestrial organisms with biogeography strongly influenced by climate. The finding that wetlands, through iron export, control DR in streams has important environmental implications. It suggests that wetlands loss, already exceeding 52 million hectares in the conterminous United States alone, poses a threat not only to local biota, but also to biodiversity of major stream producers with potentially harmful consequences for the entire ecosystem.

  1. Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples.

    PubMed

    Ghiglione, Claudio; Alvaro, Maria Chiara; Griffiths, Huw J; Linse, Katrin; Schiaparelli, Stefano

    2013-01-01

    Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V "Italica" in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project "BAMBi" (PNRA 2010/A1.10). PMID:24146597

  2. Can selection on nest size from nest predation explain the latitudinal gradient in clutch size?

    USGS Publications Warehouse

    Biancucci, L.; Martin, T.E.

    2010-01-01

    1. Latitudinal variation in clutch sizes of birds is a well described, but poorly understood pattern. Many hypotheses have been proposed, but few have been experimentally tested, and none have been universally accepted by researchers. 2. The nest size hypothesis posits that higher nest predation in the tropics favours selection for smaller nests and thereby constrains clutch size by shrinking available space for eggs and/or nestlings in the nest. We tested this hypothesis with an experiment in a tropical forest and a comparative study between temperate and tropical field sites. 3. Specifically, we tested if: (i) predation increased with nest size; (ii) tropical birds had smaller nests controlled for body size; and (iii) clutch size was explained by nest size controlled for body size. 4. Experimental swapping of nests of different sizes showed that nest predation increased with nest size in the tropical site. Moreover, nest predation rates were higher in species with larger nests in both sites. However, nest size, corrected for body mass and phylogeny, did not differ between sites and was not related to clutch size between sites. 5. Hence, nest predation can exert selection on nest size as predicted by the hypothesis. Nest size increased with adult body mass, such that adult size might indirectly influence reproductive success through effects on nest size and nest predation risk. Ultimately, however, selection from nest predation on nest size does not explain the smaller clutch sizes typical of the tropics.

  3. Local selection across a latitudinal gradient shapes nucleotide diversity in balsam poplar, Populus balsamifera L.

    PubMed

    Keller, Stephen R; Levsen, Nicholas; Ingvarsson, Pär K; Olson, Matthew S; Tiffin, Peter

    2011-08-01

    Molecular studies of adaptive evolution often focus on detecting selective sweeps driven by positive selection on a species-wide scale; however, much adaptation is local, particularly of ecologically important traits. Here, we look for evidence of range-wide and local adaptation at candidate genes for adaptive phenology in balsam poplar, Populus balsamifera, a widespread forest tree whose range extends across environmental gradients of photoperiod and growing season length. We examined nucleotide diversity of 27 poplar homologs of the flowering-time network-a group of genes that control plant developmental phenology through interactions with environmental cues such as photoperiod and temperature. Only one gene, ZTL2, showed evidence of reduced diversity and an excess of fixed replacement sites, consistent with a species-wide selective sweep. Two other genes, LFY and FRI, harbored high levels of nucleotide diversity and exhibited elevated differentiation between northern and southern accessions, suggesting local adaptation along a latitudinal gradient. Interestingly, FRI has also been identified as a target of local selection between northern and southern accessions of Arabidopsis thaliana, indicating that this gene may be commonly involved in ecological adaptation in distantly related species. Our findings suggest an important role for local selection shaping molecular diversity and reveal limitations of inferring molecular adaptation from analyses designed only to detect species-wide selective sweeps.

  4. Prospecting for ice association: characterization of freeze-thaw selected enrichment cultures from latitudinally distant soils.

    PubMed

    Wilson, Sandra L; Grogan, Paul; Walker, Virginia K

    2012-04-01

    Freeze-thaw stress has previously been shown to alter soil community structure and function. We sought to further investigate this stress on enriched microbial consortia with the aim of identifying microbes with ice-associating adaptations that facilitate survival. Enrichments were established to obtain culturable psychrotolerant microbes from soil samples from the latitudinal extremes of the Canadian Shield plateau. The resulting consortia were subjected to consecutive freeze-thaw cycles, and survivors were putatively identified by their 16S rRNA gene sequences. Even though the northerly site was exposed to longer, colder winters and large spring-time temperature fluctuations, the selective regime similarly affected both enriched consortia. Quantitative PCR and metagenomic sequencing were used to determine the frequency of a subset of the resistant microbes in the original enrichments. The metagenomes showed 22 initial genera, only 6 survived and these were not dominant prior to selection. When survivors were assayed for ice recrystallization inhibition and ice nucleation activities, over 60% had at least one of these properties. These phenotypes were not more prevalent in the northern enrichment, indicating that regarding these adaptations, the enrichment strategy yielded seemingly functionally similar consortia from each site.

  5. Implications of natural sources for the latitudinal gradients of NO/y/ in the unpolluted troposphere

    NASA Technical Reports Server (NTRS)

    Hameed, S.; Paidoussis, O. G.; Stewart, R. W.

    1981-01-01

    The latitudinal distributions of tropospheric odd nitrogen (NO/y/) due to lightning discharges and stratospheric injection are studied by estimating latitude dependences of the sources and the rainout sink from data obtained in August-September, 1977, and May-June, 1978, during project GAMETAG. A one-dimensional (latitude dependent) model is developed for the annually, zonally, and vertically averaged concentration of trace species, NO(y) being treated as a single species, which decouples the NO(y) calculation from the rest of the model since NO(y) has no chemical sources or sinks in the troposphere. The equation governing the NO(y) distribution is solved using finite differences with 33 uniformly spaced grid points in the micron range of -1 to 1. The distribution due to the stratospheric source has a minimum in the tropics, and there are broad maxima centered in the 25-30 degree region in both hemispheres. The calculated NO(y) due to lightning has a maximum near 15 degrees S, and it decreases to nearly a fourth of the maximum value near the poles. The drop off from the maximum is sharper in the Southern Hemisphere in comparison with the Northern Hemisphere.

  6. Latitudinal trends in Spartina alterniflora productivity and the response of coastal marshes to global change

    USGS Publications Warehouse

    Kirwan, Matthew L.; Guntenspergen, Glenn R.; Morris, James T.

    2009-01-01

    Marshes worldwide are actively degrading in response to increased sea level rise rates and reduced sediment delivery, though the growth rate of vegetation plays a critical role in determining their stability. We have compiled 56 measurements of above-ground annual productivity for Spartina alterniflora, the dominant macrophyte in North American coastal wetlands. Our compilation indicates a significant latitudinal gradient in productivity, which we interpret to be determined primarily by temperature and/or the length of growing season. Simple linear regression yields a 27 g m-2 yr -1 increase in productivity with an increase of mean annual temperature by one degree C. If temperatures warm 2?4 C over the next century, then marsh productivity may increase by 10?40%, though physiological research suggests that increases in the north could potentially be offset by some decreases in the south. This increase in productivity is roughly equivalent to estimates of marsh lost due to future sea level change. If a warming-induced stimulation of vegetation growth will enhance vertical accretion and limit erosion, then the combined effects of global change may be to increase the total productivity and ecosystem services of tidal wetlands, at least in Northern latitudes.

  7. Cyanobacterial diversity of western European biological soil crusts along a latitudinal gradient

    PubMed Central

    Williams, Laura; Loewen-Schneider, Katharina; Maier, Stefanie; Büdel, Burkhard

    2016-01-01

    Cyanobacteria associated with biological soil crusts (BSCs) have important attributes, such as nitrogen fixation and soil stabilisation. However, research on these organisms has been minimal, and their diversity and distribution throughout temperate Europe is currently unknown. The SCIN (Soil Crust International) project is a multidisciplinary research initiative that aims to achieve improved understanding of the BSCs of Europe, one facet being an investigation into the cyanobacterial communities of BSCs across a latitudinal gradient. Cyanobacteria assemblages were analysed by both morphological and molecular analysis. Two treatments were applied prior to DNA extraction, continued sample wetting and a dry sample process, and 16S ribosomal RNA (rRNA) amplicons were processed by Illumina MiSeq sequencing. The results reveal high and variable cyanobacterial diversity with each site showing a unique assemblage. Many common cyanobacterial genera, for example Nostoc and Microcoleus, were found in all sites but the abundances of different genera varied considerably. The polyphasic approach was found to be essential in recording the presence of important cyanobacteria that a single method itself did not highlight. The wet and dry treatments showed some differences in diversity, but mainly in abundance, this may suggest how cyanobacterial composition of BSCs changes with seasonal variability. PMID:27411981

  8. Spatial community structure of mountain pine beetle fungal symbionts across a latitudinal gradient.

    PubMed

    Roe, Amanda D; James, Patrick M A; Rice, Adrianne V; Cooke, Janice E K; Sperling, Felix A H

    2011-08-01

    Symbiont redundancy in obligate insect-fungal systems is thought to buffer the insect host against symbiont loss and to extend the environmental conditions under which the insect can persist. The mountain pine beetle is associated with at least three well-known and putatively obligate ophiostomatoid fungal symbionts that vary in their environmental tolerances. To better understand the spatial variation in beetle-fungal symbiotic associations, we examined the community composition of ophiostomatoid fungi associated with the mountain pine beetle as a function of latitude and elevation. The region investigated represents the leading edge of a recent outbreak of mountain pine beetle in western Canada. Using regression and principal components analysis, we identified significant spatial patterns in fungal species abundances that indicate symmetrical replacement between two of the three fungi along a latitudinal gradient and little variation in response to elevation. We also identified significant variation in the prevalence of pair-wise species combinations that occur within beetle galleries. Frequencies of pair-wise combinations were significantly different from what was expected given overall species abundances. These results suggest that complex processes of competitive exclusion and coexistence help determine fungal community composition and that the consequences of these processes vary spatially. The presence of three fungal symbionts in different proportions and combinations across a wide range of environmental conditions may help explain the success of mountain pine beetle attacks across a broad geographic range.

  9. Cyanobacterial diversity of western European biological soil crusts along a latitudinal gradient.

    PubMed

    Williams, Laura; Loewen-Schneider, Katharina; Maier, Stefanie; Büdel, Burkhard

    2016-10-01

    Cyanobacteria associated with biological soil crusts (BSCs) have important attributes, such as nitrogen fixation and soil stabilisation. However, research on these organisms has been minimal, and their diversity and distribution throughout temperate Europe is currently unknown. The SCIN (Soil Crust International) project is a multidisciplinary research initiative that aims to achieve improved understanding of the BSCs of Europe, one facet being an investigation into the cyanobacterial communities of BSCs across a latitudinal gradient. Cyanobacteria assemblages were analysed by both morphological and molecular analysis. Two treatments were applied prior to DNA extraction, continued sample wetting and a dry sample process, and 16S ribosomal RNA (rRNA) amplicons were processed by Illumina MiSeq sequencing. The results reveal high and variable cyanobacterial diversity with each site showing a unique assemblage. Many common cyanobacterial genera, for example Nostoc and Microcoleus, were found in all sites but the abundances of different genera varied considerably. The polyphasic approach was found to be essential in recording the presence of important cyanobacteria that a single method itself did not highlight. The wet and dry treatments showed some differences in diversity, but mainly in abundance, this may suggest how cyanobacterial composition of BSCs changes with seasonal variability.

  10. Latitudinal dependence of nonlinear interaction between electromagnetic ion cyclotron wave and terrestrial ring current ions

    SciTech Connect

    Su, Zhenpeng Zhu, Hui; Zheng, Huinan; Xiao, Fuliang; Zhang, Min; Liu, Y. C.-M.; Shen, Chao; Wang, Yuming; Wang, Shui

    2014-05-15

    Electromagnetic ion cyclotron (EMIC) waves can lead to the rapid decay (on a timescale of hours) of the terrestrial ring current. Such decay process is usually investigated in the framework of quasi-linear theory. Here, both theoretical analysis and test-particle simulation are performed to understand the nonlinear interaction between ring current ions and EMIC waves. In particular, the dependence of the nonlinear wave-particle interaction processes on the ion initial latitude is investigated in detail. These nonlinear processes are classified into the phase trapping and phase bunching, and the phase bunching is further divided into the channel and cluster effects. Compared to the prediction of the quasi-linear theory, the ring current decay rate can be reduced by the phase trapping, increased by the channel effect phase bunching, but non-deterministically influenced by the cluster effect phase bunching. The ion initial latitude changes the occurrence of the phase trapping, modulates the transport direction and strength of the cluster effect phase bunching, and only slightly affects the channel effect phase bunching. The current results suggest that the latitudinal dependence of these nonlinear processes should be considered in the evaluation of the ring current decay induced by EMIC waves.

  11. Latitudinal variation in avian incubation attentiveness and a test of the food limitation hypothesis

    USGS Publications Warehouse

    Chalfoun, A.D.; Martin, T.E.

    2007-01-01

    Avian incubation attentiveness has important fitness consequences through its influence on the number and quality of hatched young and energetic costs imposed on parents. Nest attentiveness is highly variable across species and geographical regions. We reviewed the literature and found a worldwide pattern that nest attentiveness of passerines is generally lower in south temperate and tropical regions than in north temperate regions. We also conducted a food manipulation experiment to assess the extent to which nest attentiveness may reflect proximate responses versus an evolved behaviour. We used the karoo prinia, Prinia maculosa, in South Africa, which has very low nest attentiveness (???49%) compared with that of many passerine birds. We provided supplemental food during early incubation to experimental females and compared nest attentiveness and on- and off-bout lengths of experimental and paired control females.??Nest attentiveness of females at food-provisioned nests was significantly higher than that of control females (57% versus 49%). Food-supplemented females also spent significantly less time off the nest than did control females, whereas mean on-bout lengths did not differ. However, mean nest attentiveness of food-provisioned females was still substantially below that of other similar bird species worldwide. Food can be an important proximate influence on parental care behaviour, but proximate influences of food do not explain broad latitudinal patterns of attentiveness. ?? 2007 The Association for the Study of Animal Behaviour.

  12. Diversity and distribution of freshwater testate amoebae (protozoa) along latitudinal and trophic gradients in China.

    PubMed

    Ju, Lihua; Yang, Jun; Liu, Lemian; Wilkinson, David M

    2014-11-01

    Freshwater microbial diversity is subject to multiple stressors in the Anthropocene epoch. However, the effects of climate changes and human activities on freshwater protozoa remain poorly understood. In this study, the diversity and distribution of testate amoebae from the surface sediments were investigated in 51 Chinese lakes and reservoirs along two gradients, latitude and trophic status. A total of 169 taxa belonging to 24 genera were identified, and the most diverse and dominant genera were Difflugia (78 taxa), Centropyxis (26 taxa) and Arcella (12 taxa). Our analysis revealed that biomass of testate amoebae decreased significantly along the latitudinal gradient, while Shannon-Wiener indices and species richness presented an opposite trend (P < 0.05). The relationship of diversity and latitude is, we suspect, an artifact of the altitudinal distribution of our sites. Furthermore, biomass-based Shannon-Wiener index and species richness of testate amoebae were significantly unimodally related to trophic status (P < 0.05). This is the first large-scale study showing the effects of latitude and trophic status on diversity and distribution of testate amoebae in China. Therefore, our results provide valuable baseline data on testate amoebae and contribute to lake management and our understanding of the large-scale global patterns in microorganism diversity.

  13. On Latitudinal Dependence of Secular Variations Induced by a Dissipating Gravity Wave Packet

    NASA Astrophysics Data System (ADS)

    Huang, T.; Hickey, M. P.

    2003-12-01

    A time evolution of the response of the minor species and the OH airglow to a dissipating gravity wave packet can be simulated with a 2-dimensional, time-dependent, fully nonlinear OH model developed recently by Huang and Hickey [2002]. The wave packet was simulated using a spectral full-wave model described by Hickey et al. [2000] and Hickey and Walterscheid [2001], and then input to a 2-D chemistry model to study the secular variation of the minor species and OH nightglow. Previous studies of OH nightglow at high latitudes show strong secular variations of minor species and also of the OH brightness induced by wave transience and dissipation [Huang and Hickey, 2002]. We plan to employ the same models to study the secular variations of minor species and the OH nightglow at mid- and low-latitudes. The latitudinal dependence of the secular variations can thus be deduced. Satellite observations reveal much larger OH brightness at mid-latitudes compared to those at high and low latitudes. Therefore, we expect greater secular variations induced by the same wave packet at mid-latitudes.

  14. Charge state composition in coronal hole and CME related solar wind: Latitudinal variations observed by Ulysses and WIND

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Gloeckler, G.

    1997-01-01

    Iron charge states in recurrent coronal hole-associated solar wind flows are obtained in the ecliptic by WIND/SMS, while measurements of iron and silicon from the polar coronal holes are available from Ulysses/SWICS. Ulysses/SWICS also provides ion composition of coronal mass ejection (CME)-related solar wind. Both coronal hole-associated and CME-related solar wind charge charges show heliographic latitudinal variations.

  15. Magnetic neutrino resonant spin-flavor precession, 2. Helio-latitudinal asymmetry of solar neutrino fluxes and correlation coefficients.

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.

    2001-08-01

    On the bases of available Homestake experimental data (Cleveland et al., 1998) for more than two solar cycles (1970-1994) we determine for each solar neutrino run "n" effective helio-latitude Lef(n). Then we separate all Homestake runs on three equal helio -latitudinal zones: SOUTHERLY, EQUATORIAL, and NORTHERLY with average helio-latitudes -5.3, -0.3 and +5.3 degrees, correspondingly. For each zone and each run we found effective Zurich sunspot number Zef(n), total effective surface of sunspots STef(n), as well as effective surfaces of sunspots in different non-symmetrical helio-latitudinal belts. We separated also all runs on 3 equal groups of LOW, MEDIUM and HIGH solar activity with average sunspot numbers 25.0, 80.1 and 149.9. We found that the biggest decrease of solar neutrino flux with increasing of solar activity was observed in EQUATORIAL zone: from 3.6 SNU at LOW solar activity to 2.1 SNU at HIGH solar activity. The biggest SOUTH -NORTH asymmetry in solar neutrino fluxes was observed in group of runs at LOW solar activity: 2.9 SNU in SOUTHERLY zone and 2.1 SNU in NORTHERLY zone. The SOUTHNORTH asymmetry is found also in correlation coefficients between solar neutrino fluxes in the helio-latitudinal zones SOUTHERLY, EQUATORIAL, and NORTHERLY with solar activity in different non-symmetrical helio-latitudinal belts. Obtained results support the model of magnetic neutrino resonant spin-flavor precession.

  16. The latitudinal species richness gradient in New World woody angiosperms is consistent with the tropical conservatism hypothesis.

    PubMed

    Kerkhoff, Andrew J; Moriarty, Pamela E; Weiser, Michael D

    2014-06-01

    Plant diversity, like that of most other taxonomic groups, peaks in the tropics, where climatic conditions are warm and wet, and it declines toward the temperate and polar zones as conditions become colder and drier, with more seasonally variable temperatures. Climate and evolutionary history are often considered competing explanations for the latitudinal gradient, but they are linked by the evolutionarily conserved environmental adaptations of species and the history of Earth's climate system. The tropical conservatism hypothesis (TCH) invokes niche conservatism, climatic limitations on establishment and survival, and paleoclimatic history to explain the latitudinal diversity gradient. Here, we use latitudinal distributions for over 12,500 woody angiosperm species, a fossil-calibrated supertree, and null modeling to test predictions of the TCH. Regional assemblages in the northern and southern temperate zones are less phylogenetically diverse than expected based on their species richness, because temperate taxa are clustered into relatively few clades. Moreover, lineages with temperate affinities are generally younger and nested within older, more tropical lineages. As predicted by the TCH, the vast majority of temperate lineages have arisen since global cooling began at the Eocene-Oligocene boundary (34 Mya). By linking physiological tolerances of species to evolutionary and biogeographic processes, phylogenetic niche conservatism may provide a theoretical framework for a generalized explanation for Earth's predominant pattern of biodiversity.

  17. Evolution of avian clutch size along latitudinal gradients: do seasonality, nest predation or breeding season length matter?

    PubMed

    Griebeler, E M; Caprano, T; Böhning-Gaese, K

    2010-05-01

    Birds display a latitudinal gradient in clutch size with smaller clutches in the tropics and larger in the temperate region. Three factors have been proposed to affect this pattern: seasonality of resources (SR), nest predation and length of the breeding season (LBS). Here, we test the importance of these factors by modelling clutch size evolution within bird populations under different environmental settings. We use an individual-based ecogenetic simulation model that combines principles from population ecology and life history theory. Results suggest that increasing SR from the tropics to the poles by itself or in combination with a decreasing predation rate and LBS can generate the latitudinal gradient in clutch size. Annual fecundity increases and annual adult survival rate decreases from the tropics to the poles. We further show that the annual number of breeding attempts that (together with clutch size) determines total annual egg production is an important trait to understand latitudinal patterns in these life history characteristics. Field experiments that manipulate environmental factors have to record effects not only on clutch size, but also on annual number of breeding attempts. We use our model to predict the outcome of such experiments under different environmental settings. PMID:20210827

  18. Relative effects of time for speciation and tropical niche conservatism on the latitudinal diversity gradient of phyllostomid bats.

    PubMed

    Stevens, Richard D

    2011-08-22

    Determinants of contemporary patterns of diversity, particularly those spanning extensive latitudinal gradients, are some of the most intensely debated issues in ecology. Recently, focus has shifted from a contemporary environmental perspective to a historical one in an attempt to better understand the construction of latitudinal gradients. Although the vast majority of research on historical mechanisms has focused on tropical niche conservatism (TNC), other historical scenarios could produce similar latitudinal gradients. Herein, I formalize predictions to distinguish between two such historical processes--namely time for speciation (TFS) and TNC--and test relative support based on diversity gradients of New World bats. TFS and TNC are distinctly spatial and environmental mechanisms, respectively. Nonetheless, because of the way that environmental characteristics vary spatially, these two mechanisms are hard to distinguish. Evidence provided herein suggests that TNC has had a more important effect than TFS in determining diversity gradients of New World bats. Indeed, relative effects of different historical mechanisms, as well as relative effects of historical and contemporary environmental determinants, are probably context-dependent. Future research should move away from attempting to identify the mechanism with primacy and instead attempt to understand the particular contexts in which different mechanisms have greater influence on diversity gradients. PMID:21208951

  19. Mean Annual Precipitation Explains Spatiotemporal Patterns of Cenozoic Mammal Beta Diversity and Latitudinal Diversity Gradients in North America

    PubMed Central

    Fraser, Danielle; Hassall, Christopher; Gorelick, Root; Rybczynski, Natalia

    2014-01-01

    Spatial diversity patterns are thought to be driven by climate-mediated processes. However, temporal patterns of community composition remain poorly studied. We provide two complementary analyses of North American mammal diversity, using (i) a paleontological dataset (2077 localities with 2493 taxon occurrences) spanning 21 discrete subdivisions of the Cenozoic based on North American Land Mammal Ages (36 Ma – present), and (ii) climate space model predictions for 744 extant mammals under eight scenarios of future climate change. Spatial variation in fossil mammal community structure (β diversity) is highest at intermediate values of continental mean annual precipitation (MAP) estimated from paleosols (∼450 mm/year) and declines under both wetter and drier conditions, reflecting diversity patterns of modern mammals. Latitudinal gradients in community change (latitudinal turnover gradients, aka LTGs) increase in strength through the Cenozoic, but also show a cyclical pattern that is significantly explained by MAP. In general, LTGs are weakest when continental MAP is highest, similar to modern tropical ecosystems in which latitudinal diversity gradients are weak or undetectable. Projections under modeled climate change show no substantial change in β diversity or LTG strength for North American mammals. Our results suggest that similar climate-mediated mechanisms might drive spatial and temporal patterns of community composition in both fossil and extant mammals. We also provide empirical evidence that the ecological processes on which climate space models are based are insufficient for accurately forecasting long-term mammalian response to anthropogenic climate change and inclusion of historical parameters may be essential. PMID:25203658

  20. Mean annual precipitation explains spatiotemporal patterns of Cenozoic mammal beta diversity and latitudinal diversity gradients in North America.

