Comparison of conservation metrics in a case study of lemurs.

PubMed

Gudde, Renske; Venditti, Chris

2016-12-01

Conservation planning is important to protect species from going extinct now that natural habitats are decreasing owing to human activity and climate change. However, there is considerable controversy in choosing appropriate metrics to weigh the value of species and geographic regions. For example, the added value of phylogenetic conservation-selection criteria remains disputed because high correlations between them and the nonphylogenetic criteria of species richness have been reported. We evaluated the commonly used conservation metrics species richness, endemism, phylogenetic diversity (PD), and phylogenetic endemism (PE) in a case study on lemurs of Madagascar. This enabled us to identify the conservation target of each metric and consider how they may be used in future conservation planning. We also devised a novel metric that uses a phylogeny scaled according to the rate of phenotypic evolution as a proxy for a species' ability to adapt to change. High rates of evolution may indicate generalization or specialization. Both specialization and low rates of evolution may result in an inability to adapt to changing environments. We examined conservation priorities by using the inverse of the rate of body mass evolution to account for species with low rates of evolution. In line with previous work, we found high correlations among species richness and PD (r = 0.96), and endemism and PE (r = 0.82) in Malagasy lemurs. Phylogenetic endemism in combination with rates of evolution and their inverse prioritized grid cells containing highly endemic and specialized lemurs at risk of extinction, such as Avahi occidentalis and Lepilemur edwardsi, 2 endangered lemurs with high rates of phenotypic evolution and low-quality diets, and Hapalemur aureus, a critically endangered species with a low rate of body mass evolution and a diet consisting of very high doses of cyanide. © 2016 Society for Conservation Biology.

The skeletal ontogeny of Astatotilapia burtoni - a direct-developing model system for the evolution and development of the teleost body plan.

PubMed

Woltering, Joost M; Holzem, Michaela; Schneider, Ralf F; Nanos, Vasilios; Meyer, Axel

2018-04-03

The experimental approach to the evolution and development of the vertebrate skeleton has to a large extent relied on "direct-developing" amniote model organisms, such as the mouse and the chicken. These organisms can however only be partially informative where it concerns secondarily lost features or anatomical novelties not present in their lineages. The widely used anamniotes Xenopus and zebrafish are "indirect-developing" organisms that proceed through an extended time as free-living larvae, before adopting many aspects of their adult morphology, complicating experiments at these stages, and increasing the risk for lethal pleiotropic effects using genetic strategies. Here, we provide a detailed description of the development of the osteology of the African mouthbrooding cichlid Astatotilapia burtoni, primarily focusing on the trunk (spinal column, ribs and epicentrals) and the appendicular skeleton (pectoral, pelvic, dorsal, anal, caudal fins and scales), and to a lesser extent on the cranium. We show that this species has an extremely "direct" mode of development, attains an adult body plan within 2 weeks after fertilization while living off its yolk supply only, and does not pass through a prolonged larval period. As husbandry of this species is easy, generation time is short, and the species is amenable to genetic targeting strategies through microinjection, we suggest that the use of this direct-developing cichlid will provide a valuable model system for the study of the vertebrate body plan, particularly where it concerns the evolution and development of fish or teleost specific traits. Based on our results we comment on the development of the homocercal caudal fin, on shared ontogenetic patterns between pectoral and pelvic girdles, and on the evolution of fin spines as novelty in acanthomorph fishes. We discuss the differences between "direct" and "indirect" developing actinopterygians using a comparison between zebrafish and A. burtoni development.

Primer and interviews: Molecular mechanisms of morphological evolution

PubMed Central

Kiefer, Julie C

2010-01-01

The beauty of the developing embryo, and the awe that it inspires, lure many scientists into the field of developmental biology. What compels cells to divide, migrate, and morph into a being with a complex body plan? Evolutionary developmental biologists hold similar fascinations, with dynamics that take place on a grander timescale. How do phenotypic traits diverge over evolutionary time? This primer illustrates how a deep understanding of the basic principles that underlie developmental biology have changed how scientists think about the evolution of body form. The primer culminates in a conversation with David Stern, PhD, and Michael Shapiro, PhD, who discuss current topics in morphological evolution, why the field should be of interest to classic developmental biologists, and what lies ahead. Developmental Dynamics 239:3497–3505, 2010. © 2010 Wiley-Liss, Inc. PMID:21069831

Developmental mechanisms of macroevolutionary change in the tetrapod axis: A case study of Sauropterygia

PubMed Central

Soul, Laura C.; Benson, Roger B. J.

2017-01-01

Understanding how developmental processes change on macroevolutionary timescales to generate body plan disparity is fundamental to the study of vertebrate evolution. Adult morphology of the vertebral column directly reflects the mechanisms that generate vertebral counts (somitogenesis) and their regionalisation (homeotic effects) during embryonic development. Sauropterygians were a group of Mesozoic marine reptiles that exhibited an extremely high disparity of presacral vertebral/somite counts. Using phylogenetic comparative methods, we demonstrate that somitogenesis and homeotic effects evolved in a co‐ordinated way among sauropterygians, contrasting with the wider pattern in tetrapods, in which somitogenetic and homeotic shifts are uncorrelated. Changes in sauropterygian body proportions were primarily enabled by homeotic shifts, with a lesser, but important, contribution from differences in postpatterning growth among somites. High body plan plasticity was present in Triassic sauropterygians and was maintained among their Jurassic and Cretaceous descendants. The extreme disparity in the body plan of plesiosaurian sauropterygians did not result from accelerated rates of evolutionary change in neck length, but instead reflect this ancestral versatility of sauropterygian axial development. Our results highlight variation in modes of axial development among tetrapods, and show that heterogeneous statistical models can uncover novel macroevolutionary patterns for animal body plans and the developmental mechanisms that control them. PMID:28240769

Rates of speciation and morphological evolution are correlated across the largest vertebrate radiation.

PubMed

Rabosky, Daniel L; Santini, Francesco; Eastman, Jonathan; Smith, Stephen A; Sidlauskas, Brian; Chang, Jonathan; Alfaro, Michael E

2013-01-01

Several evolutionary theories predict that rates of morphological change should be positively associated with the rate at which new species arise. For example, the theory of punctuated equilibrium proposes that phenotypic change typically occurs in rapid bursts associated with speciation events. However, recent phylogenetic studies have found little evidence linking these processes in nature. Here we demonstrate that rates of species diversification are highly correlated with the rate of body size evolution across the 30,000+ living species of ray-finned fishes that comprise the majority of vertebrate biological diversity. This coupling is a general feature of fish evolution and transcends vast differences in ecology and body-plan organization. Our results may reflect a widespread speciational mode of character change in living fishes. Alternatively, these findings are consistent with the hypothesis that phenotypic 'evolvability'-the capacity of organisms to evolve-shapes the dynamics of speciation through time at the largest phylogenetic scales.

Fossils, molecules and embryos: new perspectives on the Cambrian explosion

NASA Technical Reports Server (NTRS)

Valentine, J. W.; Jablonski, D.; Erwin, D. H.

1999-01-01

The Cambrian explosion is named for the geologically sudden appearance of numerous metazoan body plans (many of living phyla) between about 530 and 520 million years ago, only 1.7% of the duration of the fossil record of animals. Earlier indications of metazoans are found in the Neoproterozic; minute trails suggesting bilaterian activity date from about 600 million years ago. Larger and more elaborate fossil burrows appear near 543 million years ago, the beginning of the Cambrian Period. Evidence of metazoan activity in both trace and body fossils then increased during the 13 million years leading to the explosion. All living phyla may have originated by the end of the explosion. Molecular divergences among lineages leading to phyla record speciation events that have been earlier than the origins of the new body plans, which can arise many tens of millions of years after an initial branching. Various attempts to date those branchings by using molecular clocks have disagreed widely. While the timing of the evolution of the developmental systems of living metazoan body plans is still uncertain, the distribution of Hox and other developmental control genes among metazoans indicates that an extensive patterning system was in place prior to the Cambrian. However, it is likely that much genomic repatterning occurred during the Early Cambrian, involving both key control genes and regulators within their downstream cascades, as novel body plans evolved.

The Evolution of Gene Regulatory Networks that Define Arthropod Body Plans.

PubMed

Auman, Tzach; Chipman, Ariel D

2017-09-01

Our understanding of the genetics of arthropod body plan development originally stems from work on Drosophila melanogaster from the late 1970s and onward. In Drosophila, there is a relatively detailed model for the network of gene interactions that proceeds in a sequential-hierarchical fashion to define the main features of the body plan. Over the years, we have a growing understanding of the networks involved in defining the body plan in an increasing number of arthropod species. It is now becoming possible to tease out the conserved aspects of these networks and to try to reconstruct their evolution. In this contribution, we focus on several key nodes of these networks, starting from early patterning in which the main axes are determined and the broad morphological domains of the embryo are defined, and on to later stage wherein the growth zone network is active in sequential addition of posterior segments. The pattern of conservation of networks is very patchy, with some key aspects being highly conserved in all arthropods and others being very labile. Many aspects of early axis patterning are highly conserved, as are some aspects of sequential segment generation. In contrast, regional patterning varies among different taxa, and some networks, such as the terminal patterning network, are only found in a limited range of taxa. The growth zone segmentation network is ancient and is probably plesiomorphic to all arthropods. In some insects, it has undergone significant modification to give rise to a more hardwired network that generates individual segments separately. In other insects and in most arthropods, the sequential segmentation network has undergone a significant amount of systems drift, wherein many of the genes have changed. However, it maintains a conserved underlying logic and function. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

The last common bilaterian ancestor

NASA Technical Reports Server (NTRS)

Erwin, Douglas H.; Davidson, Eric H.

2002-01-01

Many regulatory genes appear to be utilized in at least superficially similar ways in the development of particular body parts in Drosophila and in chordates. These similarities have been widely interpreted as functional homologies, producing the conventional view of the last common protostome-deuterostome ancestor (PDA) as a complex organism that possessed some of the same body parts as modern bilaterians. Here we discuss an alternative view, in which the last common PDA had a less complex body plan than is frequently conceived. This reconstruction alters expectations for Neoproterozoic fossil remains that could illustrate the pathways of bilaterian evolution.

The draft genomes of soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan.

PubMed

Wang, Zhuo; Pascual-Anaya, Juan; Zadissa, Amonida; Li, Wenqi; Niimura, Yoshihito; Huang, Zhiyong; Li, Chunyi; White, Simon; Xiong, Zhiqiang; Fang, Dongming; Wang, Bo; Ming, Yao; Chen, Yan; Zheng, Yuan; Kuraku, Shigehiro; Pignatelli, Miguel; Herrero, Javier; Beal, Kathryn; Nozawa, Masafumi; Li, Qiye; Wang, Juan; Zhang, Hongyan; Yu, Lili; Shigenobu, Shuji; Wang, Junyi; Liu, Jiannan; Flicek, Paul; Searle, Steve; Wang, Jun; Kuratani, Shigeru; Yin, Ye; Aken, Bronwen; Zhang, Guojie; Irie, Naoki

2013-06-01

The unique anatomical features of turtles have raised unanswered questions about the origin of their unique body plan. We generated and analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis) and the green sea turtle (Chelonia mydas); our results indicated the close relationship of the turtles to the bird-crocodilian lineage, from which they split ∼267.9-248.3 million years ago (Upper Permian to Triassic). We also found extensive expansion of olfactory receptor genes in these turtles. Embryonic gene expression analysis identified an hourglass-like divergence of turtle and chicken embryogenesis, with maximal conservation around the vertebrate phylotypic period, rather than at later stages that show the amniote-common pattern. Wnt5a expression was found in the growth zone of the dorsal shell, supporting the possible co-option of limb-associated Wnt signaling in the acquisition of this turtle-specific novelty. Our results suggest that turtle evolution was accompanied by an unexpectedly conservative vertebrate phylotypic period, followed by turtle-specific repatterning of development to yield the novel structure of the shell.

Gastric pouches and the mucociliary sole: setting the stage for nervous system evolution

PubMed Central

Arendt, Detlev; Benito-Gutierrez, Elia; Brunet, Thibaut; Marlow, Heather

2015-01-01

Prerequisite for tracing nervous system evolution is understanding of the body plan, feeding behaviour and locomotion of the first animals in which neurons evolved. Here, a comprehensive scenario is presented for the diversification of cell types in early metazoans, which enhanced feeding efficiency and led to the emergence of larger animals that were able to move. Starting from cup-shaped, gastraea-like animals with outer and inner choanoflagellate-like cells, two major innovations are discussed that set the stage for nervous system evolution. First, the invention of a mucociliary sole entailed a switch from intra- to extracellular digestion and increased the concentration of nutrients flowing into the gastric cavity. In these animals, an initial nerve net may have evolved via division of labour from mechanosensory-contractile cells in the lateral body wall, enabling coordinated movement of the growing body that involved both mucociliary creeping and changes of body shape. Second, the inner surface of the animals folded into metameric series of gastric pouches, which optimized nutrient resorption and allowed larger body sizes. The concomitant acquisition of bilateral symmetry may have allowed more directed locomotion and, with more demanding coordinative tasks, triggered the evolution of specialized nervous subsystems. Animals of this organizational state would have resembled Ediacarian fossils such as Dickinsonia and may have been close to the cnidarian–bilaterian ancestor. In the bilaterian lineage, the mucociliary sole was used mostly for creeping, or frequently lost. One possible remnant is the enigmatic Reissner's fibre in the ventral neural tube of cephalochordates and vertebrates. PMID:26554050

Elongation of the body in eels.

PubMed

Mehta, Rita S; Ward, Andrea B; Alfaro, Michael E; Wainwright, Peter C

2010-12-01

The shape of the body affects how organisms move, where they live, and how they feed. One body plan that has long engaged the interest of both evolutionary biologists and functional morphologists is axial elongation. There is a growing interest in the correlates and evolution of elongation within different terrestrial and aquatic vertebrate clades. At first glance, Anguilliformes may appear to exhibit a single cylindrical form but there is considerable diversity underlying this seemingly simplified body plan. Here, we explore evolution of the axial skeleton in 54 anguilliform taxa and some close relatives. We describe the diversity of axial elongation as well as investigate how characters such as head length, branchial-arch length, and shape of the pectoral fins correlate with vertebral number to possibly facilitate changes in absolute diameter of the body. Overall, we find that precaudal vertebral numbers and caudal vertebral numbers are evolving independently across elopomorph fishes. We also find that precaudal and caudal vertebral aspect ratios are evolving together across elopomorph fishes. When focusing within Anguilliformes we find striking diversity in the mechanisms of elongation of the body, including almost every trend for axial elongation known within actinopterygian fishes. The three major clades of eels we examined have slightly different mechanisms of elongation. We also find a suite of morphological characters associated with elongation in anguilliform fishes that appears to coincide with a more fossorial lifestyle such as high elongation ratios, a more posteriorly extended-branchial region, and a reduction in the size of the pectoral fins. Lastly, we point out that a diverse range of derived behaviors such as head- and tail-first burrowing, rotational feeding, and knotting around prey are only found in long cylindrical vertebrates.

Progressive Loss of Function in a Limb Enhancer during Snake Evolution.

PubMed

Kvon, Evgeny Z; Kamneva, Olga K; Melo, Uirá S; Barozzi, Iros; Osterwalder, Marco; Mannion, Brandon J; Tissières, Virginie; Pickle, Catherine S; Plajzer-Frick, Ingrid; Lee, Elizabeth A; Kato, Momoe; Garvin, Tyler H; Akiyama, Jennifer A; Afzal, Veena; Lopez-Rios, Javier; Rubin, Edward M; Dickel, Diane E; Pennacchio, Len A; Visel, Axel

2016-10-20

The evolution of body shape is thought to be tightly coupled to changes in regulatory sequences, but specific molecular events associated with major morphological transitions in vertebrates have remained elusive. We identified snake-specific sequence changes within an otherwise highly conserved long-range limb enhancer of Sonic hedgehog (Shh). Transgenic mouse reporter assays revealed that the in vivo activity pattern of the enhancer is conserved across a wide range of vertebrates, including fish, but not in snakes. Genomic substitution of the mouse enhancer with its human or fish ortholog results in normal limb development. In contrast, replacement with snake orthologs caused severe limb reduction. Synthetic restoration of a single transcription factor binding site lost in the snake lineage reinstated full in vivo function to the snake enhancer. Our results demonstrate changes in a regulatory sequence associated with a major body plan transition and highlight the role of enhancers in morphological evolution. PAPERCLIP. Copyright © 2016 Elsevier Inc. All rights reserved.

Homeotic Evolution in the Mammalia: Diversification of Therian Axial Seriation and the Morphogenetic Basis of Human Origins

PubMed Central

Filler, Aaron G.

2007-01-01

Background Despite the rising interest in homeotic genes, little has been known about the course and pattern of evolution of homeotic traits across the mammalian radiation. An array of emerging and diversifying homeotic gradients revealed by this study appear to generate new body plans and drive evolution at a large scale. Methodology/Principal Findings This study identifies and evaluates a set of homeotic gradients across 250 extant and fossil mammalian species and their antecedents over a period of 220 million years. These traits are generally expressed as co-linear gradients along the body axis rather than as distinct segmental identities. Relative position or occurrence sequence vary independently and are subject to polarity reversal and mirroring. Five major gradient modification sets are identified: (1)–quantitative changes of primary segmental identity pattern that appeared at the origin of the tetrapods ; (2)–frame shift relation of costal and vertebral identity which diversifies from the time of amniote origins; (3)–duplication, mirroring, splitting and diversification of the neomorphic laminar process first commencing at the dawn of mammals; (4)–emergence of homologically variable lumbar lateral processes upon commencement of the radiation of therian mammals and ; (5)–inflexions and transpositions of the relative position of the horizontal septum of the body and the neuraxis at the emergence of various orders of therian mammals. Convergent functional changes under homeotic control include laminar articular engagement with septo-neural transposition and ventrally arrayed lumbar transverse process support systems. Conclusion/Significance Clusters of homeotic transformations mark the emergence point of mammals in the Triassic and the radiation of therians in the Cretaceous. A cluster of homeotic changes in the Miocene hominoid Morotopithecus that are still seen in humans supports establishment of a new “hominiform” clade and suggests a homeotic origin for the human upright body plan. PMID:17925867

Evolution of the chordate body plan: New insights from phylogenetic analyses of deuterostome phyla

PubMed Central

Cameron, Chris B.; Garey, James R.; Swalla, Billie J.

2000-01-01

The deuterostome phyla include Echinodermata, Hemichordata, and Chordata. Chordata is composed of three subphyla, Vertebrata, Cephalochordata (Branchiostoma), and Urochordata (Tunicata). Careful analysis of a new 18S rDNA data set indicates that deuterostomes are composed of two major clades: chordates and echinoderms + hemichordates. This analysis strongly supports the monophyly of each of the four major deuterostome taxa: Vertebrata + Cephalochordata, Urochordata, Hemichordata, and Echinodermata. Hemichordates include two distinct classes, the enteropneust worms and the colonial pterobranchs. Most previous hypotheses of deuterostome origins have assumed that the morphology of extant colonial pterobranchs resembles the ancestral deuterostome. We present a molecular phylogenetic analysis of hemichordates that challenges this long-held view. We used 18S rRNA to infer evolutionary relationships of the hemichordate classes Pterobranchia and Enteropneusta. Our data show that pterobranchs may be derived within enteropneust worms rather than being a sister clade to the enteropneusts. The nesting of the pterobranchs within the enteropneusts dramatically alters our view of the evolution of the chordate body plan and suggests that the ancestral deuterostome more closely resembled a mobile worm-like enteropneust than a sessile colonial pterobranch. PMID:10781046

Gene Regulatory Networks, Homology, and the Early Panarthropod Fossil Record.

PubMed

Tweedt, Sarah M

2017-09-01

The arthropod body plan is widely believed to have derived from an ancestral form resembling Cambrian-aged fossil lobopodians, and interpretations of morphological and molecular data have long favored this hypothesis. It is possible, however, that appendages and other morphologies observed in extinct and living panarthropods evolved independently. The key to distinguishing between morphological homology and homoplasy lies in the study of developmental gene regulatory networks (GRNs), and specifically, in determining the unique genetic circuits that construct characters. In this study, I discuss character identity and panarthropod appendage evolution within a developmental GRN framework, with a specific focus on potential limb character identity networks ("ChINs"). I summarize recent molecular studies, and argue that current data do not rule out the possibility of independent panarthropod limb evolution. The link between character identity and GRN architecture has broad implications for homology assessment, and this genetic framework offers alternative approaches to fossil character coding, phylogenetic analyses, and future research into the origin of the arthropod body plan. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

The draft genomes of soft–shell turtle and green sea turtle yield insights into the development and evolution of the turtle–specific body plan

PubMed Central

Niimura, Yoshihito; Huang, Zhiyong; Li, Chunyi; White, Simon; Xiong, Zhiqiang; Fang, Dongming; Wang, Bo; Ming, Yao; Chen, Yan; Zheng, Yuan; Kuraku, Shigehiro; Pignatelli, Miguel; Herrero, Javier; Beal, Kathryn; Nozawa, Masafumi; Li, Qiye; Wang, Juan; Zhang, Hongyan; Yu, Lili; Shigenobu, Shuji; Wang, Junyi; Liu, Jiannan; Flicek, Paul; Searle, Steve; Wang, Jun; Kuratani, Shigeru; Yin, Ye; Aken, Bronwen; Zhang, Guojie; Irie, Naoki

2014-01-01

The unique anatomical features of turtles have raised unanswered questions about the origin of their unique body plan. We generated and analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis) and the green sea turtle (Chelonia mydas); our results indicated the close relationship of the turtles to the bird-crocodilian lineage, from which they split ~267.9–248.3 million years ago (Upper Permian to Triassic). We also found extensive expansion of olfactory receptor genes in these turtles. Embryonic gene expression analysis identified an hourglass-like divergence of turtle and chicken embryogenesis, with maximal conservation around the vertebrate phylotypic period, rather than at later stages that show the amniote-common pattern. Wnt5a expression was found in the growth zone of the dorsal shell, supporting the possible co-option of limb-associated Wnt signaling in the acquisition of this turtle-specific novelty. Our results suggest that turtle evolution was accompanied by an unexpectedly conservative vertebrate phylotypic period, followed by turtle-specific repatterning of development to yield the novel structure of the shell. PMID:23624526

Studies of Planet Formation using a Hybrid N-body + Planetesimal Code

NASA Technical Reports Server (NTRS)

Kenyon, Scott J.; Bromley, Benjamin C.; Salamon, Michael (Technical Monitor)

2005-01-01

The goal of our proposal was to use a hybrid multi-annulus planetesimal/n-body code to examine the planetesimal theory, one of the two main theories of planet formation. We developed this code to follow the evolution of numerous 1 m to 1 km planetesimals as they collide, merge, and grow into full-fledged planets. Our goal was to apply the code to several well-posed, topical problems in planet formation and to derive observational consequences of the models. We planned to construct detailed models to address two fundamental issues: 1) icy planets - models for icy planet formation will demonstrate how the physical properties of debris disks, including the Kuiper Belt in our solar system, depend on initial conditions and input physics; and 2) terrestrial planets - calculations following the evolution of 1-10 km planetesimals into Earth-mass planets and rings of dust will provide a better understanding of how terrestrial planets form and interact with their environment. During the past year, we made progress on each issue. Papers published in 2004 are summarized. Summaries of work to be completed during the first half of 2005 and work planned for the second half of 2005 are included.

Molecular evolution tracks macroevolutionary transitions in Cetacea.

PubMed

McGowen, Michael R; Gatesy, John; Wildman, Derek E

2014-06-01

Cetacea (whales, dolphins, and porpoises) is a model group for investigating the molecular signature of macroevolutionary transitions. Recent research has begun to reveal the molecular underpinnings of the remarkable anatomical and behavioral transformation in this clade. This shift from terrestrial to aquatic environments is arguably the best-understood major morphological transition in vertebrate evolution. The ancestral body plan and physiology were extensively modified and, in many cases, these crucial changes are recorded in cetacean genomes. Recent studies have highlighted cetaceans as central to understanding adaptive molecular convergence and pseudogene formation. Here, we review current research in cetacean molecular evolution and the potential of Cetacea as a model for the study of other macroevolutionary transitions from a genomic perspective. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamical patterning modules: physico-genetic determinants of morphological development and evolution

NASA Astrophysics Data System (ADS)

Newman, Stuart A.; Bhat, Ramray

2008-03-01

The shapes and forms of multicellular organisms arise by the generation of new cell states and types and changes in the numbers and rearrangements of the various kinds of cells. While morphogenesis and pattern formation in all animal species are widely recognized to be mediated by the gene products of an evolutionarily conserved 'developmental-genetic toolkit', the link between these molecular players and the physics underlying these processes has been generally ignored. This paper introduces the concept of 'dynamical patterning modules' (DPMs), units consisting of one or more products of the 'toolkit' genes that mobilize physical processes characteristic of chemically and mechanically excitable meso- to macroscopic systems such as cell aggregates: cohesion, viscoelasticity, diffusion, spatiotemporal heterogeneity based on lateral inhibition and multistable and oscillatory dynamics. We suggest that ancient toolkit gene products, most predating the emergence of multicellularity, assumed novel morphogenetic functions due to change in the scale and context inherent to multicellularity. We show that DPMs, acting individually and in concert with each other, constitute a 'pattern language' capable of generating all metazoan body plans and organ forms. The physical dimension of developmental causation implies that multicellular forms during the explosive radiation of animal body plans in the middle Cambrian, approximately 530 million years ago, could have explored an extensive morphospace without concomitant genotypic change or selection for adaptation. The morphologically plastic body plans and organ forms generated by DPMs, and their ontogenetic trajectories, would subsequently have been stabilized and consolidated by natural selection and genetic drift. This perspective also solves the apparent 'molecular homology-analogy paradox', whereby widely divergent modern animal types utilize the same molecular toolkit during development by proposing, in contrast to the Neo-Darwinian principle, that phenotypic disparity early in evolution occurred in advance of, rather than closely tracked, genotypic change.

Development and myogenesis of the vermiform Buddenbrockia (Myxozoa) and implications for cnidarian body plan evolution

PubMed Central

2012-01-01

Background The enigmatic wormlike parasite Buddenbrockia plumatellae has recently been shown to belong to the Myxozoa, which are now supported as a clade within Cnidaria. Most myxozoans are morphologically extremely simplified, lacking major metazoan features such as epithelial tissue layers, gut, nervous system, body axes and gonads. This hinders comparisons to free-living cnidarians and thus an understanding of myxozoan evolution and identification of their cnidarian sister group. However, B. plumatellae is less simplified than other myxozoans and therefore is of specific significance for such evolutionary considerations. Methods We analyse and describe the development of major body plan features in Buddenbrockia worms using a combination of histology, electron microscopy and confocal microscopy. Results Early developmental stages develop a primary body axis that shows a polarity, which is manifested as a gradient of tissue development, enabling distinction between the two worm tips. This polarity is maintained in adult worms, which, in addition, often develop a pore at the distal tip. The musculature comprises tetraradially arranged longitudinal muscle blocks consisting of independent myocytes embedded in the extracellular matrix between inner and outer epithelial tissue layers. The muscle fibres are obliquely oriented and in fully grown worms consistently form an angle of 12° with respect to the longitudinal axis of the worm in each muscle block and hence confer chirality. Connecting cells form a link between each muscle block and constitute four rows of cells that run in single file along the length of the worm. These connecting cells are remnants of the inner epithelial tissue layer and are anchored to the extracellular matrix. They are likely to have a biomechanical function. Conclusions The polarised primary body axis represents an ancient feature present in the last common ancestor of Cnidaria and Bilateria. The tetraradial arrangement of musculature is consistent with a medusozoan affinity for Myxozoa. However, the chiral pattern of muscle fibre orientation is apparently novel within Cnidaria and could thus be a specific adaptation. The presence of independent myocytes instead of Cnidaria-like epitheliomuscular cells can be interpreted as further support for the presence of mesoderm in cnidarians, or it may represent convergent evolution to a bilaterian condition. PMID:22594622

A Triassic plesiosaurian skeleton and bone histology inform on evolution of a unique body plan

PubMed Central

Wintrich, Tanja; Hayashi, Shoji; Houssaye, Alexandra; Nakajima, Yasuhisa; Sander, P. Martin

2017-01-01

Secondary marine adaptation is a major pattern in amniote evolution, accompanied by specific bone histological adaptations. In the aftermath of the end-Permian extinction, diverse marine reptiles evolved early in the Triassic. Plesiosauria is the most diverse and one of the longest-lived clades of marine reptiles, but its bone histology is least known among the major marine amniote clades. Plesiosaurians had a unique and puzzling body plan, sporting four evenly shaped pointed flippers and (in most clades) a small head on a long, stiffened neck. The flippers were used as hydrofoils in underwater flight. A wide temporal, morphological, and morphometric gap separates plesiosaurians from their closest relatives (basal pistosaurs, Bobosaurus). For nearly two centuries, plesiosaurians were thought to appear suddenly in the earliest Jurassic after the end-Triassic extinctions. We describe the first Triassic plesiosaurian, from the Rhaetian of Germany, and compare its long bone histology to that of later plesiosaurians sampled for this study. The new taxon is recovered as a basal member of the Pliosauridae, revealing that diversification of plesiosaurians was a Triassic event and that several lineages must have crossed into the Jurassic. Plesiosaurian histology is strikingly uniform and different from stem sauropterygians. Histology suggests the concurrent evolution of fast growth and an elevated metabolic rate as an adaptation to cruising and efficient foraging in the open sea. The new specimen corroborates the hypothesis that open ocean life of plesiosaurians facilitated their survival of the end-Triassic extinctions. PMID:29242826

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

Kvon, Evgeny Z.; Kamneva, Olga K.; Melo, Uirá S.

The evolution of body shape is thought to be tightly coupled to changes in regulatory sequences, but specific molecular events associated with major morphological transitions in vertebrates have remained elusive. In this paper, we identified snake-specific sequence changes within an otherwise highly conserved long-range limb enhancer of Sonic hedgehog (Shh). Transgenic mouse reporter assays revealed that the in vivo activity pattern of the enhancer is conserved across a wide range of vertebrates, including fish, but not in snakes. Genomic substitution of the mouse enhancer with its human or fish ortholog results in normal limb development. In contrast, replacement with snake orthologsmore » caused severe limb reduction. Synthetic restoration of a single transcription factor binding site lost in the snake lineage reinstated full in vivo function to the snake enhancer. Our results demonstrate changes in a regulatory sequence associated with a major body plan transition and highlight the role of enhancers in morphological evolution.« less

Evolutionary crossroads in developmental biology: Cnidaria

PubMed Central

Technau, Ulrich; Steele, Robert E.

2011-01-01

There is growing interest in the use of cnidarians (corals, sea anemones, jellyfish and hydroids) to investigate the evolution of key aspects of animal development, such as the formation of the third germ layer (mesoderm), the nervous system and the generation of bilaterality. The recent sequencing of the Nematostella and Hydra genomes, and the establishment of methods for manipulating gene expression, have inspired new research efforts using cnidarians. Here, we present the main features of cnidarian models and their advantages for research, and summarize key recent findings using these models that have informed our understanding of the evolution of the developmental processes underlying metazoan body plan formation. PMID:21389047

Evolutionary crossroads in developmental biology: Cnidaria.

PubMed

Technau, Ulrich; Steele, Robert E

2011-04-01

There is growing interest in the use of cnidarians (corals, sea anemones, jellyfish and hydroids) to investigate the evolution of key aspects of animal development, such as the formation of the third germ layer (mesoderm), the nervous system and the generation of bilaterality. The recent sequencing of the Nematostella and Hydra genomes, and the establishment of methods for manipulating gene expression, have inspired new research efforts using cnidarians. Here, we present the main features of cnidarian models and their advantages for research, and summarize key recent findings using these models that have informed our understanding of the evolution of the developmental processes underlying metazoan body plan formation.

Evolution of the regionalization and patterning of the vertebrate telencephalon: what can we learn from cyclostomes?

PubMed

Sugahara, Fumiaki; Murakami, Yasunori; Adachi, Noritaka; Kuratani, Shigeru

2013-08-01

The telencephalon, the most anterior part of the vertebrate central nervous system (CNS), is a highly diversified region of the vertebrate body. Its evolutionary origin remains elusive, especially with regard to the ancestral state of its architecture as well as the origin of telencephalon-specific neuron subtypes. Cyclostomes (lampreys and hagfish), the sister group of the gnathostomes (jawed vertebrates), serve as valuable models for studying the evolution of the vertebrate CNS. Here, we summarize recent studies on the development of the telencephalon in the lamprey. By comparing detailed developmental studies in mammals, we illustrate a possible ancestral developmental plan underlying the diversification of the vertebrate telencephalon and propose possible approaches for understanding the early evolution of the telencephalon. Copyright © 2013 Elsevier Ltd. All rights reserved.

NASA Structure and Evolution of the Universe Theme: Science Overview

NASA Technical Reports Server (NTRS)

White, Nicholas E.; Margon, Bruce

2001-01-01

The NASA Office of Space Science Structure and Evolution of the Universe (SEU) theme covers a wide variety of scientific investigations, from the nearest bodies to the farthest observable distances just after the time of the Big Bang. SEU supports experiments that sense radiation of all wavelengths, together with particle and gravitational wave detection. Recently completed road mapping and strategic planning exercises have identified a number of near- and medium-term space initiatives for the 2003-2023 time frame. Each of these experiments pushes the state of the art technically, but will return incredible new insights on the formation and evolution of the universe, as well as probe fundamental laws of physics in regimes never before tested. The scientific goals and technological highlights of each mission are described.

Temporal variations in early developmental decisions: an engine of forebrain evolution.

PubMed

Bielen, H; Pal, S; Tole, S; Houart, C

2017-02-01

Tight control of developmental timing is pivotal to many major processes in developmental biology, such as patterning, fate specification, cell cycle dynamics, cell migration and connectivity. Temporal change in these ontogenetic sequences is known as heterochrony, a major force in the evolution of body plans and organogenesis. In the last 5 years, studies in fish and rodents indicate that heterochrony in signaling during early development generates diversity in forebrain size and complexity. Here, we summarize these findings and propose that, additionally to spatio-temporal tuning of neurogenesis, temporal and quantitative modulation of signaling events drive pivotal changes in shape, size and complexity of the forebrain across evolution, participating to the generation of diversity in animal behavior and emergence of cognition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chance and necessity in eye evolution.

PubMed

Gehring, Walter J

2011-01-01

Charles Darwin has proposed the theory that evolution of live organisms is based on random variation and natural selection. Jacques Monod in his classic book Chance and Necessity, published 40 years ago, presented his thesis "that the biosphere does not contain a predictable class of objects or events, but constitutes a particular occurrence, compatible indeed with the first principles, but not deducible from those principals and therefore, essentially unpredictable." Recent discoveries in eye evolution are in agreement with both of these theses. They confirm Darwin's assumption of a simple eye prototype and lend strong support for the notion of a monophyletic origin of the various eye types. Considering the complexity of the underlying gene regulatory networks the unpredictability is obvious. The evolution of the Hox gene cluster and the specification of the body plan starting from an evolutionary prototype segment is discussed. In the course of evolution, a series of similar prototypic segments gradually undergoes cephalization anteriorly and caudalization posteriorly through diversification of the Hox genes.

Chance and Necessity in Eye Evolution

PubMed Central

Gehring, Walter J.

2011-01-01

Charles Darwin has proposed the theory that evolution of live organisms is based on random variation and natural selection. Jacques Monod in his classic book Chance and Necessity, published 40 years ago, presented his thesis “that the biosphere does not contain a predictable class of objects or events, but constitutes a particular occurrence, compatible indeed with the first principles, but not deducible from those principals and therefore, essentially unpredictable.” Recent discoveries in eye evolution are in agreement with both of these theses. They confirm Darwin's assumption of a simple eye prototype and lend strong support for the notion of a monophyletic origin of the various eye types. Considering the complexity of the underlying gene regulatory networks the unpredictability is obvious. The evolution of the Hox gene cluster and the specification of the body plan starting from an evolutionary prototype segment is discussed. In the course of evolution, a series of similar prototypic segments gradually undergoes cephalization anteriorly and caudalization posteriorly through diversification of the Hox genes. PMID:21979158

Dosimetric comparison between 10MV-FFF and 6MV-FFF for lung SBRT

NASA Astrophysics Data System (ADS)

Durmus, I. F.; Atalay, E. D.

2017-02-01

Plans were prepared by using same non-coplanar fields and physical parameters in 6MV-FFF and 10MV-FFF energies for fourteen lung Stereotactic Body Radio Therapy (SBRT) patients. In two plans which have different energies, critic organ doses, PTV doses, quality of plans (Gradient Index (GI), Homogeneity Index (HI), Conformity Index (CI)) and Monitor Unit (MU) values were compared. Quality controls were performed with 2D-Array Iba MatriXX Evolution® dosimetry system for each plans. As a results, plan with 6MV-FFF energy give better results in terms of CI and GI values. In this way, when more conformal dose distributions were provided, there was a rapid dose decrease at out of target volume. Lower MU values were obtained in plans which was prepared with 10MV-FFF energy. In plan with 10MV-FFF energy lower MU values are obtained. Lower values in heart and spinal cord doses are founded and better results are obtained in Body and Ipsa-Lung V5, V10, V20 values with 6MV-FFF energies. When differences were very small in volume which were taken low dose (V5), these differences increased in volume which were taken high dose (V20). High dose rates can be reached by both two unfiltered energies and can be used in lung SBRT.

A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum

PubMed Central

Pol, Diego; Garrido, Alberto; Cerda, Ignacio A.

2011-01-01

Background The origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods. Methodology/Principal Findings A new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina). The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda. Conclusions/Significance The dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are showing that the characteristic sauropod body plan evolved gradually, with a step-wise pattern of character appearance. PMID:21298087

Neuroanatomy of the Vestimentiferan Tubeworm Lamellibrachia satsuma Provides Insights into the Evolution of the Polychaete Nervous System

PubMed Central

Miyamoto, Norio; Shinozaki, Ayuta; Fujiwara, Yoshihiro

2013-01-01

Vestimentiferan tubeworms are marine invertebrates that inhabit chemosynthetic environments, and although recent molecular phylogenetic analyses have suggested that vestimentiferan tubeworms are derived from polychaete annelids, they show some morphological features that are different from other polychaetes. For example, vestimentiferans lack a digestive tract and have less body segments and comparative neuroanatomy can provide essential insight into the vestimentiferan body plan and its evolution. In the present study, we investigated the adult nervous system in the vestimentiferan Lamellibrachia satsuma using antibodies against synapsin, serotonin, FMRMamide and acetylated α-tubulin. We also examined the expressions of neural marker genes, elav and synaptotagmin to reveal the distribution of neuronal cell bodies. Brain anatomy shows simple organization in Lamellibrachia compared to other polychaetes. This simplification is probably due to the loss of the digestive tract, passing through the body between the brain and the subesophageal ganglion. In contrast, the ventral nerve cord shows a repeated organizational structure as in the other polychaetes, despite the absence of the multiple segmentation of the trunk. These results suggest that the brain anatomy is variable depending on the function and the condition of surrounding tissues, and that the formation of the rope ladder-like nervous system of the ventral nerve cord is independent from segmentation in polychaetes. PMID:23372830

Somatic twist: a model for the evolution of decussation.

PubMed

Kinsbourne, Marcel

2013-09-01

In the chordate and vertebrate central nervous system, sensory and motor nerve tracts cross from one side to the other as they connect the brain with sensory receptors and motor neurons. These "decussations," crossings in the form of an X, relate each side of the brain to the opposite side of the body. The protochordates derive from an invertebrate ancestor, but no such contralateral arrangement occurs in any invertebrate phylum. No adaptive benefit of decussation has been established. What might explain the evolution of decussation? A brief review of relevant features of comparative morphology of invertebrates, chordates and vertebrates leads to an explanatory model of decussation. A "somatic twist model" of invertebrate-vertebrate transition accounts for decussations as byproducts of a more momentous change; the relocation of the neuraxis from the ventral to the dorsal aspect of the body. Evidence is presented that this inversion proceeded by means of a twisting of the body 180 degrees on its axis just behind its anterior pole. This rotation aligned the neuraxis with the dorsal head ganglia and brain and by twisting the nerve tracts it brought decussation in its wake. Decussation evolved as a byproduct of a genetically determined partial inversion of the body plan, which resulted in a 180 degree rotation posterior to the brain and oropharynx.

Alternate pathways of body shape evolution translate into common patterns of locomotor evolution in two clades of lizards.

PubMed

Bergmann, Philip J; Irschick, Duncan J

2010-06-01

Body shape has a fundamental impact on organismal function, but it is unknown how functional morphology and locomotor performance and kinematics relate across a diverse array of body shapes. We showed that although patterns of body shape evolution differed considerably between lizards of the Phrynosomatinae and Lerista, patterns of locomotor evolution coincided between clades. Specifically, we found that the phrynosomatines evolved a stocky phenotype through body widening and limb shortening, whereas Lerista evolved elongation through body lengthening and limb shortening. In both clades, relative limb length played a key role in locomotor evolution and kinematic strategies, with long-limbed species moving faster and taking longer strides. In Lerista, the body axis also influenced locomotor evolution. Similar patterns of locomotor evolution were likely due to constraints on how the body can move. However, these common patterns of locomotor evolution between the two clades resulted in different kinematic strategies and levels of performance among species because of their morphological differences. Furthermore, we found no evidence that distinct body shapes are adaptations to different substrates, as locomotor kinematics did not change on loose or solid substrates. Our findings illustrate the importance of studying kinematics to understand the mechanisms of locomotor evolution and phenotype-function relationships.

The Life Sciences program at the NASA Ames Research Center - An overview

NASA Technical Reports Server (NTRS)

Vernikos-Danellis, Joan; Sharp, Joseph C.

1989-01-01

The research projects planned for the Life Sciences program have a goal of answering basic questions concerning the nature of life itself and its evolution in the universe from basic elements, as well as the search for extraterrestrial intelligence. The program also includes studies of the evolution and development of life on the planet earth, and the global changes occurring today that affect life on the earth. The paper describes the simulation models developed to study the effects of space, the flight projects of the program, and the biomedical program, which currently focuses on the physiological changes in the human body that are associated with space flights and the interactions among these changes.

Evolution of the locomotory system in eels (Teleostei: Elopomorpha).

PubMed

Pfaff, Cathrin; Zorzin, Roberto; Kriwet, Jürgen

2016-08-11

Living anguilliform eels represent a distinct clade of elongated teleostean fishes inhabiting a wide range of habitats. Locomotion of these fishes is highly influenced by the elongated body shape, the anatomy of the vertebral column, and the corresponding soft tissues represented by the musculotendinous system. Up to now, the evolution of axial elongation in eels has been inferred from living taxa only, whereas the reconstruction of evolutionary patterns and functional ecology in extinct eels still is scarce. Rare but excellently preserved fossil eels from the Late Cretaceous and Cenozoic were investigated here to gain a better understanding of locomotory system evolution in anguilliforms and, consequently, their habitat occupations in deep time. The number of vertebrae in correlation with the body length separates extinct and extant anguilliforms. Even if the phylogenetic signal cannot entirely be excluded, the analyses performed here reveal a continuous shortening of the vertebral column with a simultaneous increase in vertebral numbers in conjunction with short lateral tendons throughout the order. These anatomical changes contradict previous hypotheses based on extant eels solely. The body curvatures of extant anguilliforms are highly flexible and can be clearly distinguished from extinct species. Anatomical changes of the vertebral column and musculotendinous system through time and between extinct and extant anguilliforms correlate with changes of the body plan and swimming performance and reveal significant shifts in habitat adaptation and thus behaviour. Evolutionary changes in the skeletal system of eels established here also imply that environmental shifts were triggered by abiotic rather than biotic factors (e.g., K/P boundary mass extinction event).

Correlated evolution of body and fin morphology in the cichlid fishes.

PubMed

Feilich, Kara L

2016-10-01

Body and fin shapes are chief determinants of swimming performance in fishes. Different configurations of body and fin shapes can suit different locomotor specializations. The success of any configuration is dependent upon the hydrodynamic interactions between body and fins. Despite the importance of body-fin interactions for swimming, there are few data indicating whether body and fin configurations evolve in concert, or whether these structures vary independently. The cichlid fishes are a diverse family whose well-studied phylogenetic relationships make them ideal for the study of macroevolution of ecomorphology. This study measured body, and caudal and median fin morphology from radiographs of 131 cichlid genera, using morphometrics and phylogenetic comparative methods to determine whether these traits exhibit correlated evolution. Partial least squares canonical analysis revealed that body, caudal fin, dorsal fin, and anal fin shapes all exhibited strong correlated evolution consistent with locomotor ecomorphology. Major patterns included the evolution of deep body profiles with long fins, suggestive of maneuvering specialization; and the evolution of narrow, elongate caudal peduncles with concave tails, a combination that characterizes economical cruisers. These results demonstrate that body shape evolution does not occur independently of other traits, but among a suite of other morphological changes that augment locomotor specialization. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Morphological evolution in land plants: new designs with old genes

PubMed Central

Pires, Nuno D.; Dolan, Liam

2012-01-01

The colonization and radiation of multicellular plants on land that started over 470 Ma was one of the defining events in the history of this planet. For the first time, large amounts of primary productivity occurred on the continental surface, paving the way for the evolution of complex terrestrial ecosystems and altering global biogeochemical cycles; increased weathering of continental silicates and organic carbon burial resulted in a 90 per cent reduction in atmospheric carbon dioxide levels. The evolution of plants on land was itself characterized by a series of radical transformations of their body plans that included the formation of three-dimensional tissues, de novo evolution of a multicellular diploid sporophyte generation, evolution of multicellular meristems, and the development of specialized tissues and organ systems such as vasculature, roots, leaves, seeds and flowers. In this review, we discuss the evolution of the genes and developmental mechanisms that drove the explosion of plant morphologies on land. Recent studies indicate that many of the gene families which control development in extant plants were already present in the earliest land plants. This suggests that the evolution of novel morphologies was to a large degree driven by the reassembly and reuse of pre-existing genetic mechanisms. PMID:22232763

Morphological evolution in land plants: new designs with old genes.

PubMed

Pires, Nuno D; Dolan, Liam

2012-02-19

The colonization and radiation of multicellular plants on land that started over 470 Ma was one of the defining events in the history of this planet. For the first time, large amounts of primary productivity occurred on the continental surface, paving the way for the evolution of complex terrestrial ecosystems and altering global biogeochemical cycles; increased weathering of continental silicates and organic carbon burial resulted in a 90 per cent reduction in atmospheric carbon dioxide levels. The evolution of plants on land was itself characterized by a series of radical transformations of their body plans that included the formation of three-dimensional tissues, de novo evolution of a multicellular diploid sporophyte generation, evolution of multicellular meristems, and the development of specialized tissues and organ systems such as vasculature, roots, leaves, seeds and flowers. In this review, we discuss the evolution of the genes and developmental mechanisms that drove the explosion of plant morphologies on land. Recent studies indicate that many of the gene families which control development in extant plants were already present in the earliest land plants. This suggests that the evolution of novel morphologies was to a large degree driven by the reassembly and reuse of pre-existing genetic mechanisms.

Studies of Planet Formation Using a Hybrid N-Body + Planetesimal Code

NASA Technical Reports Server (NTRS)

Kenyon, Scott J.

2004-01-01

The goal of our proposal was to use a hybrid multi-annulus planetesimal/n-body code to examine the planetesimal theory, one of the two main theories of planet formation. We developed this code to follow the evolution of numerous 1 m to 1 km planetesimals as they collide, merge, and grow into full-fledged planets. Our goal was to apply the code to several well-posed, topical problems in planet formation and to derive observational consequences of the models. We planned to construct detailed models to address two fundamental issues: (1) icy planets: models for icy planet formation will demonstrate how the physical properties of debris disks - including the Kuiper Belt in our solar system - depend on initial conditions and input physics; and (2) terrestrial planets: calculations following the evolution of 1-10 km planetesimals into Earth-mass planets and rings of dust will provide a better understanding of how terrestrial planets form and interact with their environment.

Convergent occurrence of the developmental hourglass in plant and animal embryogenesis?

PubMed

Cridge, Andrew G; Dearden, Peter K; Brownfield, Lynette R

2016-04-01

The remarkable similarity of animal embryos at particular stages of development led to the proposal of a developmental hourglass. In this model, early events in development are less conserved across species but lead to a highly conserved 'phylotypic period'. Beyond this stage, the model suggests that development once again becomes less conserved, leading to the diversity of forms. Recent comparative studies of gene expression in animal groups have provided strong support for the hourglass model. How and why might such an hourglass pattern be generated? More importantly, how might early acting events in development evolve while still maintaining a later conserved stage? The discovery that an hourglass pattern may also exist in the embryogenesis of plants provides comparative data that may help us explain this phenomenon. Whether the developmental hourglass occurs in plants, and what this means for our understanding of embryogenesis in plants and animals is discussed. Models by which conserved early-acting genes might change their functional role in the evolution of gene networks, how networks buffer these changes, and how that might constrain, or confer diversity, of the body plan are also discused. Evidence of a morphological and molecular hourglass in plant and animal embryogenesis suggests convergent evolution. This convergence is likely due to developmental constraints imposed upon embryogenesis by the need to produce a viable embryo with an established body plan, controlled by the architecture of the underlying gene regulatory networks. As the body plan is largely laid down during the middle phases of embryo development in plants and animals, then it is perhaps not surprising this stage represents the narrow waist of the hourglass where the gene regulatory networks are the oldest and most robust and integrated, limiting species diversity and constraining morphological space. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company.

The Evolution of Institutional Planning Models in Higher Education. AIR 1986 Annual Forum Paper.

ERIC Educational Resources Information Center

Winstead, Philip C.; Ruff, Dan G.

The evolution of the "planning process" from the 1940s to the present is considered, especially as it relates to higher education. It was hypothesized that institutional planning has experienced historical evolution: new planning innovations over the years have added to the existing institutional planning knowledge base. A literature…

A statistical test of unbiased evolution of body size in birds.

PubMed

Bokma, Folmer

2002-12-01

Of the approximately 9500 bird species, the vast majority is small-bodied. That is a general feature of evolutionary lineages, also observed for instance in mammals and plants. The avian interspecific body size distribution is right-skewed even on a logarithmic scale. That has previously been interpreted as evidence that body size evolution has been biased. However, a procedure to test for unbiased evolution from the shape of body size distributions was lacking. In the present paper unbiased body size evolution is defined precisely, and a statistical test is developed based on Monte Carlo simulation of unbiased evolution. Application of the test to birds suggests that it is highly unlikely that avian body size evolution has been unbiased as defined. Several possible explanations for this result are discussed. A plausible explanation is that the general model of unbiased evolution assumes that population size and generation time do not affect the evolutionary variability of body size; that is, that micro- and macroevolution are decoupled, which theory suggests is not likely to be the case.

[Evolution of methodical approaches to solve problem of evaluating and predicting the thermal status of cosmonauts in the real flight].

PubMed

Kuznets, E I; Bobrov, A F; Bekreneva, L N; Mikhailova, L I; Utekhin, B A; Pruzhinina, T I; Iakovleva, E V; Chadov, V I

1996-01-01

The problem of evaluating and predicting the thermal status of a cosmonaut in the long-term space mission is a pressing one and remains to be solved. The previous studies indicated that the best plan to be followed is to evaluate the thermal status of a cosmonaut during his egress into outer space with the use of the procedure of parotid thermometry of the mean body temperature.

From shoot to leaf: step-wise shifts in meristem and KNOX1 activity correlate with the evolution of a unifoliate body plan in Gesneriaceae.

PubMed

Nishii, Kanae; Huang, Bing-Hong; Wang, Chun-Neng; Möller, Michael

2017-01-01

Typical dicots possess equal-sized cotyledons and leaf-bearing shoots topped with a shoot apical meristem (SAM), the source of lateral organs, and where KNOX1 homeobox genes act as key regulators. New World Gesneriaceae show typical cotyledons, whereas Old World Gesneriaceae show anisocotyly, the unequal post-germination growth of cotyledons, and include unifoliate (one-leaf) plants. One-leaf plants show an extremely reduced body plan: the adult above-ground photosynthetic tissue consisting of a single cotyledon, a macrocotyledon enlarged by the basal meristem (BM), but lacking a SAM. To investigate the origin and evolution of the BM and one-leaf plants, the meristem activity and KNOX1 SHOOTMERISTEMLESS (STM) expression in cotyledons and leaves were systematically studied by RT-PCR and in situ hybridization across the family Gesneriaceae, Jovellana in Calceolariaceae (sister family to Gesneriaceae), and Antirrhinum in Plantaginaceae, all families of order Lamiales (asterids), in comparison to Arabidopsis (Brassicales, rosids). In all examined Lamiales samples, unlike Arabidopsis, BM activity accompanied by STM expression was found in both cotyledons in early stages. Foliage leaves of Gesneriaceae and Jovellana also showed the correlation of BM and STM expression. An extension of BM activity was found following a phylogenetic trajectory towards one-leaf plants where it is active throughout the lifetime of the macrocotyledon. Our results suggest that KNOX1 involvement in early cotyledon expansion originated early on in the diversification of Lamiales and is proposed as the prerequisite for the evolution of vegetative diversity in Gesneriaceae. Step-wise morphological shifts, driven by transfers of meristematic activity, as evidenced by shifts in KNOX1 expression, may be one mechanism by which morphological diversity evolves in plants.

Reactive oxygen species may play an essential role in driving biological evolution: The Cambrian Explosion as an example.

PubMed

Yang, Dong; Guo, Xuejun; Xie, Tian; Luo, Xiaoyan

2018-01-01

The Cambrian Explosion is one of the most significant events in the history of life; essentially all easily fossilizable animal body plans first evolved during this event. Although many theories have been proposed to explain this event, its cause remains unresolved. Here, we propose that the elevated level of oxygen, in combination with the increased mobility and food intake of metazoans, led to increased cellular levels of reactive oxygen species (ROS), which drove evolution by enhancing mutation rates and providing new regulatory mechanisms. Our hypothesis may provide a unified explanation for the Cambrian Explosion as it incorporates both environmental and developmental factors and is also consistent with ecological explanations for animal radiation. Future studies should focus on testing this hypothesis, and may lead to important insights into evolution. Copyright © 2017. Published by Elsevier B.V.

Space Science for the 21st Century. Strategic Plan for 1995-2000

NASA Technical Reports Server (NTRS)

1994-01-01

This publication is one of three volumes in 'Space Science for the 21st Century', the Office of Space Science Strategic plan for 1995-2000. The other two volumes are the recently released Integrated Technology Strategy and the Education Plan, which is in preparation at this publication date. The Science Plan was developed by the Office of Space Science (OSS) in partnership with the Space Science Advisory Committee. The mission of the OSS is to seek answers to fundamental questions about: the galaxy and the universe; the connection between the Sun, Earth, and Heliosphere; the origin and evolution of planetary systems; and the origin and distribution of life in the universe. The strategy to answer these questions includes completing the means to survey the universe across the entire electromagnetic spectrum; completing the survey of cosmic rays through their highest energies, and of interstellar gas; carrying out a basic new test of the Theory of General Relativity; completing development of the means to understand the mechanisms of solar variability and its effects on Earth; completing the first exploration of the inner and outer frontiers of the heliosphere; determining the plasma environments of the solar system planets and how those environments are affected by solar activity; completing development of the means to finish the reconnaissance of the entire solar system from the Sun to Pluto; beginning the comprehensive search for other planets around other stars; resuming surface exploration of solar system bodies to understand the origin and evolution of the Sun's planetary system; continuing the study of biogenic compounds and their evolution in the universe; and searching for indicators of past and present conditions conducive to life.

Convergent Evolution Associated with Habitat Decouples Phenotype from Phylogeny in a Clade of Lizards

PubMed Central

Edwards, Shelley; Vanhooydonck, Bieke; Herrel, Anthony; Measey, G. John; Tolley, Krystal A.

2012-01-01

Convergent evolution can explain similarity in morphology between species, due to selection on a fitness-enhancing phenotype in response to local environmental conditions. As selective pressures on body morphology may be strong, these have confounded our understanding of the evolutionary relationships between species. Within the speciose African radiation of lacertid lizards (Eremiadini), some species occupy a narrow habitat range (e.g. open habitat, cluttered habitat, strictly rupicolous, or strictly psammophilic), which may exert strong selective pressures on lizard body morphology. Here we show that the overall body plan is unrelated to shared ancestry in the African radiation of Eremiadini, but is instead coupled to habitat use. Comprehensive Bayesian and likelihood phylogenies using multiple representatives from all genera (2 nuclear, 2 mitochondrial markers) show that morphologically convergent species thought to represent sister taxa within the same genus are distantly related evolutionary lineages (Ichnotropis squamulosa and Ichnotropis spp.; Australolacerta rupicola and A. australis). Hierarchical clustering and multivariate analysis of morphological characters suggest that body, and head, width and height (stockiness), all of which are ecologically relevant with respect to movement through habitat, are similar between the genetically distant species. Our data show that convergence in morphology, due to adaptation to similar environments, has confounded the assignment of species leading to misidentification of the taxonomic position of I. squamulosa and the Australolacerta species. PMID:23251601

Application of Pulse Code Modulation (PCM) Technology to Aircraft Dynamics Data Acquisition.

DTIC Science & Technology

1981-04-01

and 27 is a summary of pro- jected contract awards. This plan is ordered to minimize develop- ment risks and costs in the evolution of a fully qualified...160 DOTS/INCH YES YES FORTRAN CALLABLE PLOT SOFTWARE YES YES ANALYSIS SOFTWARE YES YES 206 7. RECOMM0ENDATIONS The evaluation of the results of Phase...on metallic heat strips and specific heat sinks to provide a high degree of heat conduction from the component bodies through bonded joints to the

Cosmological N-body Simulation of Galaxy and Large-Scale Structure Formation: The Gravity Frontier

NASA Astrophysics Data System (ADS)

Klypin, Anatoly

2015-04-01

One of the first N-body simulations done almost 50 years ago had only 200 self-gravitating particles. Even this first baby step made substantial impact on understanding how astronomical objects should form. Now powerful supercomputers and new algorithms allow astronomers produce N-body simulations that employ up to a trillion dark matter particles and produce vital theoretical predictions regarding formation, evolution, structure and statistics of objects ranging from dwarf galaxies to clusters and superclusters of galaxies. With only gravity involved in these theoretical models, one would naively expect that by now we should know everything we need about N-body dynamics of cosmological fluctuations. Not the case. It appears that the Universe was not cooperative and gave us divergencies in the initial conditions generated during the Inflation epoch and subsequent expansion of the Universe - the infinite phase-space density and divergent density fluctuations. Ever increasing observational demands on statistics and accuracy of theoretical predictions is another driving force for more realistic and larger N-body simulations. Large current and new planned observational projects such as BOSS, eBOSS, Euclid, LSST will bring information on spatial distribution, motion, and properties of millions of galaxies at different redshifts. Direct simulations of evolution of gas and formation of stars for millions of forming galaxies will not be available for years leaving astronomers with the only option - to develop methods to combine large N-body simulations with models of galaxy formation to produce accurate theoretical predictions. I will discuss the current status of the field and directions of its development.

The great opportunity: Evolutionary applications to medicine and public health.

PubMed

Nesse, Randolph M; Stearns, Stephen C

2008-02-01

Evolutionary biology is an essential basic science for medicine, but few doctors and medical researchers are familiar with its most relevant principles. Most medical schools have geneticists who understand evolution, but few have even one evolutionary biologist to suggest other possible applications. The canyon between evolutionary biology and medicine is wide. The question is whether they offer each other enough to make bridge building worthwhile. What benefits could be expected if evolution were brought fully to bear on the problems of medicine? How would studying medical problems advance evolutionary research? Do doctors need to learn evolution, or is it valuable mainly for researchers? What practical steps will promote the application of evolutionary biology in the areas of medicine where it offers the most? To address these questions, we review current and potential applications of evolutionary biology to medicine and public health. Some evolutionary technologies, such as population genetics, serial transfer production of live vaccines, and phylogenetic analysis, have been widely applied. Other areas, such as infectious disease and aging research, illustrate the dramatic recent progress made possible by evolutionary insights. In still other areas, such as epidemiology, psychiatry, and understanding the regulation of bodily defenses, applying evolutionary principles remains an open opportunity. In addition to the utility of specific applications, an evolutionary perspective fundamentally challenges the prevalent but fundamentally incorrect metaphor of the body as a machine designed by an engineer. Bodies are vulnerable to disease - and remarkably resilient - precisely because they are not machines built from a plan. They are, instead, bundles of compromises shaped by natural selection in small increments to maximize reproduction, not health. Understanding the body as a product of natural selection, not design, offers new research questions and a framework for making medical education more coherent. We conclude with recommendations for actions that would better connect evolutionary biology and medicine in ways that will benefit public health. It is our hope that faculty and students will send this article to their undergraduate and medical school Deans, and that this will initiate discussions about the gap, the great opportunity, and action plans to bring the full power of evolutionary biology to bear on human health problems.

The evolution of computer monitoring of real time data during the Atlas Centaur launch countdown

NASA Technical Reports Server (NTRS)

Thomas, W. F.

1981-01-01

In the last decade, improvements in computer technology have provided new 'tools' for controlling and monitoring critical missile systems. In this connection, computers have gradually taken a large role in monitoring all flights and ground systems on the Atlas Centaur. The wide body Centaur which will be launched in the Space Shuttle Cargo Bay will use computers to an even greater extent. It is planned to use the wide body Centaur to boost the Galileo spacecraft toward Jupiter in 1985. The critical systems which must be monitored prior to liftoff are examined. Computers have now been programmed to monitor all critical parameters continuously. At this time, there are two separate computer systems used to monitor these parameters.

Convergent evolution of vascular optimization in kelp (Laminariales).

PubMed

Drobnitch, Sarah Tepler; Jensen, Kaare H; Prentice, Paige; Pittermann, Jarmila

2015-10-07

Terrestrial plants and mammals, although separated by a great evolutionary distance, have each arrived at a highly conserved body plan in which universal allometric scaling relationships govern the anatomy of vascular networks and key functional metabolic traits. The universality of allometric scaling suggests that these phyla have each evolved an 'optimal' transport strategy that has been overwhelmingly adopted by extant species. To truly evaluate the dominance and universality of vascular optimization, however, it is critical to examine other, lesser-known, vascularized phyla. The brown algae (Phaeophyceae) are one such group--as distantly related to plants as mammals, they have convergently evolved a plant-like body plan and a specialized phloem-like transport network. To evaluate possible scaling and optimization in the kelp vascular system, we developed a model of optimized transport anatomy and tested it with measurements of the giant kelp, Macrocystis pyrifera, which is among the largest and most successful of macroalgae. We also evaluated three classical allometric relationships pertaining to plant vascular tissues with a diverse sampling of kelp species. Macrocystis pyrifera displays strong scaling relationships between all tested vascular parameters and agrees with our model; other species within the Laminariales display weak or inconsistent vascular allometries. The lack of universal scaling in the kelps and the presence of optimized transport anatomy in M. pyrifera raises important questions about the evolution of optimization and the possible competitive advantage conferred by optimized vascular systems to multicellular phyla. © 2015 The Author(s).

Tetrapod axial evolution and developmental constraints; Empirical underpinning by a mouse model

PubMed Central

Woltering, Joost M.; Duboule, Denis

2015-01-01

The tetrapod vertebral column has become increasingly complex during evolution as an adaptation to a terrestrial life. At the same time, the evolution of the vertebral formula became subject to developmental constraints acting on the size of the cervical and thoraco-lumbar regions. In the course of our studies concerning the evolution of Hox gene regulation, we produced a transgenic mouse model expressing fish Hox genes, which displayed a reduced number of thoraco-lumbar vertebrae and concurrent sacral homeotic transformations. Here, we analyze this mutant stock and conclude that the ancestral, pre-tetrapodial Hox code already possessed the capacity to induce vertebrae with sacral characteristics. This suggests that alterations in the interpretation of the Hox code may have participated to the evolution of this region in tetrapods, along with potential modifications of the HOX proteins themselves. With its reduced vertebral number, this mouse stock violates a previously described developmental constraint, which applies to the thoraco-lumbar region. The resulting offset between motor neuron morphology, vertebral patterning and the relative positioning of hind limbs illustrates that the precise orchestration of the Hox-clock in parallel with other ontogenetic pathways places constraints on the evolvability of the body plan. PMID:26238020

New genus and species of the extinct aphid family Szelegiewicziidae and their implications for aphid evolution

NASA Astrophysics Data System (ADS)

Wegierek, Piotr; Żyła, Dagmara; Homan, Agnieszka; Cai, Chenyang; Huang, Diying

2017-12-01

Recently, we are witnessing an increased appreciation for the importance of the fossil record in phylogenetics and testing various evolutionary hypotheses. However, this approach brings many challenges, especially for such a complex group as aphids and requires a thorough morphological analysis of the extinct groups. The extinct aphid family Szelegiewicziidae is supposed to be one of the oviparous lineages in aphid evolution. New material from the rock fossil deposits of Shar Teg (Upper Jurassic of Mongolia), Baissa (Lower Cretaceous of Siberia-Russia), and Burmese amber (Upper Cretaceous of Myanmar) allowed us to undertake a more detailed examination of the morphological features and carry out an analysis of the taxonomical composition and evolution of the family. This led us to the conclusion that evolution of the body plan and wing structure was similar in different, often not closely related groups, probably as a result of convergence. Additionally, we present a description of a new genus and two species ( Tinaphis mongolica Żyła &Wegierek, sp. nov., and Feroorbis burmensis Wegierek & Huang, gen. et sp. nov.) that belong to this family.

New genus and species of the extinct aphid family Szelegiewicziidae and their implications for aphid evolution.

PubMed

Wegierek, Piotr; Żyła, Dagmara; Homan, Agnieszka; Cai, Chenyang; Huang, Diying

2017-10-24

Recently, we are witnessing an increased appreciation for the importance of the fossil record in phylogenetics and testing various evolutionary hypotheses. However, this approach brings many challenges, especially for such a complex group as aphids and requires a thorough morphological analysis of the extinct groups. The extinct aphid family Szelegiewicziidae is supposed to be one of the oviparous lineages in aphid evolution. New material from the rock fossil deposits of Shar Teg (Upper Jurassic of Mongolia), Baissa (Lower Cretaceous of Siberia-Russia), and Burmese amber (Upper Cretaceous of Myanmar) allowed us to undertake a more detailed examination of the morphological features and carry out an analysis of the taxonomical composition and evolution of the family. This led us to the conclusion that evolution of the body plan and wing structure was similar in different, often not closely related groups, probably as a result of convergence. Additionally, we present a description of a new genus and two species (Tinaphis mongolica Żyła &Wegierek, sp. nov., and Feroorbis burmensis Wegierek & Huang, gen. et sp. nov.) that belong to this family.

Cooperation induces other cooperation: Fruiting bodies promote the evolution of macrocysts in Dictyostelium discoideum.