    PubMed

    Fraser, Danielle; Hassall, Christopher; Gorelick, Root; Rybczynski, Natalia

    2014-01-01

    Spatial diversity patterns are thought to be driven by climate-mediated processes. However, temporal patterns of community composition remain poorly studied. We provide two complementary analyses of North American mammal diversity, using (i) a paleontological dataset (2077 localities with 2493 taxon occurrences) spanning 21 discrete subdivisions of the Cenozoic based on North American Land Mammal Ages (36 Ma--present), and (ii) climate space model predictions for 744 extant mammals under eight scenarios of future climate change. Spatial variation in fossil mammal community structure (β diversity) is highest at intermediate values of continental mean annual precipitation (MAP) estimated from paleosols (∼ 450 mm/year) and declines under both wetter and drier conditions, reflecting diversity patterns of modern mammals. Latitudinal gradients in community change (latitudinal turnover gradients, aka LTGs) increase in strength through the Cenozoic, but also show a cyclical pattern that is significantly explained by MAP. In general, LTGs are weakest when continental MAP is highest, similar to modern tropical ecosystems in which latitudinal diversity gradients are weak or undetectable. Projections under modeled climate change show no substantial change in β diversity or LTG strength for North American mammals. Our results suggest that similar climate-mediated mechanisms might drive spatial and temporal patterns of community composition in both fossil and extant mammals. We also provide empirical evidence that the ecological processes on which climate space models are based are insufficient for accurately forecasting long-term mammalian response to anthropogenic climate change and inclusion of historical parameters may be essential. PMID:25203658

  1. Mean annual precipitation explains spatiotemporal patterns of Cenozoic mammal beta diversity and latitudinal diversity gradients in North America.

    PubMed

    Fraser, Danielle; Hassall, Christopher; Gorelick, Root; Rybczynski, Natalia

    2014-01-01

    Spatial diversity patterns are thought to be driven by climate-mediated processes. However, temporal patterns of community composition remain poorly studied. We provide two complementary analyses of North American mammal diversity, using (i) a paleontological dataset (2077 localities with 2493 taxon occurrences) spanning 21 discrete subdivisions of the Cenozoic based on North American Land Mammal Ages (36 Ma--present), and (ii) climate space model predictions for 744 extant mammals under eight scenarios of future climate change. Spatial variation in fossil mammal community structure (β diversity) is highest at intermediate values of continental mean annual precipitation (MAP) estimated from paleosols (∼ 450 mm/year) and declines under both wetter and drier conditions, reflecting diversity patterns of modern mammals. Latitudinal gradients in community change (latitudinal turnover gradients, aka LTGs) increase in strength through the Cenozoic, but also show a cyclical pattern that is significantly explained by MAP. In general, LTGs are weakest when continental MAP is highest, similar to modern tropical ecosystems in which latitudinal diversity gradients are weak or undetectable. Projections under modeled climate change show no substantial change in β diversity or LTG strength for North American mammals. Our results suggest that similar climate-mediated mechanisms might drive spatial and temporal patterns of community composition in both fossil and extant mammals. We also provide empirical evidence that the ecological processes on which climate space models are based are insufficient for accurately forecasting long-term mammalian response to anthropogenic climate change and inclusion of historical parameters may be essential.

  2. Latitudinal variation in top-down and bottom-up control of a salt marsh food web.

    PubMed

    Marczak, L B; Ho, C K; Wieski, K; Vu, H; Denno, R F; Pennings, S C

    2011-02-01

    The shrub Iva frutescens, which occupies the terrestrial border of U.S. Atlantic Coast salt marshes, supports a food web that varies strongly across latitude. We tested whether latitudinal variation in plant quality (higher at high latitudes), consumption by omnivores (a crab, present only at low latitudes), consumption by mesopredators (ladybugs, present at all latitudes), or the life history stage of an herbivorous beetle could explain continental-scale field patterns of herbivore density. In a mesocosm experiment, crabs exerted strong top-down control on herbivorous beetles, ladybugs exerted strong top-down control on aphids, and both predators benefited plants through trophic cascades. Latitude of plant origin had no effect on consumers. Herbivorous beetle density was greater if mesocosms were stocked with beetle adults rather than larvae, and aphid densities were reduced in the "adult beetle" treatment. Treatment combinations representing high and low latitudes produced patterns of herbivore density similar to those in the field. We conclude that latitudinal variation in plant quality is less important than latitudinal variation in top consumers and competition in mediating food web structure. Climate may also play a strong role in structuring high-latitude salt marshes by limiting the number of herbivore generations per growing season and causing high overwintering mortality. PMID:21618906

  3. Relative effects of time for speciation and tropical niche conservatism on the latitudinal diversity gradient of phyllostomid bats.

    PubMed

    Stevens, Richard D

    2011-08-22

    Determinants of contemporary patterns of diversity, particularly those spanning extensive latitudinal gradients, are some of the most intensely debated issues in ecology. Recently, focus has shifted from a contemporary environmental perspective to a historical one in an attempt to better understand the construction of latitudinal gradients. Although the vast majority of research on historical mechanisms has focused on tropical niche conservatism (TNC), other historical scenarios could produce similar latitudinal gradients. Herein, I formalize predictions to distinguish between two such historical processes--namely time for speciation (TFS) and TNC--and test relative support based on diversity gradients of New World bats. TFS and TNC are distinctly spatial and environmental mechanisms, respectively. Nonetheless, because of the way that environmental characteristics vary spatially, these two mechanisms are hard to distinguish. Evidence provided herein suggests that TNC has had a more important effect than TFS in determining diversity gradients of New World bats. Indeed, relative effects of different historical mechanisms, as well as relative effects of historical and contemporary environmental determinants, are probably context-dependent. Future research should move away from attempting to identify the mechanism with primacy and instead attempt to understand the particular contexts in which different mechanisms have greater influence on diversity gradients.

  4. Latitudinal variation in top-down and bottom-up control of a salt marsh food web.

    PubMed

    Marczak, L B; Ho, C K; Wieski, K; Vu, H; Denno, R F; Pennings, S C

    2011-02-01

    The shrub Iva frutescens, which occupies the terrestrial border of U.S. Atlantic Coast salt marshes, supports a food web that varies strongly across latitude. We tested whether latitudinal variation in plant quality (higher at high latitudes), consumption by omnivores (a crab, present only at low latitudes), consumption by mesopredators (ladybugs, present at all latitudes), or the life history stage of an herbivorous beetle could explain continental-scale field patterns of herbivore density. In a mesocosm experiment, crabs exerted strong top-down control on herbivorous beetles, ladybugs exerted strong top-down control on aphids, and both predators benefited plants through trophic cascades. Latitude of plant origin had no effect on consumers. Herbivorous beetle density was greater if mesocosms were stocked with beetle adults rather than larvae, and aphid densities were reduced in the "adult beetle" treatment. Treatment combinations representing high and low latitudes produced patterns of herbivore density similar to those in the field. We conclude that latitudinal variation in plant quality is less important than latitudinal variation in top consumers and competition in mediating food web structure. Climate may also play a strong role in structuring high-latitude salt marshes by limiting the number of herbivore generations per growing season and causing high overwintering mortality.

  5. RNA/DNA ratios in American glass eels (Anguilla rostrata): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

    PubMed

    Laflamme, Simon; Côté, Caroline; Gagnaire, Pierre-Alexandre; Castonguay, Martin; Bernatchez, Louis

    2012-05-01

    During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution.

  6. RNA/DNA ratios in American glass eels (Anguilla rostrata): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

    PubMed

    Laflamme, Simon; Côté, Caroline; Gagnaire, Pierre-Alexandre; Castonguay, Martin; Bernatchez, Louis

    2012-05-01

    During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution. PMID:22837833

  7. RNA/DNA ratios in American glass eels (Anguilla rostrata): evidence for latitudinal variation in physiological status and constraints to oceanic migration?

    PubMed Central

    Laflamme, Simon; Côté, Caroline; Gagnaire, Pierre-Alexandre; Castonguay, Martin; Bernatchez, Louis

    2012-01-01

    During their larval leptocephalus phase, newly hatched American eels undergo an extensive oceanic migration from the Sargasso Sea toward coastal and freshwater habitats. Their subsequent metamorphosis into glass eel is accompanied by drastic morphological and physiological changes preceding settlement over a wide geographic range. The main objective of this study was to compare RNA/DNA ratios and condition factor among glass eels in order to test the null hypothesis of no difference in physiological status and metabolic activity of glass eels at the outcome of their oceanic migration. This was achieved by analyzing glass eel samples collected at the mouth of 17 tributaries covering a latitudinal gradient across the species distribution range from Florida to Gaspésie (Québec). Our main observations were (i) a latitudinal increase in mean total length; (ii) a latitudinal variation in mean RNA/DNA ratios, which was best explained by a quadratic model reaching its minimum in the central range of sampling locations; and (iii) a latitudinal variation in Fulton's condition factor, which was best explained by a quadratic model reaching its maximum in the central range of sampling locations. Below we discuss the possible links between latitudinal variation in glass eel physiological status and variable energetic and environmental constraints to oceanic migration as a function of latitudinal distribution. PMID:22837833

  8. Latitudinal variation in the recruitment dynamics of small pelagic fishes in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshiro

    2007-07-01

    The subarctic Oyashio Current flows south-westward and the subtropical Kuroshio Current flows north-eastward in the western North Pacific, converging in the waters off northern Japan to form the Kuroshio-Oyashio transition region. Some small pelagic fishes inhabit the subarctic or subtropical waters, and others seasonally migrate north and south across the major ocean fronts. Environmental conditions in the subarctic and transition waters are variable, whereas in the subtropical Kuroshio waters conditions are relatively stable. Latitudinally different environmental conditions may affect vital parameters and recruitment variability of small pelagic fishes inhabiting the various waters. Pacific saury Cololabis saira migrate seasonally from the Kuroshio to Oyashio waters and spawn in the transition waters in autumn and spring and in the Kuroshio waters in winter. During 1990-1999, the coefficients of variation (CVs) of daily growth rates (G) and instantaneous mortality coefficients (M) were large for larvae and juveniles spawned in the northern transition waters, but relatively small for those from the southern Kuroshio waters. The Pacific stock of chub mackerel Scomber japonicus spawns in the Kuroshio waters in spring and early summer and migrates to the subarctic Oyashio waters in summer for feeding, whereas the Tsushima Warm Current stock spawns in the East China Sea in spring and fish remain in the subtropical warm waters throughout their lifetime. The Pacific stock had CVs > 100% for the fish aged 0-5 during 1970-2002. In contrast, the Tsushima Warm Current stock had CVs of 34-40% during 1973-2002. Pacific herring Clupea pallasii, which inhabits subarctic waters, had CVs of 118-178% for the fish aged 3-8 y during 1910-1954. Japanese sardine Sardinops melanostictus, which spawn in the subtropical Kuroshio waters and migrate to the subarctic Oyashio waters in summer for feeding, had CVs > 120% for the fish aged 0-4 during 1976-2003. Contrasting with these subarctic

  9. Local and latitudinal variation in abundance: the mechanisms shaping the distribution of an ecosystem engineer.

    PubMed

    Crutsinger, Gregory M; Gonzalez, Angélica L; Crawford, Kerri M; Sanders, Nathan J

    2013-01-01

    Ecological processes that determine the abundance of species within ecological communities vary across space and time. These scale-dependent processes are especially important when they affect key members of a community, such as ecosystem engineers that create shelter and food resources for other species. Yet, few studies have examined the suite of processes that shape the abundance of ecosystem engineers. Here, we evaluated the relative influence of temporal variation, local processes, and latitude on the abundance of an engineering insect-a rosette-galling midge, Rhopalomyia solidaginis (Diptera: Cecidomyiidae). Over a period of 3-5 years, we studied the density and size of galls across a suite of local experiments that manipulated genetic variation, soil nutrient availability, and the removal of other insects from the host plant, Solidago altissima (tall goldenrod). We also surveyed gall density within a single growing season across a 2,300 km latitudinal transect of goldenrod populations in the eastern United States. At the local scale, we found that host-plant genotypic variation was the best predictor of rosette gall density and size within a single year. We found that the removal of other insect herbivores resulted in an increase in gall density and size. The amendment of soil nutrients for four years had no effect on gall density, but galls were smaller in carbon-added plots compared to control and nitrogen additions. Finally, we observed that gall density varied several fold across years. At the biogeographic scale, we observed that the density of rosette gallers peaked at mid-latitudes. Using meta-analytic approaches, we found that the effect size of time, followed by host-plant genetic variation and latitude were the best predictors of gall density. Taken together, our study provides a unique comparison of multiple factors across different spatial and temporal scales that govern engineering insect herbivore density.

  10. Changes in Microbial Nitrogen Dynamics with Soil Depth, and along a Latitudinal Transect in Western Siberia

    NASA Astrophysics Data System (ADS)

    Wild, B.; Schnecker, J.; Knoltsch, A.; Takriti, M.; Mooshammer, M.; Gentsch, N.; Mikutta, R.; Alves, R.; Gittel, A.; Lashchinskiy, N.; Richter, A.

    2015-12-01

    Plant productivity is often limited by low N availability, and this has been attributed to the slow breakdown of N-containing polymers such as proteins into amino acids that are small enough for uptake. Under such conditions, plants and microorganisms efficiently use the available N for growth, and the microbial release of excess N as ammonium (N mineralization), as well as the transformation of ammonium into nitrate (nitrification) is low. Nitrogen limitation is expected to increase towards high latitudes as conditions become less favourable for decomposition. On the other hand, within an ecosystem, microbial N limitation is expected to decrease with soil depth, following the decrease in the C/N ratio of organic matter. To test these hypotheses, we sampled organic topsoils, mineral topsoils and mineral subsoils from seven ecosystems along a latitudinal transect in Western Siberia, ranging from tundra (67°N) to boreal forest and further to steppe (54°N), and determined gross rates of protein depolymerization, N mineralization and nitrification using 15N pool dilution assays. We found that all rates decreased with depth following the decrease in organic matter content. Related to microbial biomass, however, only protein depolymerization decreased with depth, whereas N mineralization and nitrification significantly increased. This pattern was consistent across the seven ecosystems studied. Furthermore, we did not find indications for a decrease in microbial N limitation from arctic to temperate systems. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth. With microbial N immobilization constrained by low C availability, subsoils might harbour an easily available N pool that can contribute to plant N nutrition, but might also promote N losses from the ecosystem, e.g., by nitrate leaching, even in high latitude systems such as tundra and boreal

  11. Size-frequency distributions along a latitudinal gradient in Middle Permian fusulinoideans.

    PubMed

    Zhang, Yichun; Payne, Jonathan L

    2012-01-01

    Geographic gradients in body size within and among living species are commonly used to identify controls on the long-term evolution of organism size. However, the persistence of these gradients over evolutionary time remains largely unknown because ancient biogeographic variation in organism size is poorly documented. Middle Permian fusulinoidean foraminifera are ideal for investigating the temporal persistence of geographic gradients in organism size because they were diverse and abundant along a broad range of paleo-latitudes during this interval (~275-260 million years ago). In this study, we determined the sizes of Middle Permian fusulinoidean fossils from three different paleo-latitudinal zones in order to examine the relationship between the size of foraminifers and regional environment. We recovered the following results: keriothecal fusulinoideans are substantially larger than nonkeriothecal fusulinoideans; fusulinoideans from the equatorial zone are typically larger than those from the north and south transitional zones; neoschwagerinid specimens within a single species are generally larger in the equatorial zone than those in both transitional zones; and the nonkeriothecal fusulinoideans Staffellidae and Schubertellidae have smaller size in the north transitional zone. Fusulinoidean foraminifers differ from most other marine taxa in exhibiting larger sizes closer to the equator, contrary to Bergmann's rule. Meridional variation in seasonality, water temperature, nutrient availability, and carbonate saturation level are all likely to have favored or enabled larger sizes in equatorial regions. Temporal variation in atmospheric oxygen concentrations have been shown to account for temporal variation in fusulinoidean size during Carboniferous and Permian time, but oxygen availability appears unlikely to explain biogeographic variation in fusulinoidean sizes, because dissolved oxygen concentrations in seawater typically increase away from the equator due to

  12. Global Patterns in Dissimilatory Nitrate Reduction: A Latitudinal Gradient in Nitrogen Retention and Loss

    NASA Astrophysics Data System (ADS)

    Silver, W. L.; Thompson, A. W.; Bradbury, D.; Chapin, F. S.; Ewel, J. J.; Firestone, M. K.

    2003-12-01

    Increased nitrogen (N) deposition in humid environments has the potential to significantly increase nitrous oxide (N2O) emissions via nitrification and denitrification. This potential N loss may be significantly offset by N retention from dissimilatory nitrate reduction to ammonium (DNRA). In this study, we report on rates of dissimilatory nitrate reduction to N2O and ammonium along a latitudinal gradient from the tropics to the boreal forest. We conducted laboratory experiments with forest soils from Costa Rica, Puerto Rico, California, and Alaska to determine maximum potential rates of DNRA and N2O production. We also conducted field experiments in Costa Rica, Puerto Rico, and Alaska to estimate in situ rates. Maximum potential rates of DNRA ranged from 10 ug/g/d in fertilized poplar forests in Alaska to 0.3 ug/g/d in unfertilized polyculture plantations in Costa Rica. At all sites, rates of DNRA appeared to be nitrate limited. On average, temperate and boreal forests had greater potential rates of DNRA (5 +/- 1 ug/g/d) than tropical forests (3 +/- 1 ug/g/d). Nitrogen fertilization significantly increased rates of DNRA in Alaska. Rates of maximum potential N2O flux were generally lower than DNRA rates (0.16 to 4 ug/g/d). In field experiments, rates of DNRA were greatest in tropical rain forests in Puerto Rico, followed by wet forests in Costa Rica, and black spruce forests in Alaska. Although field DNRA rates were low in Alaska, they accounted for up to 13 % of gross mineralization and 24 % of gross nitrification. At all sites, rates of N2O flux via denitrification and nitrification were significantly lower than N retention via DNRA. Our results suggest that this previously unmeasured N cycling pathway effectively competes with processes resulting in N-trace gas loss from a range of forested ecosystems.

  13. Observed latitudinal variations in erosion as a function of glacier dynamics.

    PubMed

    Koppes, Michéle; Hallet, Bernard; Rignot, Eric; Mouginot, Jérémie; Wellner, Julia Smith; Boldt, Katherine

    2015-10-01

    Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds.

  14. Size-Frequency Distributions along a Latitudinal Gradient in Middle Permian Fusulinoideans

    PubMed Central

    Zhang, Yichun; Payne, Jonathan L.

    2012-01-01

    Geographic gradients in body size within and among living species are commonly used to identify controls on the long-term evolution of organism size. However, the persistence of these gradients over evolutionary time remains largely unknown because ancient biogeographic variation in organism size is poorly documented. Middle Permian fusulinoidean foraminifera are ideal for investigating the temporal persistence of geographic gradients in organism size because they were diverse and abundant along a broad range of paleo-latitudes during this interval (∼275–260 million years ago). In this study, we determined the sizes of Middle Permian fusulinoidean fossils from three different paleo-latitudinal zones in order to examine the relationship between the size of foraminifers and regional environment. We recovered the following results: keriothecal fusulinoideans are substantially larger than nonkeriothecal fusulinoideans; fusulinoideans from the equatorial zone are typically larger than those from the north and south transitional zones; neoschwagerinid specimens within a single species are generally larger in the equatorial zone than those in both transitional zones; and the nonkeriothecal fusulinoideans Staffellidae and Schubertellidae have smaller size in the north transitional zone. Fusulinoidean foraminifers differ from most other marine taxa in exhibiting larger sizes closer to the equator, contrary to Bergmann's rule. Meridional variation in seasonality, water temperature, nutrient availability, and carbonate saturation level are all likely to have favored or enabled larger sizes in equatorial regions. Temporal variation in atmospheric oxygen concentrations have been shown to account for temporal variation in fusulinoidean size during Carboniferous and Permian time, but oxygen availability appears unlikely to explain biogeographic variation in fusulinoidean sizes, because dissolved oxygen concentrations in seawater typically increase away from the equator due to

  15. Volatile organic compounds emitted from silver birch of different provenances across a latitudinal gradient in Finland.

    PubMed

    Maja, Mengistu M; Kasurinen, Anne; Holopainen, Toini; Kontunen-Soppela, Sari; Oksanen, Elina; Holopainen, Jarmo K

    2015-09-01

    Climate warming is having an impact on distribution, acclimation and defence capability of plants. We compared the emission rate and composition of volatile organic compounds (VOCs) from silver birch (Betula pendula (Roth)) provenances along a latitudinal gradient in a common garden experiment over the years 2012 and 2013. Micropropagated silver birch saplings from three provenances were acquired along a gradient of 7° latitude and planted at central (Joensuu 62°N) and northern (Kolari 67°N) sites. We collected VOCs emitted by shoots and assessed levels of herbivore damage of three genotypes of each provenance on three occasions at the central site and four occasions at the northern site. In 2012, trees of all provenances growing at the central site had higher total VOC emission rates than the same provenances growing at the northern site; in 2013 the reverse was true, thus indicating a variable effect of latitude. Trees of the southern provenance had lower VOC emission rates than trees of the central and northern provenances during both sampling years. However, northward or southward translocation itself had no significant effect on the total VOC emission rates, and no clear effect on insect herbivore damage. When VOC blend composition was studied, trees of all provenances usually emitted more green leaf volatiles at the northern site and more sesquiterpenes at the central site. The monoterpene composition of emissions from trees of the central provenance was distinct from that of the other provenances. In summary, provenance translocation did not have a clear effect in the short-term on VOC emissions and herbivory was not usually intense at the lower latitude. Our data did not support the hypothesis that trees growing at lower latitudes would experience more intense herbivory, and therefore allocate resources to chemical defence in the form of inducible VOC emissions. PMID:26093370

  16. Latitudinal variation in carbon storage can help predict changes in swamps affected by global warming

    USGS Publications Warehouse

    Middleton, Beth A.; McKee, Karen

    2004-01-01

    Plants may offer our best hope of removing greenhouse gases (gases that contribute to global warming) emitted to the atmosphere from the burning of fossil fuels. At the same time, global warming could change environments so that natural plant communities will either need to shift into cooler climate zones, or become extirpated (Prasad and Iverson, 1999; Crumpacker and others, 2001; Davis and Shaw, 2001). It is impossible to know the future, but studies combining field observation of production and modeling can help us make predictions about what may happen to these wetland communities in the future. Widespread wetland types such as baldcypress (Taxodium distichum) swamps in the southeastern portion of the United States could be especially good at carbon sequestration (amount of CO2 stored by forests) from the atmosphere. They have high levels of production and sometimes store undecomposed dead plant material in wet conditions with low oxygen, thus keeping gases stored that would otherwise be released into the atmosphere (fig. 1). To study the ability of baldcypress swamps to store carbon, our project has taken two approaches. The first analysis looked at published data to develop an idea (hypothesis) of how production levels change across a temperature gradient in the baldcypress region (published data study). The second study tested this idea by comparing production levels across a latitudinal range by using swamps in similar field conditions (ongoing carbon storage study). These studies will help us make predictions about the future ability of baldcypress swamps to store carbon in soil and plant biomass, as well as the ability of these forests to shift northward with global warming.

  17. Ontogenetic changes in genetic variances of age-dependent plasticity along a latitudinal gradient.

    PubMed

    Nilsson-Örtman, V; Rogell, B; Stoks, R; Johansson, F

    2015-10-01

    The expression of phenotypic plasticity may differ among life stages of the same organism. Age-dependent plasticity can be important for adaptation to heterogeneous environments, but this has only recently been recognized. Whether age-dependent plasticity is a common outcome of local adaptation and whether populations harbor genetic variation in this respect remains largely unknown. To answer these questions, we estimated levels of additive genetic variation in age-dependent plasticity in six species of damselflies sampled from 18 populations along a latitudinal gradient spanning 3600 km. We reared full sib larvae at three temperatures and estimated genetic variances in the height and slope of thermal reaction norms of body size at three points in time during ontogeny using random regression. Our data show that most populations harbor genetic variation in growth rate (reaction norm height) in all ontogenetic stages, but only some populations and ontogenetic stages were found to harbor genetic variation in thermal plasticity (reaction norm slope). Genetic variances in reaction norm height differed among species, while genetic variances in reaction norm slope differed among populations. The slope of the ontogenetic trend in genetic variances of both reaction norm height and slope increased with latitude. We propose that differences in genetic variances reflect temporal and spatial variation in the strength and direction of natural selection on growth trajectories and age-dependent plasticity. Selection on age-dependent plasticity may depend on the interaction between temperature seasonality and time constraints associated with variation in life history traits such as generation length. PMID:25649500

  18. Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia

    NASA Astrophysics Data System (ADS)

    Wild, Birgit; Schnecker, Jörg; Knoltsch, Anna; Takriti, Mounir; Mooshammer, Maria; Gentsch, Norman; Mikutta, Robert; Alves, Ricardo J. Eloy; Gittel, Antje; Lashchinskiy, Nikolay; Richter, Andreas

    2015-05-01

    Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using 15N pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67°N) to steppe (54°N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest.

  19. Observed latitudinal variations in erosion as a function of glacier dynamics.

    PubMed

    Koppes, Michéle; Hallet, Bernard; Rignot, Eric; Mouginot, Jérémie; Wellner, Julia Smith; Boldt, Katherine

    2015-10-01

    Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds. PMID:26432248

  20. Diel Vertical Migration in Deep Sea Plankton Is Finely Tuned to Latitudinal and Seasonal Day Length

    PubMed Central

    van Haren, Hans; Compton, Tanya J.

    2013-01-01

    Diel vertical migration (DVM) is a ubiquitous phenomenon in marine and freshwater plankton communities. Most commonly, plankton migrate to surface waters at dusk and return to deeper waters at dawn. Up until recently, it was thought that DVM was triggered by a relative change in visible light intensity. However, evidence has shown that DVM also occurs in the deep sea where no direct and background sunlight penetrates. To identify whether such DVM is associated with latitudinal and seasonal day light variation, one and a half years of recorded acoustic data, a measure of zooplankton abundance and movement, were examined. Acoustic Doppler current profilers, moored at eight different sub-tropical latitudes in the North-Atlantic Ocean, measured in the vertical range of 500–1600 m. DVM was observed to follow day length variation with a change in season and latitude at all depths. DVM followed the rhythm of local sunrise and sunset precisely between 500 and 650 m. It continued below 650 m, where the deepest penetrable irradiance level are <10−7 times their near-surface values, but plankton shortened their time at depth by up to about 63% at 1600 m. This suggests light was no longer a cue for DVM. This trend stayed consistent both across latitudes and between the different seasons. It is hypothesized that another mechanism, rather than light, viz. a precise biochemical clock could maintain the solar diurnal and seasonal rhythms in deep sea plankton motions. In accordance with this hypothesis, the deepest plankton were consistently the first to migrate upwards. PMID:23717613

  1. Reconstruction of Helio-Latitudinal Structure of the Solar Wind Proton Speed and Density

    NASA Astrophysics Data System (ADS)

    Sokół, Justyna M.; Swaczyna, Paweł; Bzowski, Maciej; Tokumaru, Munetoshi

    2015-09-01

    The modeling of the heliosphere requires continuous three-dimensional solar wind data. The in-situ out-of-ecliptic measurements are very rare, so that other methods of solar wind detection are needed. We use the remote-sensing data of the solar wind speed from observations of interplanetary scintillation (IPS) to reconstruct spatial and temporal structures of the solar wind proton speed from 1985 to 2013. We developed a method of filling the data gaps in the IPS observations to obtain continuous and homogeneous solar wind speed records. We also present a method to retrieve the solar wind density from the solar wind speed, utilizing the invariance of the solar wind dynamic pressure and energy flux with latitude. To construct the synoptic maps of the solar wind speed we use the decomposition into spherical harmonics of each of the Carrington rotation map. To fill the gaps in time we apply the singular spectrum analysis to the time series of the coefficients of spherical harmonics. We obtained helio-latitudinal profiles of the solar wind proton speed and density over almost three recent solar cycles. The accuracy in the reconstruction is, due to computational limitations, about 20 %. The proposed methods allow us to improve the spatial and temporal resolution of the model of the solar wind parameters presented in our previous paper (Sokół et al., Solar Phys. 285, 167, 2013) and give a better insight into the time variations of the solar wind structure. Additionally, the solar wind density is reconstructed more accurately and it fits better to the in-situ measurements from Ulysses.

  2. Dormancy release and chilling requirement of buds of latitudinal ecotypes of Betula pendula and B. pubescens.

    PubMed

    Myking, T; Heide, O M

    1995-11-01

    Bud burst and dormancy release of latitudinal ecotypes of Betula pendula Roth and B. pubescens Ehrh. from Denmark ( approximately 56 degrees N), mid-Norway ( approximately 64 degrees N) and northern Norway ( approximately 69 degrees N) were studied in controlled environments. Dormant seedlings were chilled at 0, 5 or 10 degrees C from October 4 onward and then, at monthly intervals from mid-November to February, batches of seedlings were held at 15 degrees C in an 8-h (SD) or 24-h (LD) photoperiod to permit flushing. A decline in days to bud burst occurred with increasing chilling time in all ecotypes. In November, after 44 chilling days, time to bud burst was least in plants chilled at 0 and 5 degrees C. The difference diminished with increasing chilling time, and in February, after 136 chilling days, bud burst was earliest in plants chilled at 10 degrees C. Long photoperiods during flushing significantly reduced thermal time after short chilling periods (44 and 74 days), but had no effect when the chilling requirement was fully met after 105 or more chilling days. No significant difference in these responses was found between the two species. In both species, chilling requirement decreased significantly with increasing latitude of origin. Bud burst was normal in seedlings overwintered at 12 degrees C, but was erratic and delayed in seedlings overwintered at 15 and especially at 21 degrees C, indicating that the critical overwintering temperature is between 12 and 15 degrees C. We conclude that there is little risk of a chilling deficit in birch under Scandinavian winter conditions even with a climatic warming of 7-8 degrees C. The likely effects of a climatic warming include earlier bud burst, a longer growing season and increased risk of spring frost injury, especially in high latitude ecotypes. PMID:14965987

  3. Local and latitudinal variation in abundance: the mechanisms shaping the distribution of an ecosystem engineer

    PubMed Central

    Gonzalez, Angélica L.; Crawford, Kerri M.; Sanders, Nathan J.

    2013-01-01

    Ecological processes that determine the abundance of species within ecological communities vary across space and time. These scale-dependent processes are especially important when they affect key members of a community, such as ecosystem engineers that create shelter and food resources for other species. Yet, few studies have examined the suite of processes that shape the abundance of ecosystem engineers. Here, we evaluated the relative influence of temporal variation, local processes, and latitude on the abundance of an engineering insect—a rosette-galling midge, Rhopalomyia solidaginis (Diptera: Cecidomyiidae). Over a period of 3–5 years, we studied the density and size of galls across a suite of local experiments that manipulated genetic variation, soil nutrient availability, and the removal of other insects from the host plant, Solidago altissima (tall goldenrod). We also surveyed gall density within a single growing season across a 2,300 km latitudinal transect of goldenrod populations in the eastern United States. At the local scale, we found that host-plant genotypic variation was the best predictor of rosette gall density and size within a single year. We found that the removal of other insect herbivores resulted in an increase in gall density and size. The amendment of soil nutrients for four years had no effect on gall density, but galls were smaller in carbon-added plots compared to control and nitrogen additions. Finally, we observed that gall density varied several fold across years. At the biogeographic scale, we observed that the density of rosette gallers peaked at mid-latitudes. Using meta-analytic approaches, we found that the effect size of time, followed by host-plant genetic variation and latitude were the best predictors of gall density. Taken together, our study provides a unique comparison of multiple factors across different spatial and temporal scales that govern engineering insect herbivore density. PMID:23862102

  4. Latitudinal Diversity Gradients in New World Bats: Are They a Consequence of Niche Conservatism?

    PubMed Central

    Ramos Pereira, Maria João; Palmeirim, Jorge M.

    2013-01-01

    The increase in species diversity from the Poles to the Equator is a major biogeographic pattern, but the mechanisms underlying it remain obscure. Our aim is to contribute to their clarification by describing the latitudinal gradients in species richness and in evolutionary age of species of New World bats, and testing if those patterns may be explained by the niche conservatism hypothesis. Maps of species ranges were used to estimate species richness in a 100 x 100 km grid. Root distances in a molecular phylogeny were used as a proxy for the age of species, and the mean root distance of the species in each cell of the grid was estimated. Generalised additive models were used to relate latitude with both species richness and mean root distance. This was done for each of the three most specious bat families and for all Chiroptera combined. Species richness increases towards the Equator in the whole of the Chiroptera and in the Phyllostomidae and Molossidae, families that radiated in the tropics, but the opposite trend is observed in the Vespertilionidae, which has a presumed temperate origin. In the whole of the Chiroptera, and in the three main families, there were more basal species in the higher latitudes, and more derived species in tropical areas. In general, our results were not consistent with the predictions of niche conservatism. Tropical niche conservatism seems to keep bat clades of tropical origin from colonizing temperate zones, as they lack adaptations to survive cold winters, such as the capacity to hibernate. However, the lower diversity of Vespertilionidae in the Neotropics is better explained by competition with a diverse pre-existing community of bats than by niche conservatism. PMID:23935963

  5. Observed latitudinal variations in erosion as a function of glacier dynamics

    NASA Astrophysics Data System (ADS)

    Koppes, Michéle; Hallet, Bernard; Rignot, Eric; Mouginot, Jérémie; Wellner, Julia Smith; Boldt, Katherine

    2015-10-01

    Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds.

  6. Latitudinal distribution of O2on ganymede: Observations with the hubble space telescope

    USGS Publications Warehouse

    Calvin, W.M.; Spencer, J.R.

    1997-01-01

    To help constrain the spatial variation of oxygen on Jupiter's satellite Ganymede, and hence have more clues to its mode of production and stability, we have obtained spectral data from the Faint Object Spectrograph (FOS) for a single pole-to-pole latitudinal strip, along with several Wide Field Planetary Camera 2 (WFPC2) images in three narrow band visible filters. All observations were made of the trailing hemisphere. In the FOS data we observe both visible absorptions at 0.577 and 0.627 ??m, associated with dense-phase oxygen (compressed gases, liquids, or solids). Filter options limited the WFPC2 observations to wavelengths near the weaker oxygen absorption at 0.627 ??m. These observations suggest that the dense-phase or dimer oxygen form is predominantly found in equatorial and mid-latitudes. The spectroscopic absorption feature appears in both bright and dark terrains but may be somewhat weaker in dark regions, which is consistent with the smaller mean photon path length in the surface in darker areas. Therefore, the abundance of oxygen appears more dependent on latitude and longitude constraints than surface albedo. At the highest latitudes, where the ratio spectra have a strong upturn toward the blue, the oxygen bands do not appear. This relation suggests that dimer oxygen and ozone (as seen by Galileo) have opposite trends with latitude. Possible causes include competition or variation in the preferred stable form, which depends on temperature, solar ultraviolet flux, and/or surface age; enhancement of O3at the poles due to plasma interactions; or viewing geometry effects that reduce the oxygen features at the poles when observed from Earth. The predominantly equatorial feature supports the production of O2through plasma bombardment and favors defect trapping over physical adsorption of the dimer molecules in the surface. We briefly consider the implications of Ganymede's magnetosphere for our understanding of O2and O3distribution on Ganymede. ?? 1997

  7. Diel vertical migration in deep sea plankton is finely tuned to latitudinal and seasonal day length.

    PubMed

    van Haren, Hans; Compton, Tanya J

    2013-01-01

    Diel vertical migration (DVM) is a ubiquitous phenomenon in marine and freshwater plankton communities. Most commonly, plankton migrate to surface waters at dusk and return to deeper waters at dawn. Up until recently, it was thought that DVM was triggered by a relative change in visible light intensity. However, evidence has shown that DVM also occurs in the deep sea where no direct and background sunlight penetrates. To identify whether such DVM is associated with latitudinal and seasonal day light variation, one and a half years of recorded acoustic data, a measure of zooplankton abundance and movement, were examined. Acoustic Doppler current profilers, moored at eight different sub-tropical latitudes in the North-Atlantic Ocean, measured in the vertical range of 500-1600 m. DVM was observed to follow day length variation with a change in season and latitude at all depths. DVM followed the rhythm of local sunrise and sunset precisely between 500 and 650 m. It continued below 650 m, where the deepest penetrable irradiance level are <10⁻⁷ times their near-surface values, but plankton shortened their time at depth by up to about 63% at 1600 m. This suggests light was no longer a cue for DVM. This trend stayed consistent both across latitudes and between the different seasons. It is hypothesized that another mechanism, rather than light, viz. a precise biochemical clock could maintain the solar diurnal and seasonal rhythms in deep sea plankton motions. In accordance with this hypothesis, the deepest plankton were consistently the first to migrate upwards.

  8. Life history attributes of fishes along the latitudinal gradient of the Missouri River

    USGS Publications Warehouse

    Braaten, P.J.; Guy, C.S.

    2002-01-01

    Populations of two short-lived species (emerald shiner Notropis atherinoides and sicklefin chub Macrhybopsis meeki) and three long-lived species (freshwater drum Aplodinotus grunniens, river carpsucker Carpiodes carpio, and sauger Stizostedion canadense) were studied in the Missouri River to examine spatial variations in life history characteristics across a latitudinal and thermal gradient (38??47???N to 48??03???N). The life history characteristics included longevity (maximum age), the rate at which asymptotic length was approached (K from the von Bertalanffy growth equation), the mean back-calculated length at age, and growth rates during the first year of life (mm/degree-day and mm/d). The mean water temperature and number of days in the growing season averaged 1.3 times greater in the southern than in the northern latitudes, while degree-days averaged twice as great. The longevity of all species except freshwater drum increased significantly from south to north, but the relationships between maximum age and latitude were curvilinear for short-lived species and linear for long-lived species. The von Bertalanffy growth coefficient for river carpsuckers and saugers increased from north to south, as indicated by significant negative relationships between K and latitude. Mean back-calculated length at age was negatively related to latitude for freshwater drums (???age 4) and saugers (ages 1-5) but positively related to latitude for river carpsuckers (???age 6). One of the growth rates examined (mm/degree-day) increased significantly from low to high latitudes for emerald shiners, sicklefin chubs, freshwater drums, and river carpsuckers during the first growing season. The other growth rate (mm/d) increased significantly from low to high latitudes for emerald shiners but was inversely related to latitude for saugers. These results suggest that the thermal regime related to latitude influences the life history characteristics of fishes in the Missouri River.

  9. The power of plant phenology monitoring networks - latitudinal patterns in phenology variance

    NASA Astrophysics Data System (ADS)

    Bolmgren, K.; Josefsson, J.; Langvall, O.

    2011-12-01

    Large inter-annual variation in phenology monitoring data makes it a challenge to draw quantitative conclusions about phenological change as well as differences between species, phases and different places. We looked for geographical patterns in the standard deviation of phenology data [SD(onset)]. The data used was a sub-sample of a Swedish, nation-wide plant phenology database, covering a latitudinal range of 55-67°N, collected by an observation network between 1873-1917. Forty-four different species (perennial herbs, sub-shrubs, shrubs and trees) and four different phases (spring leaf-out, flowering, fruit ripening and autumn leaf coloration) were included, which thus covered the whole growing season (approx. Julian day 100-300). In addition to the commonly found decrease of the SD(onset) over the season, this data revealed a hump for late-summer flowering and fruit ripening species. SD(onset) was similar (and lowest) for spring leaf-out and autumn leaf coloration. The power analyses suggested that for about half of the species, including all but two spring leaf-out species, 9-11 years of present-day observations are needed to statistically infer a 7-day change in onset dates. In about a third of the species there was a correlation between SD(onset), and thus power, and latitude. The inter-specific comparison revealed a hump-shaped pattern, such that for early and late season phases SD(onset) decreased with latitude, while SD(onset) increased with latitude for mid-season phases.

  10. Local and latitudinal variation in abundance: the mechanisms shaping the distribution of an ecosystem engineer.

    PubMed

    Crutsinger, Gregory M; Gonzalez, Angélica L; Crawford, Kerri M; Sanders, Nathan J

    2013-01-01

    Ecological processes that determine the abundance of species within ecological communities vary across space and time. These scale-dependent processes are especially important when they affect key members of a community, such as ecosystem engineers that create shelter and food resources for other species. Yet, few studies have examined the suite of processes that shape the abundance of ecosystem engineers. Here, we evaluated the relative influence of temporal variation, local processes, and latitude on the abundance of an engineering insect-a rosette-galling midge, Rhopalomyia solidaginis (Diptera: Cecidomyiidae). Over a period of 3-5 years, we studied the density and size of galls across a suite of local experiments that manipulated genetic variation, soil nutrient availability, and the removal of other insects from the host plant, Solidago altissima (tall goldenrod). We also surveyed gall density within a single growing season across a 2,300 km latitudinal transect of goldenrod populations in the eastern United States. At the local scale, we found that host-plant genotypic variation was the best predictor of rosette gall density and size within a single year. We found that the removal of other insect herbivores resulted in an increase in gall density and size. The amendment of soil nutrients for four years had no effect on gall density, but galls were smaller in carbon-added plots compared to control and nitrogen additions. Finally, we observed that gall density varied several fold across years. At the biogeographic scale, we observed that the density of rosette gallers peaked at mid-latitudes. Using meta-analytic approaches, we found that the effect size of time, followed by host-plant genetic variation and latitude were the best predictors of gall density. Taken together, our study provides a unique comparison of multiple factors across different spatial and temporal scales that govern engineering insect herbivore density. PMID:23862102

  11. Volatile organic compounds emitted from silver birch of different provenances across a latitudinal gradient in Finland.

    PubMed

    Maja, Mengistu M; Kasurinen, Anne; Holopainen, Toini; Kontunen-Soppela, Sari; Oksanen, Elina; Holopainen, Jarmo K

    2015-09-01

    Climate warming is having an impact on distribution, acclimation and defence capability of plants. We compared the emission rate and composition of volatile organic compounds (VOCs) from silver birch (Betula pendula (Roth)) provenances along a latitudinal gradient in a common garden experiment over the years 2012 and 2013. Micropropagated silver birch saplings from three provenances were acquired along a gradient of 7° latitude and planted at central (Joensuu 62°N) and northern (Kolari 67°N) sites. We collected VOCs emitted by shoots and assessed levels of herbivore damage of three genotypes of each provenance on three occasions at the central site and four occasions at the northern site. In 2012, trees of all provenances growing at the central site had higher total VOC emission rates than the same provenances growing at the northern site; in 2013 the reverse was true, thus indicating a variable effect of latitude. Trees of the southern provenance had lower VOC emission rates than trees of the central and northern provenances during both sampling years. However, northward or southward translocation itself had no significant effect on the total VOC emission rates, and no clear effect on insect herbivore damage. When VOC blend composition was studied, trees of all provenances usually emitted more green leaf volatiles at the northern site and more sesquiterpenes at the central site. The monoterpene composition of emissions from trees of the central provenance was distinct from that of the other provenances. In summary, provenance translocation did not have a clear effect in the short-term on VOC emissions and herbivory was not usually intense at the lower latitude. Our data did not support the hypothesis that trees growing at lower latitudes would experience more intense herbivory, and therefore allocate resources to chemical defence in the form of inducible VOC emissions.

  12. Latitudinal Variation in Carbon Storage Can Help Predict Changes in Swamps Affected by Global Warming

    USGS Publications Warehouse

    Middleton, Beth A.; McKee, Karen

    2004-01-01

    Plants may offer our best hope of removing greenhouse gases (gases that contribute to global warming) emitted to the atmosphere from the burning of fossil fuels. At the same time, global warming could change environments so that natural plant communities will either need to shift into cooler climate zones, or become extirpated (Prasad and Iverson, 1999; Crumpacker and others, 2001; Davis and Shaw, 2001). It is impossible to know the future, but studies combining field observation of production and modeling can help us make predictions about what may happen to these wetland communities in the future. Widespread wetland types such as baldcypress (Taxodium distichum) swamps in the southeastern portion of the United States could be especially good at carbon sequestration (amount of CO2 stored by forests) from the atmosphere. They have high levels of production and sometimes store undecomposed dead plant material in wet conditions with low oxygen, thus keeping gases stored that would otherwise be released into the atmosphere (fig. 1). To study the ability of baldcypress swamps to store carbon, our project has taken two approaches. The first analysis looked at published data to develop an idea (hypothesis) of how production levels change across a temperature gradient in the baldcypress region (published data study). The second study tested this idea by comparing production levels across a latitudinal range by using swamps in similar field conditions (ongoing carbon storage study). These studies will help us make predictions about the future ability of baldcypress swamps to store carbon in soil and plant biomass, as well as the ability of these forests to shift northward with global warming.

  13. Moss stable isotopes (carbon-13, oxygen-18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula.

    PubMed

    Royles, Jessica; Amesbury, Matthew J; Roland, Thomas P; Jones, Glyn D; Convey, Peter; Griffiths, Howard; Hodgson, Dominic A; Charman, Dan J

    2016-07-01

    The stable isotope compositions of moss tissue water (δ(2)H and δ(18)O) and cellulose (δ(13)C and δ(18)O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ(18)O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ(13)C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with Corythion dubium and Microcorycia radiata types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate.