PubMed

Shibasaki, Shota; Shirokawa, Yuka; Shimada, Masakazu

2017-05-21

Biological studies of the evolution of cooperation are challenging because this process is vulnerable to cheating. Many mechanisms, including kin discrimination, spatial structure, or by-products of self-interested behaviors, can explain this evolution. Here we propose that the evolution of cooperation can be induced by other cooperation. To test this idea, we used a model organism Dictyostelium discoideum because it exhibits two cooperative dormant phases, the fruiting body and the macrocyst. In both phases, the same chemoattractant, cyclic AMP (cAMP), is used to collect cells. This common feature led us to hypothesize that the evolution of macrocyst formation would be induced by coexistence with fruiting bodies. Before forming a mathematical model, we confirmed that macrocysts coexisted with fruiting bodies, at least under laboratory conditions. Next, we analyzed our evolutionary game theory-based model to investigate whether coexistence with fruiting bodies would stabilize macrocyst formation. The model suggests that macrocyst formation represents an evolutionarily stable strategy and a global invader strategy under this coexistence, but is unstable if the model ignores the fruiting body formation. This result indicates that the evolution of macrocyst formation and maintenance is attributable to coexistence with fruiting bodies. Therefore, macrocyst evolution can be considered as an example of evolution of cooperation induced by other cooperation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The mid-developmental transition and the evolution of animal body plans

PubMed Central

Cole, Alison G.; Winter, Eitan; Mostov, Natalia; Khair, Sally; Senderovich, Naftalie; Kovalev, Ekaterina; Silver, David H.; Feder, Martin; Fernandez-Valverde, Selene L.; Nakanishi, Nagayasu; Simmons, David; Simakov, Oleg; Larsson, Tomas; Liu, Shang-Yun; Jerafi-Vider, Ayelet; Yaniv, Karina; Ryan, Joseph F.; Martindale, Mark Q.; Rink, Jochen C.; Arendt, Detlev; Degnan, Sandie M.; Degnan, Bernard M.; Hashimshony, Tamar; Yanai, Itai

2016-01-01

Animals are grouped into ~35 ‘phyla’ based upon the notion of distinct body plans1–4. Morphological and molecular analyses have revealed that a stage in the middle of development—known as the phylotypic period—is conserved among species within some phyla5–9. Although these analyses provide evidence for their existence, phyla have also been criticized as lacking an objective definition, and consequently based on arbitrary groupings of animals10. Here we compare the developmental transcriptomes of ten species, each annotated to a different phylum, with a wide range of life histories and embryonic forms. We find that in all ten species, development comprises the coupling of early and late phases of conserved gene expression. These phases are linked by a divergent ‘mid-developmental transition’ that uses species-specific suites of signalling pathways and transcription factors. This mid-developmental transition overlaps with the phylotypic period that has been defined previously for three of the ten phyla, suggesting that transcriptional circuits and signalling mechanisms active during this transition are crucial for defining the phyletic body plan and that the mid-developmental transition may be used to define phylotypic periods in other phyla. Placing these observations alongside the reported conservation of mid-development within phyla, we propose that a phylum may be defined as a collection of species whose gene expression at the mid-developmental transition is both highly conserved among them, yet divergent relative to other species. PMID:26886793

Island colonisation and the evolutionary rates of body size in insular neonate snakes

PubMed Central

Aubret, F

2015-01-01

Island colonisation by animal populations is often associated with dramatic shifts in body size. However, little is known about the rates at which these evolutionary shifts occur, under what precise selective pressures and the putative role played by adaptive plasticity on driving such changes. Isolation time played a significant role in the evolution of body size in island Tiger snake populations, where adaptive phenotypic plasticity followed by genetic assimilation fine-tuned neonate body and head size (hence swallowing performance) to prey size. Here I show that in long isolated islands (>6000 years old) and mainland populations, neonate body mass and snout-vent length are tightly correlated with the average prey body mass available at each site. Regression line equations were used to calculate body size values to match prey size in four recently isolated populations of Tiger snakes. Rates of evolution in body mass and snout-vent length, calculated for seven island snake populations, were significantly correlated with isolation time. Finally, rates of evolution in body mass per generation were significantly correlated with levels of plasticity in head growth rates. This study shows that body size evolution occurs at a faster pace in recently isolated populations and suggests that the level of adaptive plasticity for swallowing abilities may correlate with rates of body mass evolution. I hypothesise that, in the early stages of colonisation, adaptive plasticity and directional selection may combine and generate accelerated evolution towards an ‘optimal' phenotype. PMID:25074570

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

PubMed

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

2017-07-01

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

Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in echinoderms.

PubMed

Rahman, Imran A; Waters, Johnny A; Sumrall, Colin D; Astolfo, Alberto

2015-10-01

Inferring the development of the earliest echinoderms is critical to uncovering the evolutionary assembly of the phylum-level body plan but has long proven problematic because early ontogenetic stages are rarely preserved as fossils. Here, we use synchrotron tomography to describe a new early post-metamorphic blastoid echinoderm from the Carboniferous (approx. 323 Ma) of China. The resulting three-dimensional reconstruction reveals a U-shaped tubular structure in the fossil interior, which is interpreted as the digestive tract. Comparisons with the developing gut of modern crinoids demonstrate that crinoids are an imperfect analogue for many extinct groups. Furthermore, consideration of our findings in a phylogenetic context allows us to reconstruct the evolution and development of the digestive system in echinoderms more broadly; there was a transition from a straight to a simple curved gut early in the phylum's evolution, but additional loops and coils of the digestive tract (as seen in crinoids) were not acquired until much later. © 2015 The Author(s).

Antagonistic Roles for KNOX1 and KNOX2 Genes in Patterning the Land Plant Body Plan Following an Ancient Gene Duplication

PubMed Central

Furumizu, Chihiro; Alvarez, John Paul; Sakakibara, Keiko; Bowman, John L.

2015-01-01

Neofunctionalization following gene duplication is thought to be one of the key drivers in generating evolutionary novelty. A gene duplication in a common ancestor of land plants produced two classes of KNOTTED-like TALE homeobox genes, class I (KNOX1) and class II (KNOX2). KNOX1 genes are linked to tissue proliferation and maintenance of meristematic potentials of flowering plant and moss sporophytes, and modulation of KNOX1 activity is implicated in contributing to leaf shape diversity of flowering plants. While KNOX2 function has been shown to repress the gametophytic (haploid) developmental program during moss sporophyte (diploid) development, little is known about KNOX2 function in flowering plants, hindering syntheses regarding the relationship between two classes of KNOX genes in the context of land plant evolution. Arabidopsis plants harboring loss-of-function KNOX2 alleles exhibit impaired differentiation of all aerial organs and have highly complex leaves, phenocopying gain-of-function KNOX1 alleles. Conversely, gain-of-function KNOX2 alleles in conjunction with a presumptive heterodimeric BELL TALE homeobox partner suppressed SAM activity in Arabidopsis and reduced leaf complexity in the Arabidopsis relative Cardamine hirsuta, reminiscent of loss-of-function KNOX1 alleles. Little evidence was found indicative of epistasis or mutual repression between KNOX1 and KNOX2 genes. KNOX proteins heterodimerize with BELL TALE homeobox proteins to form functional complexes, and contrary to earlier reports based on in vitro and heterologous expression, we find high selectivity between KNOX and BELL partners in vivo. Thus, KNOX2 genes confer opposing activities rather than redundant roles with KNOX1 genes, and together they act to direct the development of all above-ground organs of the Arabidopsis sporophyte. We infer that following the KNOX1/KNOX2 gene duplication in an ancestor of land plants, neofunctionalization led to evolution of antagonistic biochemical activity thereby facilitating the evolution of more complex sporophyte transcriptional networks, providing plasticity for the morphological evolution of land plant body plans. PMID:25671434

Evolution of Body Elongation in Gymnophthalmid Lizards: Relationships with Climate

PubMed Central

Grizante, Mariana B.; Brandt, Renata; Kohlsdorf, Tiana

2012-01-01

The evolution of elongated body shapes in vertebrates has intrigued biologists for decades and is particularly recurrent among squamates. Several aspects might explain how the environment influences the evolution of body elongation, but climate needs to be incorporated in this scenario to evaluate how it contributes to morphological evolution. Climatic parameters include temperature and precipitation, two variables that likely influence environmental characteristics, including soil texture and substrate coverage, which may define the selective pressures acting during the evolution of morphology. Due to development of geographic information system (GIS) techniques, these variables can now be included in evolutionary biology studies and were used in the present study to test for associations between variation in body shape and climate in the tropical lizard family Gymnophthalmidae. We first investigated how the morphological traits that define body shape are correlated in these lizards and then tested for associations between a descriptor of body elongation and climate. Our analyses revealed that the evolution of body elongation in Gymnophthalmidae involved concomitant changes in different morphological traits: trunk elongation was coupled with limb shortening and a reduction in body diameter, and the gradual variation along this axis was illustrated by less-elongated morphologies exhibiting shorter trunks and longer limbs. The variation identified in Gymnophthalmidae body shape was associated with climate, with the species from more arid environments usually being more elongated. Aridity is associated with high temperatures and low precipitation, which affect additional environmental features, including the habitat structure. This feature may influence the evolution of body shape because contrasting environments likely impose distinct demands for organismal performance in several activities, such as locomotion and thermoregulation. The present study establishes a connection between morphology and a broader natural component, climate, and introduces new questions about the spatial distribution of morphological variation among squamates. PMID:23166767

FTS evolution

NASA Technical Reports Server (NTRS)

Provost, David E.

1990-01-01

Viewgraphs on flight telerobotic servicer evolution are presented. Topics covered include: paths for FTS evolution; frequently performed actions; primary task states; EPS radiator panel installation; generic task definitions; path planning; non-contact alignment; contact planning and control; and human operator interface.

A systematic approach to very important person preparedness for a trauma center.

PubMed

Bulson, Julie; Mattice, Connie; Bulson, Timothy

2012-01-01

Hospitals across the United States are more involved in disaster/rapid response planning than ever. This collaboration is often driven by continuing federal and state preparedness and all-hazards planning efforts that provide cooperative agreement and/or grant support. These efforts currently include programs administered by the US assistant secretary for preparedness and response, the US Centers for Disease Control and Prevention, the US Department of Defense, and the US Department of Homeland Security. Beyond legislated support or mandates, key emergency management regulations governing hospital-specific disaster planning and response activities are required of hospitals by The Joint Commission, the largest national hospital accrediting body. Despite this ongoing, heightened awareness and inclusion of health care in local and regional emergency response planning, there is 1 partnership to yet strengthen: the relationship between community trauma centers and US Secret Service staff responsible for White House travel and health care contingency plans. One Michigan hospital system designed a program that has made preevent communications and preparedness for rapid very important person response with the Secret Service as important as other local all-hazards planning; the evolution of this partnership is the focus of this article.

NAS operational evolution plan : a foundation for capacity enhancement 2001-2010

DOT National Transportation Integrated Search

2001-06-01

This series of World Wide Web slides focuses on the Operational Evolution Plan, which is a 10-year plan for aviation operational improvements to increase capacity and safety in the United States. This plan is unique in that it integrates all actions:...

Fossils and living taxa agree on patterns of body mass evolution: a case study with Afrotheria.

PubMed

Puttick, Mark N; Thomas, Gavin H

2015-12-22

Most of life is extinct, so incorporating some fossil evidence into analyses of macroevolution is typically seen as necessary to understand the diversification of life and patterns of morphological evolution. Here we test the effects of inclusion of fossils in a study of the body size evolution of afrotherian mammals, a clade that includes the elephants, sea cows and elephant shrews. We find that the inclusion of fossil tips has little impact on analyses of body mass evolution; from a small ancestral size (approx. 100 g), there is a shift in rate and an increase in mass leading to the larger-bodied Paenungulata and Tubulidentata, regardless of whether fossils are included or excluded from analyses. For Afrotheria, the inclusion of fossils and morphological character data affect phylogenetic topology, but these differences have little impact upon patterns of body mass evolution and these body mass evolutionary patterns are consistent with the fossil record. The largest differences between our analyses result from the evolutionary model, not the addition of fossils. For some clades, extant-only analyses may be reliable to reconstruct body mass evolution, but the addition of fossils and careful model selection is likely to increase confidence and accuracy of reconstructed macroevolutionary patterns. © 2015 The Authors.

Fossils and living taxa agree on patterns of body mass evolution: a case study with Afrotheria

PubMed Central

Puttick, Mark N.; Thomas, Gavin H.

2015-01-01

Most of life is extinct, so incorporating some fossil evidence into analyses of macroevolution is typically seen as necessary to understand the diversification of life and patterns of morphological evolution. Here we test the effects of inclusion of fossils in a study of the body size evolution of afrotherian mammals, a clade that includes the elephants, sea cows and elephant shrews. We find that the inclusion of fossil tips has little impact on analyses of body mass evolution; from a small ancestral size (approx. 100 g), there is a shift in rate and an increase in mass leading to the larger-bodied Paenungulata and Tubulidentata, regardless of whether fossils are included or excluded from analyses. For Afrotheria, the inclusion of fossils and morphological character data affect phylogenetic topology, but these differences have little impact upon patterns of body mass evolution and these body mass evolutionary patterns are consistent with the fossil record. The largest differences between our analyses result from the evolutionary model, not the addition of fossils. For some clades, extant-only analyses may be reliable to reconstruct body mass evolution, but the addition of fossils and careful model selection is likely to increase confidence and accuracy of reconstructed macroevolutionary patterns. PMID:26674947

The Veiled Chameleon (Chamaeleo calyptratus Duméril and Duméril 1851): A Model for Studying Reptile Body Plan Development and Evolution.

PubMed

Diaz, Raul E; Anderson, Christopher V; Baumann, Diana P; Kupronis, Richard; Jewell, David; Piraquive, Christina; Kupronis, Jill; Winter, Kristy; Bertocchini, Federica; Trainor, Paul A

2015-08-26

Vertebrate model organisms have facilitated the discovery and exploration of morphogenetic events and developmental pathways that underpin normal and pathological embryological events. In contrast to amniotes such as Mus musculus (Mammalia) and Gallus gallus (Aves), our understanding of early patterning and developmental events in reptiles (particularly nonavians) remains weak. Squamate reptiles (lizards, snakes, and amphisbaenians) comprise approximately one-third of all living amniotes. But studies of early squamate development have been limited because, in most members of this lineage, embryo development at the time of oviposition is very advanced (limb bud stages and older). In many cases, squamates give birth to fully developed offspring. However, in the veiled chameleon (Chamaeleo calyptratus), embryos have progressed only to a primitive pregastrula stage at the time of oviposition. Furthermore, the body plan of the veiled chameleon is highly specialized for climbing in an arboreal environment. It possesses an entire suite of skeletal and soft anatomical modifications, including cranioskeletal ornamentation, lingual anatomy and biomechanics for projection, autopodial clefting for grasping, adaptations for rapid integumental color changes, a prehensile tail with a lack of caudal autotomy, the loss of the tympanum in the middle ear, and the acquisition of turreted eyes. Thus, C. calyptratus is an important model organism for studying the role of ecological niche specialization, as well as genetic and morphological evolution within an adaptive framework. More importantly, this species is easily bred in captivity, with only a small colony (<10 individuals) needed to obtain hundreds of embryos every year. © 2015 Cold Spring Harbor Laboratory Press.

Tetrapod axial evolution and developmental constraints; Empirical underpinning by a mouse model.

PubMed

Woltering, Joost M; Duboule, Denis

2015-11-01

The tetrapod vertebral column has become increasingly complex during evolution as an adaptation to a terrestrial life. At the same time, the evolution of the vertebral formula became subject to developmental constraints acting on the size of the cervical and thoraco-lumbar regions. In the course of our studies concerning the evolution of Hox gene regulation, we produced a transgenic mouse model expressing fish Hox genes, which displayed a reduced number of thoraco-lumbar vertebrae and concurrent sacral homeotic transformations. Here, we analyze this mutant stock and conclude that the ancestral, pre-tetrapodial Hox code already possessed the capacity to induce vertebrae with sacral characteristics. This suggests that alterations in the interpretation of the Hox code may have participated to the evolution of this region in tetrapods, along with potential modifications of the HOX proteins themselves. With its reduced vertebral number, this mouse stock violates a previously described developmental constraint, which applies to the thoraco-lumbar region. The resulting offset between motor neuron morphology, vertebral patterning and the relative positioning of hind limbs illustrates that the precise orchestration of the Hox-clock in parallel with other ontogenetic pathways places constraints on the evolvability of the body plan. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Body shape convergence driven by small size optimum in marine angelfishes.

PubMed

Frédérich, Bruno; Santini, Francesco; Konow, Nicolai; Schnitzler, Joseph; Lecchini, David; Alfaro, Michael E

2017-06-01

Convergent evolution of small body size occurs across many vertebrate clades and may reflect an evolutionary response to shared selective pressures. However it remains unclear if other aspects of phenotype undergo convergent evolution in miniaturized lineages. Here we present a comparative analysis of body size and shape evolution in marine angelfishes (Pomacanthidae), a reef fish family characterized by repeated transitions to small body size. We ask if lineages that evolve small sizes show convergent evolution in body shape. Our results reveal that angelfish lineages evolved three different stable size optima with one corresponding to the group of pygmy angelfishes ( Centropyge ). Then, we test if the observed shifts in body size are associated with changes to new adaptive peaks in shape. Our data suggest that independent evolution to small size optima have induced repeated convergence upon deeper body and steeper head profile in Centropyge These traits may favour manoeuvrability and visual awareness in these cryptic species living among corals, illustrating that functional demands on small size may be related to habitat specialization and predator avoidance. The absence of shape convergence in large marine angelfishes also suggests that more severe requirements exist for small than for large size optima. © 2017 The Author(s).

Perspectives on the Genetic Architecture of Divergence in Body Shape in Sticklebacks

PubMed Central

Reid, Duncan T.; Peichel, Catherine L.

2010-01-01

The body shape of fishes encompasses a number of morphological traits that are intrinsically linked to functional systems and affect various measures of performance, including swimming, feeding, and avoiding predators. Changes in shape can allow a species to exploit a new ecological niche and can lead to ecological speciation. Body shape results from the integration of morphological, behavioral and physiological traits. It has been well established that functional interdependency among traits plays a large role in constraining the evolution of shape, affecting both the speed and the repeated evolution of particular body shapes. However, it is less clear what role genetic or developmental constraints might play in biasing the rate or direction of the evolution of body shape. Here, we suggest that the threespine stickleback (Gasterosteus aculeatus) is a powerful model system in which to address the extent to which genetic or developmental constraints play a role in the evolution of body shape in fishes. We review the existing data that begins to address these issues in sticklebacks and provide suggestions for future areas of research that will be particularly fruitful for illuminating the mechanisms that contribute to the evolution of body shape in fishes. PMID:21082067

An integrative model of evolutionary covariance: a symposium on body shape in fishes.

PubMed

Walker, Jeffrey A

2010-12-01

A major direction of current and future biological research is to understand how multiple, interacting functional systems coordinate in producing a body that works. This understanding is complicated by the fact that organisms need to work well in multiple environments, with both predictable and unpredictable environmental perturbations. Furthermore, organismal design reflects a history of past environments and not a plan for future environments. How complex, interacting functional systems evolve, then, is a truly grand challenge. In accepting the challenge, an integrative model of evolutionary covariance is developed. The model combines quantitative genetics, functional morphology/physiology, and functional ecology. The model is used to convene scientists ranging from geneticists, to physiologists, to ecologists, to engineers to facilitate the emergence of body shape in fishes as a model system for understanding how complex, interacting functional systems develop and evolve. Body shape of fish is a complex morphology that (1) results from many developmental paths and (2) functions in many different behaviors. Understanding the coordination and evolution of the many paths from genes to body shape, body shape to function, and function to a working fish body in a dynamic environment is now possible given new technologies from genetics to engineering and new theoretical models that integrate the different levels of biological organization (from genes to ecology).

Big cat, small cat: reconstructing body size evolution in living and extinct Felidae.

PubMed

Cuff, A R; Randau, M; Head, J; Hutchinson, J R; Pierce, S E; Goswami, A

2015-08-01

The evolution of body mass is a fundamental topic in evolutionary biology, because it is closely linked to manifold life history and ecological traits and is readily estimable for many extinct taxa. In this study, we examine patterns of body mass evolution in Felidae (Placentalia, Carnivora) to assess the effects of phylogeny, mode of evolution, and the relationship between body mass and prey choice in this charismatic mammalian clade. Our data set includes 39 extant and 26 extinct taxa, with published body mass data supplemented by estimates based on condylobasal length. These data were run through 'SURFACE' and 'bayou' to test for patterns of body mass evolution and convergence between taxa. Body masses of felids are significantly different among prey choice groupings (small, mixed and large). We find that body mass evolution in cats is strongly influenced by phylogeny, but different patterns emerged depending on inclusion of extinct taxa and assumptions about branch lengths. A single Ornstein-Uhlenbeck optimum best explains the distribution of body masses when first-occurrence data were used for the fossil taxa. However, when mean occurrence dates or last known occurrence dates were used, two selective optima for felid body mass were recovered in most analyses: a small optimum around 5 kg and a large one around 100 kg. Across living and extinct cats, we infer repeated evolutionary convergences towards both of these optima, but, likely due to biased extinction of large taxa, our results shift to supporting a Brownian motion model when only extant taxa are included in analyses. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Phylogenomic Insights into Animal Evolution.

PubMed

Telford, Maximilian J; Budd, Graham E; Philippe, Hervé

2015-10-05

Animals make up only a small fraction of the eukaryotic tree of life, yet, from our vantage point as members of the animal kingdom, the evolution of the bewildering diversity of animal forms is endlessly fascinating. In the century following the publication of Darwin's Origin of Species, hypotheses regarding the evolution of the major branches of the animal kingdom - their relationships to each other and the evolution of their body plans - was based on a consideration of the morphological and developmental characteristics of the different animal groups. This morphology-based approach had many successes but important aspects of the evolutionary tree remained disputed. In the past three decades, molecular data, most obviously primary sequences of DNA and proteins, have provided an estimate of animal phylogeny largely independent of the morphological evolution we would ultimately like to understand. The molecular tree that has evolved over the past three decades has drastically altered our view of animal phylogeny and many aspects of the tree are no longer contentious. The focus of molecular studies on relationships between animal groups means, however, that the discipline has become somewhat divorced from the underlying biology and from the morphological characteristics whose evolution we aim to understand. Here, we consider what we currently know of animal phylogeny; what aspects we are still uncertain about and what our improved understanding of animal phylogeny can tell us about the evolution of the great diversity of animal life. Copyright © 2015 Elsevier Ltd. All rights reserved.

Patient-specific surgical simulator for the pre-operative planning of single-incision laparoscopic surgery with bimanual robots.

PubMed

Turini, Giuseppe; Moglia, Andrea; Ferrari, Vincenzo; Ferrari, Mauro; Mosca, Franco

2012-01-01

The trend of surgical robotics is to follow the evolution of laparoscopy, which is now moving towards single-incision laparoscopic surgery. The main drawback of this approach is the limited maneuverability of the surgical tools. Promising solutions to improve the surgeon's dexterity are based on bimanual robots. However, since both robot arms are completely inserted into the patient's body, issues related to possible unwanted collisions with structures adjacent to the target organ may arise. This paper presents a simulator based on patient-specific data for the positioning and workspace evaluation of bimanual surgical robots in the pre-operative planning of single-incision laparoscopic surgery. The simulator, designed for the pre-operative planning of robotic laparoscopic interventions, was tested by five expert surgeons who evaluated its main functionalities and provided an overall rating for the system. The proposed system demonstrated good performance and usability, and was designed to integrate both present and future bimanual surgical robots.

Adaptive processes drive ecomorphological convergent evolution in antwrens (Thamnophilidae).

PubMed

Bravo, Gustavo A; Remsen, J V; Brumfield, Robb T

2014-10-01

Phylogenetic niche conservatism (PNC) and convergence are contrasting evolutionary patterns that describe phenotypic similarity across independent lineages. Assessing whether and how adaptive processes give origin to these patterns represent a fundamental step toward understanding phenotypic evolution. Phylogenetic model-based approaches offer the opportunity not only to distinguish between PNC and convergence, but also to determine the extent that adaptive processes explain phenotypic similarity. The Myrmotherula complex in the Neotropical family Thamnophilidae is a polyphyletic group of sexually dimorphic small insectivorous forest birds that are relatively homogeneous in size and shape. Here, we integrate a comprehensive species-level molecular phylogeny of the Myrmotherula complex with morphometric and ecological data within a comparative framework to test whether phenotypic similarity is described by a pattern of PNC or convergence, and to identify evolutionary mechanisms underlying body size and shape evolution. We show that antwrens in the Myrmotherula complex represent distantly related clades that exhibit adaptive convergent evolution in body size and divergent evolution in body shape. Phenotypic similarity in the group is primarily driven by their tendency to converge toward smaller body sizes. Differences in body size and shape across lineages are associated to ecological and behavioral factors. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Near-Earth Objects: Targets for Future Human Exploration, Solar System Science, and Planetary Defense

NASA Technical Reports Server (NTRS)

Abell, Paul A.

2011-01-01

Human exploration of near-Earth objects (NEOs) beginning circa 2025 - 2030 is one of the stated objectives of U.S. National Space Policy. Piloted missions to these bodies would further development of deep space mission systems and technologies, obtain better understanding of the origin and evolution of our Solar System, and support research for asteroid deflection and hazard mitigation strategies. This presentation will discuss some of the physical characteristics of NEOs and review some of the current plans for NEO research and exploration from both a human and robotic mission perspective.

Advances in Liposuction: Five Key Principles with Emphasis on Patient Safety and Outcomes

PubMed Central

Tabbal, Geo N.; Ahmad, Jamil; Lista, Frank

2013-01-01

Summary: Since Illouz’s presentation of a technique for lipoplasty at the 1982 Annual Meeting of the American Society of Plastic and Reconstructive Surgeons, liposuction has become one of the most commonly performed aesthetic surgery procedures. The evolution of liposuction has seen refinements in technique and improvement of patient safety-related standards of care. Based on long-term experience with body contouring surgery, 5 principles of advanced liposuction are presented: preoperative evaluation and planning, intraoperative monitoring—safety measures, the role of wetting solutions and fluid resuscitation, circumferential contouring and complication prevention, and outcomes measurement. PMID:25289270

Radio Astronomy at the Centre for High Performance Computing in South Africa

NASA Astrophysics Data System (ADS)

Catherine Cress; UWC Simulation Team

2014-04-01

I will present results on galaxy evolution and cosmology which we obtained using the supercomputing facilities at the CHPC. These include cosmological-scale N-body simulations modelling neutral hydrogen as well as the study of the clustering of radio galaxies to probe the relationship between dark and luminous matter in the universe. I will also discuss the various roles that the CHPC is playing in Astronomy in SA, including the provision of HPC for a variety of Astronomical applications, the provision of storage for radio data, our educational programs and our participation in planning for the SKA.

Comparative analysis of early ontogeny in Bursatella leachii and Aplysia californica

PubMed Central

Vue, Zer; Capo, Thomas R.; Bardales, Ana T.

2014-01-01

Opisthobranch molluscs exhibit fascinating body plans associated with the evolution of shell loss in multiple lineages. Sea hares in particular are interesting because Aplysia californica is a well-studied model organism that offers a large suite of genetic tools. Bursatella leachii is a related tropical sea hare that lacks a shell as an adult and therefore lends itself to comparative analysis with A. californica. We have established an enhanced culturing procedure for B. leachii in husbandry that enabled the study of shell formation and loss in this lineage with respect to A. californica life staging. PMID:25538871

Mammal body size evolution in North America and Europe over 20 Myr: similar trends generated by different processes.

PubMed

Huang, Shan; Eronen, Jussi T; Janis, Christine M; Saarinen, Juha J; Silvestro, Daniele; Fritz, Susanne A

2017-02-22

Because body size interacts with many fundamental biological properties of a species, body size evolution can be an essential component of the generation and maintenance of biodiversity. Here we investigate how body size evolution can be linked to the clade-specific diversification dynamics in different geographical regions. We analyse an extensive body size dataset of Neogene large herbivores (covering approx. 50% of the 970 species in the orders Artiodactyla and Perissodactyla) in Europe and North America in a Bayesian framework. We reconstruct the temporal patterns of body size in each order on each continent independently, and find significant increases of minimum size in three of the continental assemblages (except European perissodactyls), suggesting an active selection for larger bodies. Assessment of trait-correlated birth-death models indicates that the common trend of body size increase is generated by different processes in different clades and regions. Larger-bodied artiodactyl species on both continents tend to have higher origination rates, and both clades in North America show strong links between large bodies and low extinction rate. Collectively, our results suggest a strong role of species selection and perhaps of higher-taxon sorting in driving body size evolution, and highlight the value of investigating evolutionary processes in a biogeographic context. © 2017 The Author(s).

Mammal body size evolution in North America and Europe over 20 Myr: similar trends generated by different processes

PubMed Central

Eronen, Jussi T.; Janis, Christine M.; Saarinen, Juha J.

2017-01-01

Because body size interacts with many fundamental biological properties of a species, body size evolution can be an essential component of the generation and maintenance of biodiversity. Here we investigate how body size evolution can be linked to the clade-specific diversification dynamics in different geographical regions. We analyse an extensive body size dataset of Neogene large herbivores (covering approx. 50% of the 970 species in the orders Artiodactyla and Perissodactyla) in Europe and North America in a Bayesian framework. We reconstruct the temporal patterns of body size in each order on each continent independently, and find significant increases of minimum size in three of the continental assemblages (except European perissodactyls), suggesting an active selection for larger bodies. Assessment of trait-correlated birth-death models indicates that the common trend of body size increase is generated by different processes in different clades and regions. Larger-bodied artiodactyl species on both continents tend to have higher origination rates, and both clades in North America show strong links between large bodies and low extinction rate. Collectively, our results suggest a strong role of species selection and perhaps of higher-taxon sorting in driving body size evolution, and highlight the value of investigating evolutionary processes in a biogeographic context. PMID:28202809

The amniote temporal roof and the diapsid origin of the turtle skull.

PubMed

Bever, G S; Lyson, Tyler R; Field, Daniel J; Bhullar, Bhart-Anjan S

2016-12-01

Fossils provide a glimpse into the architecturally complex origins of modern vertebrate body plans. One such origin that has been long debated is that of turtles. Although much attention has been directed toward the origin of the shell, the enigmatic evolution of the turtle skull and its anapsid temporal region has long clouded our understanding of reptile phylogeny. Two taxa, Eunotosaurus africanus and Pappochelys rosinae, were recently and independently described as long-anticipated stem turtles whose diapsid skulls would cement the evolutionary link between turtles and other modern reptile lineages. Detailed μCT analysis of the stratigraphically older and phylogenetically stemward of the two, Eunotosaurus, provides empirical insight into changing developmental trajectories that may have produced the anapsid cranial form of modern turtles and sets the stage for more comprehensive studies of early amniote cranial evolution. Copyright © 2016 Elsevier GmbH. All rights reserved.

The Amphimedon queenslandica genome and the evolution of animal complexity

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

Srivastava, Mansi; Simakov, Oleg; Chapman, Jarrod

2010-07-01

Sponges are an ancient group of animals that diverged from other metazoans over 600 million years ago. Here we present the draft genome sequence of Amphimedon queenslandica, a demosponge from the Great Barrier Reef, and show that it is remarkably similar to other animal genomes in content, structure and organization. Comparative analysis enabled by the sponge sequence reveals genomic events linked to the origin and early evolution of animals, including the appearance, expansion, and diversification of pan-metazoan transcription factor, signaling pathway, and structural genes. This diverse 'toolkit' of genes correlates with critical aspects of all metazoan body plans, and comprisesmore » cell cycle control and growth, development, somatic and germ cell specification, cell adhesion, innate immunity, and allorecognition. Notably, many of the genes associated with the emergence of animals are also implicated in cancer, which arises from defects in basic processes associated with metazoan multicellularity.« less

The statistical geometry of transcriptome divergence in cell-type evolution and cancer.

PubMed

Liang, Cong; Forrest, Alistair R R; Wagner, Günter P

2015-01-14

In evolution, body plan complexity increases due to an increase in the number of individualized cell types. Yet, there is very little understanding of the mechanisms that produce this form of organismal complexity. One model for the origin of novel cell types is the sister cell-type model. According to this model, each cell type arises together with a sister cell type through specialization from an ancestral cell type. A key prediction of the sister cell-type model is that gene expression profiles of cell types exhibit tree structure. Here we present a statistical model for detecting tree structure in transcriptomic data and apply it to transcriptomes from ENCODE and FANTOM5. We show that transcriptomes of normal cells harbour substantial amounts of hierarchical structure. In contrast, cancer cell lines have less tree structure, suggesting that the emergence of cancer cells follows different principles from that of evolutionary cell-type origination.

Phylogenomics of MADS-Box Genes in Plants - Two Opposing Life Styles in One Gene Family.

PubMed

Gramzow, Lydia; Theißen, Günter

2013-09-12

The development of multicellular eukaryotes, according to their body plan, is often directed by members of multigene families that encode transcription factors. MADS (for MINICHROMOSOME MAINTENANCE1, AGAMOUS, DEFICIENS and SERUM RESPONSE FACTOR)-box genes form one of those families controlling nearly all major aspects of plant development. Knowing the complete complement of MADS-box genes in sequenced plant genomes will allow a better understanding of the evolutionary patterns of these genes and the association of their evolution with the evolution of plant morphologies. Here, we have applied a combination of automatic and manual annotations to identify the complete set of MADS-box genes in 17 plant genomes. Furthermore, three plant genomes were reanalyzed and published datasets were used for four genomes such that more than 2,600 genes from 24 species were classified into the two types of MADS-box genes, Type I and Type II. Our results extend previous studies, highlighting the remarkably different evolutionary patterns of Type I and Type II genes and provide a basis for further studies on the evolution and function of MADS-box genes.

Smaller solar system bodies and orbits; Proceedings of Symposium 3, Workshops II, III, and XXVI, and Topical Meetings of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

NASA Technical Reports Server (NTRS)

Runcorn, S. K. (Editor); Carr, M. H. (Editor); Moehlmann, D. (Editor); Stiller, H. (Editor); Matson, D. L. (Editor); Ambrosius, B. A. C. (Editor); Kessler, D. J. (Editor)

1990-01-01

Topics discussed in this volume include the reappraisal of the moon and Mars/Phobos/Deimos; the origin and evolution of planetary and satellite systems; asteroids, comets, and dust (a post-IRAS perspective); satellite dynamics; future planetary missions; and orbital debris. Papers are presented on a comparison of the chemistry of moon and Mars, the use of a mobile surface radar to study the atmosphere and ionosphere, and laser-ionization studies with the technical models of the LIMA-D/Phobos. Attention is given to planetogonic scenarios and the evolution of relatively mass-rich preplanetary disks, the kinetic behavior of planetesimals revolving around the sun, the planetary evolution of Mars, and pre- and post-IRAS asteroid taxonomies. Consideration is also given to ocean tides and tectonic plate motions in high-precision orbit determination, the satellite altimeter calibration techniques, a theory of the motion of an artificial satellite in the earth atmosphere, ESA plans for planetary exploration, and the detection of earth orbiting objects by IRAS.

Smaller solar system bodies and orbits; Proceedings of Symposium 3, Workshops II, III, and XXVI, and Topical Meetings of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

NASA Astrophysics Data System (ADS)

Runcorn, S. K.; Carr, M. H.; Moehlmann, D.; Stiller, H.; Matson, D. L.; Ambrosius, B. A. C.; Kessler, D. J.

Topics discussed in this volume include the reappraisal of the moon and Mars/Phobos/Deimos; the origin and evolution of planetary and satellite systems; asteroids, comets, and dust (a post-IRAS perspective); satellite dynamics; future planetary missions; and orbital debris. Papers are presented on a comparison of the chemistry of moon and Mars, the use of a mobile surface radar to study the atmosphere and ionosphere, and laser-ionization studies with the technical models of the LIMA-D/Phobos. Attention is given to planetogonic scenarios and the evolution of relatively mass-rich preplanetary disks, the kinetic behavior of planetesimals revolving around the sun, the planetary evolution of Mars, and pre- and post-IRAS asteroid taxonomies. Consideration is also given to ocean tides and tectonic plate motions in high-precision orbit determination, the satellite altimeter calibration techniques, a theory of the motion of an artificial satellite in the earth atmosphere, ESA plans for planetary exploration, and the detection of earth orbiting objects by IRAS.