  14. Effect of latitudinal gradient and impact of logging on genetic diversity of Cedrela lilloi along the Argentine Yungas Rainforest

    PubMed Central

    Inza, Maria V; Zelener, Noga; Fornes, Luis; Gallo, Leonardo A

    2012-01-01

    Cedrela lilloi C. DC. (cedro coya, Meliaceae), an important south American timber species, has been historically overexploited through selective logging in Argentine Yungas Rainforest. Management and conservation programs of the species require knowledge of its genetic variation patterns; however, no information is available. Molecular genetic variability of the species was characterized to identify high-priority populations for conservation and domestication purposes. Fourteen native populations (160 individuals) along a latitudinal gradient and with different logging's intensities were assessed by 293 polymorphic AFLP (amplified fragment length polymorphism) markers. Genetic diversity was low (Ht = 0.135), according to marginal location of the species in Argentina. Most of the diversity was distributed within populations (87%). Northern populations showed significant higher genetic diversity (R2= 0.69) that agreed with latitudinal pattern of distribution of taxonomic diversity in the Yungas. Three clusters were identified by Bayesian analysis in correspondence with northern, central, and southern Yungas. An analysis of molecular variance (AMOVA) revealed significant genetic differences among latitudinal clusters even when logging (ΦRT = 0.07) and unlogging populations (ΦPT = 0.10) were separately analyzed. Loss of genetic diversity with increasing logging intensity was observed between neighboring populations with different disturbance (ΦPT = 0.03–0.10). Bottlenecks in disturbed populations are suggested as the main cause. Our results emphasize both: the necessity of maintaining the genetic diversity in protected areas that appear as possible long-term refuges of the species; and to rescue for the national system of protected areas some high genetic diversity populations that are on private fields. PMID:23170208

  15. A time series of evolution in action: a latitudinal cline in wing size in South American Drosophila subobscura.

    PubMed

    Gilchrist, George W; Huey, Raymond B; Balanyà, Joan; Pascual, Marta; Serra, Luis

    2004-04-01

    Drosophila subobscura is geographically widespread in the Old World. Around the late 1970s, it was accidentally introduced into both South and North America, where it spread rapidly over broad latitudinal ranges. This invading species offers opportunities to study the speed and predictability of trait evolution on a geographic scale. One trait of special interest is body size, which shows a strong and positive latitudinal cline in many Drosophila species, including Old World D. subobscura. Surveys made about a decade after the invasion found no evidence of a size cline in either North or South America. However, a survey made in North America about two decades after the invasion showed that a conspicuous size cline had evolved and (for females) was coincident with that for Old World flies. We have now conducted parallel studies on 10 populations (13 degrees of latitude) of flies, collected in Chile in spring 1999. After rearing flies in the laboratory for several generations, we measured wing sizes and compared geographic patterns (versus latitude or temperature) for flies on all three continents. South American females have now evolved a significant latitudinal size cline that is similar in slope to that of Old World and of North American flies. Rates of evolution (haldanes) for females are among the highest ever measured for quantitative traits. In contrast, the size cline is positive but not significant for South or North American males. At any given latitude, South American flies of both sexes are relatively large; this in part reflects the relatively cool climate of coastal Chile. Interestingly, the sections of the wing that generate the size cline for females differ among all three continents. Thus, although the evolution of overall wing size is predictable on a geographic scale (at least for females), the evolution of size of particular wing components is decidedly not.

  16. A Fluorescence Lecture Demonstration.

    ERIC Educational Resources Information Center

    Bozzelli, Joseph W.; Kemp, Marwin

    1982-01-01

    Describes fluorescence demonstrations related to several aspects of molecular theory and quantitized energy levels. Demonstrations use fluorescent chemical solutions having luminescence properties spanning the visible spectrum. Also describes a demonstration of spontaneous combustion of familiar substances in chlorine. (JN)

  17. Annual and latitudinal variations of surface fluxes and meteorological variables at Arctic terrestrial sites

    NASA Astrophysics Data System (ADS)

    Grachev, Andrey; Uttal, Taneil; Persson, Ola; Konopleva-Akish, Elena; Crepinsek, Sara; Cox, Christopher; Fairall, Christopher; Makshtas, Alexander; Repina, Irina

    2016-04-01

    This study analyzes and discusses seasonal and latitudinal variations of surface fluxes (turbulent, radiative, and soil ground heat) and other ancillary surface/snow/permafrost data based on in-situ measurements made at two long-term research observatories near the coast of the Arctic Ocean located in Canada and Russia. The hourly averaged data collected at Eureka (Canadian territory of Nunavut) and Tiksi (East Siberia) located at two quite different latitudes (80.0 N and 71.6 N respectively) are analyzed in details to describe the seasons in the Arctic. Although Eureka and Tiksi are located at the different continents and at the different latitudes, the annual course of the surface meteorology and the surface fluxes are qualitatively very similar. The air and soil temperatures display the familiar strong seasonal trend with maximum of measured temperatures in mid-summer and minimum during winter. According to our data, variation in incoming short-wave solar radiation led the seasonal pattern of the air and soil temperatures, and the turbulent fluxes. During the dark Polar nights, air and ground temperatures are strongly controlled by long-wave radiation associated generally with cloud cover. Due to the fact that in average the higher latitudes receive less solar radiation than lower latitudes, a length of the convective atmospheric boundary layer (warm season) is shorter and middle-summer amplitude of the turbulent fluxes is generally less in Eureka than in Tiksi. However, since solar elevation angle at local midnight in the middle of Arctic summer is higher for Eureka as compared to Tiksi, stable stratification and upward turbulent flux for carbon dioxide is generally did not observed at Eureka site during summer seasons. It was found a high correlation between the turbulent fluxes of sensible and latent heat, carbon dioxide and the net solar radiation. A comprehensive evaluation of energy balance closure problem is performed based on the multi-year data sets

  18. Cycling of organic and mineral nitrogen along a latitudinal transect in Western Siberia

    NASA Astrophysics Data System (ADS)

    Wild, Birgit; Schnecker, Jörg; Knoltsch, Anna; Takriti, Mounir; Mooshammer, Maria; Lashchinskiy, Nikolay; Richter, Andreas

    2014-05-01

    The availability of nitrogen in soils is constrained by the breakdown of N-rich organic polymers, in particular proteins. Oligo-peptides and amino acids derived from protein depolymerization are subsequently taken up by soil microorganisms, and, if nitrogen availability exceeds nitrogen demand, excess nitrogen will be released as ammonium ("nitrogen mineralization"), which then can be used as a substrate for nitrification. We here report on the dynamics of organic and mineral nitrogen along a latitudinal transect in Western Siberia (67°-54°N), from the tundra (tree growth restricted by low temperature), over three sites of coniferous forest (taiga) and two sites of forest steppe (deciduous forest and meadow), to steppe (tree growth restricted by low precipitation). For each of the seven sites, we sampled three soil horizons, and applied 15N pool dilution assays to determine gross rates of protein depolymerization, nitrogen mineralization, and nitrification. All nitrogen transformation rates were significantly correlated with carbon and nitrogen content, as well as microbial biomass, and decreased with depth from organic topsoil over mineral topsoil to mineral subsoil. The decrease with depth was stronger for protein depolymerization than for nitrogen mineralization and nitrification, i.e., ratios of mineralization or nitrification over protein depolymerization increased with depth. As both mineralization and nitrification depend on the degree of microbial nitrogen limitation, our findings suggest that microbial nitrogen limitation decreased with soil depth, possibly due to increasing energy limitation of microorganisms. Within the organic topsoil, protein depolymerization rates showed large variability between ecosystems, reaching the highest values in middle (60°N) and southern taiga (58°N), representing the most productive forests along the transect. We discuss these results with respect to differences of the biomes in climatic conditions, vegetation

  19. Tool Belts: Latitudinal-Belt Predictions for the Persistence of Landscapes

    NASA Astrophysics Data System (ADS)

    Willenbring, Jane; Brocard, Gilles

    2016-04-01

    The ability of rivers to cut through rock and re-establish equilibrium sets the pace of landscape response to uplift. Because of associations between tectonics, erosion, and weathering, high rates of rock uplift may initiate a cascade of processes that are linked to high rates of weathering and eventually sequestration of CO2 over geologic timescales. How long does it take to completely change the topographic form after uplift and where on Earth do relict landscapes persist despite uplift? Large expanses of subdued landscapes are common at high elevation in mountain ranges. Preservation of subdued fragments amongst steeply dissected regions can therefore be a simple matter of chance, reflecting the time it takes for dissection to remove any remaining parcel of the pre-existing topography after a tectonic perturbation. Some of these relicts may, however, possess characteristics - often a product of the climate - that make them intrinsically resistant to dissection. One common mode of conversion of a subdued landscape into a deeply dissected one is the propagation of upstream-migrating erosion waves that transmit the signal of uplift and base level lowering across entire landscapes. Following a shift in tectonic forcing, the Earth's surface progressively adjusts its topographic form over millions of years, seeking to re-establish equilibrium with the new forcing. Here, we show that a high degree of weathering leading to smaller average soil grains at the surface hinders the capacity of rivers to incise. We show that globally, rates of cosmogenic nuclide-derived denudation rates fall into latitudinal belts with (1) low rates of denudation in areas with high temperatures and high precipitation where rock fragments do not persist at the soil surface, (2) high rates of denudation at mid-latitudes where rock fragments exist and are carried efficiently by the river flow, and (3) low rates of denudation at high latitudes where large grains at the surface inhibit channelized

  20. Latitudinal changes in the standing stocks of nano- and picoeukaryotic phytoplankton in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Tarran, Glen A.; Heywood, Jane L.; Zubkov, Mikhail V.

    2006-07-01

    The latitudinal distributions of picoeukaryote phytoplankton (PEUK), coccolithophores (COCCO), cryptophytes (CRYPTO) and other nanoeukaryote phytoplankton (NEUK) were studied in the Atlantic Ocean between 49°N and 46°S in September-October 2003 and April-June 2004 by flow cytometry. Phytoplankton abundance and carbon (C) biomass varied considerably with latitude and down through the water column. Abundance and C biomass of all eukaryotic groups studied were highest in North and South Atlantic temperate waters and in the Mauritanian Upwelling off the west coast of Africa, where the total C biomass of eukaryotic phytoplankton smaller than 10 μm reached almost 150 mg C m -3. Phytoplankton in the Equatorial Upwelling region was concentrated well below the surface at 50-80 m, with total C biomass in this layer being approximately 4 times that in the mixed layer. The North and South Atlantic Gyres supported much lower eukaryotic phytoplankton C biomass, with total eukaryote C biomass only reaching 2-3 mg C m -3, peaking below 100 m. Of the four eukaryote groups studied, the PEUK were the most abundant, reaching densities of up to 40,000 cells cm -3. They often contributed between 25% and 60% of total C biomass, particularly in the deep chlorophyll maxima of the different oceanic regions and also in the South Atlantic temperate waters, both in austral spring and autumn. NEUK also contributed significantly to C biomass. They generally dominated in the mixed layer, where they contributed 65-85% of total C biomass in the subtropical gyres and in North Atlantic temperate waters. CRYPTO and COCCO were generally less abundant. CRYPTO attained highest abundance in the Southern Temperate waters of over 500 cells cm -3 on both cruises. COCCO were often undetectable but on the European continental shelf abundance reached up to 2600 cells cm -3 during AMT 14. The C biomass standing stock of eukaryotic phytoplankton (<10 μm) for the Atlantic Ocean as a whole was estimated to be

  1. Substrate use efficiency of microbial communities along a latitudinal transect through Western Siberia

    NASA Astrophysics Data System (ADS)

    Takriti, Mounir; Wild, Birgit; Schnecker, Jörg; Mooshammer, Maria; Knoltsch, Anna; Lashchinskiy, Nikolay; Eloy Alves, Ricardo J.; Gentsch, Norman; Gittel, Antje; Mikutta, Robert; Wanek, Wolfgang; Richter, Andreas

    2014-05-01

    As stable soil organic matter is largely derived from microbial compounds, the partitioning of C uptake by microorganisms into growth and respiration determines the C storage potential in soils. The proportion of substrate carbon (C) which is invested into new microbial biomass (i.e., microbial growth), compared to the fraction of substrate carbon C which is respired as as CO2,is often referred to as substrate use efficiency (SUE) or carbon use efficiency (CUE). According to stoichiometric theory, the CUE of microbes is strongly controlled by the availability of nutrients such as nitrogen (N), as microorganisms have to maintain their biomass stoichiometry within relatively narrow boundaries. Hence, when microorganisms are nitrogen limited, excess C is respired (low SUE), while conversely excess N is mineralized when C is limiting (high SUE). In this study we took advantage of the high variability in biotic and abiotic factors, such as C:N ratio and litter input quality, between samples taken from the top three soil horizons (organic topsoil, upper and lower mineral horizon) from six different ecosystems along a 1,500 km linear-distance latitudinal transect through Western Siberia. We hypothesized that SUE would increase with soil depth, as organic matter becomes successively enriched with N relative to C, and decrease with latitude, as ecosystem N availability decreases. To determine SUE we measured uptake and respiration of a mixture of 13C labeled substrate (consisting of monosaccharides, organic acids, amino acids and amino sugars), as well as C and N pools and extracellular enzyme activities. In contrast to our expectations, we found that microbial SUE in lower mineral horizons was significantly lower than in upper mineral horizons, while there was no significant difference to the organic horizons. This is contradictory to the theory of ecological stoichiometry, since microbial SUE did not increase with decreasing soil C:N. Potential oxidative enzyme activities

  2. The latitudinal distribution of putative periglacial sites on the northern martian plains.

    NASA Astrophysics Data System (ADS)

    Barrett, Alex; Balme, Matt; Patel, Manish; Hagermann, Axel

    2013-04-01

    Periglacial landscapes are found in cold regions of Earth where the freezing and thawing of the permafrost active layer plays an important role in shaping the landscape. A variety of distinctive landforms such as sorted circles, thermokarst depressions and solifluction lobes are indicative of periglacial environments on Earth. It has been suggested that similar features on the northern plains of Mars could be the result of the same, or similar processes (1). Since the formation of a periglacial landscape requires the freezing and thawing of water their presence on Mars would indicate that the thawing of water-ice has occurred in the geologically recent past. Periglacial landforms could have formed in past periods of higher obliquity when the environment was more conducive to the action of liquid water or due to the depression of the freezing point by brines under current conditions. We have conducted a survey of putative periglacial landforms across the northern Martian plains. Over 400 HiRISE images of the walls and floors of >1 km diameter craters have been examined to map the locations of these landforms across regions of Acidalia, Utopia and Arcadia Planitia between 30 and 80 Degrees North. These data allow an assessment of the latitudinal distribution of these features. Variations between the types of landform found in different regions of the Northern Plains of mars can also be assessed. Scalloped depressions and gullies have a similar latitude range, and are frequently found south of 60 Degrees North. There are a large number of scalloped depressions in Utopia as noted by other studies (2), similar features are found in both Acidalia and Arcadia but are not found over as wide a range of latitudes in Acidalia. Possible sorted landforms (lobes, polygons etc) can be found as far south as 40 and as far north as 70 Degrees North but most are found between 45-65 Degrees North. They seem to occur over a wider range of latitudes in Utopia Planitia than in Acidalia

  3. Regionally-defined niche-breadth of tropical African freshwater plant species predicts their global latitudinal range

    NASA Astrophysics Data System (ADS)

    Kennedy, Michael; Lang, Pauline; Tapia-Grimaldo, Julissa; Varandas-Martins, Sara; Bruce, Allanah; Moore, Isabel; Sichingabula, Henry; Bottino, Flávia; Murphy, Kevin

    2016-04-01

    This study tested the hypothesis that the measured niche-breadth of river plant species (macrophytes) occurring within a closely-defined geographical area in southern tropical Africa (Zambia), may predict the larger-scale biogeographical range of these species. Two measures of niche-breadth were calculated for 44 riverine macrophyte species commonly occurring in Zambia, using an approach based on PCA ordination with bio-physico-chemical ordination input variables: altitude, stream order, stream flow, pH, conductivity, soluble reactive phosphate concentration (SRP), benthic macroinvertebrate Average Score per Taxon (ASPT), and individual abundance of nine benthic macroinvertebrate families showing differing water quality tolerance, as indicated by their Sensitivity Weightings within the Zambian Invertebrate Scoring System (ZISS). Macrophyte large-scale latitudinal range was derived from world geopositional records held by online databases, supplemented by records held by the authors. The two niche-breadth metrics divided the species into narrow-niche and intermediate/broad-niche categories, showing significant variation in altitude, stream flow, conductivity, SRP and ASPT, but not stream order or pH. There was no evidence to suggest that macrophyte alpha-diversity (as a measure of number of individual niches that may co-exist in a given habitat) showed any significant relationship with individual species niche-breadth. However, macrophyte alpha-diversity was significantly positively correlated with altitude, and significantly negatively related to conductivity, pH, ASPT, SRP, stream flow, and stream order. Narrow-niche macrophyte species included a higher proportion of Afrotropical endemics than did species with broader niche size. There were significant predictive relationships between macrophyte niche breadth and latitudinal range of the target species at global and Afrotropical scales, but not for the Neotropical range of species which occurred in both the

  4. ORION II bus demonstration. Demonstration report (Final)

    SciTech Connect

    Shanley, J.

    1989-02-01

    The Central New York Regional Transportation Authority conducted an 18-month demonstration to determine how the ORION II bus operates in actual service. The ORION II vehicle is a small low floor, accessible heavy duty, diesel-powered transit bus designed to meet the needs of the elderly and handicapped. It has the capacity to seat 26 passengers with 4 wheelchair lockdowns. Side and rear doors are equipped with electrically powered ramps. Eight Thomas vehicles (22-foot, 11,500 lbs, wheelchair equipped, gasoline fueled) were also tested during the demonstration period. Operations (fuel and oil usage) and maintenance (scheduled and unscheduled) data were collected and charted-out in the report as well as driver, passenger, and maintenance surveys. This report provides descriptions, photographs, and comparison charts of both the diesel-fueled ORION II transit bus and the gasoline-fueled Thomas vehicles along with the demonstration test plan, evaluations, conclusions, and survey results.

  5. Herschel's Interference Demonstration.

    ERIC Educational Resources Information Center

    Perkalskis, Benjamin S.; Freeman, J. Reuben

    2000-01-01

    Describes Herschel's demonstration of interference arising from many coherent rays. Presents a method for students to reproduce this demonstration and obtain beautiful multiple-beam interference patterns. (CCM)

  6. Why Demonstrations Matter

    ERIC Educational Resources Information Center

    Black, Richard

    2005-01-01

    With the current focus on constructivist perspectives, science demonstrations have fallen out of favor in some circles. Demonstrations are easy to do and offer many benefits and unique opportunities in the constructivist classroom. With careful use, demonstrations can be powerful teaching tools. A wonderful quality of a demonstration (or a series…

  7. LIMB Demonstration Project Extension and Coolside Demonstration

    SciTech Connect

    Goots, T.R.; DePero, M.J.; Nolan, P.S.

    1992-11-10

    This report presents results from the limestone Injection Multistage Burner (LIMB) Demonstration Project Extension. LIMB is a furnace sorbent injection technology designed for the reduction of sulfur dioxide (SO[sub 2]) and nitrogen oxides (NO[sub x]) emissions from coal-fired utility boilers. The testing was conducted on the 105 Mwe, coal-fired, Unit 4 boiler at Ohio Edison's Edgewater Station in Lorain, Ohio. In addition to the LIMB Extension activities, the overall project included demonstration of the Coolside process for S0[sub 2] removal for which a separate report has been issued. The primary purpose of the DOE LIMB Extension testing, was to demonstrate the generic applicability of LIMB technology. The program sought to characterize the S0[sub 2] emissions that result when various calcium-based sorbents are injected into the furnace, while burning coals having sulfur content ranging from 1.6 to 3.8 weight percent. The four sorbents used included calcitic limestone, dolomitic hydrated lime, calcitic hydrated lime, and calcitic hydrated lime with a small amount of added calcium lignosulfonate. The results include those obtained for the various coal/sorbent combinations and the effects of the LIMB process on boiler and plant operations.

  8. Latitudinal variation of leaf stomatal traits from species to community level in forests: linkage with ecosystem productivity.

    PubMed

    Wang, Ruili; Yu, Guirui; He, Nianpeng; Wang, Qiufeng; Zhao, Ning; Xu, Zhiwei; Ge, Jianping

    2015-09-25

    To explore the latitudinal variation of stomatal traits from species to community level and their linkage with net primary productivity (NPP), we investigated leaf stomatal density (SDL) and stomatal length (SLL) across 760 species from nine forest ecosystems in eastern China, and calculated the community-level SD (SDC) and SL (SLC) through species-specific leaf area index (LAI). Our results showed that latitudinal variation in species-level SDL and SLL was minimal, but community-level SDC and SLC decreased clearly with increasing latitude. The relationship between SD and SL was negative across species and different plant functional types (PFTs), but positive at the community level. Furthermore, community-level SDC correlated positively with forest NPP, and explained 51% of the variation in NPP. These findings indicate that the trade-off by regulating SDL and SLL may be an important strategy for plant individuals to adapt to environmental changes, and temperature acts as the main factor influencing community-level stomatal traits through alteration of species composition. Importantly, our findings provide new insight into the relationship between plant traits and ecosystem function.

  9. Phylogenomic analyses reveal latitudinal population structure and polymorphisms in heat stress genes in the North Atlantic snail Nucella lapillus.

    PubMed

    Chu, Nathaniel D; Kaluziak, Stefan T; Trussell, Geoffrey C; Vollmer, Steven V

    2014-04-01

    North Atlantic rocky intertidal species have been shaped by repeated glaciations and strong latitudinal temperature gradients, making them an excellent system to study postglacial phylogeography and thermal tolerance. Population genetics data from northwestern Atlantic species, however, often show patterns inconsistent with the prediction that high dispersal should generate weaker genetic structure among populations. Here, we used next-generation sequencing restriction-associated DNA tags (RAD-seq) and a transcriptome assembled from RNA-seq data to analyse the genetic structure of northwestern Atlantic populations of the low-dispersal intertidal snail Nucella lapillus. Although previous studies in this region have detected almost no genetic structure in N. lapillus, our phylogenomic approach identified a well-supported split between northern and southern clades. By comparing RAD-seq data and our transcriptome assembly, we identified thousands of fixed single-nucleotide polymorphisms (SNPs) between these latitudinal clades that map to protein-coding genes, including genes associated with heat stress tolerance. These fixed SNPs might represent loci under selection for different thermal regimes in the northwestern Atlantic. PMID:24471495

  10. Latitudinal variation of leaf stomatal traits from species to community level in forests: linkage with ecosystem productivity.