Gene regulation in amphioxus: An insight from transgenic studies in amphioxus and vertebrates.

PubMed

Kozmikova, Iryna; Kozmik, Zbynek

2015-12-01

Cephalochordates, commonly known as amphioxus or lancelets, are the most basal subphylum of chordates. Cephalochordates are thus key to understanding the origin of vertebrates and molecular mechanisms underlying vertebrate evolution. The evolution of developmental control mechanisms during invertebrate-to-vertebrate transition involved not only gene duplication events, but also specific changes in spatial and temporal expression of many genes. To get insight into the spatiotemporal regulation of gene expression during invertebrate-to-vertebrate transition, functional studies of amphioxus gene regulatory elements are highly warranted. Here, we review transgenic studies performed in amphioxus and vertebrates using promoters and enhancers derived from the genome of Branchiostoma floridae. We describe the current methods of transgenesis in amphioxus, provide evidence of Tol2 transposon-generated transgenic embryos of Branchiostoma lanceolatum and discuss possible future directions. We envision that comparative transgenic analysis of gene regulatory sequences in the context of amphioxus and vertebrate embryos will likely provide an important mechanistic insight into the evolution of vertebrate body plan. Copyright © 2015 Elsevier B.V. All rights reserved.

Body composition in Pan paniscus compared with Homo sapiens has implications for changes during human evolution.

PubMed

Zihlman, Adrienne L; Bolter, Debra R

2015-06-16

The human body has been shaped by natural selection during the past 4-5 million years. Fossils preserve bones and teeth but lack muscle, skin, fat, and organs. To understand the evolution of the human form, information about both soft and hard tissues of our ancestors is needed. Our closest living relatives of the genus Pan provide the best comparative model to those ancestors. Here, we present data on the body composition of 13 bonobos (Pan paniscus) measured during anatomical dissections and compare the data with Homo sapiens. These comparative data suggest that both females and males (i) increased body fat, (ii) decreased relative muscle mass, (iii) redistributed muscle mass to lower limbs, and (iv) decreased relative mass of skin during human evolution. Comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition.

Body composition in Pan paniscus compared with Homo sapiens has implications for changes during human evolution

PubMed Central

Zihlman, Adrienne L.; Bolter, Debra R.

2015-01-01

The human body has been shaped by natural selection during the past 4–5 million years. Fossils preserve bones and teeth but lack muscle, skin, fat, and organs. To understand the evolution of the human form, information about both soft and hard tissues of our ancestors is needed. Our closest living relatives of the genus Pan provide the best comparative model to those ancestors. Here, we present data on the body composition of 13 bonobos (Pan paniscus) measured during anatomical dissections and compare the data with Homo sapiens. These comparative data suggest that both females and males (i) increased body fat, (ii) decreased relative muscle mass, (iii) redistributed muscle mass to lower limbs, and (iv) decreased relative mass of skin during human evolution. Comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition. PMID:26034269

Internal anatomy of Haliclystus antarcticus (Cnidaria, Staurozoa) with a discussion on histological features used in Staurozoan taxonomy.

PubMed

Miranda, Lucília S; Collins, Allen G; Marques, Antonio C

2013-12-01

Stauromedusae have relatively few macromorphological characters, making both their taxonomy and identification difficult. For this reason, histological characters are also employed in the taxonomy of the group. This study presents a detailed description of the histomorphology of Haliclystus antarcticus Pfeffer, 1889 (Cnidaria, Staurozoa). We make new observations for the species and for the class, and address functional, taxonomical, and evolutionary aspects of staurozoan histo-anatomy. A complete reconstruction of H. antarcticus body plan is used to guide a more detailed observation, based on light microscopy, of structures rarely cited in the literature, such as the intertentacular lobules, the ostia between adjacent perradial pockets, and the male and female gonadal vesicles. Two possible regions of nematocyst formation are hypothesized and discussed. We also provide a review of the current use of histological characters in the taxonomy of the group. Understanding the body plan of stauromedusae is a challenge, because each single individual presents characters found in medusae and in polyps of other medusozoans. Comprehensive histological descriptions are important to establish relations of homology within Staurozoa and Cnidaria, providing crucial data on their evolution. Copyright © 2013 Wiley Periodicals, Inc.

Rates of ecological divergence and body size evolution are correlated with species diversification in scaly tree ferns

PubMed Central

Ramírez-Barahona, Santiago; Barrera-Redondo, Josué; Eguiarte, Luis E.

2016-01-01

Variation in species richness across regions and between different groups of organisms is a major feature of evolution. Several factors have been proposed to explain these differences, including heterogeneity in the rates of species diversification and the age of clades. It has been frequently assumed that rapid rates of diversification are coupled to high rates of ecological and morphological evolution, leading to a prediction that remains poorly explored for most species: the positive association between ecological niche divergence, morphological evolution and species diversification. We combined a time-calibrated phylogeny with distribution, ecological and body size data for scaly tree ferns (Cyatheaceae) to test whether rates of species diversification are predicted by the rates at which clades have evolved distinct ecological niches and body sizes. We found that rates of species diversification are positively correlated with rates of ecological and morphological evolution, with rapidly diversifying clades also showing rapidly evolving ecological niches and body sizes. Our results show that rapid diversification of scaly tree ferns is associated with the evolution of species with comparable morphologies that diversified into similar, yet distinct, environments. This suggests parallel evolutionary pathways opening in different tropical regions whenever ecological and geographical opportunities arise. Accordingly, rates of ecological niche and body size evolution are relevant to explain the current patterns of species richness in this ‘ancient’ fern lineage across the tropics. PMID:27412279

Rates of ecological divergence and body size evolution are correlated with species diversification in scaly tree ferns.

PubMed

Ramírez-Barahona, Santiago; Barrera-Redondo, Josué; Eguiarte, Luis E

2016-07-13

Variation in species richness across regions and between different groups of organisms is a major feature of evolution. Several factors have been proposed to explain these differences, including heterogeneity in the rates of species diversification and the age of clades. It has been frequently assumed that rapid rates of diversification are coupled to high rates of ecological and morphological evolution, leading to a prediction that remains poorly explored for most species: the positive association between ecological niche divergence, morphological evolution and species diversification. We combined a time-calibrated phylogeny with distribution, ecological and body size data for scaly tree ferns (Cyatheaceae) to test whether rates of species diversification are predicted by the rates at which clades have evolved distinct ecological niches and body sizes. We found that rates of species diversification are positively correlated with rates of ecological and morphological evolution, with rapidly diversifying clades also showing rapidly evolving ecological niches and body sizes. Our results show that rapid diversification of scaly tree ferns is associated with the evolution of species with comparable morphologies that diversified into similar, yet distinct, environments. This suggests parallel evolutionary pathways opening in different tropical regions whenever ecological and geographical opportunities arise. Accordingly, rates of ecological niche and body size evolution are relevant to explain the current patterns of species richness in this 'ancient' fern lineage across the tropics. © 2016 The Author(s).

Grid Integration Studies: Advancing Clean Energy Planning and Deployment

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

Katz, Jessica; Chernyakhovskiy, Ilya

2016-07-01

Integrating significant variable renewable energy (VRE) into the grid requires an evolution in power system planning and operation. To plan for this evolution, power system stakeholders can undertake grid integration studies. This Greening the Grid document reviews grid integration studies, common elements, questions, and guidance for system planners.

The evolutionary origin of the vertebrate body plan: the problem of head segmentation.

PubMed

Onai, Takayuki; Irie, Naoki; Kuratani, Shigeru

2014-01-01

The basic body plan of vertebrates, as typified by the complex head structure, evolved from the last common ancestor approximately 530 Mya. In this review, we present a brief overview of historical discussions to disentangle the various concepts and arguments regarding the evolutionary development of the vertebrate body plan. We then explain the historical transition of the arguments about the vertebrate body plan from merely epistemological comparative morphology to comparative embryology as a scientific treatment on this topic. Finally, we review the current progress of molecular evidence regarding the basic vertebrate body plan, focusing on the link between the basic vertebrate body plan and the evolutionarily conserved developmental stages (phylotypic stages).

Highlights of Astronomy, Vol. 16

NASA Astrophysics Data System (ADS)

Montmerle, Thierry

2015-04-01

Part I. Invited Discourses: 1. The Herschel view of star formation; 2. Past, present and future of Chinese astronomy; 3. The zoo of galaxies; 4. Supernovae, the accelerating cosmos, and dark energy; Part II. Joint Discussion: 5. Very massive stars in the local universe; 6. 3-D views of the cycling Sun in stellar context; 7. Ultraviolet emission in early-type galaxies; 8. From meteors and meteorites to their parent bodies: current status and future developments; 9. The connection between radio properties and high-energy emission in AGNs; 10. Space-time reference systems for future research; Part III. Special Sessions: 11. Origin and complexity of massive star clusters; 12. Cosmic evolution of groups and clusters of galaxies; 13. Galaxy evolution through secular processes; 14. New era for studying interstellar and intergalactic magnetic fields; 15. The IR view of massive stars: the main sequence and beyond; 16. Science with large solar telescopes; 17. The impact hazard: current activities and future plans; 18. Calibration of star-formation rate measurements across the electromagnetic spectrum; 19. Future large scale facilities; 20. Dynamics of the star-planet relations strategic plan and the Global Office of Astronomy for Development; 21. Strategic plan and the Global Office of Astronomy for Development; 22. Modern views of the interstellar medium; 23. High-precision tests of stellar physics from high-precision photometry; 24. Communicating astronomy with the public for scientists; 25. Data intensive astronomy; 26. Unexplained spectral phenomena in the interstellar medium; 27. Light pollution: protecting astronomical sites and increasing global awareness through education.

Genetics of Rapid and Extreme Size Evolution in Island Mice

PubMed Central

Gray, Melissa M.; Parmenter, Michelle D.; Hogan, Caley A.; Ford, Irene; Cuthbert, Richard J.; Ryan, Peter G.; Broman, Karl W.; Payseur, Bret A.

2015-01-01

Organisms on islands provide a revealing window into the process of adaptation. Populations that colonize islands often evolve substantial differences in body size from their mainland relatives. Although the ecological drivers of this phenomenon have received considerable attention, its genetic basis remains poorly understood. We use house mice (subspecies: Mus musculus domesticus) from remote Gough Island to provide a genetic portrait of rapid and extreme size evolution. In just a few hundred generations, Gough Island mice evolved the largest body size among wild house mice from around the world. Through comparisons with a smaller-bodied wild-derived strain from the same subspecies (WSB/EiJ), we demonstrate that Gough Island mice achieve their exceptional body weight primarily by growing faster during the 6 weeks after birth. We use genetic mapping in large F2 intercrosses between Gough Island mice and WSB/EiJ to identify 19 quantitative trait loci (QTL) responsible for the evolution of 16-week weight trajectories: 8 QTL for body weight and 11 QTL for growth rate. QTL exhibit modest effects that are mostly additive. We conclude that body size evolution on islands can be genetically complex, even when substantial size changes occur rapidly. In comparisons to published studies of laboratory strains of mice that were artificially selected for divergent body sizes, we discover that the overall genetic profile of size evolution in nature and in the laboratory is similar, but many contributing loci are distinct. Our results underscore the power of genetically characterizing the entire growth trajectory in wild populations and lay the foundation necessary for identifying the mutations responsible for extreme body size evolution in nature. PMID:26199233

Genetics of Rapid and Extreme Size Evolution in Island Mice.

PubMed

Gray, Melissa M; Parmenter, Michelle D; Hogan, Caley A; Ford, Irene; Cuthbert, Richard J; Ryan, Peter G; Broman, Karl W; Payseur, Bret A

2015-09-01

Organisms on islands provide a revealing window into the process of adaptation. Populations that colonize islands often evolve substantial differences in body size from their mainland relatives. Although the ecological drivers of this phenomenon have received considerable attention, its genetic basis remains poorly understood. We use house mice (subspecies: Mus musculus domesticus) from remote Gough Island to provide a genetic portrait of rapid and extreme size evolution. In just a few hundred generations, Gough Island mice evolved the largest body size among wild house mice from around the world. Through comparisons with a smaller-bodied wild-derived strain from the same subspecies (WSB/EiJ), we demonstrate that Gough Island mice achieve their exceptional body weight primarily by growing faster during the 6 weeks after birth. We use genetic mapping in large F(2) intercrosses between Gough Island mice and WSB/EiJ to identify 19 quantitative trait loci (QTL) responsible for the evolution of 16-week weight trajectories: 8 QTL for body weight and 11 QTL for growth rate. QTL exhibit modest effects that are mostly additive. We conclude that body size evolution on islands can be genetically complex, even when substantial size changes occur rapidly. In comparisons to published studies of laboratory strains of mice that were artificially selected for divergent body sizes, we discover that the overall genetic profile of size evolution in nature and in the laboratory is similar, but many contributing loci are distinct. Our results underscore the power of genetically characterizing the entire growth trajectory in wild populations and lay the foundation necessary for identifying the mutations responsible for extreme body size evolution in nature. Copyright © 2015 by the Genetics Society of America.

Plant evolution at the interface of paleontology and developmental biology: An organism-centered paradigm.

PubMed

Rothwell, Gar W; Wyatt, Sarah E; Tomescu, Alexandru M F

2014-06-01

Paleontology yields essential evidence for inferring not only the pattern of evolution, but also the genetic basis of evolution within an ontogenetic framework. Plant fossils provide evidence for the pattern of plant evolution in the form of transformational series of structure through time. Developmentally diagnostic structural features that serve as "fingerprints" of regulatory genetic pathways also are preserved by plant fossils, and here we provide examples of how those fingerprints can be used to infer the mechanisms by which plant form and development have evolved. When coupled with an understanding of variations and systematic distributions of specific regulatory genetic pathways, this approach provides an avenue for testing evolutionary hypotheses at the organismal level that is analogous to employing bioinformatics to explore genetics at the genomic level. The positions where specific genes, gene families, and developmental regulatory mechanisms first appear in phylogenies are correlated with the positions where fossils with the corresponding structures occur on the tree, thereby yielding testable hypotheses that extend our understanding of the role of developmental changes in the evolution of the body plans of vascular plant sporophytes. As a result, we now have new and powerful methodologies for characterizing major evolutionary changes in morphology, anatomy, and physiology that have resulted from combinations of genetic regulatory changes and that have produced the synapomorphies by which we recognize major clades of plants. © 2014 Botanical Society of America, Inc.

Differential-Evolution Control Parameter Optimization for Unmanned Aerial Vehicle Path Planning

PubMed Central

Kok, Kai Yit; Rajendran, Parvathy

2016-01-01

The differential evolution algorithm has been widely applied on unmanned aerial vehicle (UAV) path planning. At present, four random tuning parameters exist for differential evolution algorithm, namely, population size, differential weight, crossover, and generation number. These tuning parameters are required, together with user setting on path and computational cost weightage. However, the optimum settings of these tuning parameters vary according to application. Instead of trial and error, this paper presents an optimization method of differential evolution algorithm for tuning the parameters of UAV path planning. The parameters that this research focuses on are population size, differential weight, crossover, and generation number. The developed algorithm enables the user to simply define the weightage desired between the path and computational cost to converge with the minimum generation required based on user requirement. In conclusion, the proposed optimization of tuning parameters in differential evolution algorithm for UAV path planning expedites and improves the final output path and computational cost. PMID:26943630

The evolution of body size and shape in the human career.

PubMed

Jungers, William L; Grabowski, Mark; Hatala, Kevin G; Richmond, Brian G

2016-07-05

Body size is a fundamental biological property of organisms, and documenting body size variation in hominin evolution is an important goal of palaeoanthropology. Estimating body mass appears deceptively simple but is laden with theoretical and pragmatic assumptions about best predictors and the most appropriate reference samples. Modern human training samples with known masses are arguably the 'best' for estimating size in early bipedal hominins such as the australopiths and all members of the genus Homo, but it is not clear if they are the most appropriate priors for reconstructing the size of the earliest putative hominins such as Orrorin and Ardipithecus The trajectory of body size evolution in the early part of the human career is reviewed here and found to be complex and nonlinear. Australopith body size varies enormously across both space and time. The pre-erectus early Homo fossil record from Africa is poor and dominated by relatively small-bodied individuals, implying that the emergence of the genus Homo is probably not linked to an increase in body size or unprecedented increases in size variation. Body size differences alone cannot explain the observed variation in hominin body shape, especially when examined in the context of small fossil hominins and pygmy modern humans.This article is part of the themed issue 'Major transitions in human evolution'. © 2016 The Author(s).

The Ohio Department of Education L10H23 "Critical Analysis of Evolution"; Innovative Lesson Plan or Stealthy Advocacy Tool?

ERIC Educational Resources Information Center

Day, Robert

2006-01-01

This paper will discuss the ongoing controversy surrounding a particular Ohio Department of Education tenth grade lesson plan titled "Critical Analysis of Evolution" (Ohio Department of Education identification L10H23). The lesson professes to encourage students to "critically examine" evidences for and against evolution and…

The A/P axis in echinoderm ontogeny and evolution: evidence from fossils and molecules

NASA Technical Reports Server (NTRS)

Peterson, K. J.; Arenas-Mena, C.; Davidson, E. H.

2000-01-01

Even though echinoderms are members of the Bilateria, the location of their anterior/posterior axis has remained enigmatic. Here we propose a novel solution to the problem employing three lines of evidence: the expression of a posterior class Hox gene in the coeloms of the nascent adult body plan within the larva; the anatomy of certain early fossil echinoderms; and finally the relation between endoskeletal plate morphology and the associated coelomic tissues. All three lines of evidence converge on the same answer, namely that the location of the adult mouth is anterior, and the anterior/posterior axis runs from the mouth through the adult coelomic compartments. This axis then orients the animal such that there is but a single plane of symmetry dividing the animal into left and right halves. We tentatively hypothesize that this plane of symmetry is positioned along the dorsal/ventral axis. These axis identifications lead to the conclusion that the five ambulacra are not primary body axes, but instead are outgrowths from the central anterior/posterior axis. These identifications also shed insight into several other evolutionary mysteries of various echinoderm clades such as the independent evolution of bilateral symmetry in irregular echinoids, but do not elucidate the underlying mechanisms of the adult coelomic architecture.

The evolution of helicopters

NASA Astrophysics Data System (ADS)

Chen, R.; Wen, C. Y.; Lorente, S.; Bejan, A.

2016-07-01

Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between body size, engine size, and the fuel load. Furthermore, the engine efficiency increases with the engine size, and the propeller radius is roughly the same as the length scale of the whole body. These trends are in accord with the constructal law, which accounts for the engine efficiency trend and the proportionality between "motor" size and body size in animals and vehicles. These body-size effects are qualitatively the same as those uncovered earlier for the evolution of aircraft. The present study adds to this theoretical body of research the evolutionary design of all technologies [A. Bejan, The Physics of Life: The Evolution of Everything (St. Martin's Press, New York, 2016)].

HIGH RATES OF EVOLUTION PRECEDED THE ORIGIN OF BIRDS

PubMed Central

Puttick, Mark N; Thomas, Gavin H; Benton, Michael J; Polly, P David

2014-01-01

The origin of birds (Aves) is one of the great evolutionary transitions. Fossils show that many unique morphological features of modern birds, such as feathers, reduction in body size, and the semilunate carpal, long preceded the origin of clade Aves, but some may be unique to Aves, such as relative elongation of the forelimb. We study the evolution of body size and forelimb length across the phylogeny of coelurosaurian theropods and Mesozoic Aves. Using recently developed phylogenetic comparative methods, we find an increase in rates of body size and body size dependent forelimb evolution leading to small body size relative to forelimb length in Paraves, the wider clade comprising Aves and Deinonychosauria. The high evolutionary rates arose primarily from a reduction in body size, as there were no increased rates of forelimb evolution. In line with a recent study, we find evidence that Aves appear to have a unique relationship between body size and forelimb dimensions. Traits associated with Aves evolved before their origin, at high rates, and support the notion that numerous lineages of paravians were experimenting with different modes of flight through the Late Jurassic and Early Cretaceous. PMID:24471891

The evolution of airplanes

NASA Astrophysics Data System (ADS)

Bejan, A.; Charles, J. D.; Lorente, S.

2014-07-01

The prevailing view is that we cannot witness biological evolution because it occurred on a time scale immensely greater than our lifetime. Here, we show that we can witness evolution in our lifetime by watching the evolution of the flying human-and-machine species: the airplane. We document this evolution, and we also predict it based on a physics principle: the constructal law. We show that the airplanes must obey theoretical allometric rules that unite them with the birds and other animals. For example, the larger airplanes are faster, more efficient as vehicles, and have greater range. The engine mass is proportional to the body size: this scaling is analogous to animal design, where the mass of the motive organs (muscle, heart, lung) is proportional to the body size. Large or small, airplanes exhibit a proportionality between wing span and fuselage length, and between fuel load and body size. The animal-design counterparts of these features are evident. The view that emerges is that the evolution phenomenon is broader than biological evolution. The evolution of technology, river basins, and animal design is one phenomenon, and it belongs in physics.

Telecommunications systems evolution for Mars Exploration

NASA Technical Reports Server (NTRS)

Noreen, Gary; De Paula, Ramon P.; Edwards, Charles D. Jr; Komarek, Thomas; Edwards, Bernard L.; Edwards, Bernard L.; Kerridge, Stuart J.; Diehl, Roger; Franklin, Stephen F.

2003-01-01

This paper describes the evolution of telecommunication systems at Mars. It reviews the telecommunications capabilities, technology and limiting factors of current and planned Mars orbiters from Mars Global Surveyor to the planned Mars Telecommunications Orbiter (MTO).

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

Boore, Jeffrey L.; Staton, Joseph

We have determined the sequence of about half (7470 nts) of the mitochondrial genome of the sipunculid Phascolopsis gouldii, the first representative of this phylum to be so studied. All of the 19 identified genes are transcribed from the same DNA strand. The arrangement of these genes is remarkably similar to that of the oligochaete annelid Lumbricus terrestris. Comparison of both the inferred amino acid sequences and the gene arrangements of a variety of diverse metazoan taxa reveals that the phylum Sipuncula is more closely related to Annelida than to Mollusca. This requires reinterpretation of the homology of several embryologicalmore » features and of patterns of animal body plan evolution.« less

Tipping the scales: Evolution of the allometric slope independent of average trait size.

PubMed

Stillwell, R Craig; Shingleton, Alexander W; Dworkin, Ian; Frankino, W Anthony

2016-02-01

The scaling of body parts is central to the expression of morphology across body sizes and to the generation of morphological diversity within and among species. Although patterns of scaling-relationship evolution have been well documented for over one hundred years, little is known regarding how selection acts to generate these patterns. In part, this is because it is unclear the extent to which the elements of log-linear scaling relationships-the intercept or mean trait size and the slope-can evolve independently. Here, using the wing-body size scaling relationship in Drosophila melanogaster as an empirical model, we use artificial selection to demonstrate that the slope of a morphological scaling relationship between an organ (the wing) and body size can evolve independently of mean organ or body size. We discuss our findings in the context of how selection likely operates on morphological scaling relationships in nature, the developmental basis for evolved changes in scaling, and the general approach of using individual-based selection experiments to study the expression and evolution of morphological scaling. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

How the pterosaur got its wings.

PubMed

Tokita, Masayoshi

2015-11-01

Throughout the evolutionary history of life, only three vertebrate lineages took to the air by acquiring a body plan suitable for powered flight: birds, bats, and pterosaurs. Because pterosaurs were the earliest vertebrate lineage capable of powered flight and included the largest volant animal in the history of the earth, understanding how they evolved their flight apparatus, the wing, is an important issue in evolutionary biology. Herein, I speculate on the potential basis of pterosaur wing evolution using recent advances in the developmental biology of flying and non-flying vertebrates. The most significant morphological features of pterosaur wings are: (i) a disproportionately elongated fourth finger, and (ii) a wing membrane called the brachiopatagium, which stretches from the posterior surface of the arm and elongated fourth finger to the anterior surface of the leg. At limb-forming stages of pterosaur embryos, the zone of polarizing activity (ZPA) cells, from which the fourth finger eventually differentiates, could up-regulate, restrict, and prolong expression of 5'-located Homeobox D (Hoxd) genes (e.g. Hoxd11, Hoxd12, and Hoxd13) around the ZPA through pterosaur-specific exploitation of sonic hedgehog (SHH) signalling. 5'Hoxd genes could then influence downstream bone morphogenetic protein (BMP) signalling to facilitate chondrocyte proliferation in long bones. Potential expression of Fgf10 and Tbx3 in the primordium of the brachiopatagium formed posterior to the forelimb bud might also facilitate elongation of the phalanges of the fourth finger. To establish the flight-adapted musculoskeletal morphology shared by all volant vertebrates, pterosaurs probably underwent regulatory changes in the expression of genes controlling forelimb and pectoral girdle musculoskeletal development (e.g. Tbx5), as well as certain changes in the mode of cell-cell interactions between muscular and connective tissues in the early phase of their evolution. Developmental data now accumulating for extant vertebrate taxa could be helpful in understanding the cellular and molecular mechanisms of body-plan evolution in extinct vertebrates as well as extant vertebrates with unique morphology whose embryonic materials are hard to obtain. © 2014 The Author. Biological Reviews © 2014 Cambridge Philosophical Society.

SU-E-T-812: Volumetric Modulated Arc Therapy-Total Body Irradiation (VMAT-TBI) V.s. Conventional Extended SSD-TBI (cTBI): A Dosimetric Comparisom

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

Ouyang, L; Folkerts, M; Lee, H

2015-06-15

Purpose: To perform a dosimetric evaluation on a new developed volumetric modulated arc therapy based total body irradiation (VMAT-TBI). Methods: Three patients were CT scanned with an indexed rotatable body frame to get whole body CT images. Concatenated CT images were imported in Pinnacle treatment planning system and whole body and lung were contoured as PTV and organ at risk, respectively. Treatment plans were generated by matching multiple isocenter volumetric modulated arc (VMAT) fields of the upper body and multiple isocenter parallel-opposed fields of the lower body. For each plan, 1200 cGy in 8 fractions was prescribed to the wholemore » body volume and the lung dose was constrained to a mean dose of 750 cGy. Such a two-level dose plan was achieved by inverse planning of the torso VMAT fields. For comparison, conventional standing TBI (cTBI) plans were generated on the same whole body CT images at an extended SSD (550cm).The shape of compensators and lung blocks are simulated using body segments and lung contours Compensation was calculated based on the patient CT images, in mimic of the standing TBI treatment. The whole body dose distribution of cTBI plans were calculated with a home-developed GPU Monte Carlo dose engine. Calculated cTBI dose distribution was prescribed to the mid-body point at umbilical level. Results: The VMAT-TBI treatment plans of three patients’ plans achieved 80.2%±5.0% coverage of the total body volume within ±10% of the prescription dose, while cTBI treatment plans achieved 72.2%±4.0% coverage of the total body volume. The averaged mean lung dose of all three patients is lower for VMAT-TBI (7.48 cGy) than for cTBI (8.96 cGy). Conclusion: The proposed patient comfort-oriented VMAT-TBI technique provides for a uniform dose distribution within the total body while reducing the dose to the lungs.« less

Lockheed Martin approach to a Reusable Launch Vehicle (RLV)

NASA Astrophysics Data System (ADS)

Elvin, John D.

1996-03-01

This paper discusses Lockheed Martin's perspective on the development of a cost effective Reusable Launch Vehicle (RLV). Critical to a successful Single Stage To Orbit (SSTO) program are; an economic development plan sensitive to fiscal constraints; a vehicle concept satisfying present and future US launch needs; and an operations concept commensurate with a market driven program. Participation in the economic plan by government, industry, and the commercial sector is a key element of integrating our development plan and funding profile. The RLV baseline concept design, development evolution and several critical trade studies illustrate the superior performance achieved by our innovative approach to the problem of SSTO. Findings from initial aerodynamic and aerothermodynamic wind tunnel tests and trajectory analyses on this concept confirm the superior characteristics of the lifting body shape combined with the Linear Aerospike rocket engine. This Aero Ballistic Rocket (ABR) concept captures the essence of The Skunk Works approach to SSTO RLV technology integration and system engineering. These programmatic and concept development topics chronicle the key elements to implementing an innovative market driven next generation RLV.

Nervous systems and scenarios for the invertebrate-to-vertebrate transition

PubMed Central

Holland, Nicholas D.

2016-01-01

Older evolutionary scenarios for the origin of vertebrates often gave nervous systems top billing in accordance with the notion that a big-brained Homo sapiens crowned a tree of life shaped mainly by progressive evolution. Now, however, tree thinking positions all extant organisms equidistant from the tree's root, and molecular phylogenies indicate that regressive evolution is more common than previously suspected. Even so, contemporary theories of vertebrate origin still focus on the nervous system because of its functional importance, its richness in characters for comparative biology, and its central position in the two currently prominent scenarios for the invertebrate-to-vertebrate transition, which grew out of the markedly neurocentric annelid and enteropneust theories of the nineteenth century. Both these scenarios compare phyla with diverse overall body plans. This diversity, exacerbated by the scarcity of relevant fossil data, makes it challenging to establish plausible homologies between component parts (e.g. nervous system regions). In addition, our current understanding of the relation between genotype and phenotype is too preliminary to permit us to convert gene network data into structural features in any simple way. These issues are discussed here with special reference to the evolution of nervous systems during proposed transitions from invertebrates to vertebrates. PMID:26598728

An Overview of Hox Genes in Lophotrochozoa: Evolution and Functionality

PubMed Central

Barucca, Marco; Canapa, Adriana; Biscotti, Maria Assunta

2016-01-01

Hox genes are regulators of animal embryonic development. Changes in the number and sequence of Hox genes as well as in their expression patterns have been related to the evolution of the body plan. Lophotrochozoa is a clade of Protostomia characterized by several phyla which show a wide morphological diversity. Despite that the works summarized in this review emphasize the fragmentary nature of the data available regarding the presence and expression of Hox genes, they also offer interesting insight into the evolution of the Hox cluster and the role played by Hox genes in several phyla. However, the number of genes involved in the cluster of the lophotrochozoan ancestor is still a question of debate. The data presented here suggest that at least nine genes were present while two other genes, Lox4 and Post-2, may either have been present in the ancestor or may have arisen as a result of duplication in the Brachiopoda-Mollusca-Annelida lineage. Spatial and temporal collinearity is a feature of Hox gene expression which was probably present in the ancestor of deuterostomes and protostomes. However, in Lophotrochozoa, it has been detected in only a few species belonging to Annelida and Mollusca. PMID:29615580

Unsegmented annelids? Possible origins of four lophotrochozoan worm taxa.

PubMed

Halanych, Kenneth M; Dahlgren, Thomas G; McHugh, Damhnait

2002-07-01

In traditional classification schemes, the Annelida consists of the Polychaeta and the Clitellata (the latter including the Oligochaeta and Hirudinida). However, recent analyses suggest that annelids are much more diverse than traditionally believed, and that polychaetes are paraphyletic. Specifically, some lesser-known taxa (previously regarded as separate phyla) appear to fall within the annelid radiation. Abundant molecular, developmental, and morphological data show that the Siboglinidae, which includes the formerly recognized Pogonophora and Vestimentifera, are derived annelids; recent data from the Elongation Factor-1α (EF-1α) gene also suggest that echiurids are of annelid ancestry. Further, the phylogenetic origins of two other lesser-known groups of marine worms, the Myzostomida and Sipuncula, have recently been called into question. Whereas some authors advocate annelid affinities, others argue that these taxa do not fall within the annelid radiation. With advances in our understanding of annelid phylogeny, our perceptions of body plan evolution within the Metazoa are changing. The evolution of segmentation probably is more plastic than traditionally believed. However, as our understanding of organismal evolution is being revised, we are also forced to reconsider the specific characters being examined. Should segmentation be considered a developmental process or an ontological endpoint?

The tempo and mode of evolution: body sizes of island mammals.

PubMed

Raia, Pasquale; Meiri, Shai

2011-07-01

The tempo and mode of body size evolution on islands are believed to be well known. It is thought that body size evolves relatively quickly on islands toward the mammalian modal value, thus generating extreme cases of size evolution and the island rule. Here, we tested both theories in a phylogenetically explicit context, by using two different species-level mammalian phylogenetic hypotheses limited to sister clades dichotomizing into an exclusively insular and an exclusively mainland daughter nodes. Taken as a whole, mammals were found to show a largely punctuational mode of size evolution. We found that, accounting for this, and regardless of the phylogeny used, size evolution on islands is no faster than on the continents. We compared different selection regimes using a set of Ornstein-Uhlenbeck models to examine the effects of insularity of the mode of evolution. The models strongly supported clade-specific selection regimes. Under this regime, however, an evolutionary model allowing insular species to evolve differently from their mainland relatives performs worse than a model that ignores insularity as a factor. Thus, insular taxa do not experience statistically different selection from their mainland relatives. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Darwin-Wallace Demons: survival of the fastest in populations of duckweeds and the evolutionary history of an enigmatic group of angiosperms.

PubMed

Kutschera, U; Niklas, K J

2015-01-01

In evolutionary biology, the term 'Darwinian fitness' refers to the lifetime reproductive success of an individual within a population of conspecifics. The idea of a 'Darwinian Demon' emerged from this concept and is defined here as an organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever. It has been argued that duckweeds (sub-family Lemnoideae, order Alismatales), a group containing five genera and 34 species of small aquatic monocotyledonous plants with a reduced body plan, can be interpreted as examples of 'Darwinian Demons'. Here we focus on the species Spirodela polyrhiza (Great duckweed) and show that these miniaturised aquatic angiosperms display features that fit the definition of the hypothetical organism that we will call a 'Darwin-Wallace Demon' in recognition of the duel proponents of evolution by natural selection. A quantitative analysis (log-log bivariate plot of annual growth in dry biomass versus standing dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real-world conditions (environmental constraints and other limitations), 'Darwin-Wallace Demons' cannot exist, although the concept remains useful in much the same way that the Hardy-Weinberg law does. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

TP53 copy number expansion is associated with the evolution of increased body size and an enhanced DNA damage response in elephants

PubMed Central

Sulak, Michael; Fong, Lindsey; Mika, Katelyn; Chigurupati, Sravanthi; Yon, Lisa; Mongan, Nigel P; Emes, Richard D; Lynch, Vincent J

2016-01-01

A major constraint on the evolution of large body sizes in animals is an increased risk of developing cancer. There is no correlation, however, between body size and cancer risk. This lack of correlation is often referred to as 'Peto's Paradox'. Here, we show that the elephant genome encodes 20 copies of the tumor suppressor gene TP53 and that the increase in TP53 copy number occurred coincident with the evolution of large body sizes, the evolution of extreme sensitivity to genotoxic stress, and a hyperactive TP53 signaling pathway in the elephant (Proboscidean) lineage. Furthermore, we show that several of the TP53 retrogenes (TP53RTGs) are transcribed and likely translated. While TP53RTGs do not appear to directly function as transcription factors, they do contribute to the enhanced sensitivity of elephant cells to DNA damage and the induction of apoptosis by regulating activity of the TP53 signaling pathway. These results suggest that an increase in the copy number of TP53 may have played a direct role in the evolution of very large body sizes and the resolution of Peto's paradox in Proboscideans. DOI: http://dx.doi.org/10.7554/eLife.11994.001 PMID:27642012

Evolution of extreme body size disparity in monitor lizards (Varanus).