    PubMed

    Wang, Ruili; Yu, Guirui; He, Nianpeng; Wang, Qiufeng; Zhao, Ning; Xu, Zhiwei; Ge, Jianping

    2015-01-01

    To explore the latitudinal variation of stomatal traits from species to community level and their linkage with net primary productivity (NPP), we investigated leaf stomatal density (SDL) and stomatal length (SLL) across 760 species from nine forest ecosystems in eastern China, and calculated the community-level SD (SDC) and SL (SLC) through species-specific leaf area index (LAI). Our results showed that latitudinal variation in species-level SDL and SLL was minimal, but community-level SDC and SLC decreased clearly with increasing latitude. The relationship between SD and SL was negative across species and different plant functional types (PFTs), but positive at the community level. Furthermore, community-level SDC correlated positively with forest NPP, and explained 51% of the variation in NPP. These findings indicate that the trade-off by regulating SDL and SLL may be an important strategy for plant individuals to adapt to environmental changes, and temperature acts as the main factor influencing community-level stomatal traits through alteration of species composition. Importantly, our findings provide new insight into the relationship between plant traits and ecosystem function. PMID:26403303

  11. Diversity of planktonic fish larvae along a latitudinal gradient in the Eastern Atlantic Ocean estimated through DNA barcodes

    PubMed Central

    Morote, Elvira; Kochzius, Marc; Garcia-Vazquez, Eva

    2016-01-01

    Mid-trophic pelagic fish are essential components of marine ecosystems because they represent the link between plankton and higher predators. Moreover, they are the basis of the most important fisheries resources; for example, in African waters. In this study, we have sampled pelagic fish larvae in the Eastern Atlantic Ocean along a latitudinal gradient between 37°N and 2°S. We have employed Bongo nets for plankton sampling and sorted visually fish and fish larvae. Using the cytochrome oxidase I gene (COI) as a DNA barcode, we have identified 44 OTUs down to species level that correspond to 14 families, with Myctophidae being the most abundant. A few species were cosmopolitan and others latitude-specific, as was expected. The latitudinal pattern of diversity did not exhibit a temperate-tropical cline; instead, it was likely correlated with environmental conditions with a decline in low-oxygen zones. Importantly, gaps and inconsistencies in reference DNA databases impeded accurate identification to the species level of 49% of the individuals. Fish sampled from tropical latitudes and some orders, such as Perciformes, Myctophiformes and Stomiiformes, were largely unidentified due to incomplete references. Some larvae were identified based on morphology and COI analysis for comparing time and costs employed from each methodology. These results suggest the need of reinforcing DNA barcoding reference datasets of Atlantic bathypelagic tropical fish that, as main prey of top predators, are crucial for ecosystem-based management of fisheries resources. PMID:27761307

  12. Effects of Latitudinally Dependent Solar Wind Speed on Diffusion Coefficients of Cosmic Rays in the Presence of Adiabatic Focusing

    NASA Astrophysics Data System (ADS)

    He, H.-Q.; Schlickeiser, R.

    2015-02-01

    The solar wind is observed to display high speeds in high heliolatitude coronal holes and low speeds near the ecliptic plane. The heliospheric magnetic field associated with the solar wind plays a very important role in the transport and modulation of charged energetic particles, including galactic cosmic rays (GCRs) and solar energetic particles (SEPs), in the three-dimensional heliosphere. In previous studies, a constant solar wind speed, which is independent of heliolatitude, was assumed and commonly used in modulation modeling of cosmic rays. In this work, we investigate the realistic latitudinally dependent solar wind speed and utilize the theoretical models in hyperbolic and piecewise polynomial forms to explore the important effects on the heliospheric magnetic field and the diffusion coefficients (parallel, perpendicular, and drift scale) of cosmic rays in the presence of adiabatic focusing. Comparisons of the diffusion coefficients derived from standard Parker field and modified magnetic fields are presented. Since the structures and properties of different solar wind sources (coronal streamer belt, polar coronal hole, and transition region between them) differ from each other in essence, we suggest that the latitudinally dependent solar wind speed and the corresponding heliospheric magnetic field and diffusion coefficients with adiabatic focusing should be employed in the global modeling studies of GCRs and SEPs in the heliosphere.

  13. Latitudinal temperature gradient during the Cretaceous Upper Campanian-Middle Maastrichtian: δ 18O record of continental vertebrates

    NASA Astrophysics Data System (ADS)

    Amiot, Romain; Lécuyer, Christophe; Buffetaut, Eric; Fluteau, Frédéric; Legendre, Serge; Martineau, François

    2004-09-01

    Latitudinal variations in model biogenic apatite δ18O values were calculated using fractionation equations of vertebrates and weighted rainfall δ18O values along with mean annual air temperatures provided by IAEA-WMO meteorological stations. The reference equation obtained was used to compute a continental temperature gradient for the Late Campanian-Middle Maastrichtian interval by using published and new δ18O values of phosphate from vertebrates. Samples are mainly tooth enamel from crocodilians and dinosaurs that lived at paleolatitudes ranging from 83-9+4°N (Alaska) to 32±3°S (Madagascar). The temperature gradient was less steep (0.4±0.1 °C/°latitude) than the present-day one (0.6 °C/°latitude) with temperatures that decreased from about 30 °C near the equator to about -5 °C at the poles. Above 30° of paleolatitude, air temperatures were higher than at present. The validity of these results is discussed by comparison with climatic criteria inferred from paleontological, paleobotanical and sedimentological data. The latitudinal distribution of oxygen isotope compositions of continental vertebrates is potentially a powerful tool for quantifying Mesozoic terrestrial climates.

  14. [Variability of vegetation growth season in different latitudinal zones of North China: a monitoring by NOAA NDVI and MSAVI].

    PubMed

    Wang, Hong; Li, Xiaobing; Han, Ruibo; Ge, Yongqin

    2006-12-01

    In this study, North China was latitudinally divided into five zones, i.e., 32 degrees - 36 degrees N (Zone I), 36 degrees - 40 degrees N (Zone II), 40 degrees - 44 degrees N (Zone III), 44 degrees - 48 degrees N (Zone IV) and 48 degrees - 52 degrees N (Zone V), and the NOAA/ AVHRR NDVI and MSAVI time-series images from 1982 to 1999 were smoothed with Savitzky-Golay filter algorithm. Based on the EOF analysis, the principal components of NDVI and MSAVI for the vegetations in different latitudinal zones of North China were extracted, the annual beginning and ending dates and the length of growth season in 1982 - 1999 were estimated, and the related parameters were linearly fitted, aimed to analyze the variability of vegetation growth season. The results showed that the beginning date of the growth season in different zones tended to be advanced, while the ending date tended to be postponed with increasing latitude. The length of the growth season was also prolonged, with the prolonging time exceeded 10 days.

  15. Do turtles follow the rules? Latitudinal gradients in species richness, body size, and geographic range area of the world's turtles.

    PubMed

    Angielczyk, Kenneth D; Burroughs, Robert W; Feldman, Chris R

    2015-05-01

    Understanding how and why biodiversity is structured across the globe has been central to ecology, evolution, and biogeography even before those disciplines took their modern forms. Three global-scale patterns in particular have been the focus of research and debate for decades: latitudinal gradients in species richness (richness decreases with increasing latitude), body size (body size increases with increasing latitude in endotherms; Bergmann's rule), and geographic range size (range size increases with increasing latitude; Rapoport's rule). Despite decades of study, the generality and robustness of these trends have been debated, as have their underlying causes. Here we investigate latitudinal gradients in species richness, body size, and range size in the world's turtles (Testudines), and add more evidence that these rules do not seem to apply across all taxa. We show that turtle diversity actually peaks at 25° north, a highly unusual global pattern. Turtles also fail to follow Bergmann's Rule, and may show the converse (larger at lower latitudes), though trends are weak. Turtles also show a complex relationship between latitude and range size that does not directly follow Rapoport's rule. Body size and geographic range size are significantly correlated, and multiple abiotic and biotic variables help explain the relationships between latitude and species diversity, body size, and range size. Although we show that turtles do not strictly follow some classic biogeographical rules, we also call for further in-depth research to investigate potential causal mechanisms for these atypical patterns. PMID:25588662

  16. Temperature and diet effects on omnivorous fish performance: Implications for the latitudinal diversity gradient in herbivorous fishes

    USGS Publications Warehouse

    Behrens, M.D.; Lafferty, K.D.

    2007-01-01

    Herbivorous fishes show a clear latitudinal diversity gradient, making up a larger proportion of the fish species in a community in tropical waters than in temperate waters. One proposed mechanism that could drive this gradient is a physiological constraint due to temperature. One prediction based on this mechanism is that if herbivorous fishes could shift their diet to animal material, they would be better able to grow, survive, and reproduce in cold waters. We tested this prediction on the omnivore Girella nigricans under different temperature and diet regimes using RNA-DNA ratios as an indicator of performance. Fish had increased performance (100%) at low temperatures (12??C) when their diet was supplemented with animal material. In contrast, at higher temperatures (17, 22, and 27??C) fish showed no differences between diets. This indicates that omnivorous fishes could increase their performance at low temperatures by consuming more animal matter. This study supports the hypothesis that a relative increase in the nutritional value of plant material at warmer temperatures could drive the latitudinal diversity gradient in herbivorous fishes. ?? 2007 NRC.

  17. Latitudinal variation of leaf stomatal traits from species to community level in forests: linkage with ecosystem productivity

    PubMed Central

    Wang, Ruili; Yu, Guirui; He, Nianpeng; Wang, Qiufeng; Zhao, Ning; Xu, Zhiwei; Ge, Jianping

    2015-01-01

    To explore the latitudinal variation of stomatal traits from species to community level and their linkage with net primary productivity (NPP), we investigated leaf stomatal density (SDL) and stomatal length (SLL) across 760 species from nine forest ecosystems in eastern China, and calculated the community-level SD (SDC) and SL (SLC) through species-specific leaf area index (LAI). Our results showed that latitudinal variation in species-level SDL and SLL was minimal, but community-level SDC and SLC decreased clearly with increasing latitude. The relationship between SD and SL was negative across species and different plant functional types (PFTs), but positive at the community level. Furthermore, community-level SDC correlated positively with forest NPP, and explained 51% of the variation in NPP. These findings indicate that the trade-off by regulating SDL and SLL may be an important strategy for plant individuals to adapt to environmental changes, and temperature acts as the main factor influencing community-level stomatal traits through alteration of species composition. Importantly, our findings provide new insight into the relationship between plant traits and ecosystem function. PMID:26403303

  18. Do turtles follow the rules? Latitudinal gradients in species richness, body size, and geographic range area of the world's turtles.

    PubMed

    Angielczyk, Kenneth D; Burroughs, Robert W; Feldman, Chris R

    2015-05-01

    Understanding how and why biodiversity is structured across the globe has been central to ecology, evolution, and biogeography even before those disciplines took their modern forms. Three global-scale patterns in particular have been the focus of research and debate for decades: latitudinal gradients in species richness (richness decreases with increasing latitude), body size (body size increases with increasing latitude in endotherms; Bergmann's rule), and geographic range size (range size increases with increasing latitude; Rapoport's rule). Despite decades of study, the generality and robustness of these trends have been debated, as have their underlying causes. Here we investigate latitudinal gradients in species richness, body size, and range size in the world's turtles (Testudines), and add more evidence that these rules do not seem to apply across all taxa. We show that turtle diversity actually peaks at 25° north, a highly unusual global pattern. Turtles also fail to follow Bergmann's Rule, and may show the converse (larger at lower latitudes), though trends are weak. Turtles also show a complex relationship between latitude and range size that does not directly follow Rapoport's rule. Body size and geographic range size are significantly correlated, and multiple abiotic and biotic variables help explain the relationships between latitude and species diversity, body size, and range size. Although we show that turtles do not strictly follow some classic biogeographical rules, we also call for further in-depth research to investigate potential causal mechanisms for these atypical patterns.

  19. Latitudinal patterns in the life-history traits of three isolated Atlantic populations of the deep-water shrimp Plesionika edwardsii (Decapoda, Pandalidae)

    NASA Astrophysics Data System (ADS)

    González, José A.; Pajuelo, José G.; Triay-Portella, Raül; Ruiz-Díaz, Raquel; Delgado, João; Góis, Ana R.; Martins, Albertino

    2016-11-01

    Patterns in the life-history traits of the pandalid shrimp Plesionika edwardsii are studied for the first time in three isolated Atlantic populations (Madeira, Canaries and Cape Verde Islands) to gain an understanding of their latitudinal variations. The maximum carapace size of the populations studied, as well as the maximum weight, showed clear latitudinal patterns. The patterns observed may be a consequence of the temperature experienced by shrimps during development, 1.37 ° C higher in the Canaries and 5.96 ° C higher in the Cape Verde Islands than in Madeira. These temperature differences among populations may have induced phenotypic plasticity because the observed final body size decreased as the temperature increased. A latitudinal north-south pattern was also observed in the maximum size of ovigerous females, with larger sizes found in the Madeira area and lower sizes observed in the Cape Verde Islands. A similar pattern was observed in the brood size and maximum egg size. Females of P. edwardsii produced smaller eggs in the Cape Verde Islands than did those at the higher latitude in Madeira. P. edwardsii was larger at sexual maturity in Madeira than in the Cape Verde Islands. The relative size at sexual maturity is not affected by latitude or environmental factors and is the same in the three areas studied, varying slightly between 0.568 and 0.585. P. edwardsii had a long reproductive season with ovigerous females observed all year round, although latitudinal variations were observed. Seasonally, there were more ovigerous females in spring and summer in Madeira and from winter to summer in the Cape Verde Islands. P. edwardsii showed a latitudinal pattern in size, with asymptotic size and growth rate showing a latitudinal compensation gradient as a result of an increased growth performance in the Madeira population compared to that of the Cape Verde Islands.

  20. Altitudinal vs Latitudinal Climactic Drivers: A Comparison of a Relict Picea and Abies Forest in the Southern Appalachians versus the Hemi-Boreal Transition Zone off Southern Canada

    NASA Astrophysics Data System (ADS)

    Evans, A.; Lafon, C. W.

    2015-12-01

    Identification of biotic and abiotic determinants of tree species range limits is critical for understanding the effects of climate change on species distributions. Upward shifts of species distributions in montane areas have been widely reported but there have been few reports of latitudinal range retractions. Previous studies have indicated that southern latitudinal limits of a species range are dictated by biotic factors such as competition while others have suggested that abiotic factors, such as temperature, dictate these limits. We investigated the potential climatic gradients at the southern latitudinal limit of the Spruce (Picea) and Fir (Abies) species that dominate the Canadian boreal forest community as well as relict boreal forests containing similar species found in the high elevation areas of the Southern Appalachians. Existing research has suggested that relict ecosystems are more sensitive to climate change and can be indicative of future changes at latitudinal range limits. Expanding on this literature, we hypothesized that we would see similar gradients in climatic variables at the southern latitudinal limit of the Canadian boreal forest and those in the relict boreal forests southern Appalachians acting as controlling factors of these species distributions. We used forty years of climate data from weather stations along the southern edge of the boreal forest in the Canadian Shield provinces, species distribution data from the Canadian National Forest Inventory, (CNFI) geospatial data from the National Park Service (NPS), and historical weather data from the National Oceanic and Atmospheric Administration (NOAA) to perform our analysis. Our results indicate different climate variables act as controls of warm edge range limits of the Canadian boreal forest than those of the relict boreal forest of the southern Appalachians. However, we believe range retractions of the relict forest may be indicative of a more gradual response of similar species

  1. Woody plant encroachment effect on soil organic carbon dynamics: results from a latitudinal gradient in Italy

    NASA Astrophysics Data System (ADS)

    Pellis, Guido; Chiti, Tommaso; Moscatelli, Maria Cristina; Marinari, Sara; Papale, Dario

    2016-04-01

    Woody plant encroachment into pastures and grasslands represents a significant land cover change phenomenon, with a considerable impact on carbon dynamics at an ecosystem level. It was estimated that 7.64% of the Southern Europe land was subject to that process between 1950 to 2010. As a result of woody encroachment, changes in vegetation composition can produce substantial changes to the soil organic carbon (SOC) cycle. Despite the numerous papers published on land-use change, an evaluation of the IPCC terrestrial carbon pools changes occurring during woody encroachment on abandoned pastures and grasslands is still lacking, particularly for the Italian territory. Therefore, the aim of this study was to investigate the role of woody encroachment on carbon sequestration over abandoned pastures and grasslands in Alpine and Apennine ecosystems, with a particular focus on the SOC. We applied a chronosequence approach to seven selected sites located along a latitudinal gradient in Italy. Each chronosequence consisted of a pasture currently managed, three sites abandoned at different times in the past and, finally, a mature forest stand representing the last phase of the succession. The European Commission sampling protocols to certify SOC changes was adopted to estimate the variations following woody encroachment. Soil samples were collected at different depths in the topsoil (0-30 cm) and subsoil (30-70 cm), despite the original protocol formulation being limited to the topsoil only. In addition, aboveground living biomass (AGB), dead wood and litter were also measured following international protocols. Considering all C pools together, woody plant encroachment leads to a progressive C stock accumulation in all the chronosequences. The total C stock of mature forest stands ranges from 1.78±0.11 times (Eastern Alps) to 2.48±0.31 times (central Apennine) the initial value on pastures. Unsurprisingly, the C stocks of AGB, dead wood and litter all increase during the

  2. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris, Ed.

    1987-01-01

    Describes several chemistry demonstrations that use an overhead projector. Some of the demonstrations deal with electrochemistry, and another deals with the reactions of nonvolatile immiscible liquid in water. (TW)

  3. Traveling Wave Demonstration.

    ERIC Educational Resources Information Center

    Kluger-Bell, Barry

    1995-01-01

    Describes a traveling-wave demonstration that uses inexpensive materials (crepe-paper streamers) and is simple to assemble and perform. Explains how the properties of light waves are illustrated using the demonstration apparatus. (LZ)

  4. Polarized Light Corridor Demonstrations.

    ERIC Educational Resources Information Center

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  5. Adolescents' Demonstrative Behavior Research

    ERIC Educational Resources Information Center

    Parfilova, Gulfiya G.; Karimova, Lilia Sh.

    2016-01-01

    The problem of demonstrative behavior is very topical among teenagers and this issue has become the subject of systematic scientific research. Demonstrative manifestations in adolescents disrupt the favorable socialization; therefore, understanding, prevention and correction of demonstrative behavior at this age is relevant and requires special…

  6. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris, Ed.

    1988-01-01

    Details two demonstrations for use with an overhead projector in a chemistry lecture. Includes "A Very Rapidly Growing Silicate Crystal" and "A Colorful Demonstration to Simulate Orbital Hybridization." The materials and directions for each demonstration are included as well as a brief explanation of the essential learning involved. (CW)

  7. A Boyle's Law Demonstrator.

    ERIC Educational Resources Information Center

    Sathe, Dileep V.

    1984-01-01

    The usual apparatus for demonstrating Boyle's law produces reasonably accurate results, but is not impressive as a demonstration because students cannot easily appreciate the change in pressure. An apparatus designed to produce a more effective demonstration is described. Procedures employed are also described. (JN)

  8. Classroom Demonstrations: Individual Differences.

    ERIC Educational Resources Information Center

    Singer, Sandra M.

    These demonstrations stress individual differences, a concept becoming increasingly important in psychological research. Intended for use in undergraduate psychology courses, four demonstrations that illustrate common examples of human variation are described. The demonstrations deal with the following individual differences: taste blindness,…

  9. Edible Astronomy Demonstrations

    NASA Astrophysics Data System (ADS)

    Lubowich, D. A.

    2006-08-01

    By using astronomy demonstrations with edible ingredients, I have been able to increase student interest and knowledge of astronomical concepts. This approach has been successful with all age groups from elementary school through college students. I will present some of the edible demonstrations I have created including using popcorn to simulate radioactivity; using chocolate, nuts, and marshmallows to illustrate density and differentiation during the formation of the planets; and making big-bang brownies or chocolate chip-cookies to illustrate the expansion of the Universe. Sometimes the students eat the results of the astronomical demonstrations. These demonstrations are an effective teaching tool and the students remember these demonstrations after they are presented.

  10. Strategy Guideline. Demonstration Home

    SciTech Connect

    Hunt, A.; Savage, C.

    2012-12-01

    This guideline will provide a general overview of the different kinds of demonstration home projects, a basic understanding of the different roles and responsibilities involved in the successful completion of a demonstration home, and an introduction into some of the lessons learned from actual demonstration home projects. Also, this guideline will specifically look at the communication methods employed during demonstration home projects. And lastly, we will focus on how to best create a communication plan for including an energy efficient message in a demonstration home project and carry that message to successful completion.

  11. Strategy Guideline: Demonstration Home

    SciTech Connect

    Savage, C.; Hunt, A.

    2012-12-01

    This guideline will provide a general overview of the different kinds of demonstration home projects, a basic understanding of the different roles and responsibilities involved in the successful completion of a demonstration home, and an introduction into some of the lessons learned from actual demonstration home projects. Also, this guideline will specifically look at the communication methods employed during demonstration home projects. And lastly, we will focus on how to best create a communication plan for including an energy efficient message in a demonstration home project and carry that message to successful completion.

  12. Sap-feeding insects on forest trees along latitudinal gradients in northern Europe: a climate-driven patterns.

    PubMed

    Kozlov, Mikhail V; Stekolshchikov, Andrey V; Söderman, Guy; Labina, Eugenia S; Zverev, Vitali; Zvereva, Elena L

    2015-01-01

    Knowledge of the latitudinal patterns in biotic interactions, and especially in herbivory, is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. We used sap-feeding insects as a model group to test the hypotheses that the strength of plant-herbivore interactions in boreal forests decreases with latitude and that this latitudinal pattern is driven primarily by midsummer temperatures. We used a replicated sampling design and quantitatively collected and identified all sap-feeding insects from four species of forest trees along five latitudinal gradients (750-1300 km in length, ten sites in each gradient) in northern Europe (59 to 70°N and 10 to 60°E) during 2008-2011. Similar decreases in diversity of sap-feeding insects with latitude were observed in all gradients during all study years. The sap-feeder load (i.e. insect biomass per unit of foliar biomass) decreased with latitude in typical summers, but increased in an exceptionally hot summer and was independent of latitude during a warm summer. Analysis of combined data from all sites and years revealed dome-shaped relationships between the loads of sap-feeders and midsummer temperatures, peaking at 17 °C in Picea abies, at 19.5 °C in Pinus sylvestris and Betula pubescens and at 22 °C in B. pendula. From these relationships, we predict that the losses of forest trees to sap-feeders will increase by 0-45% of the current level in southern boreal forests and by 65-210% in subarctic forests with a 1 °C increase in summer temperatures. The observed relationships between temperatures and the loads of sap-feeders differ between the coniferous and deciduous tree species. We conclude that climate warming will not only increase plant losses to sap-feeding insects, especially in subarctic forests, but can also alter plant-plant interactions, thereby affecting both the productivity and the structure of future forest ecosystems. PMID

  13. Sap-feeding insects on forest trees along latitudinal gradients in northern Europe: a climate-driven patterns.

    PubMed

    Kozlov, Mikhail V; Stekolshchikov, Andrey V; Söderman, Guy; Labina, Eugenia S; Zverev, Vitali; Zvereva, Elena L

    2015-01-01

    Knowledge of the latitudinal patterns in biotic interactions, and especially in herbivory, is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. We used sap-feeding insects as a model group to test the hypotheses that the strength of plant-herbivore interactions in boreal forests decreases with latitude and that this latitudinal pattern is driven primarily by midsummer temperatures. We used a replicated sampling design and quantitatively collected and identified all sap-feeding insects from four species of forest trees along five latitudinal gradients (750-1300 km in length, ten sites in each gradient) in northern Europe (59 to 70°N and 10 to 60°E) during 2008-2011. Similar decreases in diversity of sap-feeding insects with latitude were observed in all gradients during all study years. The sap-feeder load (i.e. insect biomass per unit of foliar biomass) decreased with latitude in typical summers, but increased in an exceptionally hot summer and was independent of latitude during a warm summer. Analysis of combined data from all sites and years revealed dome-shaped relationships between the loads of sap-feeders and midsummer temperatures, peaking at 17 °C in Picea abies, at 19.5 °C in Pinus sylvestris and Betula pubescens and at 22 °C in B. pendula. From these relationships, we predict that the losses of forest trees to sap-feeders will increase by 0-45% of the current level in southern boreal forests and by 65-210% in subarctic forests with a 1 °C increase in summer temperatures. The observed relationships between temperatures and the loads of sap-feeders differ between the coniferous and deciduous tree species. We conclude that climate warming will not only increase plant losses to sap-feeding insects, especially in subarctic forests, but can also alter plant-plant interactions, thereby affecting both the productivity and the structure of future forest ecosystems.