PubMed

Collar, David C; Schulte, James A; Losos, Jonathan B

2011-09-01

Many features of species' biology, including life history, physiology, morphology, and ecology are tightly linked to body size. Investigation into the causes of size divergence is therefore critical to understanding the factors shaping phenotypic diversity within clades. In this study, we examined size evolution in monitor lizards (Varanus), a clade that includes the largest extant lizard species, the Komodo dragon (V. komodoensis), as well as diminutive species that are nearly four orders of magnitude smaller in adult body mass. We demonstrate that the remarkable body size disparity of this clade is a consequence of different selective demands imposed by three major habitat use patterns-arboreality, terrestriality, and rock-dwelling. We reconstructed phylogenetic relationships and ancestral habitat use and applied model selection to determine that the best-fitting evolutionary models for species' adult size are those that infer oppositely directed adaptive evolution associated with terrestriality and rock-dwelling, with terrestrial lineages evolving extremely large size and rock-dwellers becoming very small. We also show that habitat use affects the evolution of several ecologically important morphological traits independently of body size divergence. These results suggest that habitat use exerts a strong, multidimensional influence on the evolution of morphological size and shape disparity in monitor lizards. © 2011 The Author(s).

On the effects of higher convection modes on the thermal evolution of small planetary bodies

NASA Technical Reports Server (NTRS)

Arkani-Hamed, J.

1979-01-01

The effects of higher modes of convection on the thermal evolution of a small planetary body is investigated. Three sets of models are designed to specify an initially cold and differentiated, an initially hot and differentiated, and an initially cold and undifferentiated Moon-type body. The strong temperature dependence of viscosity enhances the thickening of lithosphere so that a lithosphere of about 400 km thickness is developed within the first billion years of the evolution of a Moon-type body. The thermally isolating effect of such a lithosphere hampers the heat flux out of the body and increases the temperature of the interior, causing the solid-state convection to occur with high velocity so that even the lower modes of convection can maintain an adiabatic temperature gradient there. It is demonstrated that the effect of solid-state convection on the thermal evolution of the models may be adequately determined by a combination of convection modes up to the third or the fourth order harmonic. The inclusion of higher modes does not affect the results significantly.

High expression of new genes in trochophore enlightening the ontogeny and evolution of trochozoans.

PubMed

Xu, Fei; Domazet-Lošo, Tomislav; Fan, Dingding; Dunwell, Thomas L; Li, Li; Fang, Xiaodong; Zhang, Guofan

2016-10-04

Animals with trochophore larvae belong to Trochozoa, one of the main branches of Bilateria. In addition to exhibiting spiral cleavage and early cell fate determination, trochozoans typically undergo indirect development, which contributes to the most unique characteristics of their ontogeny. The indirect development of trochozoans has provoked discussion regarding the origin and evolution of marine larvae and is interesting from the perspective of phylogeny-ontogeny correspondence. While these phylo-onto correlations have an hourglass shape in Deuterostomia, Ecdysozoa, plants and even fungi, they have seldom been studied in Trochozoa, and even Lophotrochozoa. Here, we compared the ontogenetic transcriptomes of the Pacific oyster, Crassostrea gigas (Bivalvia, Mollusca), the Pacific abalone, Haliotis discus hannai (Gastropoda, Mollusca), and the sand worm Perinereis aibuhitensis (Polychaeta, Annelida) using several complementary phylotranscriptomic methods to examine their evolutionary trajectories. The results revealed the late trochophore stage as the phylotypic phase. However, this basic pattern is accompanied with increased use of new genes in the trochophore stages which marks specific adaptations of the larval body plans.

The Ciona intestinalis genome: when the constraints are off

NASA Technical Reports Server (NTRS)

Holland, Linda Z.; Gibson-Brown, Jeremy J.

2003-01-01

The recent genome sequencing of a non-vertebrate deuterostome, the ascidian tunicate Ciona intestinalis, makes a substantial contribution to the fields of evolutionary and developmental biology.1 Tunicates have some of the smallest bilaterian genomes, embryos with relatively few cells, fixed lineages and early determination of cell fates. Initial analyses of the C. intestinalis genome indicate that it has been evolving rapidly. Comparisons with other bilaterians show that C. intestinalis has lost a number of genes, and that many genes linked together in most other bilaterians have become uncoupled. In addition, a number of independent, lineage-specific gene duplications have been detected. These new results, although interesting in themselves, will take on a deeper significance once the genomes of additional invertebrate deuterostomes (e.g. echinoderms, hemichordates and amphioxus) have been sequenced. With such a broadened database, comparative genomics can begin to ask pointed questions about the relationship between the evolution of genomes and the evolution of body plans. Copyright 2003 Wiley Periodicals, Inc.

Cnidarian Cell Type Diversity and Regulation Revealed by Whole-Organism Single-Cell RNA-Seq.

PubMed

Sebé-Pedrós, Arnau; Saudemont, Baptiste; Chomsky, Elad; Plessier, Flora; Mailhé, Marie-Pierre; Renno, Justine; Loe-Mie, Yann; Lifshitz, Aviezer; Mukamel, Zohar; Schmutz, Sandrine; Novault, Sophie; Steinmetz, Patrick R H; Spitz, François; Tanay, Amos; Marlow, Heather

2018-05-31

The emergence and diversification of cell types is a leading factor in animal evolution. So far, systematic characterization of the gene regulatory programs associated with cell type specificity was limited to few cell types and few species. Here, we perform whole-organism single-cell transcriptomics to map adult and larval cell types in the cnidarian Nematostella vectensis, a non-bilaterian animal with complex tissue-level body-plan organization. We uncover eight broad cell classes in Nematostella, including neurons, cnidocytes, and digestive cells. Each class comprises different subtypes defined by the expression of multiple specific markers. In particular, we characterize a surprisingly diverse repertoire of neurons, which comparative analysis suggests are the result of lineage-specific diversification. By integrating transcription factor expression, chromatin profiling, and sequence motif analysis, we identify the regulatory codes that underlie Nematostella cell-specific expression. Our study reveals cnidarian cell type complexity and provides insights into the evolution of animal cell-specific genomic regulation. Copyright © 2018 Elsevier Inc. All rights reserved.

A Dome-Headed Stem Archosaur Exemplifies Convergence among Dinosaurs and Their Distant Relatives.

PubMed

Stocker, Michelle R; Nesbitt, Sterling J; Criswell, Katharine E; Parker, William G; Witmer, Lawrence M; Rowe, Timothy B; Ridgely, Ryan; Brown, Matthew A

2016-10-10

Similarities in body plan evolution, such as wings in pterosaurs, birds, and bats or limblessness in snakes and amphisbaenians, can be recognized as classical examples of convergence among animals [1-3]. We introduce a new Triassic stem archosaur that is unexpectedly and remarkably convergent with the "dome-headed" pachycephalosaur dinosaurs that lived over 100 million years later. Surprisingly, numerous additional taxa in the same assemblage (the Otis Chalk assemblage from the Dockum Group of Texas) demonstrate the early acquisition of morphological novelties that were later convergently evolved by post-Triassic dinosaurs. As one of the most successful clades of terrestrial vertebrates, dinosaurs came to occupy an extensive morphospace throughout their diversification in the Mesozoic Era [4, 5], but their distant relatives were first to evolve many of those "dinosaurian" body plans in the Triassic Period [6-8]. Our analysis of convergence between archosauromorphs from the Triassic Period and post-Triassic archosaurs demonstrates the early and extensive exploration of morphospace captured in a single Late Triassic assemblage, and we hypothesize that many of the "novel" morphotypes interpreted to occur among archosaurs later in the Mesozoic already were in place during the initial Triassic archosauromorph, largely non-dinosaurian, radiation and only later convergently evolved in diverse dinosaurian lineages. Copyright © 2016 Elsevier Ltd. All rights reserved.

The evolution of vertebral formulae in Hominoidea.

PubMed

Thompson, Nathan E; Almécija, Sergio

2017-09-01

Primate vertebral formulae have long been investigated because of their link to locomotor behavior and overall body plan. Knowledge of the ancestral vertebral formulae in the hominoid tree of life is necessary to interpret the pattern of evolution among apes, and to critically evaluate the morphological adaptations involved in the transition to hominin bipedalism. Though many evolutionary hypotheses have been proposed based on living and fossil species, the application of quantitative phylogenetic methods for thoroughly reconstructing ancestral vertebral formulae and formally testing patterns of vertebral evolution is lacking. To estimate the most probable scenarios of hominoid vertebral evolution, we utilized an iterative ancestral state reconstruction approach to determine likely ancestral vertebral counts in apes, humans, and other anthropoid out-groups. All available ape and hominin fossil taxa with an inferred regional vertebral count were included in the analysis. Sensitivity iterations were performed both by changing the phylogenetic position of fossil taxa with a contentious placement, and by changing the inferred number of vertebrae in taxa with uncertain morphology. Our ancestral state reconstruction results generally support a short-backed hypothesis of human evolution, with a Pan-Homo last common ancestor possessing a vertebral formulae of 7:13:4:6 (cervical:thoracic:lumbar:sacral). Our results indicate that an initial reduction in lumbar vertebral count and increase in sacral count is a synapomorphy of crown hominoids (supporting an intermediate-backed hypothesis for the origins of the great ape-human clade). Further reduction in lumbar count occurs independently in orangutans and African apes. Our results highlight the complexity and homoplastic nature of vertebral count evolution, and give little support to the long-backed hypothesis of human evolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Approaches to Legacy System Evolution.

DTIC Science & Technology

1997-12-01

such as migrating legacy systems, to more distributed open environments. This framework draws out the important global issues early in the planning...ongoing system evolution initiatives, for drawing out important global issues early in the planning cycle using the checklists as a guide, and for

Body shape transformation along a shared axis of anatomical evolution in labyrinth fishes (Anabantoidei).

PubMed

Collar, David C; Quintero, Michelle; Buttler, Bernardo; Ward, Andrea B; Mehta, Rita S

2016-03-01

Major morphological transformations, such as the evolution of elongate body shape in vertebrates, punctuate evolutionary history. A fundamental step in understanding the processes that give rise to such transformations is identification of the underlying anatomical changes. But as we demonstrate in this study, important insights can also be gained by comparing these changes to those that occur in ancestral and closely related lineages. In labyrinth fishes (Anabantoidei), rapid evolution of a highly derived torpedo-shaped body in the common ancestor of the pikehead (Luciocephalus aura and L. pulcher) occurred primarily through exceptional elongation of the head, with secondary contributions involving reduction in body depth and lengthening of the precaudal vertebral region. This combination of changes aligns closely with the primary axis of anatomical diversification in other anabantoids, revealing that pikehead evolution involved extraordinarily rapid change in structures that were ancestrally labile. Finer-scale examination of the anatomical components that determine head elongation also shows alignment between the pikehead evolutionary trajectory and the primary axis of cranial diversification in anabantoids, with much higher evolutionary rates leading to the pikehead. Altogether, our results show major morphological transformation stemming from extreme change along a shared morphological axis in labyrinth fishes. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Musculature in sipunculan worms: ontogeny and ancestral states.

PubMed

Schulze, Anja; Rice, Mary E

2009-01-01

Molecular phylogenetics suggests that the Sipuncula fall into the Annelida, although they are morphologically very distinct and lack segmentation. To understand the evolutionary transformations from the annelid to the sipunculan body plan, it is important to reconstruct the ancestral states within the respective clades at all life history stages. Here we reconstruct the ancestral states for the head/introvert retractor muscles and the body wall musculature in the Sipuncula using Bayesian statistics. In addition, we describe the ontogenetic transformations of the two muscle systems in four sipunculan species with different developmental modes, using F-actin staining with fluorescent-labeled phalloidin in conjunction with confocal laser scanning microscopy. All four species, which have smooth body wall musculature and less than the full set of four introvert retractor muscles as adults, go through developmental stages with four retractor muscles that are eventually reduced to a lower number in the adult. The circular and sometimes the longitudinal body wall musculature are split into bands that later transform into a smooth sheath. Our ancestral state reconstructions suggest with nearly 100% probability that the ancestral sipunculan had four introvert retractor muscles, longitudinal body wall musculature in bands and circular body wall musculature arranged as a smooth sheath. Species with crawling larvae have more strongly developed body wall musculature than those with swimming larvae. To interpret our findings in the context of annelid evolution, a more solid phylogenetic framework is needed for the entire group and more data on ontogenetic transformations of annelid musculature are desirable.

Adaptive evolution of body size subject to indirect effect in trophic cascade system.

PubMed

Wang, Xin; Fan, Meng; Hao, Lina

2017-09-01

Trophic cascades represent a classic example of indirect effect and are wide-spread in nature. Their ecological impact are well established, but the evolutionary consequences have received even less theoretical attention. We theoretically and numerically investigate the trait (i.e., body size of consumer) evolution in response to indirect effect in a trophic cascade system. By applying the quantitative trait evolutionary theory and the adaptive dynamic theory, we formulate and explore two different types of eco-evolutionary resource-consumer-predator trophic cascade model. First, an eco-evolutionary model incorporating the rapid evolution is formulated to investigate the effect of rapid evolution of the consumer's body size, and to explore the impact of density-mediate indirect effect on the population dynamics and trait dynamics. Next, by employing the adaptive dynamic theory, a long-term evolutionary model of consumer body size is formulated to evaluate the effect of long-term evolution on the population dynamics and the effect of trait-mediate indirect effect. Those models admit rich dynamics that has not been observed yet in empirical studies. It is found that, both in the trait-mediated and density-mediated system, the body size of consumer in predator-consumer-resource interaction (indirect effect) evolves smaller than that in consumer-resource and predator-consumer interaction (direct effect). Moreover, in the density-mediated system, we found that the evolution of consumer body size contributes to avoiding consumer extinction (i.e., evolutionary rescue). The trait-mediate and density-mediate effects may produce opposite evolutionary response. This study suggests that the trophic cascade indirect effect affects consumer evolution, highlights a more comprehensive mechanistic understanding of the intricate interplay between ecological and evolutionary force. The modeling approaches provide avenue for study on indirect effects from an evolutionary perspective. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental influences on the evolution of body size in Ammonoids

NASA Astrophysics Data System (ADS)

Hines, S.; Khong, C.; Pelagio, M.; Seixas, G.; Payne, J.

2012-12-01

A major debate in evolutionary biology and paleobiology focuses on the relative importance of ecological interactions between species versus changes in the physical environment in governing large-scale evolutionary patterns. Body size is among the most important traits of any organism, and so identifying the factors that influence size evolution can shed light on both the causes and consequences of many major evolutionary trends. However, the extent to which body size evolution over time can be explained by changes in the physical versus ecological context remains unknown. In this study, we examined body size evolution in ammonoids, an extinct group of marine cephalopods. We collected a representative body size for each genus from illustrated specimens in the Treatise on Invertebrate Paleontology. We then examined relative statistical support for six models of size evolution: random walk, directional trend, stasis, and environmental control by oxygen availability, temperature, and global sea level. No model is unambiguously supported over all others. Unbiased random walk was the best supported model (34%) and environmental control by atmospheric pO2 was the second best supported model (22%). Stasis received the least support (<<1%). Because we find pO2 to be inversely correlated with ammonoid size, we suspect that the observed correlation does not reflect a direct causal relationship. Overall, our results suggest that no single, simple model can be used to characterize the evolution of ammonoid size over the entire history of this clade. We speculate that controls on ammonoid size evolution varied through geological time, both due to long-term shifts in the ecological structure of marine communities and short-term perturbations associated with major extinction events.

Are rates of species diversification and body size evolution coupled in the ferns?

PubMed

Testo, Weston L; Sundue, Michael A

2018-03-01

Understanding the relationship between phenotypic evolution and lineage diversification is a central goal of evolutionary biology. To extend our understanding of the role morphological evolution plays in the diversification of plants, we examined the relationship between leaf size evolution and lineage diversification across ferns. We tested for an association between body size evolution and lineage diversification using a comparative phylogenetic approach that combined a time-calibrated phylogeny and leaf size data set for 2654 fern species. Rates of leaf size change and lineage diversification were estimated using BAMM, and rate correlations were performed for rates obtained for all families and individual species. Rates and patterns of rate-rate correlation were also analyzed separately for terrestrial and epiphytic taxa. We find no significant correlation between rates of leaf area change and lineage diversification, nor was there a difference in this pattern when growth habit is considered. Our results are consistent with the findings of an earlier study that reported decoupled rates of body size evolution and diversification in the Polypodiaceae, but conflict with a recent study that reported a positive correlation between body size evolution and lineage diversification rates in the tree fern family Cyatheaceae. Our findings indicate that lineage diversification in ferns is largely decoupled from shifts in body size, in contrast to several other groups of organisms. Speciation in ferns appears to be primarily driven by hybridization and isolation along elevational gradients, rather than adaptive radiations featuring prominent morphological restructuring. The exceptional diversity of leaf morphologies in ferns appears to reflect a combination of ecophysiological constraints and adaptations that are not key innovations. © 2018 Botanical Society of America.

On the stability of the solutions of the general problem of three bodies

NASA Technical Reports Server (NTRS)

Standish, E. M., Jr.

1976-01-01

The extent through which the initial conditions of a given three-body system may be varied without completely changing the qualitative nature of the subsequent system evolution is investigated. It is assumed that the three masses are equal, all initial velocities are zero, the first two bodies initially lie on the x-axis, and the position of the third body is confined to a specific region of space. Analysis of the system evolution for different initial positions of the third body shows that there is a whole area or 'island' in the x-y plane throughout which the initial position of the third body may be moved in a continuous fashion to produce an evolution which also changes in a continuous manner. A Monte Carlo approach is adopted to determine the full extent of this island in the general problem. It is concluded that the stability of a full solution may be directly related to the size of its island in phase space.

The evolution of the Ecdysozoa.

PubMed

Telford, Maximilian J; Bourlat, Sarah J; Economou, Andrew; Papillon, Daniel; Rota-Stabelli, Omar

2008-04-27

Ecdysozoa is a clade composed of eight phyla: the arthropods, tardigrades and onychophorans that share segmentation and appendages and the nematodes, nematomorphs, priapulids, kinorhynchs and loriciferans, which are worms with an anterior proboscis or introvert. Ecdysozoa contains the vast majority of animal species and there is a great diversity of body plans among both living and fossil members. The monophyly of the clade has been called into question by some workers based on analyses of whole genome datasets. We review the evidence that now conclusively supports the unique origin of these phyla. Relationships within Ecdysozoa are also controversial and we discuss the molecular and morphological evidence for a number of monophyletic groups within this superphylum.

Body size reductions in nonmammalian eutheriodont therapsids (Synapsida) during the end-Permian mass extinction.

PubMed

Huttenlocker, Adam K

2014-01-01

The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the 'Lilliput effect,' a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts) using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion) models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma) consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1) active, directional evolution in size traits is rare over macroevolutionary time scales and 2) geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns.

The International Space Station Evolution Data Book: An Overview and Status

NASA Technical Reports Server (NTRS)

Antol, Jeffrey; Jorgensen, Catherine A.

1999-01-01

The evolution and enhancement of the International Space Station (ISS) is currently being planned in conjunction with the on-orbit construction of the baseline configuration. Three principal areas have been identified that will contribute to the evolution of ISS: Pre-Planned Program Improvement (P3I), Utilization & Commercialization, and Human Exploration and Development of Space (HEDS) missions. The ISS Evolution Strategy, under development by the Spacecraft and Sensors Branch of NASA Langley Research Center, seeks to coordinate the P3I technology development with Commercialization/Utilization activities and HEDS advanced mission accommodation to provide synergistic technology developments for all three areas. The focal point of this proposed strategy is the ISS Evolution Data Book (EDB), a tool for aiding the evolution and enhancement of ISS beyond Assembly Complete. This paper will discuss the strategy and provide an overview of the EDB, describing the contents of each section. It will also discuss potential applications of the EDB and present an example Design Reference Mission (DRM). The latest status of the EDB and the plans for completing and enhancing the book will also be summarized.

Vesta Evolution from Surface Mineralogy: Mafic and Ultramafic Mineral Distribution

NASA Technical Reports Server (NTRS)

DeSanctis, M. C.; Ammannito, E.; Palomba, E.; Longobardo, A.; Mittlefehldt, D. W.; McSween, H. Y; Marchi, S.; Capria, M. T.; Capaccioni, F.; Frigeri, A.;

Neoblasts and the evolution of whole-body regeneration.

PubMed

Gehrke, Andrew R; Srivastava, Mansi

2016-10-01

The molecular mechanisms underlying whole-body regeneration are best understood in the planarian flatworm Schmidtea mediterranea, where a heterogeneous population of somatic stem cells called neoblasts provides new tissue for regeneration of essentially any missing body part. Studies on Schmidtea have provided a detailed description of neoblasts and their role in regeneration, but comparatively little is known about the evolutionary history of these cells and their underlying developmental programs. Acoels, an understudied group of aquatic worms that are also capable of extensive whole-body regeneration, have arisen as an attractive group to study the evolution of regenerative processes due to their phylogenetically distant position relative to flatworms. Here, we review the phylogenetic distribution of neoblast cells and compare their anatomical locations, transcriptional profiles, and roles during regeneration in flatworms and acoels to understand the evolution of whole-body regeneration. While the general role of neoblasts appears conserved in species separated by 550 million years of evolution, the extrinsic inputs they receive during regeneration can vary, making the distinction between homology and convergence of mechanism unclear. A more detailed understanding of the precise mechanisms behind whole-body regeneration in diverse phyla is necessary to understand the evolutionary history of this powerful process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rates of molecular evolution in tree ferns are associated with body size, environmental temperature, and biological productivity.

PubMed

Barrera-Redondo, Josué; Ramírez-Barahona, Santiago; Eguiarte, Luis E

2018-05-01

Variation in rates of molecular evolution (heterotachy) is a common phenomenon among plants. Although multiple theoretical models have been proposed, fundamental questions remain regarding the combined effects of ecological and morphological traits on rate heterogeneity. Here, we used tree ferns to explore the correlation between rates of molecular evolution in chloroplast DNA sequences and several morphological and environmental factors within a Bayesian framework. We revealed direct and indirect effects of body size, biological productivity, and temperature on substitution rates, where smaller tree ferns living in warmer and less productive environments tend to have faster rates of molecular evolution. In addition, we found that variation in the ratio of nonsynonymous to synonymous substitution rates (dN/dS) in the chloroplast rbcL gene was significantly correlated with ecological and morphological variables. Heterotachy in tree ferns may be influenced by effective population size associated with variation in body size and productivity. Macroevolutionary hypotheses should go beyond explaining heterotachy in terms of mutation rates and instead, should integrate population-level factors to better understand the processes affecting the tempo of evolution at the molecular level. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Evolution of brain-body allometry in Lake Tanganyika cichlids.

PubMed

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

2016-07-01

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

[Analysis on property of meridian supramolecules by biological evolution path].

PubMed

Deng, Kaiwen; Tao, Yeqin; Tang, Wenhan; He, Fuyuan; Liu, Wenlong; Shi, Jilian; Yang, Yantao; Zhou, Yiqun; Chang, Xiaorong

2017-03-12

With human placed in the whole nature, by following the biologic evolution path, the property of channel structure for "imprinting template" in meridian and zang-fu was explored with supramolecular chemistry. In the history of biologic evolution, each molecule in "molecule society" gradually developed into various highly-ordered supramolecular bodies based on self-identification, self-assembly, self-organization, self-replicating of"imprinting template", and thereby the original biochemical system was established, and finally evolved into human. In the forming process of supramolecular bodies, the channel structure of"imprinting template" in guest supramolecular bodies would be kept by host supramolecular bodies, and communicate with the outside to exchange materials, energy, information, otherwise life phenomenon could not continue, for which it was the chemical nature of biolo-gical supramolecular bodies for body to develop meridian. Therefore, the human was a gigantic and complicated supramolecules body in biological nature, and possessed the supramolecules "imprinting template" at each stage of evolution, for which the meridians were formed. When meridians converged, acupoints appeared; when acupointsconverged, zang-fu appeared. With the promotion of the blood from heart, according to"imprinting template", the guest supramolecular bodies and host meridian produced qi -analysis, which was the qi -phenomenon of guest in meridian. It presented as zang-fu image of physiology and pathology as well as action regularities of medication and acupuncture tolerance, by which current various meridian viewpoints could be explained and propose the hypothesis of meridian supramolecular bodies. The meridian and its phenomenon was decide by its "imprinting template" of supramolecular bodies and self-reaction regularities, which abided through the living nature. This was the substance for meridian biology.

Hox, Wnt, and the evolution of the primary body axis: insights from the early-divergent phyla

PubMed Central

Ryan, Joseph F; Baxevanis, Andreas D

2007-01-01

The subkingdom Bilateria encompasses the overwhelming majority of animals, including all but four early-branching phyla: Porifera, Ctenophora, Placozoa, and Cnidaria. On average, these early-branching phyla have fewer cell types, tissues, and organs, and are considered to be significantly less specialized along their primary body axis. As such, they present an attractive outgroup from which to investigate how evolutionary changes in the genetic toolkit may have contributed to the emergence of the complex animal body plans of the Bilateria. This review offers an up-to-date glimpse of genome-scale comparisons between bilaterians and these early-diverging taxa. Specifically, we examine these data in the context of how they may explain the evolutionary development of primary body axes and axial symmetry across the Metazoa. Next, we re-evaluate the validity and evolutionary genomic relevance of the zootype hypothesis, which defines an animal by a specific spatial pattern of gene expression. Finally, we extend the hypothesis that Wnt genes may be the earliest primary body axis patterning mechanism by suggesting that Hox genes were co-opted into this patterning network prior to the last common ancestor of cnidarians and bilaterians. Reviewed by Pierre Pontarotti, Gáspár Jékely, and L Aravind. For the full reviews, please go to the Reviewers' comments section. PMID:18078518

The 25 kW power module evolution study. Part 3: Conceptual designs for power module evolution. Volume 2: Program plans

NASA Technical Reports Server (NTRS)

1979-01-01

A plan is presented for the evolutionary development and deployment of the power module system with performance capabilities required to support the 1983 to 1990 user requirements. Aspects summarized include program functional, operational, and hardware elements; program work breakdown and specification items; development plans and schedules for developmental and technology milestones; test concepts and timeliness; and ground and orbit operations concepts.

The evolution of host specificity in dove body lice.

PubMed

Johnson, Kevin P; Weckstein, Jason D; Bush, Sarah E; Clayton, Dale H

2011-11-01

Conventional wisdom suggests that parasites evolve increased host specialization over time. Host specificity, which describes the number of host species parasitized, is one aspect of host specialization. Recent studies of vertebrate parasites indicate that highly host-specific parasite lineages are not, in fact, evolutionary dead ends; host generalists can evolve from host specialists. Using phylogenetic reconstruction methods, we evaluate these patterns in the body lice (Insecta: Phthiraptera) of pigeons and doves, which are permanent ectoparasites that complete their entire life cycle on the body of the host. We find that species of body lice that parasitize more than one species of host (generalists) are invariably derived from lice parasitizing only one species of host (specialists). A previous study of the wing lice of pigeons and doves also found that generalists were derived from specialists, and that these changes were correlated with the presence of a potentially competing species of wing louse on the same host. For body lice we did not find such a correlation with competition. Instead, the evolution of host generalists in body lice was correlated with host ecology. When we compared body lice that parasitize terrestrial versus arboreal hosts, we found that the evolution of host generalists was associated with terrestrial hosts. In contrast, wing lice showed no correlation between the evolution of generalists and host ecology. The correlation in body lice suggests that dispersal between host species may occur via the ground. This, in turn, suggests that body lice may fall to the ground more often than wing lice. To test this hypothesis, we conducted an experiment to compare the rate at which body and wing lice are dislodged from the bodies of preening pigeons. Interestingly, our results showed that body lice are dislodged four times more often than wing lice. Therefore, species of terrestrial doves are far more likely to encounter body lice than wing lice on the ground.

The Difficulties of School Development Planning

ERIC Educational Resources Information Center

Xaba, Mgadla

2006-01-01

The South African Schools Act No. 84 of 1996 requires that school governing bodies develop school mission statements and, by implication, school development plans. The Gauteng Regulations and Rules for Public School Governing Bodies specifically direct school governing bodies to draw up and amend school development plans. Whilst training in…

Measurement-based quantum computation on two-body interacting qubits with adiabatic evolution.

PubMed

Kyaw, Thi Ha; Li, Ying; Kwek, Leong-Chuan

2014-10-31

A cluster state cannot be a unique ground state of a two-body interacting Hamiltonian. Here, we propose the creation of a cluster state of logical qubits encoded in spin-1/2 particles by adiabatically weakening two-body interactions. The proposal is valid for any spatial dimensional cluster states. Errors induced by thermal fluctuations and adiabatic evolution within finite time can be eliminated ensuring fault-tolerant quantum computing schemes.

Male pregnancy and the evolution of body segmentation in seahorses and pipefishes.

PubMed

Hoffman, Eric A; Mobley, Kenyon B; Jones, Adam G

2006-02-01

The evolution of complex traits, which are specified by the interplay of multiple genetic loci and environmental effects, is a topic of central importance in evolutionary biology. Here, we show that body and tail vertebral numbers in fishes of the pipefish and seahorse family (Syngnathidae) can serve as a model for studies of quantitative trait evolution. A quantitative genetic analysis of body and tail vertebrae from field-collected families of the Gulf pipefish, Syngnathus scovelli, shows that both traits exhibit significantly positive additive genetic variance, with heritabilities of 0.75 +/- 0.13 (mean +/- standard error) and 0.46 +/- 0.18, respectively. We do not find any evidence for either phenotypic or genetic correlations between the two traits. Pipefish are characterized by male pregnancy, and phylogenetic consideration of body proportions suggests that the position of eggs on the pregnant male's body may have contributed to the evolution of vertebral counts. In terms of numbers of vertebrae, tail-brooding males have longer tails for a given trunk size than do trunk-brooding males. Overall, these results suggest that vertebral counts in pipefish are heritable traits, capable of a response to selection, and they may have experienced an interesting history of selection due to the phenomenon of male pregnancy. Given that these traits vary among populations within species as well as among species, they appear to provide an excellent model for further research on complex trait evolution. Body segmentation may thus afford excellent opportunities for comparative study of homologous complex traits among disparate vertebrate taxa.

Molecular insights into the origin of the Hox-TALE patterning system

PubMed Central

Hudry, Bruno; Thomas-Chollier, Morgane; Volovik, Yael; Duffraisse, Marilyne; Dard, Amélie; Frank, Dale; Technau, Ulrich; Merabet, Samir

2014-01-01

Despite tremendous body form diversity in nature, bilaterian animals share common sets of developmental genes that display conserved expression patterns in the embryo. Among them are the Hox genes, which define different identities along the anterior–posterior axis. Hox proteins exert their function by interaction with TALE transcription factors. Hox and TALE members are also present in some but not all non-bilaterian phyla, raising the question of how Hox–TALE interactions evolved to provide positional information. By using proteins from unicellular and multicellular lineages, we showed that these networks emerged from an ancestral generic motif present in Hox and other related protein families. Interestingly, Hox-TALE networks experienced additional and extensive molecular innovations that were likely crucial for differentiating Hox functions along body plans. Together our results highlight how homeobox gene families evolved during eukaryote evolution to eventually constitute a major patterning system in Eumetazoans. DOI: http://dx.doi.org/10.7554/eLife.01939.001 PMID:24642410

Molecular insights into the origin of the Hox-TALE patterning system.

PubMed

Hudry, Bruno; Thomas-Chollier, Morgane; Volovik, Yael; Duffraisse, Marilyne; Dard, Amélie; Frank, Dale; Technau, Ulrich; Merabet, Samir

2014-03-18

Despite tremendous body form diversity in nature, bilaterian animals share common sets of developmental genes that display conserved expression patterns in the embryo. Among them are the Hox genes, which define different identities along the anterior-posterior axis. Hox proteins exert their function by interaction with TALE transcription factors. Hox and TALE members are also present in some but not all non-bilaterian phyla, raising the question of how Hox-TALE interactions evolved to provide positional information. By using proteins from unicellular and multicellular lineages, we showed that these networks emerged from an ancestral generic motif present in Hox and other related protein families. Interestingly, Hox-TALE networks experienced additional and extensive molecular innovations that were likely crucial for differentiating Hox functions along body plans. Together our results highlight how homeobox gene families evolved during eukaryote evolution to eventually constitute a major patterning system in Eumetazoans. DOI: http://dx.doi.org/10.7554/eLife.01939.001.

Lunar and Planetary Geology

NASA Astrophysics Data System (ADS)

Basilevsky, Alexander T.

2018-05-01

Lunar and planetary geology can be described using examples such as the geology of Earth (as the reference case) and geologies of the Earth's satellite the Moon; the planets Mercury, Mars and Venus; the satellite of Saturn Enceladus; the small stony asteroid Eros; and the nucleus of the comet 67P Churyumov-Gerasimenko. Each body considered is illustrated by its global view, with information given as to its position in the solar system, size, surface, environment including gravity acceleration and properties of its atmosphere if it is present, typical landforms and processes forming them, materials composing these landforms, information on internal structure of the body, stages of its geologic evolution in the form of stratigraphic scale, and estimates of the absolute ages of the stratigraphic units. Information about one body may be applied to another body and this, in particular, has led to the discovery of the existence of heavy "meteoritic" bombardment in the early history of the solar system, which should also significantly affect Earth. It has been shown that volcanism and large-scale tectonics may have not only been an internal source of energy in the form of radiogenic decay of potassium, uranium and thorium, but also an external source in the form of gravity tugging caused by attractions of the neighboring bodies. The knowledge gained by lunar and planetary geology is important for planning and managing space missions and for the practical exploration of other bodies of the solar system and establishing manned outposts on them.

statement of significance, location map, site plan, landscape plan, site ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

statement of significance, location map, site plan, landscape plan, site sections, evolution of cemetery landscape. - San Francisco National Cemetery, 1 Lincoln Boulevard, San Francisco, San Francisco County, CA

The Compact Body Plan of Tardigrades Evolved by the Loss of a Large Body Region.