  14. Exploration Technology Development & Demonstration

    NASA Video Gallery

    Chris Moore delivers a presentation from the Exploration Technology Development & Demonstration (ETDD) study team on May 25, 2010, at the NASA Exploration Enterprise Workshop held in Galveston, TX....

  15. LIMB demonstration project extension

    SciTech Connect

    Not Available

    1990-09-21

    The purpose of the DOE limestone injection multistage burner (LIMB) Demonstration Project Extension is to extend the data base on LIMB technology and to expand DOE's list of Clean Coal Technologies by demonstrating the Coolside process as part of the project. The main objectives of this project are: to demonstrate the general applicability of LIMB technology by testing 3 coals and 4 sorbents (total of 12 coal/sorbent combinations) at the Ohio Edison Edgewater plant; and to demonstrate that Coolside is a viable technology for improving precipitator performance and reducing sulfur dioxide emissions while acceptable operability is maintained. Progress is reported. 3 figs.

  16. Demonstrating Bacterial Flagella.

    ERIC Educational Resources Information Center

    Porter, John R.; And Others

    1992-01-01

    Describes an effective laboratory method for demonstrating bacterial flagella that utilizes the Proteus mirabilis organism and a special harvesting technique. Includes safety considerations for the laboratory exercise. (MDH)

  17. Altitudinal and latitudinal dependence of future warming in an island of multi climate zones: Taiwan as an example

    NASA Astrophysics Data System (ADS)

    Lin, Chuan-yao; Chua, Ying-Jea; sheng, Yang-Fan; Hsu, Huang-Hsiung; Cheng, Chao-Tzuen; Lin, Yi-Yin

    2014-05-01

    In this study, a global model, ECHAM5, and a mesoscale regional model, Weather Research Forecasting (WRF) were combined to perform dynamic downscaling of Taiwan's climate in the recent past (1979-2003) and climate change projection of near and distant future (2015-2039 and 2075-2099, respectively). Simulation results showed close correlation between fine-resolution downscaling by ECHAM5-WRF and the actual observation data for the period 1979-2003. Projection of future climate changes revealed both altitudinal and latitudinal variations in warming trend, with more significant temperature increase in mountain areas than in plain areas toward the end of the 21st century and more obvious warming in the north than in the south of Taiwan. These findings have essential implications on climate impact issues such as mountain ecology and disease transmission. The results obtained in this study can be applied to other regions of similar latitudes and with comparable relief.

  18. Correlation of the Global Photospheric Magnetic Field Structure with the Latitudinal Sunspot Distribution in the solar cycles 23

    NASA Astrophysics Data System (ADS)

    Gavryuseva, E.; Zharkov, S.; Zharkova, V.

    begin table htbp begin center begin tabular p 442pt hline begin itemize item We compare a basic topology of large scale solar magnetic field with newline the distribution of the sunspot activity in latitude and newline in time in the past 2 solar cycles newline The large scale magnetic fields were composed from the data of WSO observatory the sunspot characteristics we extracted for the cycle 23 from the Solar Feature Catalogues underline http solar inf brad ac uk newline newline The magnetic field variations reveal a 4-zonal structure with 22-year periodicity and running waves through the solar latitudes with the two years periods The results are compared with the sunspot latitudinal variations in time and cumulitative variations in the butterfly diagrams The comparison results are used to explain the double peaks and variable character of the solar activity that can be used for its modelling and prediction end itemize hline end tabular label tab6 end center end table

  19. Latitudinal and altitudinal variation of size distribution of stratospheric aerosols inferred from SAGE aerosol extinction coefficient measurements at two wavelengths

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Deepak, A.

    1984-01-01

    A method of retrieving aerosol size distribution from the measured extinction of solar radiation at wavelengths of 0.45 microns and 1.0 microns has recently been proposed. This method is utilized to obtain latitudinal and altitudinal variations of size distributions of stratospheric aerosols from the Stratospheric Aerosol and Gas Experiment data for March 1979. Small particles are found in the lower stratosphere of the tropical region, and large particles are found at higher altitudes and latitudes in both hemispheres. Results of this study are consistent with the suggestion that the upper troposphere in tropical regions is a source of condensation nuclei in the stratosphere, and they become mature as they move to higher altitudes and latitude.

  20. Adaptive population differentiation in phenology across a latitudinal gradient in European aspen (Populus tremula, L.): a comparison of neutral markers, candidate genes and phenotypic traits.

    PubMed

    Hall, David; Luquez, Virginia; Garcia, Victoria M; St Onge, Kate R; Jansson, Stefan; Ingvarsson, Pär K

    2007-12-01

    A correct timing of growth cessation and dormancy induction represents a critical ecological and evolutionary trade-off between survival and growth in most forest trees (Rehfeldt et al. 1999; Horvath et al. 2003; Howe et al. 2003). We have studied the deciduous tree European Aspen (Populus tremula) across a latitudinal gradient and compared genetic differentiation in phenology traits with molecular markers. Trees from 12 different areas covering 10 latitudinal degrees were cloned and planted in two common gardens. Several phenology traits showed strong genetic differentiation and clinal variation across the latitudinal gradient, with Q(ST) values generally exceeding 0.5. This is in stark contrast to genetic differentiation at several classes of genetic markers (18 neutral SSRs, 7 SSRs located close to phenology candidate genes and 50 SNPs from five phenology candidate genes) that all showed F(ST) values around 0.015. We thus find strong evidence for adaptive divergence in phenology traits across the latitudinal gradient. However, the strong population structure seen at the quantitative traits is not reflected in underlying candidate genes. This result fit theoretical expectations that suggest that genetic differentiation at candidate loci is better described by F(ST) at neutral loci rather than by Q(ST) at the quantitative traits themselves.

  1. Demonstrating Phase Changes.

    ERIC Educational Resources Information Center

    Rohr, Walter

    1995-01-01

    Presents two experiments that demonstrate phase changes. The first experiment explores phase changes of carbon dioxide using powdered dry ice sealed in a piece of clear plastic tubing. The second experiment demonstrates an equilibrium process in which a crystal grows in equilibrium with its saturated solution. (PVD)

  2. Levitation Kits Demonstrate Superconductivity.

    ERIC Educational Resources Information Center

    Worthy, Ward

    1987-01-01

    Describes the "Project 1-2-3" levitation kit used to demonstrate superconductivity. Summarizes the materials included in the kit. Discusses the effect demonstrated and gives details on how to obtain kits. Gives an overview of the documentation that is included. (CW)

  3. USFWS demonstration fees

    USGS Publications Warehouse

    Taylor, Jonathan; Vaske, Jerry; Donnelly, Maureen; Shelby, Lori

    2002-01-01

    This study examined National Wildlife Refuge (NWR) visitors' reactions to changes in fees implemented as part of the fee demonstration program. Visitors' evaluations of the fees paid were examined in addition to their beliefs about fees and the fee demonstration program, and the impact of fees paid on their intention to return. All results were analyzed relative to socio-demographic characteristics.

  4. A Stellar Demonstrator

    ERIC Educational Resources Information Center

    Ros, Rosa M.

    2009-01-01

    The main purpose of the stellar demonstrator is to help explain the movement of stars. In particular, students have difficulties understanding why, if they are living in the Northern Hemisphere, they may observe starts in the Southern Hemisphere, or why circumpolar stars are not the same in different parts of Europe. Using the demonstrator, these…

  5. Toy Demonstrator's "VISIT" Handbook.

    ERIC Educational Resources Information Center

    Levenstein, Phyllis

    The role of the toy demonstrator in a home-based, mother-involved intervention effort (Verbal Interaction Project) is presented in this handbook for staff members. It is believed that the prerequisites for functioning in the toy demonstrator's role are a sense of responsibility, patience with the children and their mothers, and willingness to be…

  6. Demonstrating Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Pearlman, Howard; Stocker, Dennis; Gotti, Daniel; Urban, David; Ross, Howard; Sours, Thomas

    1996-01-01

    A miniature drop tower, Reduced-Gravity Demonstrator is developed to illustrate the effects of gravity on a variety of phenomena including the way fluids flow, flames burn, and mechanical systems (such as pendulum) behave. A schematic and description of the demonstrator and payloads are given, followed by suggestions for how one can build his (her) own.

  7. Better Ira Remsen Demonstration

    ERIC Educational Resources Information Center

    Dalby, David K.; Maynard, James H.; Moore, John W.

    2011-01-01

    Many versions of the classic Ira Remsen experience involving copper and concentrated nitric acid have been used as lecture demonstrations. Remsen's original reminiscence from 150 years ago is included in the Supporting Information, and his biography can be found on the Internet. This article presents a new version that makes the demonstration more…

  8. Kinetics and Catalysis Demonstrations.

    ERIC Educational Resources Information Center

    Falconer, John L.; Britten, Jerald A.

    1984-01-01

    Eleven videotaped kinetics and catalysis demonstrations are described. Demonstrations include the clock reaction, oscillating reaction, hydrogen oxidation in air, hydrogen-oxygen explosion, acid-base properties of solids, high- and low-temperature zeolite reactivity, copper catalysis of ammonia oxidation and sodium peroxide decomposition, ammonia…

  9. A Greener Chemiluminescence Demonstration

    ERIC Educational Resources Information Center

    Jilani, Osman; Donahue, Trisha M.; Mitchell, Miguel O.

    2011-01-01

    Because they are dramatic and intriguing, chemiluminescence demonstrations have been used for decades to stimulate interest in chemistry. One of the most intense chemiluminescent reactions is the oxidation of diaryl oxalate diesters with hydrogen peroxide in the presence of a fluorescer. In typical lecture demonstrations, the commercially…

  10. Demonstration Experiments in Physics

    ERIC Educational Resources Information Center

    Sutton, Richard M.

    2003-01-01

    This book represents a "cookbook" for teachers of physics, a book of recipes for the preparation of demonstration experiments to illustrate the principles that make the subject of physics so fascinating. Illustrations and explanations of each demonstration are done in an easy-to-understand format. Each can be adapted to be used as a demonstration…

  11. The Microgravity Demonstrator.

    ERIC Educational Resources Information Center

    Rogers, Melissa J. B.; Wargo, Michael J.

    The Microgravity Demonstrator is a tool used to create microgravity conditions in the classroom. A series of demonstrations is used to provide a dramatically visual, physical connection between free-fall and microgravity conditions in order to understand why various types of experiments are performed under microgravity conditions. The manual is…

  12. Demonstrating Newton's Second Law.

    ERIC Educational Resources Information Center

    Fricker, H. S.

    1994-01-01

    Describes an apparatus for demonstrating the second law of motion. Provides sample data and discusses the merits of this method over traditional methods of supplying a constant force. The method produces empirical best-fit lines which convincingly demonstrate that for a fixed mass, acceleration is proportional to force. (DDR)

  13. A genetically-based latitudinal cline in the emission of herbivore-induced plant volatile organic compounds.

    PubMed

    Wason, Elizabeth L; Agrawal, Anurag A; Hunter, Mark D

    2013-08-01

    The existence of predictable latitudinal variation in plant defense against herbivores remains controversial. A prevailing view holds that higher levels of plant defense evolve at low latitudes compared to high latitudes as an adaptive plant response to higher herbivore pressure on low-latitude plants. To date, this prediction has not been examined with respect to volatile organic compounds (VOCs) that many plants emit, often thus attracting the natural enemies of herbivores. Here, we compared genetically-based constitutive and herbivore-induced aboveground vegetative VOC emissions from plants originating across a gradient of more than 10° of latitude (>1,500 km). We collected headspace VOCs from Asclepias syriaca (common milkweed) originating from 20 populations across its natural range and grown in a common garden near the range center. Feeding by specialist Danaus plexippus (monarch) larvae induced VOCs, and field environmental conditions (temperature, light, and humidity) also influenced emissions. Monarch damage increased plant VOC concentrations and altered VOC blends. We found that genetically-based induced VOC emissions varied with the latitude of plant population origin, although the pattern followed the reverse of that predicted-induced VOC concentration increased with increasing latitude. This pattern appeared to be driven by a greater induction of sesquiterpenoids at higher latitudes. In contrast, constitutive VOC emission did not vary systematically with latitude, and the induction of green leafy volatiles declined with latitude. Our results do not support the prevailing view that plant defense is greater at lower than at higher latitudes. That the pattern holds only for herbivore-induced VOC emission, and not constitutive emission, suggests that latitudinal variation in VOCs is not a simple adaptive response to climatic factors.

  14. The geography of fear: a latitudinal gradient in anti-predator escape distances of birds across Europe.

    PubMed

    Díaz, Mario; Møller, Anders Pape; Flensted-Jensen, Einar; Grim, Tomáš; Ibáñez-Álamo, Juan Diego; Jokimäki, Jukka; Markó, Gábor; Tryjanowski, Piotr

    2013-01-01

    All animals flee from potential predators, and the distance at which this happens is optimized so the benefits from staying are balanced against the costs of flight. Because predator diversity and abundance decreases with increasing latitude, and differs between rural and urban areas, we should expect escape distance when a predator approached the individual to decrease with latitude and depend on urbanization. We measured the distance at which individual birds fled (flight initiation distance, FID, which represents a reliable and previously validated surrogate measure of response to predation risk) following a standardized protocol in nine pairs of rural and urban sites along a ca. 3000 km gradient from Southern Spain to Northern Finland during the breeding seasons 2009-2010. Raptor abundance was estimated by means of standard point counts at the same sites where FID information was recorded. Data on body mass and phylogenetic relationships among bird species sampled were extracted from the literature. An analysis of 12,495 flight distances of 714 populations of 159 species showed that mean FID decreased with increasing latitude after accounting for body size and phylogenetic effects. This decrease was paralleled by a similar cline in an index of the abundance of raptors. Urban populations had consistently shorter FIDs, supporting previous findings. The difference between rural and urban habitats decreased with increasing latitude, also paralleling raptor abundance trends. Overall, the latitudinal gradient in bird fear was explained by raptor abundance gradients, with additional small effects of latitude and intermediate effects of habitat. This study provides the first empirical documentation of a latitudinal trend in anti-predator behavior, which correlated positively with a similar trend in the abundance of predators.

  15. The geography of fear: a latitudinal gradient in anti-predator escape distances of birds across Europe.

    PubMed

    Díaz, Mario; Møller, Anders Pape; Flensted-Jensen, Einar; Grim, Tomáš; Ibáñez-Álamo, Juan Diego; Jokimäki, Jukka; Markó, Gábor; Tryjanowski, Piotr

    2013-01-01

    All animals flee from potential predators, and the distance at which this happens is optimized so the benefits from staying are balanced against the costs of flight. Because predator diversity and abundance decreases with increasing latitude, and differs between rural and urban areas, we should expect escape distance when a predator approached the individual to decrease with latitude and depend on urbanization. We measured the distance at which individual birds fled (flight initiation distance, FID, which represents a reliable and previously validated surrogate measure of response to predation risk) following a standardized protocol in nine pairs of rural and urban sites along a ca. 3000 km gradient from Southern Spain to Northern Finland during the breeding seasons 2009-2010. Raptor abundance was estimated by means of standard point counts at the same sites where FID information was recorded. Data on body mass and phylogenetic relationships among bird species sampled were extracted from the literature. An analysis of 12,495 flight distances of 714 populations of 159 species showed that mean FID decreased with increasing latitude after accounting for body size and phylogenetic effects. This decrease was paralleled by a similar cline in an index of the abundance of raptors. Urban populations had consistently shorter FIDs, supporting previous findings. The difference between rural and urban habitats decreased with increasing latitude, also paralleling raptor abundance trends. Overall, the latitudinal gradient in bird fear was explained by raptor abundance gradients, with additional small effects of latitude and intermediate effects of habitat. This study provides the first empirical documentation of a latitudinal trend in anti-predator behavior, which correlated positively with a similar trend in the abundance of predators. PMID:23724070

  16. Insect herbivores associated with Baccharis dracunculifolia (Asteraceae): responses of gall-forming and free-feeding insects to latitudinal variation.

    PubMed

    Fagundes, Marcílio; Fernandes, G Wilson

    2011-09-01

    The spatial heterogeneity hypothesis has been invoked to explain the increase in species diversity from the poles to the tropics: the tropics may be more diverse because they contain more habitats and micro-habitats. In this paper, the spatial heterogeneity hypothesis prediction was tested by evaluating the variation in richness of two guilds of insect herbivores (gall-formers and free-feeders) associated with Baccharis dracunculifolia (Asteraceae) along a latitudinal variation in Brazil. The seventeen populations of B. dracunculifolia selected for insect herbivores sampling were within structurally similar habitats, along the N-S distributional limit of the host plant, near the Brazilian sea coast. Thirty shrubs were surveyed in each host plant population. A total of 8 201 galls and 864 free-feeding insect herbivores belonging to 28 families and 88 species were sampled. The majority of the insects found on B. dracunculifolia were restricted to a specific site rather than having a geographic distribution mirroring that of the host plant. Species richness of free-feeding insects was not affected by latitudinal variation corroborating the spatial heterogeneity hypothesis. Species richness of gall-forming insects was positively correlated with latitude, probably because galling insect associated with Baccharris genus radiated in Southern Brazil. Other diversity indices and evenness estimated for both gall-forming and free feeding insect herbivores, did not change with latitude, suggesting a general structure for different assemblages of herbivores associated with the host plant B. dracunculifolia. Thus it is probable that, insect fauna sample in each site resulted of large scale events, as speciation, migration and coevolution, while at local level, the population of these insects is regulated by ecological forces which operate in the system. PMID:22017142

  17. Thermal tolerance in the Andean toad Rhinella spinulosa (Anura: Bufonidae) at three sites located along a latitudinal gradient in Chile.

    PubMed

    Riquelme, Nicza Alveal; Díaz-Páez, Helen; Ortiz, Juan Carlos

    2016-08-01

    Rhinella spinulosa is one of the anuran species with the greatest presence in Chile. This species mainly inhabits mountain habitats and is distributed latitudinally along the western slope of the Andes Range. These habitats undergo great temperature fluctuations, exerting pressure on the amphibian. To identify the physiological strategies and thermal behavior of this species, we analyzed the temperature variables CTmin, CTmax, TTR, τheat, and τcool in individuals of three sites from a latitudinal gradient (22°S to 37°S). The amphibians were acclimated to 10°C and 20°C and fed ad libitum. The results indicate that the species has a high thermal tolerance range, with a mean of 38.14±1.34°C, a critical thermal maxima of 34.6-41.4°C, and a critical thermal minima of 2.6-0.8°C, classifying the species as eurythermic. Furthermore, there were significant differences in CTmáx and TTR only in the northern site. The differences in thermal time constants between sites are due to the effects of size and body mass. For example, those from the central site had larger size and greater thermal inertia; therefore, they warmed and cooled in a slower manner. The wide thermal limits determined in R. spinulosa confirm that it is a thermo-generalist species, a characteristic that allows the species to survive in adverse microclimatic conditions. The level of plasticity in critical temperatures seems ecologically relevant and supports the acclimatization of thermal limits as an important factor for ectothermic animals to adapt to climate change.

  18. Latitudinal exposure to DDTs, HCB, PCBs, PBDEs and DP in giant petrels (Macronectes spp.) across the Southern Ocean.

    PubMed

    Roscales, Jose L; González-Solís, Jacob; Zango, Laura; Ryan, Peter G; Jiménez, Begoña

    2016-07-01

    Studies on Persistent Organic Pollutants (POPs) in Antarctic wildlife are scarce, and usually limited to a single locality. As a result, wildlife exposure to POPs across the Southern Ocean is poorly understood. In this study, we report the differential exposure of the major southern ocean scavengers, the giant petrels, to POPs across a wide latitudinal gradient. Selected POPs (PCBs, HCB, DDTs, PBDEs) and related compounds, such as Dechlorane Plus (DP), were analyzed in plasma of southern giant petrels (Macronectes giganteus) breeding on Livingston (62°S 61°W, Antarctica), Marion (46°S 37°E, sub-Antarctic), and Gough (40°S 10°W, cool temperate) islands. Northern giant petrels (Macronectes halli) from Marion Island were also studied. Stable isotope ratios of C and N (δ(13)C and δ(15)N) were used as dietary tracers of the marine habitat and trophic level, respectively. Breeding locality was a major factor explaining petrel exposure to POPs compared with species and sex. Significant relationships between δ(13)C values and POP burdens, at both inter- and intra-population levels, support latitudinal variations in feeding grounds as a key factor in explaining petrel pollutant burdens. Overall, pollutant levels in giant petrels decreased significantly with latitude, but the relative abundance (%) of the more volatile POPs increased towards Antarctica. DP was found at negligible levels compared with legacy POPs in Antarctic seabirds. Spatial POP patterns found in giant petrels match those predicted by global distribution models, and reinforce the hypothesis of atmospheric long-range transport as the main source of POPs in Antarctica. Our results confirm that wildlife movements out of the polar region markedly increase their exposure to POPs. Therefore, strategies for Antarctic wildlife conservation should consider spatial heterogeneity in exposure to marine pollution. Of particular relevance is the need to clarify the exposure of Antarctic predators to emerging

  19. Insect herbivores associated with Baccharis dracunculifolia (Asteraceae): responses of gall-forming and free-feeding insects to latitudinal variation.

    PubMed

    Fagundes, Marcílio; Fernandes, G Wilson

    2011-09-01

    The spatial heterogeneity hypothesis has been invoked to explain the increase in species diversity from the poles to the tropics: the tropics may be more diverse because they contain more habitats and micro-habitats. In this paper, the spatial heterogeneity hypothesis prediction was tested by evaluating the variation in richness of two guilds of insect herbivores (gall-formers and free-feeders) associated with Baccharis dracunculifolia (Asteraceae) along a latitudinal variation in Brazil. The seventeen populations of B. dracunculifolia selected for insect herbivores sampling were within structurally similar habitats, along the N-S distributional limit of the host plant, near the Brazilian sea coast. Thirty shrubs were surveyed in each host plant population. A total of 8 201 galls and 864 free-feeding insect herbivores belonging to 28 families and 88 species were sampled. The majority of the insects found on B. dracunculifolia were restricted to a specific site rather than having a geographic distribution mirroring that of the host plant. Species richness of free-feeding insects was not affected by latitudinal variation corroborating the spatial heterogeneity hypothesis. Species richness of gall-forming insects was positively correlated with latitude, probably because galling insect associated with Baccharris genus radiated in Southern Brazil. Other diversity indices and evenness estimated for both gall-forming and free feeding insect herbivores, did not change with latitude, suggesting a general structure for different assemblages of herbivores associated with the host plant B. dracunculifolia. Thus it is probable that, insect fauna sample in each site resulted of large scale events, as speciation, migration and coevolution, while at local level, the population of these insects is regulated by ecological forces which operate in the system.