PubMed

Smith, Frank W; Boothby, Thomas C; Giovannini, Ilaria; Rebecchi, Lorena; Jockusch, Elizabeth L; Goldstein, Bob

2016-01-25

The superphylum Panarthropoda (Arthropoda, Onychophora, and Tardigrada) exhibits a remarkable diversity of segment morphologies, enabling these animals to occupy diverse ecological niches. The molecular identities of these segments are specified by Hox genes and other axis patterning genes during development [1, 2]. Comparisons of molecular segment identities between arthropod and onychophoran species have yielded important insights into the origins and diversification of their body plans [3-9]. However, the relationship of the segments of tardigrades to those of arthropods and onychophorans has remained enigmatic [10, 11], limiting our understanding of early panarthropod body plan diversification. Here, we reveal molecular identities for all of the segments of a tardigrade. Based on our analysis, we conclude that tardigrades have lost a large intermediate region of the body axis-a region corresponding to the entire thorax and most of the abdomen of insects-and that they have lost the Hox genes that originally specified this region. Our data suggest that nearly the entire tardigrade body axis is homologous to just the head region of arthropods. Based on our results, we reconstruct a last common ancestor of Panarthropoda that had a relatively elongate body plan like most arthropods and onychophorans, rather than a compact, tardigrade-like body plan. These results demonstrate that the body plan of an animal phylum can originate by the loss of a large part of the body. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of the Consolidation of Real Property Maintenance Activities (RPMA) in the U.S. Army Engineer Activity, Capital Area (USAEA, CA). Volume 2. Evaluation

DTIC Science & Technology

1990-03-01

MANAGEMENT ................................... 62 Scope of Current Operations 62 Evolution of the Original RMD Plan 66 Financial Management Support Operations...Scope of Current Operations 76 Evolution of SMD From IPG Plan 78 SMD Support to RPMA 81 Efficiency of Supply Service 85 7 PROCUREMENT AND CONTRACTING...RPMA are to be realized. This chapter investigates these controls in terms of scope, evolution , operations (a functional assessment), and efficiency

Body Size Reductions in Nonmammalian Eutheriodont Therapsids (Synapsida) during the End-Permian Mass Extinction

PubMed Central

Huttenlocker, Adam K.

2014-01-01

The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the ‘Lilliput effect,’ a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts) using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion) models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma) consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1) active, directional evolution in size traits is rare over macroevolutionary time scales and 2) geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns. PMID:24498335

Four-year evolution of insulin regimens, glycaemic control, hypoglycaemia and body weight after starting insulin therapy in type 2 diabetes across three continents.

PubMed

Home, Philip D; Dain, Marie-Paule; Freemantle, Nick; Kawamori, Ryuzo; Pfohl, Martin; Brette, Sandrine; Pilorget, Valérie; Scherbaum, Werner A; Vespasiani, Giacomo; Vincent, Maya; Balkau, Beverley

2015-05-01

It is of interest to understand how insulin therapy currently evolves in clinical practice, in the years after starting insulin in people with type 2 diabetes. We aimed to describe this evolution prospectively over 4 years, to assist health care planning. People who had started any insulin were identified from 12 countries on three continents. Baseline, then yearly follow-up, data were extracted from clinical records over 4 years. Of the 2999 eligible people, 2272 were followed over 4 years. When starting insulin, mean (SD) duration of diabetes was 10.6 (7.8) years, HbA1c 9.5 (2.0)% (80 [22]mmol/mol) and BMI 29.3 (6.3)kg/m(2). Initial insulin therapy was basal 52%, premix 23%, mealtime+basal 14%, mealtime 8% and other 3%; at 4 years, 30%, 25%, 33%, 2% and 5%, respectively, with 5% not on insulin. Insulin dose was 20.2U/day at the start and 45.8U/day at year 4. There were 1258 people (55%) on their original regimen at 4 years, and this percentage differed according to baseline insulin regimen. HbA1c change was -2.0 (2.2)% (-22 [24]mmol/mol) and was similar by final insulin regimen. Hypoglycaemia prevalence was <20% in years 1-4. Body weight change was mostly in year 1, and was very variable, mean +2.7 (7.5)kg at year 4. Different insulin regimens were started in people with differing characteristics, and they evolved differently; insulin dose, hypoglycaemia and body weight change were diverse and largely independent of regimen. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

On the orbital evolution of radiating binary systems

NASA Astrophysics Data System (ADS)

Bekov, A. A.; Momynov, S. B.

2018-05-01

The evolution of dynamic parameters of radiating binary systems with variable mass is studied. As a dynamic model, the problem of two gravitating and radiating bodies is considered, taking into account the gravitational attraction and the light pressure of the interacting bodies with the additional assumption of isotropic variability of their masses. The problem combines the Gylden-Meshchersky problem, acquiring a new physical meaning, and the two-body photogravitational Radzievsky problem. The evolving orbit is presented, unlike Kepler, with varying orbital elements - parameter and eccentricity, defines by the parameter µ(t), area integral C and quasi-integral energy h(t). Adiabatic invariants of the problem, which are of interest for the slow evolution of orbits, are determined. The general course of evolution of orbits of binary systems with radiation are determined by the change of the parameter µ(t) and the total energy of the system.

In situ methods for measuring thermal properties and heat flux on planetary bodies.

PubMed

Kömle, Norbert I; Hütter, Erika S; Macher, Wolfgang; Kaufmann, Erika; Kargl, Günter; Knollenberg, Jörg; Grott, Matthias; Spohn, Tilman; Wawrzaszek, Roman; Banaszkiewicz, Marek; Seweryn, Karoly; Hagermann, Axel

2011-06-01

The thermo-mechanical properties of planetary surface and subsurface layers control to a high extent in which way a body interacts with its environment, in particular how it responds to solar irradiation and how it interacts with a potentially existing atmosphere. Furthermore, if the natural temperature profile over a certain depth can be measured in situ, this gives important information about the heat flux from the interior and thus about the thermal evolution of the body. Therefore, in most of the recent and planned planetary lander missions experiment packages for determining thermo-mechanical properties are part of the payload. Examples are the experiment MUPUS on Rosetta's comet lander Philae, the TECP instrument aboard NASA's Mars polar lander Phoenix, and the mole-type instrument HP(3) currently developed for use on upcoming lunar and Mars missions. In this review we describe several methods applied for measuring thermal conductivity and heat flux and discuss the particular difficulties faced when these properties have to be measured in a low pressure and low temperature environment. We point out the abilities and disadvantages of the different instruments and outline the evaluation procedures necessary to extract reliable thermal conductivity and heat flux data from in situ measurements.

A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs.

PubMed

Carballido, José L; Pol, Diego; Otero, Alejandro; Cerda, Ignacio A; Salgado, Leonardo; Garrido, Alberto C; Ramezani, Jahandar; Cúneo, Néstor R; Krause, Javier M

2017-08-16

Titanosauria was the most diverse and successful lineage of sauropod dinosaurs. This clade had its major radiation during the middle Early Cretaceous and survived up to the end of that period. Among sauropods, this lineage has the most disparate values of body mass, including the smallest and largest sauropods known. Although recent findings have improved our knowledge on giant titanosaur anatomy, there are still many unknown aspects about their evolution, especially for the most gigantic forms and the evolution of body mass in this clade. Here we describe a new giant titanosaur, which represents the largest species described so far and one of the most complete titanosaurs. Its inclusion in an extended phylogenetic analysis and the optimization of body mass reveals the presence of an endemic clade of giant titanosaurs inhabited Patagonia between the Albian and the Santonian. This clade includes most of the giant species of titanosaurs and represents the major increase in body mass in the history of Titanosauria. © 2017 The Author(s).

Evolution of the organizer and the chordate body plan

NASA Technical Reports Server (NTRS)

Gerhart, J.

2001-01-01

The discovery of the organizer by Spemann and Mangold in 1924 raised two kinds of questions: those about the means of patterning the chordate body axis and those about the mechanisms of cell determination by induction. Some researchers, stressing the second, have suggested over the years that the organizer is poorly named and doesn't really organize because inducers act permissively, because they are not unique to the organizer, and because multipotent responsive cells develop complex local differentiations under artificial conditions. Furthermore, with the discovery of meso-endoderm induction in 1969, the possibility arose that this earlier induction generates as much organization as, or more than, does the organizer itself. Evidence is summarized in this article that the organizer does fulfill its title with regard to pattern formation: it adds greatly to embryonic organization by providing information about time, place, scale, and orientation for development by nearby members of the large multipotent competence groups surrounding the organizer. Embryos having smaller or larger organizers due to experimental intervention develop defective axial organization. Without an organizer the embryo develops no body axis and none of the four chordate characters: the notochord, gill slits, dorsal hollow nerve chord, and post-anal tail. For normal axis formation, the organizer's tripartite organization is needed. Each part differs in inducers, morphogenesis, and self-differentiation. The organizer is a trait of development of all members of the chordate phylum. In comparison to hemichordates, which constitute a phylum with some similarities to chordates, the chordamesoderm part is unique to the chordate organizer (the trunk-tail organizer). Its convergent extension displaces the gastrula posterior pole from alignment with the animal-vegetal axis and generates a new anteroposterior axis orthogonal to this old one. Once it has extended to full length, its signaling modifies the dorsoventral dimension. This addition to the organizer is seen as a major event in chordate evolution, bringing body organization beyond that achieved by oocyte organization and meso-endoderm induction in other groups.

Missing link in the evolution of Hox clusters.

PubMed

Ogishima, Soichi; Tanaka, Hiroshi

2007-01-31

Hox cluster has key roles in regulating the patterning of the antero-posterior axis in a metazoan embryo. It consists of the anterior, central and posterior genes; the central genes have been identified only in bilaterians, but not in cnidarians, and are responsible for archiving morphological complexity in bilaterian development. However, their evolutionary history has not been revealed, that is, there has been a "missing link". Here we show the evolutionary history of Hox clusters of 18 bilaterians and 2 cnidarians by using a new method, "motif-based reconstruction", examining the gain/loss processes of evolutionarily conserved sequences, "motifs", outside the homeodomain. We successfully identified the missing link in the evolution of Hox clusters between the cnidarian-bilaterian ancestor and the bilaterians as the ancestor of the central genes, which we call the proto-central gene. Exploring the correspondent gene with the proto-central gene, we found that one of the acoela Hox genes has the same motif repertory as that of the proto-central gene. This interesting finding suggests that the acoela Hox cluster corresponds with the missing link in the evolution of the Hox cluster between the cnidarian-bilaterian ancestor and the bilaterians. Our findings suggested that motif gains/diversifications led to the explosive diversity of the bilaterian body plan.

Nervous systems and scenarios for the invertebrate-to-vertebrate transition.

PubMed

Holland, Nicholas D

2016-01-05

Older evolutionary scenarios for the origin of vertebrates often gave nervous systems top billing in accordance with the notion that a big-brained Homo sapiens crowned a tree of life shaped mainly by progressive evolution. Now, however, tree thinking positions all extant organisms equidistant from the tree's root, and molecular phylogenies indicate that regressive evolution is more common than previously suspected. Even so, contemporary theories of vertebrate origin still focus on the nervous system because of its functional importance, its richness in characters for comparative biology, and its central position in the two currently prominent scenarios for the invertebrate-to-vertebrate transition, which grew out of the markedly neurocentric annelid and enteropneust theories of the nineteenth century. Both these scenarios compare phyla with diverse overall body plans. This diversity, exacerbated by the scarcity of relevant fossil data, makes it challenging to establish plausible homologies between component parts (e.g. nervous system regions). In addition, our current understanding of the relation between genotype and phenotype is too preliminary to permit us to convert gene network data into structural features in any simple way. These issues are discussed here with special reference to the evolution of nervous systems during proposed transitions from invertebrates to vertebrates. © 2015 The Author(s).

The evolution of body size and shape in the human career

PubMed Central

Grabowski, Mark; Hatala, Kevin G.; Richmond, Brian G.

2016-01-01

Body size is a fundamental biological property of organisms, and documenting body size variation in hominin evolution is an important goal of palaeoanthropology. Estimating body mass appears deceptively simple but is laden with theoretical and pragmatic assumptions about best predictors and the most appropriate reference samples. Modern human training samples with known masses are arguably the ‘best’ for estimating size in early bipedal hominins such as the australopiths and all members of the genus Homo, but it is not clear if they are the most appropriate priors for reconstructing the size of the earliest putative hominins such as Orrorin and Ardipithecus. The trajectory of body size evolution in the early part of the human career is reviewed here and found to be complex and nonlinear. Australopith body size varies enormously across both space and time. The pre-erectus early Homo fossil record from Africa is poor and dominated by relatively small-bodied individuals, implying that the emergence of the genus Homo is probably not linked to an increase in body size or unprecedented increases in size variation. Body size differences alone cannot explain the observed variation in hominin body shape, especially when examined in the context of small fossil hominins and pygmy modern humans. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298459

Biomechanical trade-offs bias rates of evolution in the feeding apparatus of fishes

PubMed Central

Holzman, Roi; Collar, David C.; Price, Samantha A.; Hulsey, C. Darrin; Thomson, Robert C.; Wainwright, Peter C.

2012-01-01

Morphological diversification does not proceed evenly across the organism. Some body parts tend to evolve at higher rates than others, and these rate biases are often attributed to sexual and natural selection or to genetic constraints. We hypothesized that variation in the rates of morphological evolution among body parts could also be related to the performance consequences of the functional systems that make up the body. Specifically, we tested the widely held expectation that the rate of evolution for a trait is negatively correlated with the strength of biomechanical trade-offs to which it is exposed. We quantified the magnitude of trade-offs acting on the morphological components of three feeding-related functional systems in four radiations of teleost fishes. After accounting for differences in the rates of morphological evolution between radiations, we found that traits that contribute more to performance trade-offs tend to evolve more rapidly, contrary to the prediction. While ecological and genetic factors are known to have strong effects on rates of phenotypic evolution, this study highlights the role of the biomechanical architecture of functional systems in biasing the rates and direction of trait evolution. PMID:21993506

Biomechanical trade-offs bias rates of evolution in the feeding apparatus of fishes.

PubMed

Holzman, Roi; Collar, David C; Price, Samantha A; Hulsey, C Darrin; Thomson, Robert C; Wainwright, Peter C

2012-04-07

Morphological diversification does not proceed evenly across the organism. Some body parts tend to evolve at higher rates than others, and these rate biases are often attributed to sexual and natural selection or to genetic constraints. We hypothesized that variation in the rates of morphological evolution among body parts could also be related to the performance consequences of the functional systems that make up the body. Specifically, we tested the widely held expectation that the rate of evolution for a trait is negatively correlated with the strength of biomechanical trade-offs to which it is exposed. We quantified the magnitude of trade-offs acting on the morphological components of three feeding-related functional systems in four radiations of teleost fishes. After accounting for differences in the rates of morphological evolution between radiations, we found that traits that contribute more to performance trade-offs tend to evolve more rapidly, contrary to the prediction. While ecological and genetic factors are known to have strong effects on rates of phenotypic evolution, this study highlights the role of the biomechanical architecture of functional systems in biasing the rates and direction of trait evolution.

An evaluation of end-point trajectory planning during skilled kicking.

PubMed

Ford, Paul; Hodges, Nicola J; Mark Williams, A

2009-01-01

There is evidence that actions are planned by anticipation of their external effects, with the strength of this effect being dependent on the amount of prior practice. In Experiment 1, skilled soccer players performed a kicking task under four conditions: planning in terms of an external action effect (i.e., ball trajectory) or in terms of body movements, either with or without visual error feedback. When feedback was withheld, a ball focus resulted in more accurate outcomes than a body focus. When visual feedback was allowed, there was no difference between these two conditions. In Experiment 2, both skilled and novice soccer players were tested with the addition of a control condition and in the absence of visual feedback. For both groups there was evidence that a ball focus was more beneficial for performance than a body focus, particularly in terms of movement kinematics where correlations across the joints were generally higher for body rather than ball planning. Most skilled participants reported that ball planning felt more normal than body planning. These experiments provide some evidence that actions are planned in terms of their external action effects, supporting the common-coding hypothesis of action planning.

Quasi-Tangency Points on the Orbits of a Small Body and a Planet at the Low-Velocity Encounter

NASA Astrophysics Data System (ADS)

Emel'yanenko, N. Yu.

2018-03-01

We propose a method for selecting a low-velocity encounter of a small body with a planet from the evolution of the orbital elements. Polar orbital coordinates of the quasi-tangency point on the orbit of a small body are determined. Rectangular heliocentric coordinates of the quasi-tangency point on the orbit of a planet are determined. An algorithm to search for low-velocity encounters in the evolution of the orbital elements of small bodies is described. The low-velocity encounter of comet 39P/Oterma with Jupiter is considered as an example.

Comparative internal anatomy of Staurozoa (Cnidaria), with functional and evolutionary inferences

PubMed Central

Collins, Allen G.; Hirano, Yayoi M.; Mills, Claudia E.

2016-01-01

Comparative efforts to understand the body plan evolution of stalked jellyfishes are scarce. Most characters, and particularly internal anatomy, have neither been explored for the class Staurozoa, nor broadly applied in its taxonomy and classification. Recently, a molecular phylogenetic hypothesis was derived for Staurozoa, allowing for the first broad histological comparative study of staurozoan taxa. This study uses comparative histology to describe the body plans of nine staurozoan species, inferring functional and evolutionary aspects of internal morphology based on the current phylogeny of Staurozoa. We document rarely-studied structures, such as ostia between radial pockets, intertentacular lobules, gametoducts, pad-like adhesive structures, and white spots of nematocysts (the last four newly proposed putative synapomorphies for Staurozoa). Two different regions of nematogenesis are documented. This work falsifies the view that the peduncle region of stauromedusae only retains polypoid characters; metamorphosis from stauropolyp to stauromedusa occurs both at the apical region (calyx) and basal region (peduncle). Intertentacular lobules, observed previously in only a small number of species, are shown to be widespread. Similarly, gametoducts were documented in all analyzed genera, both in males and females, thereby elucidating gamete release. Finally, ostia connecting adjacent gastric radial pockets appear to be universal for Staurozoa. Detailed histological studies of medusozoan polyps and medusae are necessary to further understand the relationships between staurozoan features and those of other medusozoan cnidarians. PMID:27812408

Self-Efficacy, Planning, or a Combination of Both? A Longitudinal Experimental Study Comparing Effects of Three Interventions on Adolescents' Body Fat.

PubMed

Luszczynska, Aleksandra; Hagger, Martin S; Banik, Anna; Horodyska, Karolina; Knoll, Nina; Scholz, Urte

2016-01-01

The superiority of an intervention combining two sets of theory-based behavior change techniques targeting planning and self-efficacy over an intervention targeting planning only or self-efficacy only has rarely been investigated. We compared the influence of self-efficacy, planning, and self-efficacy+planning interventions with an education-based control condition on adolescents' body fat, assuming mediating effects of respective social cognitive variables and moderate-to-vigorous physical activity (MVPA). The moderating role of the built environment was examined. Participants (N = 1217, aged 14-18 years) were randomly assigned to four conditions: planning (n = 270), self-efficacy (n = 311), self-efficacy+planning (n = 351), and control (n = 285). The measurement was conducted at baseline (T1), two-month follow-up (T2), and fourteen-month follow-up (T3). Interventions/control group procedures were delivered at T1 and T2. Percent of body fat tissue (measured at T1 and T3) was the main outcome. Social cognitive mediators (self-efficacy and planning) were assessed at T1 and T2. The behavioral mediator (MVPA) and the presence of built MVPA facilities (the moderator) were evaluated at T1 and T3. Similar small increases of body fat were found across the three intervention groups, but the increment of body fat was significantly larger in the control group. On average, differences between control and intervention groups translated to approximately 1% of body fat. Effects of the interventions on body fat were mediated by relevant social cognitive variables and MVPA. A lower increase of body fat was found among intervention group participants who had access to newly-built MVPA facilities. We found no superiority of an intervention targeting two social cognitive variables over the intervention targeting one cognition only.

News and Views: Betelgeuse bubbles up dust; Hydrothermal activity on early asteroids; Is this a record? Galaxy evolution in 3D; LOFAR looks farther; IOPD makes plans

NASA Astrophysics Data System (ADS)

2011-08-01

Red supergiant star Betelgeuse is surrounded by a vast halo of silicate and aluminium dust, visible in false colour in this infrared image from the European Southern Observatory's Very Large Telescope. This material may eventually form planets around a new star. Biochemical analysis of the Tagish Lake meteorites, some of the most pristine samples of carbonaceous chondrites known, suggests that much of the variation in organic matter between different meteorite samples can be ascribed to hydrothermal activity on meteorite parent bodies. European Southern Observatory astronomers have discovered the most distant quasar yet - and reckon it is one of the brightest objects in the early universe.

Controlling dynamical entanglement in a Josephson tunneling junction

NASA Astrophysics Data System (ADS)

Ziegler, K.

2017-12-01

We analyze the evolution of an entangled many-body state in a Josephson tunneling junction and its dependence on the number of bosons and interaction strength. A N00N state, which is a superposition of two complementary Fock states, appears in the evolution with sufficient probability only for a moderate many-body interaction on an intermediate time scale. This time scale is inversely proportional to the tunneling rate. Many-body interaction strongly supports entanglement: The probability for creating an entangled state decays exponentially with the number of particles without many-body interaction, whereas it decays only like the inverse square root of the number of particles in the presence of many-body interaction.

Plant cell walls throughout evolution: towards a molecular understanding of their design principles

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

Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

Throughout their life, plants typically remain in one location utilizing sunlight for the synthesis of carbohydrates, which serve as their sole source of energy as well as building blocks of a protective extracellular matrix, called the cell wall. During the course of evolution, plants have repeatedly adapted to their respective niche,which is reflected in the changes of their body plan and the specific design of cell walls. Cell walls not only changed throughout evolution but also are constantly remodelled and reconstructed during the development of an individual plant, and in response to environmental stress or pathogen attacks. Carbohydrate-rich cell wallsmore » display complex designs, which together with the presence of phenolic polymers constitutes a barrier for microbes, fungi, and animals. Throughout evolution microbes have co-evolved strategies for efficient breakdown of cell walls. Our current understanding of cell walls and their evolutionary changes are limited as our knowledge is mainly derived from biochemical and genetic studies, complemented by a few targeted yet very informative imaging studies. Comprehensive plant cell wall models will aid in the re-design of plant cell walls for the purpose of commercially viable lignocellulosic biofuel production as well as for the timber, textile, and paper industries. Such knowledge will also be of great interest in the context of agriculture and to plant biologists in general. It is expected that detailed plant cell wall models will require integrated correlative multimodal, multiscale imaging and modelling approaches, which are currently underway.« less

Discrete and morphometric traits reveal contrasting patterns and processes in the macroevolutionary history of a clade of scorpions.

PubMed

Mongiardino Koch, N; Ceccarelli, F S; Ojanguren-Affilastro, A A; Ramírez, M J

2017-04-01

Many palaeontological studies have investigated the evolution of entire body plans, generally relying on discrete character-taxon matrices. In contrast, macroevolutionary studies performed by neontologists have mostly focused on morphometric traits. Although these data types are very different, some studies have suggested that they capture common patterns. Nonetheless, the tests employed to support this claim have not explicitly incorporated a phylogenetic framework and may therefore be susceptible to confounding effects due to the presence of common phylogenetic structure. We address this question using the scorpion genus Brachistosternus Pocock 1893 as case study. We make use of a time-calibrated multilocus molecular phylogeny, and compile discrete and traditional morphometric data sets, both capturing the overall morphology of the organisms. We find that morphospaces derived from these matrices are significantly different, and that the degree of discordance cannot be replicated by simulations of random character evolution. Moreover, we find strong support for contrasting modes of evolution, with discrete characters being congruent with an 'early burst' scenario whereas morphometric traits suggest species-specific adaptations to have driven morphological evolution. The inferred macroevolutionary dynamics are therefore contingent on the choice of character type. Finally, we confirm that metrics of correlation fail to detect these profound differences given common phylogenetic structure in both data sets, and that methods incorporating a phylogenetic framework and accounting for expected covariance should be favoured. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Plant cell walls throughout evolution: towards a molecular understanding of their design principles.

PubMed

Sarkar, Purbasha; Bosneaga, Elena; Auer, Manfred

2009-01-01

Throughout their life, plants typically remain in one location utilizing sunlight for the synthesis of carbohydrates, which serve as their sole source of energy as well as building blocks of a protective extracellular matrix, called the cell wall. During the course of evolution, plants have repeatedly adapted to their respective niche, which is reflected in the changes of their body plan and the specific design of cell walls. Cell walls not only changed throughout evolution but also are constantly remodelled and reconstructed during the development of an individual plant, and in response to environmental stress or pathogen attacks. Carbohydrate-rich cell walls display complex designs, which together with the presence of phenolic polymers constitutes a barrier for microbes, fungi, and animals. Throughout evolution microbes have co-evolved strategies for efficient breakdown of cell walls. Our current understanding of cell walls and their evolutionary changes are limited as our knowledge is mainly derived from biochemical and genetic studies, complemented by a few targeted yet very informative imaging studies. Comprehensive plant cell wall models will aid in the re-design of plant cell walls for the purpose of commercially viable lignocellulosic biofuel production as well as for the timber, textile, and paper industries. Such knowledge will also be of great interest in the context of agriculture and to plant biologists in general. It is expected that detailed plant cell wall models will require integrated correlative multimodal, multiscale imaging and modelling approaches, which are currently underway.

Expanding the Understanding of Evolution

ERIC Educational Resources Information Center

Musante, Susan

2011-01-01

Originally designed for K-12 teachers, the Understanding Evolution (UE) Web site ("www.understandingevolution.org") is a one-stop shop for all of a teacher's evolution education needs, with lesson plans, teaching tips, lists of common evolution misconceptions, and much more. However, during the past five years, the UE project team learned that…

Hox genes and chordate evolution.

PubMed

Holland, P W; Garcia-Fernàndez, J

1996-02-01

Hox genes are implicated in the control of axial patterning during embryonic development of many, perhaps all, animals. Here we review recent data on Hox gene diversity, genomic organization, and embryonic expression in chordates (including tunicates, amphioxus, hagfish, lampreys, teleosts) plus their putative sister group, the hemichordates. We consider the potential of comparative Hox gene data to resolve some outstanding controversies in chordate phylogeny. The use of Hox gene expression patterns to identify homologies between body plans both within the vertebrates and between the chordate subphyla is also discussed. Homology between the vertebrate hindbrain and an extensive region of amphioxus neural tube is suggested by comparison of Hox-3 homologues and strengthened by new data on amphioxus Hox-1 gene expression reported here. Finally, we give two examples of how Hox genes are giving glimpses into chordate developmental evolution. The first relates changes in Hox gene expression to transposition of vertebral of vertebral identities; the second describes a correlation between vertebrate origins and Hox gene cluster duplication. We suggest that the simultaneous duplication of many classes of genes, often interacting in gene networks, allowed the elaboration of new developmental control mechanisms at vertebrate origins.

Insect evolution.

PubMed

Engel, Michael S

2015-10-05

It goes without saying that insects epitomize diversity, and with over a million documented species they stand out as one of the most remarkable lineages in the 3.5-billion-year history of life on earth (Figure 1). This reality is passé to even the layperson and is taken for granted in the same way none of us think much of our breathing as we go about our day, and yet insects are just as vital to our existence. Insects are simultaneously familiar and foreign to us, and while a small fraction are beloved or reviled, most are simply ignored. These inexorable evolutionary overachievers outnumber us all, their segmented body plan is remarkably labile, they combine a capacity for high rates of speciation with low levels of natural extinction, and their history of successes eclipses those of the more familiar ages of dinosaurs and mammals alike. It is their evolution - persisting over vast expanses of geological time and inextricably implicated in the diversification of other lineages - that stands as one of the most expansive subjects in biology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Storytelling, behavior planning, and language evolution in context.

PubMed

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes.

Storytelling, behavior planning, and language evolution in context

PubMed Central

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes. PMID:25360123

A Mudball Model for the Evolution of Carbonaceous Asteroids

NASA Astrophysics Data System (ADS)

Travis, B. J.; Bland, P. A.

2018-05-01

We simulation the evolution of carbonaceous chondrite parent bodies from initially unconsolidated aggregations of rock grains and ice crystals. Application of the numerical model MAGHNUM to evolution of CM type planetesimals and Ceres is described.

Proceedings of the MEVTV Workshop on The Evolution of Magma Bodies on Mars

NASA Technical Reports Server (NTRS)

Mouginis-Mark, P. (Editor); Holloway, J. (Editor)

1990-01-01

The workshop focused on many of the diverse approaches related to the evolution of magma bodies on Mars that have been pursued during the course of the Mars Evolution of Volcanism, Tectonism, and Volatiles (MEVTV) Program. Approximately 35 scientists from the Mars volcanology, petrology, geochemistry, and modeling communities attended. Segments of the meeting concentrated of laboratory analyses and investigations of SNC meteorites, the interpretation of Viking Orbiter and Lander datasets, and the interpretation of computer codes that model volcanic and tectonic processes on Mars. Abstracts of these reports are presented.

Shape Evolution of Detached Bridgman Crystals Grown in Microgravity

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.

2015-01-01

A theory describing the shape evolution of detached Bridgman crystals in microgravity has been developed. A starting crystal of initial radius r0 will evolve to one of the following states: Stable detached gap; Attachment to the crucible wall; Meniscus collapse. Only crystals where alpha plus omega is great than 180 degrees will achieve stable detached growth in microgravity. Results of the crystal shape evolution theory are consistent with predictions of the dynamic stability of crystallization (Tatarchenko, Shaped Crystal Growth, Kluwer, 1993). Tests of transient crystal evolution are planned for ICESAGE, a series of Ge and GeSi crystal growth experiments planned to be conducted on the International Space Station (ISS).

Evolutionary changes of Hox genes and relevant regulatory factors provide novel insights into mammalian morphological modifications.

PubMed

Li, Kui; Sun, Xiaohui; Chen, Meixiu; Sun, Yingying; Tian, Ran; Wang, Zhengfei; Xu, Shixia; Yang, Guang

2018-01-01

The diversity of body plans of mammals accelerates the innovation of lifestyles and the extensive adaptation to different habitats, including terrestrial, aerial and aquatic habitats. However, the genetic basis of those phenotypic modifications, which have occurred during mammalian evolution, remains poorly explored. In the present study, we synthetically surveyed the evolutionary pattern of Hox clusters that played a powerful role in the morphogenesis along the head-tail axis of animal embryos and the main regulatory factors (Mll, Bmi1 and E2f6) that control the expression of Hox genes. A deflected density of repetitive elements and lineage-specific radical mutations of Mll have been determined in marine mammals with morphological changes, suggesting that evolutionary changes may alter Hox gene expression in these lineages, leading to the morphological modification of these lineages. Although no positive selection was detected at certain ancestor nodes of lineages, the increased ω values of Hox genes implied the relaxation of functional constraints of these genes during the mammalian evolutionary process. More importantly, 49 positively-selected sites were identified in mammalian lineages with phenotypic modifications, indicating adaptive evolution acting on Hox genes and regulatory factors. In addition, 3 parallel amino acid substitutions in some Hox genes were examined in marine mammals, which might be responsible for their streamlined body. © 2017 The Authors. Integrative Zoology published by International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Origin of the vertebrate body plan via mechanically biased conservation of regular geometrical patterns in the structure of the blastula.

PubMed

Edelman, David B; McMenamin, Mark; Sheesley, Peter; Pivar, Stuart

2016-09-01

We present a plausible account of the origin of the archetypal vertebrate bauplan. We offer a theoretical reconstruction of the geometrically regular structure of the blastula resulting from the sequential subdivision of the egg, followed by mechanical deformations of the blastula in subsequent stages of gastrulation. We suggest that the formation of the vertebrate bauplan during development, as well as fixation of its variants over the course of evolution, have been constrained and guided by global mechanical biases. Arguably, the role of such biases in directing morphology-though all but neglected in previous accounts of both development and macroevolution-is critical to any substantive explanation for the origin of the archetypal vertebrate bauplan. We surmise that the blastula inherently preserves the underlying geometry of the cuboidal array of eight cells produced by the first three cleavages that ultimately define the medial-lateral, dorsal-ventral, and anterior-posterior axes of the future body plan. Through graphical depictions, we demonstrate the formation of principal structures of the vertebrate body via mechanical deformation of predictable geometrical patterns during gastrulation. The descriptive rigor of our model is supported through comparisons with previous characterizations of the embryonic and adult vertebrate bauplane. Though speculative, the model addresses the poignant absence in the literature of any plausible account of the origin of vertebrate morphology. A robust solution to the problem of morphogenesis-currently an elusive goal-will only emerge from consideration of both top-down (e.g., the mechanical constraints and geometric properties considered here) and bottom-up (e.g., molecular and mechano-chemical) influences. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Body posture modulates action perception.

PubMed

Zimmermann, Marius; Toni, Ivan; de Lange, Floris P

2013-04-03

Recent studies have highlighted cognitive and neural similarities between planning and perceiving actions. Given that action planning involves a simulation of potential action plans that depends on the actor's body posture, we reasoned that perceiving actions may also be influenced by one's body posture. Here, we test whether and how this influence occurs by measuring behavioral and cerebral (fMRI) responses in human participants predicting goals of observed actions, while manipulating postural congruency between their own body posture and postures of the observed agents. Behaviorally, predicting action goals is facilitated when the body posture of the observer matches the posture achieved by the observed agent at the end of his action (action's goal posture). Cerebrally, this perceptual postural congruency effect modulates activity in a portion of the left intraparietal sulcus that has previously been shown to be involved in updating neural representations of one's own limb posture during action planning. This intraparietal area showed stronger responses when the goal posture of the observed action did not match the current body posture of the observer. These results add two novel elements to the notion that perceiving actions relies on the same predictive mechanism as planning actions. First, the predictions implemented by this mechanism are based on the current physical configuration of the body. Second, during both action planning and action observation, these predictions pertain to the goal state of the action.

Investigating yellow dung fly body size evolution in the field: Response to climate change?

PubMed

Blanckenhorn, Wolf U

2015-08-01

Uncovering genetic responses to selection in wild populations typically requires tracking individuals over generations and use of animal models. Our group monitored the body size of one Swiss Yellow Dung Fly (Scathophaga stercoraria; Diptera: Scathophagidae) field population over 15 years, including intermittent common-garden rearing in the laboratory to assess body size with minimized environmental and maximized genetic variation. Contrary to expectations based on repeated heritability and phenotypic selection assessments over the years (reported elsewhere), field body sizes declined by >10% and common-garden laboratory sizes by >5% from 1993 to 2009. Our results confirm the temperature-size rule (smaller when warmer) and, albeit entirely correlational, could be mediated by climate change, as over this period mean temperature at the site increased by 0.5°C, although alternative systematic environmental changes cannot be entirely excluded. Monitoring genetic responses to selection in wild invertebrate populations is thus possible, though indirect, and wild populations may evolve in directions not consistent with strongly positive directional selection favoring large body size. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

The evolution of dinosaurs.

PubMed

Sereno, P C

1999-06-25

The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.

COUPLED SPIN AND SHAPE EVOLUTION OF SMALL RUBBLE-PILE ASTEROIDS: SELF-LIMITATION OF THE YORP EFFECT

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

Cotto-Figueroa, Desireé; Statler, Thomas S.; Richardson, Derek C.

2015-04-10

We present the first self-consistent simulations of the coupled spin-shape evolution of small gravitational aggregates under the influence of the YORP effect. Because of YORP’s sensitivity to surface topography, even small centrifugally driven reconfigurations of aggregates can alter the YORP torque dramatically, resulting in spin evolution that can differ qualitatively from the rigid-body prediction. One-third of our simulations follow a simple evolution described as a modified YORP cycle. Two-thirds exhibit one or more of three distinct behaviors—stochastic YORP, self-governed YORP, and stagnating YORP—which together result in YORP self-limitation. Self-limitation confines rotation rates of evolving aggregates to far narrower ranges thanmore » those expected in the classical YORP cycle, greatly prolonging the times over which objects can preserve their sense of rotation. Simulated objects are initially randomly packed, disordered aggregates of identical spheres in rotating equilibrium, with low internal angles of friction. Their shape evolution is characterized by rearrangement of the entire body, including the deep interior. They do not evolve to axisymmetric top shapes with equatorial ridges. Mass loss occurs in one-third of the simulations, typically in small amounts from the ends of a prolate-triaxial body. We conjecture that YORP self-limitation may inhibit formation of top-shapes, binaries, or both, by restricting the amount of angular momentum that can be imparted to a deformable body. Stochastic YORP, in particular, will affect the evolution of collisional families whose orbits drift apart under the influence of Yarkovsky forces, in observable ways.« less

Body size evolution in an old insect order: No evidence for Cope's Rule in spite of fitness benefits of large size.

PubMed

Waller, John T; Svensson, Erik I

2017-09-01

We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or nonexistent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult life-stage. This lack of stabilizing selection during the adult life-stage was independently supported by a literature survey on different male and female fitness components from several odonate species. We did detect several significant body size shifts among extant taxa using comparative methods and a large new molecular phylogeny for odonates. We suggest that the lack of Cope's rule in odonates results from conflicting selection between fitness advantages of large adult size and costs of long larval development. We also discuss competing explanations for body size stasis in this insect group. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Cryptic lineage diversity, body size divergence, and sympatry in a species complex of Australian lizards (Gehyra).

PubMed

Moritz, Craig C; Pratt, Renae C; Bank, Sarah; Bourke, Gayleen; Bragg, Jason G; Doughty, Paul; Keogh, J Scott; Laver, Rebecca J; Potter, Sally; Teasdale, Luisa C; Tedeschi, Leonardo G; Oliver, Paul M

2018-01-01

Understanding the joint evolutionary and ecological underpinnings of sympatry among close relatives remains a key challenge in biology. This problem can be addressed through joint phylogenomic and phenotypic analysis of complexes of closely related lineages within, and across, species and hence representing the speciation continuum. For a complex of tropical geckos from northern Australia-Gehyra nana and close relatives-we combine mtDNA phylogeography, exon-capture sequencing, and morphological data to resolve independently evolving lineages and infer their divergence history and patterns of morphological evolution. Gehyra nana is found to include nine divergent lineages and is paraphyletic with four other species from the Kimberley region of north-west Australia. Across these 13 taxa, 12 of which are restricted to rocky habitats, several lineages overlap geographically, including on the diverse Kimberley islands. Morphological evolution is dominated by body size shifts, and both body size and shape have evolved gradually across the group. However, larger body size shifts are observed among overlapping taxa than among closely related parapatric lineages of G. nana, and sympatric lineages are more divergent than expected at random. Whether elevated body size differences among sympatric lineages are due to ecological sorting or character displacement remains to be determined. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

The evolution of island gigantism and body size variation in tortoises and turtles

PubMed Central

Jaffe, Alexander L.; Slater, Graham J.; Alfaro, Michael E.

2011-01-01

Extant chelonians (turtles and tortoises) span almost four orders of magnitude of body size, including the startling examples of gigantism seen in the tortoises of the Galapagos and Seychelles islands. However, the evolutionary determinants of size diversity in chelonians are poorly understood. We present a comparative analysis of body size evolution in turtles and tortoises within a phylogenetic framework. Our results reveal a pronounced relationship between habitat and optimal body size in chelonians. We found strong evidence for separate, larger optimal body sizes for sea turtles and island tortoises, the latter showing support for the rule of island gigantism in non-mammalian amniotes. Optimal sizes for freshwater and mainland terrestrial turtles are similar and smaller, although the range of body size variation in these forms is qualitatively greater. The greater number of potential niches in freshwater and terrestrial environments may mean that body size relationships are more complicated in these habitats. PMID:21270022

The Planning Wheel: Value Added Performance.

ERIC Educational Resources Information Center

Murk, Peter J.; Walls, Jeffrey L.

The "Planning Wheel" is an evolution of the original Systems Approach Model (SAM) that was introduced in 1986 by Murk and Galbraith. Unlike most current planning models, which are linear in design and concept, the Planning Wheel bridges the gap between linear and nonlinear processes. The "Program Planning Wheel" is designed to…

Evolution and devolution : a national perspective on the changing role of metropolitan planning organizations in areawide intermodal planning.

DOT National Transportation Integrated Search

1997-01-01

The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) dramatically changed the metropolitan planning process by presenting new opportunities and responsibilities to the institutions in charge of metropolitan planning. The legislation f...

The Evolution of U.S. e-Learning Policy: A Content Analysis of the National Education Technology Plans

ERIC Educational Resources Information Center

Roumell, Elizabeth Anne; Salajan, Florin Daniel

2016-01-01

The purpose of this study was threefold: to expand on existing reviews of 20 years of educational technology policy in the United States, to perform an empirical content analysis of the four National Education Technology Plan (NETP) documents issued by the Department of Education since 1996, and to provide a dialectic analysis of the evolution of…

Self-Efficacy, Planning, or a Combination of Both? A Longitudinal Experimental Study Comparing Effects of Three Interventions on Adolescents’ Body Fat

PubMed Central

Luszczynska, Aleksandra; Hagger, Martin S.; Banik, Anna; Horodyska, Karolina; Knoll, Nina; Scholz, Urte

2016-01-01

Background The superiority of an intervention combining two sets of theory-based behavior change techniques targeting planning and self-efficacy over an intervention targeting planning only or self-efficacy only has rarely been investigated. Purpose We compared the influence of self-efficacy, planning, and self-efficacy+planning interventions with an education-based control condition on adolescents’ body fat, assuming mediating effects of respective social cognitive variables and moderate-to-vigorous physical activity (MVPA). The moderating role of the built environment was examined. Methods Participants (N = 1217, aged 14–18 years) were randomly assigned to four conditions: planning (n = 270), self-efficacy (n = 311), self-efficacy+planning (n = 351), and control (n = 285). The measurement was conducted at baseline (T1), two-month follow-up (T2), and fourteen-month follow-up (T3). Interventions/control group procedures were delivered at T1 and T2. Percent of body fat tissue (measured at T1 and T3) was the main outcome. Social cognitive mediators (self-efficacy and planning) were assessed at T1 and T2. The behavioral mediator (MVPA) and the presence of built MVPA facilities (the moderator) were evaluated at T1 and T3. Results Similar small increases of body fat were found across the three intervention groups, but the increment of body fat was significantly larger in the control group. On average, differences between control and intervention groups translated to approximately 1% of body fat. Effects of the interventions on body fat were mediated by relevant social cognitive variables and MVPA. A lower increase of body fat was found among intervention group participants who had access to newly-built MVPA facilities. Conclusions We found no superiority of an intervention targeting two social cognitive variables over the intervention targeting one cognition only. PMID:27410961

Tightly congruent bursts of lineage and phenotypic diversification identified in a continental ant radiation.

PubMed

Price, Shauna L; Etienne, Rampal S; Powell, Scott

2016-04-01

Adaptive diversification is thought to be shaped by ecological opportunity. A prediction of this ecological process of diversification is that it should result in congruent bursts of lineage and phenotypic diversification, but few studies have found this expected association. Here, we study the relationship between rates of lineage diversification and body size evolution in the turtle ants, a diverse Neotropical clade. Using a near complete, time-calibrated phylogeny we investigated lineage diversification dynamics and body size disparity through model fitting analyses and estimation of per-lineage rates of cladogenesis and phenotypic evolution. We identify an exceptionally high degree of congruence between the high rates of lineage and body size diversification in a young clade undergoing renewed diversification in the ecologically distinct Chacoan biogeographical region of South America. It is likely that the region presented turtle ants with novel ecological opportunity, which facilitated a nested burst of diversification and phenotypic evolution within the group. Our results provide a compelling quantitative example of tight congruence between rates of lineage and phenotypic diversification, meeting the key predicted pattern of adaptive diversification shaped by ecological opportunity. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Bony cranial ornamentation linked to rapid evolution of gigantic theropod dinosaurs

NASA Astrophysics Data System (ADS)

Gates, Terry A.; Organ, Chris; Zanno, Lindsay E.

2016-09-01

Exaggerated cranial structures such as crests and horns, hereafter referred to collectively as ornaments, are pervasive across animal species. These structures perform vital roles in visual communication and physical interactions within and between species. Yet the origin and influence of ornamentation on speciation and ecology across macroevolutionary time scales remains poorly understood for virtually all animals. Here, we explore correlative evolution of osseous cranial ornaments with large body size in theropod dinosaurs using a phylogenetic comparative framework. We find that body size evolved directionally toward phyletic giantism an order of magnitude faster in theropod species possessing ornaments compared with unadorned lineages. In addition, we find a body mass threshold below which bony cranial ornaments do not originate. Maniraptoriform dinosaurs generally lack osseous cranial ornaments despite repeatedly crossing this body size threshold. Our study provides novel, quantitative support for a shift in selective pressures on socio-sexual display mechanisms in theropods coincident with the evolution of pennaceous feathers.

Diversification rates and phenotypic evolution in venomous snakes (Elapidae).

PubMed

Lee, Michael S Y; Sanders, Kate L; King, Benedict; Palci, Alessandro

2016-01-01

The relationship between rates of diversification and of body size change (a common proxy for phenotypic evolution) was investigated across Elapidae, the largest radiation of highly venomous snakes. Time-calibrated phylogenetic trees for 175 species of elapids (more than 50% of known taxa) were constructed using seven mitochondrial and nuclear genes. Analyses using these trees revealed no evidence for a link between speciation rates and changes in body size. Two clades (Hydrophis, Micrurus) show anomalously high rates of diversification within Elapidae, yet exhibit rates of body size evolution almost identical to the general elapid 'background' rate. Although correlations between speciation rates and rates of body size change exist in certain groups (e.g. ray-finned fishes, passerine birds), the two processes appear to be uncoupled in elapid snakes. There is also no detectable shift in diversification dynamics associated with the colonization of Australasia, which is surprising given that elapids appear to be the first clade of venomous snakes to reach the continent.

Bony cranial ornamentation linked to rapid evolution of gigantic theropod dinosaurs

PubMed Central

Gates, Terry A.; Organ, Chris; Zanno, Lindsay E.

2016-01-01

Exaggerated cranial structures such as crests and horns, hereafter referred to collectively as ornaments, are pervasive across animal species. These structures perform vital roles in visual communication and physical interactions within and between species. Yet the origin and influence of ornamentation on speciation and ecology across macroevolutionary time scales remains poorly understood for virtually all animals. Here, we explore correlative evolution of osseous cranial ornaments with large body size in theropod dinosaurs using a phylogenetic comparative framework. We find that body size evolved directionally toward phyletic giantism an order of magnitude faster in theropod species possessing ornaments compared with unadorned lineages. In addition, we find a body mass threshold below which bony cranial ornaments do not originate. Maniraptoriform dinosaurs generally lack osseous cranial ornaments despite repeatedly crossing this body size threshold. Our study provides novel, quantitative support for a shift in selective pressures on socio-sexual display mechanisms in theropods coincident with the evolution of pennaceous feathers. PMID:27676310

Evolution of body size in Galapagos marine iguanas.

PubMed

Wikelski, Martin

2005-10-07

Body size is one of the most important traits of organisms and allows predictions of an individual's morphology, physiology, behaviour and life history. However, explaining the evolution of complex traits such as body size is difficult because a plethora of other traits influence body size. Here I review what we know about the evolution of body size in a group of island reptiles and try to generalize about the mechanisms that shape body size. Galapagos marine iguanas occupy all 13 larger islands in this Pacific archipelago and have maximum island body weights between 900 and 12 000g. The distribution of body sizes does not match mitochondrial clades, indicating that body size evolves independently of genetic relatedness. Marine iguanas lack intra- and inter-specific food competition and predators are not size-specific, discounting these factors as selective agents influencing body size. Instead I hypothesize that body size reflects the trade-offs between sexual and natural selection. We found that sexual selection continuously favours larger body sizes. Large males establish display territories and some gain over-proportional reproductive success in the iguanas' mating aggregations. Females select males based on size and activity and are thus responsible for the observed mating skew. However, large individuals are strongly selected against during El Niño-related famines when dietary algae disappear from the intertidal foraging areas. We showed that differences in algae sward ('pasture') heights and thermal constraints on large size are causally responsible for differences in maximum body size among populations. I hypothesize that body size in many animal species reflects a trade-off between foraging constraints and sexual selection and suggest that future research could focus on physiological and genetic mechanisms determining body size in wild animals. Furthermore, evolutionary stable body size distributions within populations should be analysed to better understand selection pressures on individual body size.

Evolution of body size in Galapagos marine iguanas

PubMed Central

Wikelski, Martin

2005-01-01

Body size is one of the most important traits of organisms and allows predictions of an individual's morphology, physiology, behaviour and life history. However, explaining the evolution of complex traits such as body size is difficult because a plethora of other traits influence body size. Here I review what we know about the evolution of body size in a group of island reptiles and try to generalize about the mechanisms that shape body size. Galapagos marine iguanas occupy all 13 larger islands in this Pacific archipelago and have maximum island body weights between 900 and 12 000 g. The distribution of body sizes does not match mitochondrial clades, indicating that body size evolves independently of genetic relatedness. Marine iguanas lack intra- and inter-specific food competition and predators are not size-specific, discounting these factors as selective agents influencing body size. Instead I hypothesize that body size reflects the trade-offs between sexual and natural selection. We found that sexual selection continuously favours larger body sizes. Large males establish display territories and some gain over-proportional reproductive success in the iguanas' mating aggregations. Females select males based on size and activity and are thus responsible for the observed mating skew. However, large individuals are strongly selected against during El Niño-related famines when dietary algae disappear from the intertidal foraging areas. We showed that differences in algae sward (‘pasture’) heights and thermal constraints on large size are causally responsible for differences in maximum body size among populations. I hypothesize that body size in many animal species reflects a trade-off between foraging constraints and sexual selection and suggest that future research could focus on physiological and genetic mechanisms determining body size in wild animals. Furthermore, evolutionary stable body size distributions within populations should be analysed to better understand selection pressures on individual body size. PMID:16191607

Observing Planets and Small Bodies in Sputtered High Energy Atom (SHEA) Fluxes

NASA Technical Reports Server (NTRS)

Milillo, A.; Orsini, S.; Hsieh, K. C.; Baragiola, R.; Fama, M.; Johnson, R.; Mura, A.; Plainaki, Ch.; Sarantos, M.; Cassidy, T. A.;

A Workable In-Depth Curriculum Evaluation Plan.

ERIC Educational Resources Information Center

Wakim, Judith H.

1983-01-01

Describes the six-year evolution of a comprehensive evaluation plan used to enhance a nursing program. Includes the plan with specific questions, deadlines, and documentation procedures. The plan provides a rational basis for improvements, orients newcomers, and lets everyone know what their evaluation responsibilities are. (JOW)

49 CFR 266.15 - Requirements for State Rail Plan.

Code of Federal Regulations, 2013 CFR

2013-10-01

... regional governmental bodies to review and comment on appropriate elements of the State Rail Plan...) Describe the State's methodology for determining the ratio of benefits to the costs of proposed projects...) Describe the planning process participation of local and regional governmental bodies, the railroads...

49 CFR 266.15 - Requirements for State Rail Plan.

Code of Federal Regulations, 2011 CFR

2011-10-01

... regional governmental bodies to review and comment on appropriate elements of the State Rail Plan...) Describe the State's methodology for determining the ratio of benefits to the costs of proposed projects...) Describe the planning process participation of local and regional governmental bodies, the railroads...

49 CFR 266.15 - Requirements for State Rail Plan.

Code of Federal Regulations, 2014 CFR

2014-10-01

... regional governmental bodies to review and comment on appropriate elements of the State Rail Plan...) Describe the State's methodology for determining the ratio of benefits to the costs of proposed projects...) Describe the planning process participation of local and regional governmental bodies, the railroads...

49 CFR 266.15 - Requirements for State Rail Plan.

Code of Federal Regulations, 2012 CFR

2012-10-01

... regional governmental bodies to review and comment on appropriate elements of the State Rail Plan...) Describe the State's methodology for determining the ratio of benefits to the costs of proposed projects...) Describe the planning process participation of local and regional governmental bodies, the railroads...

The effect of tidal forces on the minimum energy configurations of the full three-body problem

NASA Astrophysics Data System (ADS)

Levine, Edward

We investigate the evolution of minimum energy configurations for the Full Three Body Problem (3BP). A stable ternary asteroid system will gradually become unstable due to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect and an unpredictable trajectory will ensue. Through the interaction of tidal torques, energy in the system will dissipate in the form of heat until a stable minimum energy configuration is reached. We present a simulation that describes the dynamical evolution of three bodies under the mutual effects of gravity and tidal torques. Simulations show that bodies do not get stuck in local minima and transition to the predicted minimum energy configuration.

Managing Decisions on Changes in the Virtual Enterprise Evolution

NASA Astrophysics Data System (ADS)

Drissen-Silva, Marcus Vinicius; Rabelo, Ricardo José

VE evolution deals with problems that happen during the VE operation and that put on risk planned results. This requires the application of problem-solving mechanisms to guarantee the construction of a new but feasible VE plan. Grounded on Project Management and Decision Support Systems foundations, this paper proposes a distributed collaborative decision support system to manage the VE evolution. Its main rationale is that VE’s members are autonomous and hence that all the affected partners should discuss about the necessary changes on the current VE’s plan. In the proposed approach, this discussion is guided by a decision protocol, and the impact of decisions can be evaluated. Results of a first prototype implementation are presented and discussed, with a special focus on the part which regulates the argumentation, voting and comparison of possible solutions.

N-body simulations of collective effects in spiral and barred galaxies

NASA Astrophysics Data System (ADS)

Zhang, X.

2016-10-01

We present gravitational N-body simulations of the secular morphological evolution of disk galaxies induced by density wave modes. In particular, we address the demands collective effects place on the choice of simulation parameters, and show that the common practice of the use of a large gravity softening parameter was responsible for the failure of past simulations to correctly model the secular evolution process in galaxies, even for those simulations where the choice of basic state allows an unstable mode to emerge, a prerequisite for obtaining the coordinated radial mass flow pattern needed for secular evolution of galaxies along the Hubble sequence. We also demonstrate that the secular evolution rates measured in our improved simulations agree to an impressive degree with the corresponding rates predicted by the recently-advanced theories of dynamically-driven secular evolution of galaxies. The results of the current work, besides having direct implications on the cosmological evolution of galaxies, also shed light on the general question of how irreversibility emerges from a nominally reversible physical system.

In situ methods for measuring thermal properties and heat flux on planetary bodies

PubMed Central

Kömle, Norbert I.; Hütter, Erika S.; Macher, Wolfgang; Kaufmann, Erika; Kargl, Günter; Knollenberg, Jörg; Grott, Matthias; Spohn, Tilman; Wawrzaszek, Roman; Banaszkiewicz, Marek; Seweryn, Karoly; Hagermann, Axel

2011-01-01

The thermo-mechanical properties of planetary surface and subsurface layers control to a high extent in which way a body interacts with its environment, in particular how it responds to solar irradiation and how it interacts with a potentially existing atmosphere. Furthermore, if the natural temperature profile over a certain depth can be measured in situ, this gives important information about the heat flux from the interior and thus about the thermal evolution of the body. Therefore, in most of the recent and planned planetary lander missions experiment packages for determining thermo-mechanical properties are part of the payload. Examples are the experiment MUPUS on Rosetta's comet lander Philae, the TECP instrument aboard NASA's Mars polar lander Phoenix, and the mole-type instrument HP3 currently developed for use on upcoming lunar and Mars missions. In this review we describe several methods applied for measuring thermal conductivity and heat flux and discuss the particular difficulties faced when these properties have to be measured in a low pressure and low temperature environment. We point out the abilities and disadvantages of the different instruments and outline the evaluation procedures necessary to extract reliable thermal conductivity and heat flux data from in situ measurements. PMID:21760643

Dynamics of multiple bodies in a corotation resonance

NASA Astrophysics Data System (ADS)

A'Hearn, Joseph; Hedman, Matthew

2018-04-01

The orbital evolution of multiple massive bodies trapped in the same corotation resonance site has not yet been studied in depth, but could be relevant to the origins and history of small moons like Saturn's moon Aegaeon. We conduct numerical simulations of multiple bodies trapped within a corotation resonance and examine what happens to these bodies when they have close encounters. Compared to simulations with equal mass bodies, simulations with one body more massive than the others may be more likely to feature an asymmetry in the phase space of semi-major axis and mean longitude. That is, bodies on one side of phase space have a slightly greater tendency to lose angular momentum, while bodies on the other side gain angular momentum. With this asymmetry, the transfer of angular momentum during gravitational encounters makes it more likely for the most massive body rather than other bodies to approach the center of the corotation site. More work is needed to determine if this sort of process can significantly affect the orbital evolution of small moons like Aegaeon.

Physical aspects of total-body irradiation at the Middlesex Hospital (UCL group of hospitals), London 1988-1993: II. In vivo planning and dosimetry.

PubMed

Planskoy, B; Tapper, P D; Bedford, A M; Davis, F M

1996-11-01

Part II of this paper gives the results of applying the TBI methods described in part I, to in vivo patient planning and dosimetry. Patients are planned on nine CT based body slices, five of which pass through the lungs. Planned doses are verified with ten silicon diodes applied bi-laterally to five body sites, at each treatment. LiF TLDs are applied to seven other body sites at the first treatment only. For 84 patients and at least 1016 measurements per body site with the diodes, the mean measured total doses agreed with planned doses within at most 2% except at lung levels, where the mean measured dose was 3% too low. Standard deviations of the measurements about the mean were between 2.4 and 3.1%. For the LiF TLDs, the mean measured doses for all seven body sites were with in +/- 5% of planned doses. A separate assessment of measured entrance and transmitted doses showed that the former agreed well with planned doses, but that the latter tended to be low, especially over the lungs, and that they had a wider dispersion. Possible reasons for this are discussed. These results show measurement uncertainties similar to those for non-TBI treatments of Nilsson et al, Leunens et al and Essers et al. An analysis of the treatment plans showed a mean dose inhomogeneity in the body (75 patients, nine slices) of 19 +/- 6.0% (1 s.d.) and in the lungs (40 patients, five slices) of 9.2 +/- 2.85% (1 s.d.). The conclusions are that, overall, the methods are reasonably satisfactory but that, with an extra effort, even closer agreement between measured and planned doses and a further limited reduction in the body dose inhomogeneity could be obtained. However, if it were thought desirable to make a substantial reduction in the dose inhomogeneity in the body and lungs, this could only be achieved with the available equipment by changing from lateral to anterior-posterior irradiation and any potential advantages of this change would have to be balanced against a likely deterioration in patient comfort and an increase in treatment set-up times.

Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia.

PubMed

Head, Jason J; Gunnell, Gregg F; Holroyd, Patricia A; Hutchison, J Howard; Ciochon, Russell L

2013-07-22

Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which provides a historical test of factors controlling body size in herbivorous squamates. We infer a predominately herbivorous feeding ecology for the new acrodontan based on dental anatomy, phylogenetic relationships and body size. Ranking body masses for Pondaung Formation vertebrates indicates that the lizard occupied a size niche among the larger herbivores and was larger than most carnivorous mammals. Paleotemperature estimates of Pondaung Formation environments based on the body size of the new lizard are approximately 2-5°C higher than modern. These results indicate that competitive exclusion and predation by mammals did not restrict body size evolution in these herbivorous squamates, and elevated temperatures relative to modern climates during the Paleogene greenhouse may have resulted in the evolution of gigantism through elevated poikilothermic metabolic rates and in response to increases in floral productivity.

Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia

PubMed Central

Head, Jason J.; Gunnell, Gregg F.; Holroyd, Patricia A.; Hutchison, J. Howard; Ciochon, Russell L.

2013-01-01

Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which provides a historical test of factors controlling body size in herbivorous squamates. We infer a predominately herbivorous feeding ecology for the new acrodontan based on dental anatomy, phylogenetic relationships and body size. Ranking body masses for Pondaung Formation vertebrates indicates that the lizard occupied a size niche among the larger herbivores and was larger than most carnivorous mammals. Paleotemperature estimates of Pondaung Formation environments based on the body size of the new lizard are approximately 2–5°C higher than modern. These results indicate that competitive exclusion and predation by mammals did not restrict body size evolution in these herbivorous squamates, and elevated temperatures relative to modern climates during the Paleogene greenhouse may have resulted in the evolution of gigantism through elevated poikilothermic metabolic rates and in response to increases in floral productivity. PMID:23740779

Planning Systems for Distributed Operations

NASA Technical Reports Server (NTRS)

Maxwell, Theresa G.

2002-01-01

This viewgraph representation presents an overview of the mission planning process involving distributed operations (such as the International Space Station (ISS)) and the computer hardware and software systems needed to support such an effort. Topics considered include: evolution of distributed planning systems, ISS distributed planning, the Payload Planning System (PPS), future developments in distributed planning systems, Request Oriented Scheduling Engine (ROSE) and Next Generation distributed planning systems.

Genomics, evolution and development of amphioxus and tunicates: The Goldilocks principle.

PubMed

Holland, Linda Z

2015-06-01

Morphological comparisons among extant animals have long been used to infer their long-extinct ancestors for which the fossil record is poor or non-existent. For evolution of the vertebrates, the comparison has typically involved amphioxus and vertebrates. Both groups are evolving relatively slowly, and their genomes share a high level of synteny. Both vertebrates and amphioxus have regulative development in which cell fates become fixed only gradually during embryogenesis. Thus, their development fits a modified hourglass model in which constraints are greatest at the phylotypic stage (i.e., the late neurula/early larva), but are somewhat greater on earlier development than on later development. In contrast, the third group of chordates, the tunicates, which are sister group to vertebrates, are evolving rapidly. Constraints on evolution of tunicate genomes are relaxed, and they have discarded key developmental genes and organized much of their coding sequences into operons, which are transcribed as a single mRNA that undergoes trans-splicing. This contrasts with vertebrates and amphioxus, whose genomes are not organized into operons. Concomitantly, tunicates have switched to determinant development with very early fixation of cell fates. Thus, tunicate development more closely fits a progressive divergence model (shaped more like a wine glass than an hourglass) in which the constraints on the zygote and very early development are greatest. This model can help explain why tunicate body plans are so very diverse. The relaxed constraints on development after early cleavage stages are correlated with relaxed constraints on genome evolution. The question remains: which came first? © 2014 Wiley Periodicals, Inc.

Massive increase in visual range preceded the origin of terrestrial vertebrates

PubMed Central

MacIver, Malcolm A.; Schmitz, Lars; Mugan, Ugurcan; Murphey, Todd D.; Mobley, Curtis D.

2017-01-01

The evolution of terrestrial vertebrates, starting around 385 million years ago, is an iconic moment in evolution that brings to mind images of fish transforming into four-legged animals. Here, we show that this radical change in body shape was preceded by an equally dramatic change in sensory abilities akin to transitioning from seeing over short distances in a dense fog to seeing over long distances on a clear day. Measurements of eye sockets and simulations of their evolution show that eyes nearly tripled in size just before vertebrates began living on land. Computational simulations of these animal’s visual ecology show that for viewing objects through water, the increase in eye size provided a negligible increase in performance. However, when viewing objects through air, the increase in eye size provided a large increase in performance. The jump in eye size was, therefore, unlikely to have arisen for seeing through water and instead points to an unexpected hybrid of seeing through air while still primarily inhabiting water. Our results and several anatomical innovations arising at the same time suggest lifestyle similarity to crocodiles. The consequent combination of the increase in eye size and vision through air would have conferred a 1 million-fold increase in the amount of space within which objects could be seen. The “buena vista” hypothesis that our data suggest is that seeing opportunities from afar played a role in the subsequent evolution of fully terrestrial limbs as well as the emergence of elaborated action sequences through planning circuits in the nervous system. PMID:28270619

The tardigrade Hypsibius dujardini, a new model for studying the evolution of development.

PubMed

Gabriel, Willow N; McNuff, Robert; Patel, Sapna K; Gregory, T Ryan; Jeck, William R; Jones, Corbin D; Goldstein, Bob

2007-12-15

Studying development in diverse taxa can address a central issue in evolutionary biology: how morphological diversity arises through the evolution of developmental mechanisms. Two of the best-studied developmental model organisms, the arthropod Drosophila and the nematode Caenorhabditis elegans, have been found to belong to a single protostome superclade, the Ecdysozoa. This finding suggests that a closely related ecdysozoan phylum could serve as a valuable model for studying how developmental mechanisms evolve in ways that can produce diverse body plans. Tardigrades, also called water bears, make up a phylum of microscopic ecdysozoan animals. Tardigrades share many characteristics with C. elegans and Drosophila that could make them useful laboratory models, but long-term culturing of tardigrades historically has been a challenge, and there have been few studies of tardigrade development. Here, we show that the tardigrade Hypsibius dujardini can be cultured continuously for decades and can be cryopreserved. We report that H. dujardini has a compact genome, a little smaller than that of C. elegans or Drosophila, and that sequence evolution has occurred at a typical rate. H. dujardini has a short generation time, 13-14 days at room temperature. We have found that the embryos of H. dujardini have a stereotyped cleavage pattern with asymmetric cell divisions, nuclear migrations, and cell migrations occurring in reproducible patterns. We present a cell lineage of the early embryo and an embryonic staging series. We expect that these data can serve as a platform for using H. dujardini as a model for studying the evolution of developmental mechanisms.

SU-E-T-644: Evaluation of Angular Dependence Correction for 2D Array Detector Using for Quality Assurance of Volumetric Modulated Arc Therapy

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

Karthikeyan, N; Ganesh, K M; Vikraman, S

2014-06-15

Purpose: To evaluate the angular dependence correction for Matrix Evolution 2D array detector in quality assurance of volumetric modulated arc therapy(VMAT). Methods: Total ten patients comprising of different sites were planned for VMAT and taken for the study. Each plan was exposed on Matrix Evolution 2D array detector with Omnipro IMRT software based on the following three different methods using 6MV photon beams from Elekta Synergy linear accelerator. First method, VMAT plan was delivered on Matrix Evolution detector as it gantry mounted with dedicated holder with build-up of 2.3cm. Second, the VMAT plan was delivered with the static gantry anglemore » on to the table mounted setup. Third, the VMAT plan was delivered with actual gantry angle on Matrix Evolution detector fixed in Multicube phantom with gantry angle sensor and angular dependence correction were applied to quantify the plan quality. For all these methods, the corresponding QA plans were generated in TPS and the dose verification was done for both point and 2D fluence analysis with pass criteria of 3% dose difference and 3mm distance to agreement. Results: The measured point dose variation for the first method was observed as 1.58±0.6% of mean and SD with TPS calculated. For second and third method, the mean and standard deviation(SD) was observed as 1.67±0.7% and 1.85±0.8% respectively. The 2D fluence analysis of measured and TPS calculated has the mean and SD of 97.9±1.1%, 97.88±1.2% and 97.55±1.3% for first, second and third methods respectively. The calculated two-tailed Pvalue for point dose and 2D fluence analysis shows the insignificance with values of 0.9316 and 0.9015 respectively, among the different methods of QA. Conclusion: The qualitative evaluation of angular dependence correction for Matrix Evolution 2D array detector shows its competency in accuracy of quality assurance measurement of composite dose distribution of volumetric modulated arc therapy.« less

Ecological specialization and morphological diversification in Greater Antillean boas.

PubMed

Reynolds, R Graham; Collar, David C; Pasachnik, Stesha A; Niemiller, Matthew L; Puente-Rolón, Alberto R; Revell, Liam J

2016-08-01

Colonization of islands can dramatically influence the evolutionary trajectories of organisms, with both deterministic and stochastic processes driving adaptation and diversification. Some island colonists evolve extremely large or small body sizes, presumably in response to unique ecological circumstances present on islands. One example of this phenomenon, the Greater Antillean boas, includes both small (<90 cm) and large (4 m) species occurring on the Greater Antilles and Bahamas, with some islands supporting pairs or trios of body-size divergent species. These boas have been shown to comprise a monophyletic radiation arising from a Miocene dispersal event to the Greater Antilles, though it is not known whether co-occurrence of small and large species is a result of dispersal or in situ evolution. Here, we provide the first comprehensive species phylogeny for this clade combined with morphometric and ecological data to show that small body size evolved repeatedly on separate islands in association with specialization in substrate use. Our results further suggest that microhabitat specialization is linked to increased rates of head shape diversification among specialists. Our findings show that ecological specialization following island colonization promotes morphological diversity through deterministic body size evolution and cranial morphological diversification that is contingent on island- and species-specific factors. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Sex-specific patterns of morphological diversification: evolution of reaction norms and static allometries in neriid flies.