  20. Abundance of Two Pelagibacter ubique Bacteriophage Genotypes along a Latitudinal Transect in the North and South Atlantic Oceans

    PubMed Central

    Eggleston, Erin M.; Hewson, Ian

    2016-01-01

    This study characterizes viral and bacterial dynamics along a latitudinal transect in the Atlantic Ocean from approximately 10 N–40 S. Overall viral abundance decreased with depth, on average there were 1.64 ± 0.71 × 107 virus like particles (VLPs) in surface waters, decreasing to an average of 6.50 ± 2.26 × 105 VLPs in Antarctic Bottom Water. This decrease was highly correlated to bacterial abundance. There are six major water masses in the Southern Tropical Atlantic Ocean, and inclusion of water mass, temperature and salinity variables explained a majority of the variation in total viral abundance. Recent discovery of phages infecting bacteria of the SAR11 clade of Alphaproteobacteria (i.e., pelagiphages) leads to intriguing questions about the roles they play in shaping epipelagic communities. Viral-size fraction DNA from epipelagic water was used to quantify the abundance of two pelagiphages, using pelagiphage-specific quantitative PCR primers and probes along the transect. We found that HTVC010P, a member of a podoviridae sub-family, was most abundant in surface waters. Copy numbers ranged from an average of 1.03 ± 2.38 × 105 copies ml−1 in surface waters, to 5.79 ± 2.86 × 103 in the deep chlorophyll maximum. HTVC008M, a T4-like myovirus, was present in the deep chlorophyll maximum (5.42 ± 2.8 × 103 copies ml−1 on average), although it was not as highly abundant as HTVC010P in surface waters (6.05 ± 3.01 × 103 copies ml−1 on average). Interestingly, HTVC008M was only present at a few of the most southern stations, suggesting latitudinal biogeography of SAR11 phages. PMID:27733846

  1. Thermal tolerance in the Andean toad Rhinella spinulosa (Anura: Bufonidae) at three sites located along a latitudinal gradient in Chile.

    PubMed

    Riquelme, Nicza Alveal; Díaz-Páez, Helen; Ortiz, Juan Carlos

    2016-08-01

    Rhinella spinulosa is one of the anuran species with the greatest presence in Chile. This species mainly inhabits mountain habitats and is distributed latitudinally along the western slope of the Andes Range. These habitats undergo great temperature fluctuations, exerting pressure on the amphibian. To identify the physiological strategies and thermal behavior of this species, we analyzed the temperature variables CTmin, CTmax, TTR, τheat, and τcool in individuals of three sites from a latitudinal gradient (22°S to 37°S). The amphibians were acclimated to 10°C and 20°C and fed ad libitum. The results indicate that the species has a high thermal tolerance range, with a mean of 38.14±1.34°C, a critical thermal maxima of 34.6-41.4°C, and a critical thermal minima of 2.6-0.8°C, classifying the species as eurythermic. Furthermore, there were significant differences in CTmáx and TTR only in the northern site. The differences in thermal time constants between sites are due to the effects of size and body mass. For example, those from the central site had larger size and greater thermal inertia; therefore, they warmed and cooled in a slower manner. The wide thermal limits determined in R. spinulosa confirm that it is a thermo-generalist species, a characteristic that allows the species to survive in adverse microclimatic conditions. The level of plasticity in critical temperatures seems ecologically relevant and supports the acclimatization of thermal limits as an important factor for ectothermic animals to adapt to climate change. PMID:27503738

  2. A genetically-based latitudinal cline in the emission of herbivore-induced plant volatile organic compounds.

    PubMed

    Wason, Elizabeth L; Agrawal, Anurag A; Hunter, Mark D

    2013-08-01

    The existence of predictable latitudinal variation in plant defense against herbivores remains controversial. A prevailing view holds that higher levels of plant defense evolve at low latitudes compared to high latitudes as an adaptive plant response to higher herbivore pressure on low-latitude plants. To date, this prediction has not been examined with respect to volatile organic compounds (VOCs) that many plants emit, often thus attracting the natural enemies of herbivores. Here, we compared genetically-based constitutive and herbivore-induced aboveground vegetative VOC emissions from plants originating across a gradient of more than 10° of latitude (>1,500 km). We collected headspace VOCs from Asclepias syriaca (common milkweed) originating from 20 populations across its natural range and grown in a common garden near the range center. Feeding by specialist Danaus plexippus (monarch) larvae induced VOCs, and field environmental conditions (temperature, light, and humidity) also influenced emissions. Monarch damage increased plant VOC concentrations and altered VOC blends. We found that genetically-based induced VOC emissions varied with the latitude of plant population origin, although the pattern followed the reverse of that predicted-induced VOC concentration increased with increasing latitude. This pattern appeared to be driven by a greater induction of sesquiterpenoids at higher latitudes. In contrast, constitutive VOC emission did not vary systematically with latitude, and the induction of green leafy volatiles declined with latitude. Our results do not support the prevailing view that plant defense is greater at lower than at higher latitudes. That the pattern holds only for herbivore-induced VOC emission, and not constitutive emission, suggests that latitudinal variation in VOCs is not a simple adaptive response to climatic factors. PMID:23888386

  3. Inherited variability in multiple traits determines fitness in populations of an annual legume from contrasting latitudinal origins

    PubMed Central

    Milla, Rubén; Escudero, Adrián; Iriondo, Jose María

    2009-01-01

    Background and Aims Variation in fitness depends on corresponding variation in multiple traits which have both genetically controlled and plastic components. These traits are subjected to varying degrees of local adaptation in specific populations and, consequently, are genetically controlled to different extents. In this study it is hypothesized that modulation of different traits would have contrasting relevance for the fitness of populations of diverse origins. Specifically, assuming that environmental pressures vary across a latitudinal gradient, it is suggested that inherited variation in traits differentially determines fitness in annual Lupinus angustifolius populations from contrasting latitudinal origins in western Spain. Methods Seeds of L. angustifolius from three contrasting origins were grown in a common garden. Traits related to more plastic vegetative growth and more genetically conserved phenology were measured, together with estimates of reproductive success. Fitness was estimated by the number of viable seeds per plant. Structural Equation Models were used to infer causal relationships among multiple traits and fitness, separating the direct and indirect effects of morphological, phenological and reproductive traits. Key Results Phenological, vegetative and reproductive traits accounted for most of the fitness variation. Fitness was highest in plants of southernmost origin, mainly due to earlier flowering. Fitness within each seed origin was controlled by variation in different traits. Southern origin plants that grew to a larger size achieved higher fitness. However, plant size in plants of northernmost origin was irrelevant, but early flowering promoted higher fitness. Variation in fruit and seed set had a greater effect on the fitness of plants of central origin than phenological and size variation. Conclusions It is concluded that modulation of a functional trait can be relevant to fitness in a given population (i.e. affecting intensity and

  4. Osmoregulatory capacity and the ability to use marine food sources in two coastal songbirds (Cinclodes: Furnariidae) along a latitudinal gradient.

    PubMed

    Sabat, Pablo; Maldonado, Karin; Fariña, Jose Miguel; del Rio, Carlos Martínez

    2006-06-01

    Cinclodes nigrofumosus and C. oustaleti are two closely related songbirds that inhabit the northern Chilean coast during the austral fall and winter. This stretch spans a dramatic north to south latitudinal gradient in rainfall and temperature. Whereas C. nigrofumosus lives exclusively on coastal environments, C. oustaleti shifts seasonally from coastal environments to inland freshwater ones. We used the delta13C of these two species' tissues to investigate whether the reliance on marine versus terrestrial sources varied from the hyper-arid north to the wet south. We also investigated latitudinal variation in the renal traits that mediate how these birds cope with dehydration and a salty marine diet. Both species increased the incorporation of terrestrial carbon, as measured by delta13C, as terrestrial productivity increased southwards. However, C. nigrofumosus had consistently more positive (i.e. more marine) and less variable delta13C values than C. oustaleti. The osmoregulatory traits of both species varied with latitude as well. Urine osmolality decreased from extremely high values in the north to moderate values in the south, while C. nigrofumosus produced more concentrated urine than C. oustaleti. In both species, the proportion of kidney devoted to medullary tissue decreased from north to south, and kidney size increased significantly with latitude. Cinclodes nigrofumosus had larger kidneys with larger proportions of medullary tissue than C. oustaleti. C. nigrofumosus and C. oustaleti are terrestrial organisms subsidized by a rich marine environment where it is adjacent to an unproductive terrestrial. Variation in the reliance on marine food sources seems to be accompanied by adjustments in the osmoregulatory mechanisms used by these birds to cope with salt and dehydration. PMID:16496181

  5. Latitudinal exposure to DDTs, HCB, PCBs, PBDEs and DP in giant petrels (Macronectes spp.) across the Southern Ocean.

    PubMed

    Roscales, Jose L; González-Solís, Jacob; Zango, Laura; Ryan, Peter G; Jiménez, Begoña

    2016-07-01

    Studies on Persistent Organic Pollutants (POPs) in Antarctic wildlife are scarce, and usually limited to a single locality. As a result, wildlife exposure to POPs across the Southern Ocean is poorly understood. In this study, we report the differential exposure of the major southern ocean scavengers, the giant petrels, to POPs across a wide latitudinal gradient. Selected POPs (PCBs, HCB, DDTs, PBDEs) and related compounds, such as Dechlorane Plus (DP), were analyzed in plasma of southern giant petrels (Macronectes giganteus) breeding on Livingston (62°S 61°W, Antarctica), Marion (46°S 37°E, sub-Antarctic), and Gough (40°S 10°W, cool temperate) islands. Northern giant petrels (Macronectes halli) from Marion Island were also studied. Stable isotope ratios of C and N (δ(13)C and δ(15)N) were used as dietary tracers of the marine habitat and trophic level, respectively. Breeding locality was a major factor explaining petrel exposure to POPs compared with species and sex. Significant relationships between δ(13)C values and POP burdens, at both inter- and intra-population levels, support latitudinal variations in feeding grounds as a key factor in explaining petrel pollutant burdens. Overall, pollutant levels in giant petrels decreased significantly with latitude, but the relative abundance (%) of the more volatile POPs increased towards Antarctica. DP was found at negligible levels compared with legacy POPs in Antarctic seabirds. Spatial POP patterns found in giant petrels match those predicted by global distribution models, and reinforce the hypothesis of atmospheric long-range transport as the main source of POPs in Antarctica. Our results confirm that wildlife movements out of the polar region markedly increase their exposure to POPs. Therefore, strategies for Antarctic wildlife conservation should consider spatial heterogeneity in exposure to marine pollution. Of particular relevance is the need to clarify the exposure of Antarctic predators to emerging

  6. Demonstrating Natural Selection

    ERIC Educational Resources Information Center

    Hinds, David S.; Amundson, John C.

    1975-01-01

    Describes laboratory exercises with chickens selecting their food from dyed and natural corn kernels as a method of demonstrating natural selection. The procedure is based on the fact that organisms that blend into their surroundings escape predation. (BR)

  7. Flagship Technology Demonstrations (FTD)

    NASA Video Gallery

    Mike Conley delivers a presentation from the Flagship Technology Demonstrations (FTD) study team on May 25, 2010, at the NASA Exploration Enterprise Workshop held in Galveston, TX. The purpose of t...

  8. Technology Demonstration Missions

    NASA Video Gallery

    NASA's Technology Demonstration Missions (TDM) Program seeks to infuse new technology into space applications, bridging the gap between mature “lab-proven” technology and "flight-ready" status....

  9. Floating Magnet Demonstration.

    ERIC Educational Resources Information Center

    Wake, Masayoshi

    1990-01-01

    A room-temperature demonstration of a floating magnet using a high-temperature superconductor is described. The setup and operation of the apparatus are described. The technical details of the effect are discussed. (CW)

  10. Spacecraft servicing demonstration plan

    NASA Technical Reports Server (NTRS)

    Bergonz, F. H.; Bulboaca, M. A.; Derocher, W. L., Jr.

    1984-01-01

    A preliminary spacecraft servicing demonstration plan is prepared which leads to a fully verified operational on-orbit servicing system based on the module exchange, refueling, and resupply technologies. The resulting system can be applied at the space station, in low Earth orbit with an orbital maneuvering vehicle (OMV), or be carried with an OMV to geosynchronous orbit by an orbital transfer vehicle. The three phase plan includes ground demonstrations, cargo bay demonstrations, and free flight verifications. The plan emphasizes the exchange of multimission modular spacecraft (MMS) modules which involves space repairable satellites. Three servicer mechanism configurations are the engineering test unit, a protoflight quality unit, and two fully operational units that have been qualified and documented for use in free flight verification activity. The plan balances costs and risks by overlapping study phases, utilizing existing equipment for ground demonstrations, maximizing use of existing MMS equipment, and rental of a spacecraft bus.

  11. EVA Retriever Demonstration

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The EVA retriever is demonstrated in the Manipulator Development Facility (MDF). The retriever moves on the air bearing table 'searching' for its target, in this case tools 'dropped' by astronauts on orbit.

  12. Commissioning the Majorana Demonstrator

    NASA Astrophysics Data System (ADS)

    Xu, Wenqin; Majorana Collaboration

    2016-03-01

    The Majorana Demonstrator deploys high purity germanium (HPGe) detector modules to search for neutrinoless double beta (0 νββ) decay in 76Ge. The experiment is aimed at demonstrating the technical feasibility and low backgrounds for a next generation Ge-based BBz experiment. The program of testing and commissioning the Demonstrator modules is a critical step to debug and improve the experimental apparatus, to establish and refine operational procedures, and to develop data analysis tools. In this talk, we will discuss our experience commissioning the Demonstrator modules and show how this program leads to successful data-taking. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

  13. Methanol Cannon Demonstrations Revisited.

    ERIC Educational Resources Information Center

    Dolson, David A.; And Others

    1995-01-01

    Describes two variations on the traditional methanol cannon demonstration. The first variation is a chain reaction using real metal chains. The second example involves using easily available components to produce sequential explosions that can be musical in nature. (AIM)

  14. Five amazing physics demonstrations

    NASA Astrophysics Data System (ADS)

    Downie, Neil

    2015-04-01

    There's nothing better than a good physics demonstration to illustrate the subject's fundamental principles. Neil Downie, who has run Saturday science clubs for children for more than two decades, presents his five best demos of all time.

  15. Demonstration of Surface Tension.

    ERIC Educational Resources Information Center

    Rosenthal, Andrew J.

    2001-01-01

    Surface tension is a fundamental obstacle in the spontaneous formation of bubbles, droplets, and crystal nuclei in liquids. Describes a simple overhead projector demonstration that illustrates the power of surface tension that can prevent so many industrial processes. (ASK)

  16. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Hambly, Gordon F.; Goldsmith, Robert H.

    1988-01-01

    Presented is a method of demonstrating the optical activity of glucose using an overhead projector and easily obtainable materials. Explores the difference between reflected and transmitted light (Tyndall Effect) using sodium thiosulfate, hydrochloric acid, and an overhead projector. (ML)

  17. Classroom Demonstration of Sunspots.

    ERIC Educational Resources Information Center

    Callaway, Thomas O.; And Others

    1982-01-01

    An overhead projector, projection screen, and clear tungsten Filament light bulb operated through a dimmer or variac switch are used to demonstrate the fact that black appearance of sunspots is due only to contrast and that sunspots are bright. (SK)

  18. Remote Agent Demonstration

    NASA Technical Reports Server (NTRS)

    Dorais, Gregory A.; Kurien, James; Rajan, Kanna

    1999-01-01

    We describe the computer demonstration of the Remote Agent Experiment (RAX). The Remote Agent is a high-level, model-based, autonomous control agent being validated on the NASA Deep Space 1 spacecraft.

  19. Education Payload Operation - Demonstrations

    NASA Technical Reports Server (NTRS)

    Keil, Matthew

    2009-01-01

    Education Payload Operation - Demonstrations (EPO-Demos) are recorded video education demonstrations performed on the International Space Station (ISS) by crewmembers using hardware already onboard the ISS. EPO-Demos are videotaped, edited, and used to enhance existing NASA education resources and programs for educators and students in grades K-12. EPO-Demos are designed to support the NASA mission to inspire the next generation of explorers.

  20. Edible Astronomy Demonstrations

    NASA Astrophysics Data System (ADS)

    Lubowich, Donald A.

    2007-12-01

    Astronomy demonstrations with edible ingredients are an effective way to increase student interest and knowledge of astronomical concepts. This approach has been successful with all age groups from elementary school through college students - and the students remember these demonstrations after they are presented. In this poster I describe edible demonstrations I have created to simulate the expansion of the universe (using big-bang chocolate chip cookies); differentiation during the formation of the Earth and planets (using chocolate or chocolate milk with marshmallows, cereal, candy pieces or nuts); and radioactivity/radioactive dating (using popcorn). Other possible demonstrations include: plate tectonics (crackers with peanut butter and jelly); convection (miso soup or hot chocolate); mud flows on Mars (melted chocolate poured over angel food cake); formation of the Galactic disk (pizza); formation of spiral arms (coffee with cream); the curvature of Space (Pringles); constellations patterns with chocolate chips and chocolate chip cookies; planet shaped cookies; star shaped cookies with different colored frostings; coffee or chocolate milk measurement of solar radiation; Oreo cookie lunar phases. Sometimes the students eat the results of the astronomical demonstrations. These demonstrations are an effective teaching tool and can be adapted for cultural, culinary, and ethnic differences among the students.

  1. Demonstrations in Introductory Geophysics

    NASA Astrophysics Data System (ADS)

    Schramm, K. A.; Stein, S.; van der Lee, S.; Swafford, L.; Klosko, E.; Delaughter, J.; Wysession, M.

    2005-12-01

    Geophysical concepts are challenging to teach at introductory levels, because students need to understand both the underlying physics and its geological application. To address this, our introductory courses include class demonstrations and experiments to demonstrate underlying physical principles and their geological applications. Demonstrations and experiments have several advantages over computer simulations. First, computer simulations "work" even if the basic principle is wrong. In contrast, simple demonstrations show that a principle is physically correct, rather than a product of computer graphics. Second, many students are unfamiliar with once-standard experiments demonstrating ideas of classical physics used in geophysics. Demonstrations are chosen that we consider stimulating, relevant, inexpensive, and easy to conduct in a non-lab classroom. These come in several groups. Many deal with aspects of seismic waves, using springs, light beams, and other methods such as talking from outside the room to illustrate the frequency dependence of diffraction (hearing but not seeing around a corner). Others deal with heat and mass transfer, such as illustrating fractional crystallization with apple juice and the surface/volume effect in planetary evolution with ice. Plate motions are illustrated with paper cutouts showing effects like motion on transform faults and how the Euler vector geometry changes a plate boundary from spreading, to strike-slip, to convergence along the Pacific-North America boundary from the Gulf of California to Alaska. Radioactive decay is simulated by having the class rise and sit down as a result of coin flips (one tail versus two gives different decay rates and hence half lives). This sessions' goal of exchanging information about demonstrations is an excellent idea: some of ours are described on http://www.earth.nwu.edu/people/seth/202.

  2. Dealer model site demonstrations

    SciTech Connect

    Mann, H.C.

    1992-08-01

    Model site demonstrations are joint efforts between TVA and cooperating organizations to improve the industry's environmental stewardship. Program objectives are to develop, demonstrate, and transfer technologies and management practices to help retail fertilizer/agricultural chemical dealers minimize adverse environmental impacts. The model site demonstrations serve as 'real life' laboratories for researchers, technologists, educators and participants. The retail dealership is treated as a complete unit. The program recognizes the need to: Develop information and experience to guide others; Test numerous methods of containment, materials of construction, management practices, and monitoring techniques; Strengthen and highlight industry's commitment to envirorunental stewardship; Identify future research needs; and Provide a catalyst for cooperation across a broad spectrum of groups and organizations to identify problems and develop solutions appropriate for fertilizer and agrichemical dealers. Emphasis is on transferring current technology and developing and introducing needed new technologies. Field testing and applied research are encouraged at demonstration sites. One of the key concepts is to bridge the gap between research findings and their practical application and evaluation in field settings. Primary audiences include fertilizer dealers and professional workers in agriculture, the fertilizer industry, the environmental arena, and related institutions across the nation. Experiences at participating dealer sites are shared through organized tours, open houses, news articles and publications. Sixteen sites have been selected for demonstrations, and at least four more are planned. TVA provides assistance in engineering, design and educational forums. Dealers pay for installation of needed containment and related features.

  3. TRUEX hot demonstration

    SciTech Connect

    Chamberlain, D.B.; Leonard, R.A.; Hoh, J.C.; Gay, E.C.; Kalina, D.G.; Vandegrift, G.F.

    1990-04-01

    In FY 1987, a program was initiated to demonstrate technology for recovering transuranic (TRU) elements from defense wastes. This hot demonstration was to be carried out with solution from the dissolution of irradiated fuels. This recovery would be accomplished with both PUREX and TRUEX solvent extraction processes. Work planned for this program included preparation of a shielded-cell facility for the receipt and storage of spent fuel from commercial power reactors, dissolution of this fuel, operation of a PUREX process to produce specific feeds for the TRUEX process, operation of a TRUEX process to remove residual actinide elements from PUREX process raffinates, and processing and disposal of waste and product streams. This report documents the work completed in planning and starting up this program. It is meant to serve as a guide for anyone planning similar demonstrations of TRUEX or other solvent extraction processing in a shielded-cell facility.

  4. Demonstrating marketing accountability.

    PubMed

    Gombeski, William R; Britt, Jason; Taylor, Jan; Riggs, Karen; Wray, Tanya; Adkins, Wanda; Springate, Suzanne

    2008-01-01

    Pressure on health care marketers to demonstrate effectiveness of their strategies and show their contribution to organizational goals is growing. A seven-tiered model based on the concepts of structure (having the right people, systems), process (doing the right things in the right way), and outcomes (results) is discussed. Examples of measures for each tier are provided and the benefits of using the model as a tool for measuring, organizing, tracking, and communicating appropriate information are provided. The model also provides a framework for helping management understand marketing's value and can serve as a vehicle for demonstrating marketing accountability.

  5. Gigashot Optical Laser Demonstrator

    SciTech Connect

    Deri, R. J.

    2015-10-13

    The Gigashot Optical Laser Demonstrator (GOLD) project has demonstrated a novel optical amplifier for high energy pulsed lasers operating at high repetition rates. The amplifier stores enough pump energy to support >10 J of laser output, and employs conduction cooling for thermal management to avoid the need for expensive and bulky high-pressure helium subsystems. A prototype amplifier was fabricated, pumped with diode light at 885 nm, and characterized. Experimental results show that the amplifier provides sufficient small-signal gain and sufficiently low wavefront and birefringence impairments to prove useful in laser systems, at repetition rates up to 60 Hz.

  6. Organic Lecture Demonstrations.

    ERIC Educational Resources Information Center

    Silversmith, Ernest F.

    1988-01-01

    Provides a listing of 35 demonstrations designed to generate interest in organic chemistry and help put points across. Topics include opening lecture; molecular structure and properties; halogenation; nucleophilic substitution, alkenes and dienes, stereochemistry, spectroscopy, alcohols and phenols, aldehydes and ketones; carboxylic acids, amines,…

  7. Calculus Demonstrations Using MATLAB

    ERIC Educational Resources Information Center

    Dunn, Peter K.; Harman, Chris

    2002-01-01

    The note discusses ways in which technology can be used in the calculus learning process. In particular, five MATLAB programs are detailed for use by instructors or students that demonstrate important concepts in introductory calculus: Newton's method, differentiation and integration. Two of the programs are animated. The programs and the…

  8. A Magnetic Circuit Demonstration.

    ERIC Educational Resources Information Center

    Vanderkooy, John; Lowe, June

    1995-01-01

    Presents a demonstration designed to illustrate Faraday's, Ampere's, and Lenz's laws and to reinforce the concepts through the analysis of a two-loop magnetic circuit. Can be made dramatic and challenging for sophisticated students but is suitable for an introductory course in electricity and magnetism. (JRH)

  9. Participatory Lecture Demonstrations.

    ERIC Educational Resources Information Center

    Battino, Rubin

    1979-01-01

    The use of participatory lecture demonstrations in the classroom is described. Examples are given for the following topics: chromatography, chemical kinetics, balancing equations, the gas laws, kinetic molecular theory, Henry's law of gas solubility, electronic energy levels in atoms, and translational, vibrational, and rotational energies of…

  10. Demonstrating carbon capture

    SciTech Connect

    Qader, A.; Hooper, B.; Stevens, G.

    2009-11-15

    Australia is at the forefront of advancing CCS technology. The CO2CRC's H3 (Post-combustion) and Mulgrave (pre-combustion) capture projects are outlined. The capture technologies for these 2 demonstration projects are described. 1 map., 2 photos.

  11. Demonstrating Poisson Statistics.

    ERIC Educational Resources Information Center

    Vetterling, William T.

    1980-01-01

    Describes an apparatus that offers a very lucid demonstration of Poisson statistics as applied to electrical currents, and the manner in which such statistics account for shot noise when applied to macroscopic currents. The experiment described is intended for undergraduate physics students. (HM)

  12. Passive damping technology demonstration

    NASA Astrophysics Data System (ADS)

    Holman, Robert E.; Spencer, Susan M.; Austin, Eric M.; Johnson, Conor D.

    1995-05-01

    A Hughes Space Company study was undertaken to (1) acquire the analytical capability to design effective passive damping treatments and to predict the damped dynamic performance with reasonable accuracy; (2) demonstrate reasonable test and analysis agreement for both baseline and damped baseline hardware; and (3) achieve a 75% reduction in peak transmissibility and 50% reduction in rms random vibration response. Hughes Space Company teamed with CSA Engineering to learn how to apply passive damping technology to their products successfully in a cost-effective manner. Existing hardware was selected for the demonstration because (1) previous designs were lightly damped and had difficulty in vibration test; (2) multiple damping concepts could be investigated; (3) the finite element model, hardware, and test fixture would be available; and (4) damping devices could be easily implemented. Bracket, strut, and sandwich panel damping treatments that met the performance goals were developed by analysis. The baseline, baseline with damped bracket, and baseline with damped strut designs were built and tested. The test results were in reasonable agreement with the analytical predictions and demonstrated that the desired reduction in dynamic response could be achieved. Having successfully demonstrated this approach, it can now be used with confidence for future designs as a means for reducing weight and enhancing reliability.

  13. The "Golden Penny" Demonstration.

    ERIC Educational Resources Information Center

    Szczepankiewicz, Steven H.; And Others

    1995-01-01

    Presents the view that the explanation of the Golden Penny Experiment found in popular chemistry textbooks is insufficient or incorrect in part. Reports a series of electrochemical measurements that lead to a logical explanation for this demonstration and to a simplified design that makes it safer. (DDR)

  14. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris, Ed.

    1988-01-01

    Provides two demonstrations: (1) electrolyte migration of ions using colored ions which cross a strip of gelatin allowing for noticeable migration; and (2) photochemical reduction of Fe+3 by the citrate ion. Points out both reactions can be done in a Petri dish using common lab materials. (MVL)

  15. Astronomy Demonstrations and Models.

    ERIC Educational Resources Information Center

    Eckroth, Charles A.

    Demonstrations in astronomy classes seem to be more necessary than in physics classes for three reasons. First, many of the events are very large scale and impossibly remote from human senses. Secondly, while physics courses use discussions of one- and two-dimensional motion, three-dimensional motion is the normal situation in astronomy; thus,…

  16. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris, Ed.

    1989-01-01

    Described are three chemistry demonstrations: (1) a simple qualitative technique for taste pattern recognition in structure-activity relationships; (2) a microscale study of gaseous diffusion using bleach, HCl, ammonia, and phenolphthalein; and (3) the rotation of polarized light by stereoisomers of limonene. (MVL)

  17. Why Demonstrations Matter

    ERIC Educational Resources Information Center

    Black, Richard

    2005-01-01

    The author remembers how exciting it was when the teacher had "stuff" on the front desk: unfamiliar objects and other things out of place in the traditional classroom. Years later, as a new teacher, the author learned the importance of building lessons around concepts and that demonstrations are an integral part of concept development in science.…

  18. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris, Ed.

    1989-01-01

    Presents two demonstrations using the overhead projector: (1) describes how to build a projecting voltmeter and presents uses for the classroom; and (2) investigates the color of fluorescent solutions by studying the absorption and transmission of light through the solutions. (MVL)

  19. Demonstrating the Gas Laws.

    ERIC Educational Resources Information Center

    Holko, David A.

    1982-01-01

    Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…

  20. A Biofeedback Demonstration.

    ERIC Educational Resources Information Center

    Garrity, Michael K.

    1978-01-01

    Describes a demonstration for measurement of biophysical signals produced by the human body. The signals, after amplification, could provide acoustical feedback through a voltage-controlled oscillator (VCO), or they could be seen either with an oscilloscope or a high speed chart recorder. (GA)

  1. A Fruity Biochemistry Demonstration

    ERIC Educational Resources Information Center

    Shmaefsky, Brian R.

    2005-01-01

    Classroom demonstrations are a great vehicle for getting students to apply information they have heard in a lecture. Educational research is replete with data showing that concept application in an inquiry setting reinforces long-term science content retention. This means that students learn best when they experience applications of concepts and…

  2. The Breaking Broomstick Demonstration.

    ERIC Educational Resources Information Center

    Mamola, Karl C.; Pollock, Joseph T.

    1993-01-01

    Describes and explains the breaking broomstick demonstration first reported in 1532. A needle is fixed at each end of the broomstick, and these needles are made to rest on two glasses, placed on chairs. If the broomstick is struck violently with another stout stick, the former will be broken, but the glasses will remain intact. (PR)

  3. Large-scale Altitudinal and Latitudinal Variability of Vegetation Phenology in a Tropical Montane Landscape: A Remote Sensing Perspective

    NASA Astrophysics Data System (ADS)

    Streher, A. S.; Sobreiro, J. F. F.; Morellato, P.; Silva, T. S. F.

    2015-12-01

    Mountain ecosystems are particularly vulnerable to climatic change, given the reduced potential of species to disperse uphill. Studies have been concentrated at higher latitudes, and relatively little is known about montane vegetation and ecosystem dynamics in tropical mountains. We assessed climatic, latitudinal and altitudinal effects on leafing phenology for the Espinhaço Range, a South American tropical mountain landscape comprised of a mosaic of savannas, grasslands, rock outcrops, cloud forests, and semi-deciduous to deciduous forests. We assessed a time series of 884 MODIS/NDVI images acquired between 2002 and 2015, at 7-day intervals. We classified broad vegetation types based on elevation (SRTM) and the mean and variance of each pixel in the entire series. We then extracted the phenological indicators of start, end and length of the growing season, green-up and brown-down rates, NDVI peak, and integral of the growing curve, using the TIMESAT algorithm. We also obtained precipitation data from the TRMM dataset, and calculated the Topographic Wetness Index and clear-sky radiation budgets based on the SRTM dataset. Our results show that the start of the growing season was noticeably more variable than the end date, suggesting that season length is an important factor for tropical montane vegetation. The start of the growing season decreased linearly with altitude, with vegetation at higher elevations having a later start, while no clear relation was found for the end of season. For montane vegetation above 800m, we observed shorter season lengths. Green-up rates were higher in woody seasonal formations, and became progressively slower with increasing altitudes. Higher green-up rates were also associated with rainfall patterns, where dry seasons are longer. Brown-down rates had the opposite trend, with rapid brown-down at higher altitudes. Our results quantify previously unreported seasonal, latitudinal and altitudinal variations in vegetation phenology for a

  4. Nucla CFB Demonstration Project

    SciTech Connect

    Not Available

    1990-12-01

    This report documents Colorado-Ute Electric Association's Nucla Circulating Atmospheric Fluidized-Bed Combustion (AFBC) demonstration project. It describes the plant equipment and system design for the first US utility-size circulating AFBC boiler and its support systems. Included are equipment and system descriptions, design/background information and appendices with an equipment list and selected information plus process flow and instrumentation drawings. The purpose of this report is to share the information gathered during the Nucla circulating AFBC demonstration project and present it so that the general public can evaluate the technical feasibility and cost effectiveness of replacing pulverized or stoker-fired boiler units with circulating fluidized-bed boiler units. (VC)

  5. AVNG system demonstration

    SciTech Connect

    Thron, Jonathan Louis; Mac Arthur, Duncan W; Kondratov, Sergey; Livke, Alexander; Razinkov, Sergey

    2010-01-01

    An attribute measurement system (AMS) measures a number of unclassified attributes of potentially classified material. By only displaying these unclassified results as red or green lights, the AMS protects potentially classified information while still generating confidence in the measurement result. The AVNG implementation that we describe is an AMS built by RFNC - VNIIEF in Sarov, Russia. To provide additional confidence, the AVNG was designed with two modes of operation. In the secure mode, potentially classified measurements can be made with only the simple red light/green light display. In the open mode, known unclassified material can be measured with complete display of the information collected from the radiation detectors. The AVNG demonstration, which occurred in Sarov, Russia in June 2009 for a joint US/Russian audience, included exercising both modes of AVNG operation using a number of multi-kg plutonium sources. In addition to describing the demonstration, we will show photographs and/or video taken of AVNG operation.

  6. LIMB Demonstration Project Extension

    SciTech Connect

    Not Available

    1989-11-15

    The basic goal of the Limestone Injection Mitigation Burner (LIMB) demonstration is to extend LIMB technology development to a full- scale application on a representative wall-fired utility boiler. The successful retrofit of LIMB to an existing boiler is expected to demonstrate that (a) reductions of 50 percent or greater in SO{sub x} and NO{sub x} emissions can be achieved at a fraction of the cost of add-on FGD systems, (b) boiler reliability, operability, and steam production can be maintained at levels existing prior to LIMB retrofit, and (c) technical difficulties attributable to LIMB operation, such as additional slagging and fouling, changes in ash disposal requirements, and an increased particulate load, can be resolved in a cost-effective manner. The primary fuel to be used will be an Ohio bituminous coal having a nominal sulfur content of 3 percent or greater.

  7. Chemical Domino Demonstration

    NASA Astrophysics Data System (ADS)

    Alexander, M. Dale

    1998-04-01

    The Chemical Domino Demonstration is both educational and entertaining. It provides an excellent means for a review of chemical concepts at the conclusion of a general chemistry course. This demonstration consists of a number of different chemical reactions occurring in sequence in a Rube Goldberg-type apparatus. These reactions include the reduction of water by an active metal, the oxidation of a moderately active metal by an acid, reduction of metallic ions by a metal of greater activity, acid-base neutralization reactions in solution monitored with indicators, a gas-phase acid-base neutralization reaction, decomposition of a compound, precipitation of an insoluble salt, substitution reactions of coordination complexes, and pyrotechnic oxidation-reduction reactions including a hypergolic oxidation-reduction reaction, an intramolecular oxidation-reduction reaction, and the combustion of a flammable gas.

  8. Automatic lighting controls demonstration

    SciTech Connect

    Rubinstein, F.; Verderber, R.

    1990-03-01

    The purpose of this work was to demonstrate, in a real building situation, the energy and peak demand reduction capabilities of an electronically ballasted lighting control system that can utilize all types of control strategies to efficiently manage lighting. The project has demonstrated that a state-of-the-art electronically ballasted dimmable lighting system can reduce energy and lighting demand by as least 50% using various combinations of control strategies. By reducing light levels over circulation areas (tuning) and reducing after hours light levels to accommodate the less stringent lighting demands of the cleaning crew (scheduling), lighting energy consumption on weekdays was reduced an average of 54% relative to the initial condition. 10 refs., 14 figs., 3 tabs.

  9. Space Fabrication Demonstration System

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The completion of assembly of the beam builder and its first automatic production of truss is discussed. A four bay, hand assembled, roll formed members truss was built and tested to ultimate load. Detail design of the fabrication facility (beam builder) was completed and designs for subsystem debugging are discussed. Many one bay truss specimens were produced to demonstrate subsystem operation and to detect problem areas.

  10. The Blowgun Demonstration Experiment

    ERIC Educational Resources Information Center

    Tsukamoto, Koji; Uchino, Masanori

    2008-01-01

    We have found that a simple demonstration experiment using a match or a cotton swab and a drinking straw or an acrylic pipe serves as an effective introduction to dynamics. The most basic apparatus has a cotton swab serving as a dart and the straw as the blowgun. When blown from a starting point near the exit end of the straw, the cotton swab does…

  11. The Majorana Demonstrator

    SciTech Connect

    Aguayo, Estanislao; Fast, James E.; Hoppe, Eric W.; Keillor, Martin E.; Kephart, Jeremy D.; Kouzes, Richard T.; LaFerriere, Brian D.; Merriman, Jason H.; Orrell, John L.; Overman, Nicole R.; Avignone, Frank T.; Back, Henning O.; Combs, Dustin C.; Leviner, L.; Young, A.; Barabash, Alexander S.; Konovalov, S.; Vanyushin, I.; Yumatov, Vladimir; Bergevin, M.; Chan, Yuen-Dat; Detwiler, Jason A.; Loach, J. C.; Martin, R. D.; Poon, Alan; Prior, Gersende; Vetter, Kai; Bertrand, F.; Cooper, R. J.; Radford, D. C.; Varner, R. L.; Yu, Chang-Hong; Boswell, M.; Elliott, S.; Gehman, Victor M.; Hime, Andrew; Kidd, M. F.; LaRoque, B. H.; Rielage, Keith; Ronquest, M. C.; Steele, David; Brudanin, V.; Egorov, Viatcheslav; Gusey, K.; Kochetov, Oleg; Shirchenko, M.; Timkin, V.; Yakushev, E.; Busch, Matthew; Esterline, James H.; Tornow, Werner; Christofferson, Cabot-Ann; Horton, Mark; Howard, S.; Sobolev, V.; Collar, J. I.; Fields, N.; Creswick, R.; Doe, Peter J.; Johnson, R. A.; Knecht, A.; Leon, Jonathan D.; Marino, Michael G.; Miller, M. L.; Robertson, R. G. H.; Schubert, Alexis G.; Wolfe, B. A.; Efremenko, Yuri; Ejiri, H.; Hazama, R.; Nomachi, Masaharu; Shima, T.; Finnerty, P.; Fraenkle, Florian; Giovanetti, G. K.; Green, M.; Henning, Reyco; Howe, M. A.; MacMullin, S.; Phillips, D.; Snavely, Kyle J.; Strain, J.; Vorren, Kris R.; Guiseppe, Vincente; Keller, C.; Mei, Dong-Ming; Perumpilly, Gopakumar; Thomas, K.; Zhang, C.; Hallin, A. L.; Keeter, K.; Mizouni, Leila; Wilkerson, J. F.

    2011-09-03

    A brief review of the history and neutrino physics of double beta decay is given. A description of the MAJORANA DEMONSTRATOR research and development program, including background reduction techniques, is presented in some detail. The application of point contact (PC) detectors to the experiment is discussed, including the effectiveness of pulse shape analysis. The predicted sensitivity of a PC detector array enriched to 86% to 76Ge is given.

  12. Projectile Motion Demonstration

    NASA Astrophysics Data System (ADS)

    Graf, Erlend H.

    2008-12-01

    For a recent lecture, I went to our apparatus stock room and took out our venerable Sargent-Welch projectile apparatus that demonstrates that a dropped ball and a horizontally launched ball hit the floor at the same time, if they are simultaneously released. A problem with this apparatus is that its small size makes it difficult for a large class to see what is going on. Furthermore, the projectiles are ball bearings, which tend to roll under chairs, benches, etc.

  13. Carbohydrate Dehydration Demonstrations

    NASA Astrophysics Data System (ADS)

    Dolson, David A.; Battino, Rubin; Letcher, Trevor M.; Pegel, K. H.; Revaprasadu, N.

    1995-10-01

    The "charring reaction" of a carbohydrate with concentrated H2SO4 is a demonstration of the dehydrating power of H2SO4. In this paper several sugars and supermarket carbohydrates are systematically studied with respect to size of particles, addition of water, and amount of H2SO4 added. The results are tabulated as to the amount of time to blackening and to the attainment of a particular volume of the charred material. Detailed safety precautions are included.

  14. Joined Beryllium Mirror Demonstrator

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Parsonage, Tom; Burdine, Robert (Technical Monitor)

    2001-01-01

    Fabrications of large Beryllium optical components are fundamentally limited by available facility capabilities. To overcome this limitation, NASA funded Brush Wellman Corp to study a Be joining process. Four 76 mm diameters samples and a 0.5 mm diameter Joined Beryllium Mirror Demonstrator (JBMD) were fabricated. This presentation will review the fabrication of these samples and summarize the results of their cryogenic testing at MSFCs XRCF.

  15. Overhead Projector Demonstrations.

    ERIC Educational Resources Information Center

    Kolb, Doris

    1988-01-01

    Describes two oscillating reactions: the Briggs-Raucher reaction using H202, KIO3, malonic acid, and MnSO4 which changes from yellow to blue, and the Belousov-Zhabotinskii reaction uses NaBrO3, NaBr, malonic acid, and ferroin solution and changes from red to blue. Includes a third color demonstration on the six oxidation states of manganese. (MVL)

  16. Lunar Water Resource Demonstration

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.

    2008-01-01

    In cooperation with the Canadian Space Agency, the Northern Centre for Advanced Technology, Inc., the Carnegie-Mellon University, JPL, and NEPTEC, NASA has undertaken the In-Situ Resource Utilization (ISRU) project called RESOLVE. This project is a ground demonstration of a system that would be sent to explore permanently shadowed polar lunar craters, drill into the regolith, determine what volatiles are present, and quantify them in addition to recovering oxygen by hydrogen reduction. The Lunar Prospector has determined these craters contain enhanced hydrogen concentrations averaging about 0.1%. If the hydrogen is in the form of water, the water concentration would be around 1%, which would translate into billions of tons of water on the Moon, a tremendous resource. The Lunar Water Resource Demonstration (LWRD) is a part of RESOLVE designed to capture lunar water and hydrogen and quantify them as a backup to gas chromatography analysis. This presentation will briefly review the design of LWRD and some of the results of testing the subsystem. RESOLVE is to be integrated with the Scarab rover from CMIJ and the whole system demonstrated on Mauna Kea on Hawaii in November 2008. The implications of lunar water for Mars exploration are two-fold: 1) RESOLVE and LWRD could be used in a similar fashion on Mars to locate and quantify water resources, and 2) electrolysis of lunar water could provide large amounts of liquid oxygen in LEO, leading to lower costs for travel to Mars, in addition to being very useful at lunar outposts.

  17. Relationships between growth, population dynamics, and environmental parameters in the solitary non-zooxanthellate scleractinian coral Caryophyllia inornata along a latitudinal gradient in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Caroselli, E.; Ricci, F.; Brambilla, V.; Mattioli, G.; Levy, O.; Falini, G.; Dubinsky, Z.; Goffredo, S.

    2016-06-01

    The ecology of scleractinian corals may be understood through comparisons between population demographic data and environmental parameters. Growth (growth constant and maximum size) and demographic parameters (population structure stability, instantaneous mortality rate, average age of individuals, percentage of immature individuals, age at maximum biomass, and average age of biomass) of the solitary, non-zooxanthellate, and temperate coral Caryophyllia inornata were investigated at six sites along an 8° latitudinal gradient of temperature and solar radiation (SR) on the western Italian coasts. Growth parameters were homogeneous among populations across the investigated latitudinal range. While demographic parameters were not correlated with depth temperature, populations were progressively less stable and showed a deficiency of young individuals with increasing SR, likely as a result of the lowered energetic resources due to reduced zooplankton availability. These results contrast with data from another Mediterranean non-zooxanthellate solitary coral, Leptopsammia pruvoti, investigated along the same gradient, which shows no correlation between population demography and temperature or SR.

  18. TRW utility demonstration unit

    SciTech Connect

    Not Available

    1990-01-01

    The TRW Advanced Entrained Coal Combustor Demonstration Project consists of retrofitting Orange and Rockland (O R) Utility Corporation's Lovett Plant Unit No. 3 with four (4) slagging combustors which will allow the gas/oil unit to fire 2.5% sulfur coal. The slagging combustor process will provide NO{sub x} and SO{sub x} emissions that meet NSPS and New York State Environmental Standards. During this report period, activity continued to address the total program funding shortfall. Ideas and responsibilities for further evaluation have been put forward to reduce the shortfall. In addition, an effort aimed at gaining additional program sponsorships, was initiated.

  19. NAVAJO ELECTRIFICATION DEMONSTRATION PROJECT

    SciTech Connect

    Terry W. Battiest

    2008-06-11

    The Navajo Electrification Demonstration Project (NEDP) is a multi-year project which addresses the electricity needs of the unserved and underserved Navajo Nation, the largest American Indian tribe in the United States. The program serves to cumulatively provide off-grid electricty for families living away from the electricty infrastructure, line extensions for unserved families living nearby (less than 1/2 mile away from) the electricity, and, under the current project called NEDP-4, the construction of a substation to increase the capacity and improve the quality of service into the central core region of the Navajo Nation.

  20. Demonstrating induced recharge

    SciTech Connect

    Caswell, B. )

    1990-03-01

    This paper describes an attempt by a New England community to explore for an aquifer that would yield 1 million gallons of ground water per day. After the discovery of a glacial sand and gravel aquifer, a demonstration of a hydraulic coupling between the aquifer and an adjacent stream was undertaken. This connection was needed to maintain recharge capacity of the well. The paper goes on to describe the techniques needed and used to determine the induced recharge caused by drawdown in these test wells.