PubMed

Cassidy, Elizabeth J; Bath, Eleanor; Chenoweth, Stephen F; Bonduriansky, Russell

2014-02-01

The consequences of sex-specific selection for patterns of diversification remain poorly known. Because male secondary sexual traits are typically costly to express, and both costs and benefits are likely to depend on ambient environment and individual condition, such traits may be expected to diversify via changes in reaction norms as well as the scaling of trait size with body size (static allometry). We investigated morphological diversification within two species of Australian neriid flies (Telostylinus angusticollis, Telostylinus lineolatus) by rearing larvae from several populations on larval diets varying sixfold in nutrient concentration. Mean body size varied among populations of T. angusticollis, but body size reaction norms did not vary within either species. However, we detected diversification of reaction norms for body shape in males and females within both species. Moreover, unlike females, males also diversified in static allometry slope and reaction norms for static allometry slope of sexual and nonsexual traits. Our findings reveal qualitative sex differences in patterns of morphological diversification, whereby shape-size relationships diversify extensively in males, but remain conserved in females despite extensive evolution of trait means. Our results highlight the importance of incorporating plasticity and allometry in studies of adaptation and diversification. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

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

PubMed

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

2015-08-01

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

Long-term patterns of body mass and stature evolution within the hominin lineage.

PubMed

Will, Manuel; Pablos, Adrián; Stock, Jay T

2017-11-01

Body size is a central determinant of a species' biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4 Ma to the Holocene using multi-level chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of small-bodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo , stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5-0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4 Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi ( ca 0.3 Ma) and Homo floresiensis ( ca 100-60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo . At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in comparable frequency since early Homo .

Long-term patterns of body mass and stature evolution within the hominin lineage

PubMed Central

Pablos, Adrián; Stock, Jay T.

2017-01-01

Body size is a central determinant of a species' biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4 Ma to the Holocene using multi-level chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of small-bodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo, stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5–0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4 Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi (ca 0.3 Ma) and Homo floresiensis (ca 100–60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo. At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in comparable frequency since early Homo. PMID:29291118

Particle number dependence in the non-linear evolution of N-body self-gravitating systems

NASA Astrophysics Data System (ADS)

Benhaiem, D.; Joyce, M.; Sylos Labini, F.; Worrakitpoonpon, T.

2018-01-01

Simulations of purely self-gravitating N-body systems are often used in astrophysics and cosmology to study the collisionless limit of such systems. Their results for macroscopic quantities should then converge well for sufficiently large N. Using a study of the evolution from a simple space of spherical initial conditions - including a region characterized by so-called 'radial orbit instability' - we illustrate that the values of N at which such convergence is obtained can vary enormously. In the family of initial conditions we study, good convergence can be obtained up to a few dynamical times with N ∼ 103 - just large enough to suppress two body relaxation - for certain initial conditions, while in other cases such convergence is not attained at this time even in our largest simulations with N ∼ 105. The qualitative difference is due to the stability properties of fluctuations introduced by the N-body discretisation, of which the initial amplitude depends on N. We discuss briefly why the crucial role which such fluctuations can potentially play in the evolution of the N body system could, in particular, constitute a serious problem in cosmological simulations of dark matter.

Island Rule, quantitative genetics and brain–body size evolution in Homo floresiensis

PubMed Central

2017-01-01

Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in Homo floresiensis, a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60–90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of H. floresiensis requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that H. floresiensis may be most likely derived from an early Indonesian H. erectus, which is coherent with currently accepted biogeographical scenario for Homo expansion out of Africa. PMID:28637851

Island Rule, quantitative genetics and brain-body size evolution in Homo floresiensis.

PubMed

Diniz-Filho, José Alexandre Felizola; Raia, Pasquale

2017-06-28

Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in Homo floresiensis , a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60-90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of H. floresiensis requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that H. floresiensis may be most likely derived from an early Indonesian H. erectus , which is coherent with currently accepted biogeographical scenario for Homo expansion out of Africa. © 2017 The Author(s).

Trophic specialization drives morphological evolution in sea snakes.

PubMed

Sherratt, Emma; Rasmussen, Arne R; Sanders, Kate L

2018-03-01

Viviparous sea snakes are the most rapidly speciating reptiles known, yet the ecological factors underlying this radiation are poorly understood. Here, we reconstructed dated trees for 75% of sea snake species and quantified body shape (forebody relative to hindbody girth), maximum body length and trophic diversity to examine how dietary specialization has influenced morphological diversification in this rapid radiation. We show that sea snake body shape and size are strongly correlated with the proportion of burrowing prey in the diet. Specialist predators of burrowing eels have convergently evolved a 'microcephalic' morphotype with dramatically reduced forebody relative to hindbody girth and intermediate body length. By comparison, snakes that predominantly feed on burrowing gobies are generally short-bodied and small-headed, but there is no evidence of convergent evolution. The eel specialists also exhibit faster rates of size and shape evolution compared to all other sea snakes, including those that feed on gobies. Our results suggest that trophic specialization to particular burrowing prey (eels) has invoked strong selective pressures that manifest as predictable and rapid morphological changes. Further studies are needed to examine the genetic and developmental mechanisms underlying these dramatic morphological changes and assess their role in sea snake speciation.

School Site Strategic Planning To Improve District Performance.

ERIC Educational Resources Information Center

Lytle, James H.

This paper describes the evolution of a school-based planning model that accommodates independent approaches to School District of Philadelphia goals. The description centers on key strategic planning decisions made during a 6-year period and three components of the planning model: the organizational monitoring and feedback system; organizational…

Additive genetic variation in the craniofacial skeleton of baboons (genus Papio) and its relationship to body and cranial size.

PubMed

Joganic, Jessica L; Willmore, Katherine E; Richtsmeier, Joan T; Weiss, Kenneth M; Mahaney, Michael C; Rogers, Jeffrey; Cheverud, James M

2018-02-01

Determining the genetic architecture of quantitative traits and genetic correlations among them is important for understanding morphological evolution patterns. We address two questions regarding papionin evolution: (1) what effect do body and cranial size, age, and sex have on phenotypic (V P ) and additive genetic (V A ) variation in baboon crania, and (2) how might additive genetic correlations between craniofacial traits and body mass affect morphological evolution? We use a large captive pedigreed baboon sample to estimate quantitative genetic parameters for craniofacial dimensions (EIDs). Our models include nested combinations of the covariates listed above. We also simulate the correlated response of a given EID due to selection on body mass alone. Covariates account for 1.2-91% of craniofacial V P . EID V A decreases across models as more covariates are included. The median genetic correlation estimate between each EID and body mass is 0.33. Analysis of the multivariate response to selection reveals that observed patterns of craniofacial variation in extant baboons cannot be attributed solely to correlated response to selection on body mass, particularly in males. Because a relatively large proportion of EID V A is shared with body mass variation, different methods of correcting for allometry by statistically controlling for size can alter residual V P patterns. This may conflate direct selection effects on craniofacial variation with those resulting from a correlated response to body mass selection. This shared genetic variation may partially explain how selection for increased body mass in two different papionin lineages produced remarkably similar craniofacial phenotypes. © 2017 Wiley Periodicals, Inc.

On dangerous ground: the evolution of body armour in cordyline lizards.

PubMed

Broeckhoven, Chris; El Adak, Yousri; Hui, Cang; Van Damme, Raoul; Stankowich, Theodore

2018-06-13

Animal body armour is often considered an adaptation that protects prey against predatory attacks, yet comparative studies that link the diversification of these allegedly protective coverings to differential predation risk or pressure are scarce. Here, we examine the evolution of body armour, including spines and osteoderms, in Cordylinae, a radiation of southern African lizards. Using phylogenetic comparative methods, we attempt to identify the ecological and environmental correlates of body armour that may hint at the selective pressures responsible for defensive trait diversification. Our results show that species inhabiting arid environments are more likely to possess elaborated body armour, specifically osteoderms. We did not find any effect of estimated predation pressure or risk on the degree of body armour. These findings suggest that body armour might not necessarily evolve in response to direct interactions with predators, but rather as a result of increased habitat-mediated predation risk. Furthermore, we discuss the possibility that osteoderms might have been shaped by factors unrelated to predation. © 2018 The Author(s).

Dissociation of somatic growth from segmentation drives gigantism in snakes.

PubMed

Head, Jason J; David Polly, P

2007-06-22

Body size is significantly correlated with number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that change in number of body segments produced during somitogenesis is an important factor in evolutionary change in body size, but the role of segmentation in the evolution of extreme sizes, including gigantism, has not been examined. We explored the relationship between body size and vertebral count in basal snakes that exhibit gigantism. Boids, pythonids and the typhlopid genera, Typhlops and Rhinotyphlops, possess a positive relationship between body size and vertebral count, confirming the importance of pleomerism; however, giant taxa possessed fewer than expected vertebrae, indicating that a separate process underlies the evolution of gigantism in snakes. The lack of correlation between body size and vertebral number in giant taxa demonstrates dissociation of segment production in early development from somatic growth during maturation, indicating that gigantism is achieved by modifying development at a different stage from that normally selected for changes in body size.

SU-F-P-28: A Method of Maximize the Noncoplanar Beam Orientations and Assure the Beam Delivery Clearance for Stereotactic Body Radiation Therapy (SBRT)

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

Zhu, J

2016-06-15

Purpose: Develop a method to maximize the noncoplanar beam orientations and assure the beam delivery clearance for SBRT, therefore, optimize the dose conformality to the target, increase the dose sparing to the critical normal organs and reduce the hot spots in the body. Methods: A SBRT body frame (Elekta, Stockholm, Sweden) was used for patient immobilization and target localization. The SBRT body frame has CT fiducials on its side frames. After patient’s CT scan, the radiation treatment isocenter was defined and its coordinators referring to the body frame was calculated in the radiation treatment planning process. Meanwhile, initial beam orientationsmore » were designed based on the patient target and critical organ anatomy. The body frame was put on the linear accelerator couch and positioned to the calculated isocenter. Initially designed beam orientations were manually measured by tuning the body frame position on the couch, the gantry and couch angles. The finalized beam orientations were put into the treatment planning for dosimetric calculations. Results: Without patient presence, an optimal set of beam orientations were designed and validated. The radiation treatment plan was optimized and guaranteed for delivery clearance. Conclusion: The developed method is beneficial and effective in SBRT treatment planning for individual patient. It first allows maximizing the achievable noncoplanar beam orientation space, therefore, optimize the treatment plan for specific patient. It eliminates the risk that a plan needs to be modified due to the gantry and couch collision during patient setup.« less

Implementation of a volumetric modulated arc therapy treatment planning solution for kidney and adrenal stereotactic body radiation therapy

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

Sonier, Marcus, E-mail: Marcus.Sonier@bccancer.bc.ca; Chu, William; Department of Radiation Oncology, University of Toronto, Toronto, ON

To develop a volumetric modulated arc therapy (VMAT) treatment planning solution in the treatment of primary renal cell carcinoma and oligometastatic adrenal lesions with stereotactic body radiation therapy. Single-arc VMAT plans (n = 5) were compared with clinically delivered step-and-shoot intensity-modulated radiotherapy (IMRT) with planning target volume coverage normalized between techniques. Target volume conformity, organ-at-risk (OAR) dose, treatment time, and monitor units were compared. A VMAT planning solution, created from a combination of arc settings and optimization constraints, auto-generated treatment plans in a single optimization. The treatment planning solution was evaluated on 15 consecutive patients receiving kidney and adrenal stereotacticmore » body radiation therapy. Treatment time was reduced from 13.0 ± 2.6 to 4.0 ± 0.9 minutes for IMRT and VMAT, respectively. The VMAT planning solution generated treatment plans with increased target homogeneity, improved 95% conformity index, and a reduced maximum point dose to nearby OARs but with increased intermediate dose to distant OARs. The conformity of the 95% isodose improved from 1.32 ± 0.39 to 1.12 ± 0.05 for IMRT and VMAT treatment plans, respectively. Evaluation of the planning solution showed clinically acceptable dose distributions for 13 of 15 cases with tight conformity of the prescription isodose to the planning target volume of 1.07 ± 0.04, delivering minimal dose to OARs. The introduction of a stereotactic body radiation therapy VMAT treatment planning solution improves the efficiency of planning and delivery time, producing treatment plans of comparable or superior quality to IMRT in the case of primary renal cell carcinoma and oligometastatic adrenal lesions.« less

Lunar Net—a proposal in response to an ESA M3 call in 2010 for a medium sized mission

NASA Astrophysics Data System (ADS)

Smith, Alan; Crawford, I. A.; Gowen, Robert Anthony; Ambrosi, R.; Anand, M.; Banerdt, B.; Bannister, N.; Bowles, N.; Braithwaite, C.; Brown, P.; Chela-Flores, J.; Cholinser, T.; Church, P.; Coates, A. J.; Colaprete, T.; Collins, G.; Collinson, G.; Cook, T.; Elphic, R.; Fraser, G.; Gao, Y.; Gibson, E.; Glotch, T.; Grande, M.; Griffiths, A.; Grygorczuk, J.; Gudipati, M.; Hagermann, A.; Heldmann, J.; Hood, L. L.; Jones, A. P.; Joy, K. H.; Khavroshkin, O. B.; Klingelhoefer, G.; Knapmeyer, M.; Kramer, G.; Lawrence, D.; Marczewski, W.; McKenna-Lawlor, S.; Miljkovic, K.; Narendranath, S.; Palomba, E.; Phipps, A.; Pike, W. T.; Pullan, D.; Rask, J.; Richard, D. T.; Seweryn, K.; Sheridan, S.; Sims, M.; Sweeting, M.; Swindle, T.; Talboys, D.; Taylor, L.; Teanby, N.; Tong, V.; Ulamec, S.; Wawrzaszek, R.; Wieczorek, M.; Wilson, L.; Wright, I.

2012-04-01

Emplacement of four or more kinetic penetrators geographically distributed over the lunar surface can enable a broad range of scientific exploration objectives of high priority and provide significant synergy with planned orbital missions. Whilst past landed missions achieved a great deal, they have not included a far-side lander, or investigation of the lunar interior apart from a very small area on the near side. Though the LCROSS mission detected water from a permanently shadowed polar crater, there remains in-situ confirmation, knowledge of concentration levels, and detailed identification of potential organic chemistry of astrobiology interest. The planned investigations will also address issues relating to the origin and evolution of the Earth-Moon system and other Solar System planetary bodies. Manned missions would be enhanced with use of water as a potential in-situ resource; knowledge of potential risks from damaging surface Moonquakes, and exploitation of lunar regolith for radiation shielding. LunarNet is an evolution of the 2007 LunarEX proposal to ESA (European Space Agency) which draws on recent significant advances in mission definition and feasibility. In particular, the successful Pendine full-scale impact trials have proved impact survivability for many of the key technology items, and a penetrator system study has greatly improved the definition of descent systems, detailed penetrator designs, and required resources. LunarNet is hereby proposed as an exciting stand-alone mission, though is also well suited in whole or in-part to contribute to the jigsaw of upcoming lunar missions, including that of a significant element to the ILN (International Lunar Network).

Orthonectids Are Highly Degenerate Annelid Worms.

PubMed

Schiffer, Philipp H; Robertson, Helen E; Telford, Maximilian J

2018-05-24

The animal groups of Orthonectida and Dicyemida are tiny, extremely simple, vermiform endoparasites of various marine animals and have been linked in the Mesozoa (Figure 1). The Orthonectida (Figures 1A and 1B) have a few hundred cells, including a nervous system of just ten cells [2], and the Dicyemida (Figure 1C) are even simpler, with ∼40 cells [3]. They are classic "Problematica" [4]-the name Mesozoa suggests an evolutionary position intermediate between Protozoa and Metazoa (animals) [5] and implies that their simplicity is a primitive state, but molecular data have shown they are members of Lophotrochozoa within Bilateria [6-9], which means that they derive from a more complex ancestor. Their precise affinities remain uncertain, however, and it is disputed whether they even constitute a clade. Ascertaining their affinities is complicated by the very fast evolution observed in their genes, potentially leading to the common systematic error of long-branch attraction (LBA) [10]. Here, we use mitochondrial and nuclear gene sequence data and show that both dicyemids and orthonectids are members of the Lophotrochozoa. Carefully addressing the effects of unequal rates of evolution, we show that the Mesozoa is polyphyletic. While the precise position of dicyemids remains unresolved within Lophotrochozoa, we identify orthonectids as members of the phylum Annelida. This result reveals one of the most extreme cases of body-plan simplification in the animal kingdom; our finding makes sense of an annelid-like cuticle in orthonectids [2] and suggests that the circular muscle cells repeated along their body [11] may be segmental in origin. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

PubMed

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

2016-08-01

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

Ejaculate quality and constraints in relation to sperm competition levels among eutherian mammals.

PubMed

Lüpold, Stefan

2013-10-01

The outcome of sperm competition is influenced by the relative quantity and quality of sperm among competing ejaculates. Whereas it is well established that individual ejaculate traits evolve rapidly under postcopulatory sexual selection, little is known about other factors that might influence the evolution of ejaculates. For example, the metabolic rate is likely to affect the sperm production rate and the cellular activity or metabolism of sperm, and it has recently been suggested to constrain the evolution of sperm length in large but not small mammals. I thus examined in eutherian mammals how ejaculate quality traits vary with one another and with testis mass, body size, and metabolism. I found all ejaculate traits to covary positively with one another and to increase with relative testis mass. When controlling for testis mass, small-bodied species showed superior sperm quality (but not sperm number). Furthermore, sperm motility and viability were positively associated with the mass-corrected metabolic rate, but the percentage of morphologically normal and acrosome-intact sperm were not. These results indicate that body size and the energy budget may also influence the evolution of ejaculate quality, although these influences appear to vary among traits. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Spinal metastases: multimodality imaging in diagnosis and stereotactic body radiation therapy planning.

PubMed

Jabehdar Maralani, Pejman; Lo, Simon S; Redmond, Kristin; Soliman, Hany; Myrehaug, Sten; Husain, Zain A; Heyn, Chinthaka; Kapadia, Anish; Chan, Aimee; Sahgal, Arjun

2017-01-01

Due to increased effectiveness of cancer treatments and increasing survival rates, metastatic disease has become more frequent compared to the past, with the spine being the most common site of bony metastases. Diagnostic imaging is an integral part of screening, diagnosis and follow-up of spinal metastases. In this article, we review the principles of multimodality imaging for tumor detection with respect to their value for diagnosis and stereotactic body radiation therapy planning for spinal metastases. We will also review the current international consensus agreement for stereotactic body radiation therapy planning, and the role of imaging in achieving the best possible treatment plan.

Predicting Physical Activity-Related Outcomes in Overweight and Obese Adults: A Health Action Process Approach.

PubMed

Hattar, Anne; Pal, Sebely; Hagger, Martin S

2016-03-01

We tested the adequacy of a model based on the Health Action Process Approach (HAPA) in predicting changes in psychological, body composition, and cardiovascular risk outcomes with respect to physical activity participation in overweight and obese adults. Measures of HAPA constructs (action and maintenance self-efficacy, outcome expectancies, action planning, risk perceptions, intentions, behaviour), psychological outcomes (quality of life, depression, anxiety, stress symptoms), body composition variables (body weight, body fat mass), cardiovascular risk measures (total cholesterol, low density lipoprotein), and self-reported physical activity behaviour were administered to participants (N = 74) at baseline, and 6 and 12 weeks later. Data were analysed using variance-based structural equation modelling with residualised change scores for HAPA variables. The model revealed effects of action self-efficacy and outcome expectancies on physical activity intentions, action self-efficacy on maintenance self-efficacy, and maintenance self-efficacy and intentions on action planning. Intention predicted psychological and body composition outcomes indirectly through physical activity behaviour. Action planning was a direct predictor of psychological, cardiovascular, and body composition outcomes. Data supported HAPA hypotheses in relation to intentions and behaviour, but not the role of action planning as a mediator of the intention-behaviour relationship. Action planning predicted outcomes independent of intentions and behaviour. © 2016 The International Association of Applied Psychology.

Evolution of the axial system in craniates: morphology and function of the perivertebral musculature

PubMed Central

2011-01-01

The axial musculoskeletal system represents the plesiomorphic locomotor engine of the vertebrate body, playing a central role in locomotion. In craniates, the evolution of the postcranial skeleton is characterized by two major transformations. First, the axial skeleton became increasingly functionally and morphologically regionalized. Second, the axial-based locomotion plesiomorphic for craniates became progressively appendage-based with the evolution of extremities in tetrapods. These changes, together with the transition to land, caused increased complexity in the planes in which axial movements occur and moments act on the body and were accompanied by profound changes in axial muscle function. To increase our understanding of the evolutionary transformations of the structure and function of the perivertebral musculature, this review integrates recent anatomical and physiological data (e.g., muscle fiber types, activation patterns) with gross-anatomical and kinematic findings for pivotal craniate taxa. This information is mapped onto a phylogenetic hypothesis to infer the putative character set of the last common ancestor of the respective taxa and to conjecture patterns of locomotor and muscular evolution. The increasing anatomical and functional complexity in the muscular arrangement during craniate evolution is associated with changes in fiber angulation and fiber-type distribution, i.e., increasing obliqueness in fiber orientation and segregation of fatigue-resistant fibers in deeper muscle regions. The loss of superficial fatigue-resistant fibers may be related to the profound gross anatomical reorganization of the axial musculature during the tetrapod evolution. The plesiomorphic function of the axial musculature -mobilization- is retained in all craniates. Along with the evolution of limbs and the subsequent transition to land, axial muscles additionally function to globally stabilize the trunk against inertial and extrinsic limb muscle forces as well as gravitational forces. Associated with the evolution of sagittal mobility and a parasagittal limb posture, axial muscles in mammals also stabilize the trunk against sagittal components of extrinsic limb muscle action as well as the inertia of the body's center of mass. Thus, the axial system is central to the static and dynamic control of the body posture in all craniates and, in gnathostomes, additionally provides the foundation for the mechanical work of the appendicular system. PMID:21306656

Space station evolution: Planning for the future

NASA Technical Reports Server (NTRS)

Diaz, Alphonso V.; Askins, Barbara S.

1987-01-01

The need for permanently manned presence in space has been recognized by the United States and its international partners for many years. The development of this capability was delayed due to the concurrent recognition that reusable earth-to-orbit transportation was also needed and should be developed first. While the decision to go ahead with a permanently manned Space Station was on hold, requirements for the use of the Station were accumulating as ground-based research and the data from unmanned spacecraft sparked the imagination of both scientists and entrepreneurs. Thus, by the time of the Space Station implementation decision in the early 1980's, a variety of disciplines, with a variety of requirements, needed to be accommodated on one Space Station. Additional future requirements could be forecast for advanced missions that were still in the early planning stages. The logical response was the development of a multi-purpose Space Station with the ability to evolve on-orbit to new capabilities as required by user needs and national or international decisions, i.e., to build an evolutionary Space Station. Planning for evolution is conducted in parallel with the design and development of the baseline Space Station. Evolution planning is a strategic management process to facilitate change and protect future decisions. The objective is not to forecast the future, but to understand the future options and the implications of these on today's decisions. The major actions required now are: (1) the incorporation of evolution provisions (hooks and scars) in the baseline Space Station; and (2) the initiation of an evolution advanced development program.

Space station evolution: Planning for the future

NASA Astrophysics Data System (ADS)

Diaz, Alphonso V.; Askins, Barbara S.

1987-06-01

The need for permanently manned presence in space has been recognized by the United States and its international partners for many years. The development of this capability was delayed due to the concurrent recognition that reusable earth-to-orbit transportation was also needed and should be developed first. While the decision to go ahead with a permanently manned Space Station was on hold, requirements for the use of the Station were accumulating as ground-based research and the data from unmanned spacecraft sparked the imagination of both scientists and entrepreneurs. Thus, by the time of the Space Station implementation decision in the early 1980's, a variety of disciplines, with a variety of requirements, needed to be accommodated on one Space Station. Additional future requirements could be forecast for advanced missions that were still in the early planning stages. The logical response was the development of a multi-purpose Space Station with the ability to evolve on-orbit to new capabilities as required by user needs and national or international decisions, i.e., to build an evolutionary Space Station. Planning for evolution is conducted in parallel with the design and development of the baseline Space Station. Evolution planning is a strategic management process to facilitate change and protect future decisions. The objective is not to forecast the future, but to understand the future options and the implications of these on today's decisions. The major actions required now are: (1) the incorporation of evolution provisions (hooks and scars) in the baseline Space Station; and (2) the initiation of an evolution advanced development program.

Enterprise Framework for the Disciplined Evolution of Legacy Systems

DTIC Science & Technology

1997-10-01

out important global issues early in the planning cycle and provides insight for developing a synergistic set of management and technical practices to achieve a disciplined approach to system evolution.

Is retinoic acid genetic machinery a chordate innovation?

PubMed

Cañestro, Cristian; Postlethwait, John H; Gonzàlez-Duarte, Roser; Albalat, Ricard

2006-01-01

Development of many chordate features depends on retinoic acid (RA). Because the action of RA during development seems to be restricted to chordates, it had been previously proposed that the "invention" of RA genetic machinery, including RA-binding nuclear hormone receptors (Rars), and the RA-synthesizing and RA-degrading enzymes Aldh1a (Raldh) and Cyp26, respectively, was an important step for the origin of developmental mechanisms leading to the chordate body plan. We tested this hypothesis by conducting an exhaustive survey of the RA machinery in genomic databases for twelve deuterostomes. We reconstructed the evolution of these genes in deuterostomes and showed for the first time that RA genetic machinery--that is Aldh1a, Cyp26, and Rar orthologs--is present in nonchordate deuterostomes. This finding implies that RA genetic machinery was already present during early deuterostome evolution, and therefore, is not a chordate innovation. This new evolutionary viewpoint argues against the hypothesis that the acquisition of gene families underlying RA metabolism and signaling was a key event for the origin of chordates. We propose a new hypothesis in which lineage-specific duplication and loss of RA machinery genes could be related to the morphological radiation of deuterostomes.

Phylogenetic mapping of bacterial morphology

NASA Technical Reports Server (NTRS)

Siefert, J. L.; Fox, G. E.

1998-01-01

The availability of a meaningful molecular phylogeny for bacteria provides a context for examining the historical significance of various developments in bacterial evolution. Herein, the classical morphological descriptions of selected members of the domain Bacteria are mapped upon the genealogical ancestry deduced from comparison of small-subunit rRNA sequences. For the species examined in this study, a distinct pattern emerges which indicates that the coccus shape has arisen and accumulated independently multiple times in separate lineages and typically survived as a persistent end-state morphology. At least two other morphologies persist but have evolved only once. This study demonstrates that although bacterial morphology is not useful in defining bacterial phylogeny, it is remarkably consistent with that phylogeny once it is known. An examination of the experimental evidence available for morphogenesis as well as microbial fossil evidence corroborates these findings. It is proposed that the accumulation of persistent morphologies is a result of the biophysical properties of peptidoglycan and their genetic control, and that an evolved body-plan strategy based on peptidoglycan may have been a fate-sealing step in the evolution of Bacteria. More generally, this study illustrates that significant evolutionary insights can be obtained by examining biological and biochemical data in the context of a reliable phylogenetic structure.

Tracing ancient evolutionary divergence in parasites.

PubMed

Tinsley, Richard C; Tinsley, Matthew C

2016-12-01

For parasitic platyhelminths that generally lack a fossil record, there is little information on the pathways of morphological change during evolution. Polystomatid monogeneans are notable for their evolutionary diversification, having originated from ancestors on fish and radiated in parallel with tetrapod vertebrates over more than 425 million years (My). This study focuses on the genus Polystomoides that occurs almost worldwide on freshwater chelonian reptiles. Morphometric data show a major divergence in structural adaptations for attachment; this correlates with a dichotomy in micro-environmental conditions in habitats within the hosts. Species infecting the urinary tract have attachment organs with large hamuli and small suckers; species in the oro-nasal tract differ fundamentally, having small hamuli and large suckers. Zoogeographical and molecular evidence supports ancient separation of these site-specific clades: a new genus is proposed - Uropolystomoides - containing urinary tract species distinct from Polystomoides sensu stricto in oro-nasal sites. Aside from differences in attachment adaptations, body plans have probably changed little over perhaps 150 My. This case contrasts markedly with polystomatids in other vertebrate groups where major morphological changes have evolved over much shorter timescales; the chelonian parasites show highly stable morphology across their global distribution over a long period of evolution, exemplifying 'living fossils'.

A phenology of the evolution of endothermy in birds and mammals.

PubMed

Lovegrove, Barry G

2017-05-01

Recent palaeontological data and novel physiological hypotheses now allow a timescaled reconstruction of the evolution of endothermy in birds and mammals. A three-phase iterative model describing how endothermy evolved from Permian ectothermic ancestors is presented. In Phase One I propose that the elevation of endothermy - increased metabolism and body temperature (T b ) - complemented large-body-size homeothermy during the Permian and Triassic in response to the fitness benefits of enhanced embryo development (parental care) and the activity demands of conquering dry land. I propose that Phase Two commenced in the Late Triassic and Jurassic and was marked by extreme body-size miniaturization, the evolution of enhanced body insulation (fur and feathers), increased brain size, thermoregulatory control, and increased ecomorphological diversity. I suggest that Phase Three occurred during the Cretaceous and Cenozoic and involved endothermic pulses associated with the evolution of muscle-powered flapping flight in birds, terrestrial cursoriality in mammals, and climate adaptation in response to Late Cenozoic cooling in both birds and mammals. Although the triphasic model argues for an iterative evolution of endothermy in pulses throughout the Mesozoic and Cenozoic, it is also argued that endothermy was potentially abandoned at any time that a bird or mammal did not rely upon its thermal benefits for parental care or breeding success. The abandonment would have taken the form of either hibernation or daily torpor as observed in extant endotherms. Thus torpor and hibernation are argued to be as ancient as the origins of endothermy itself, a plesiomorphic characteristic observed today in many small birds and mammals. © 2016 Cambridge Philosophical Society.

Simulation of radiofrequency ablation in real human anatomy.

PubMed

Zorbas, George; Samaras, Theodoros

2014-12-01

The objective of the current work was to simulate radiofrequency ablation treatment in computational models with realistic human anatomy, in order to investigate the effect of realistic geometry in the treatment outcome. The body sites considered in the study were liver, lung and kidney. One numerical model for each body site was obtained from Duke, member of the IT'IS Virtual Family. A spherical tumour was embedded in each model and a single electrode was inserted into the tumour. The same excitation voltage was used in all cases to underline the differences in the resulting temperature rise, due to different anatomy at each body site investigated. The same numerical calculations were performed for a two-compartment model of the tissue geometry, as well as with the use of an analytical approximation for a single tissue compartment. Radiofrequency ablation (RFA) therapy appears efficient for tumours in liver and lung, but less efficient in kidney. Moreover, the time evolution of temperature for a realistic geometry differs from that for a two-compartment model, but even more for an infinite homogenous tissue model. However, it appears that the most critical parameters of computational models for RFA treatment planning are tissue properties rather than tissue geometry. Computational simulations of realistic anatomy models show that the conventional technique of a single electrode inside the tumour volume requires a careful choice of both the excitation voltage and treatment time in order to achieve effective treatment, since the ablation zone differs considerably for various body sites.

Radiation-reaction force on a small charged body to second order

NASA Astrophysics Data System (ADS)

Moxon, Jordan; Flanagan, Éanna

2018-05-01

In classical electrodynamics, an accelerating charged body emits radiation and experiences a corresponding radiation-reaction force, or self-force. We extend to higher order in the total charge a previous rigorous derivation of the electromagnetic self-force in flat spacetime by Gralla, Harte, and Wald. The method introduced by Gralla, Harte, and Wald computes the self-force from the Maxwell field equations and conservation of stress-energy in a limit where the charge, size, and mass of the body go to zero, and it does not require regularization of a singular self-field. For our higher-order computation, an adjustment of the definition of the mass of the body is necessary to avoid including self-energy from the electromagnetic field sourced by the body in the distant past. We derive the evolution equations for the mass, spin, and center-of-mass position of the body through second order. We derive, for the first time, the second-order acceleration dependence of the evolution of the spin (self-torque), as well as a mixing between the extended body effects and the acceleration-dependent effects on the overall body motion.

Flight Planning for the International Space Station-Levitation Observation of Dendrite Evolution in Steel Ternary Alloy Rapid Solidification

NASA Technical Reports Server (NTRS)

Flemings, M. C.; Matson, D. M.; Loser, W.; Hyers, R. W.; Rogers, J. R.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The paper is an overview of the status and science for the LODESTARS (Levitation Observation of Dendrite Evolution in Steel Ternary Alloy Rapid Solidification) research project. The program is aimed at understanding how melt convection influences phase selection and the evolution of rapid solidification microstructures.

Physical aspects of total-body irradiation at the Middlesex Hospital (UCL group of hospitals), London 1988 - 1993: II. In vivo planning and dosimetry

NASA Astrophysics Data System (ADS)

Planskoy, B.; Tapper, P. D.; Bedford, A. M.; Davis, F. M.

1996-11-01

Part II of this paper gives the results of applying the TBI methods described in part I, to in vivo patient planning and dosimetry. Patients are planned on nine CT based body slices, five of which pass through the lungs. Planned doses are verified with ten silicon diodes applied bi-laterally to five body sites, at each treatment. LiF TLDs are applied to seven other body sites at the first treatment only. For 84 patients and at least 1016 measurements per body site with the diodes, the mean measured total doses agreed with planned doses within at most 2% except at lung levels, where the mean measured dose was 3% too low. Standard deviations of the measurements about the mean were between 2.4 and 3.1%. For the LiF TLDs, the mean measured doses for all seven body sites were within of planned doses. A separate assessment of measured entrance and transmitted doses showed that the former agreed well with planned doses, but that the latter tended to be low, especially over the lungs, and that they had a wider dispersion. Possible reasons for this are discussed. These results show measurement uncertainties similar to those for non-TBI treatments of Nilsson et al, Leunens et al and Essers et al. An analysis of the treatment plans showed a mean dose inhomogeneity in the body (75 patients, nine slices) of (1 s.d.) and in the lungs (40 patients, five slices) of (1 s.d.). The conclusions are that, overall, the methods are reasonably satisfactory but that, with an extra effort, even closer agreement between measured and planned doses and a further limited reduction in the body dose inhomogeneity could be obtained. However, if it were thought desirable to make a substantial reduction in the dose inhomogeneity in the body and lungs, this could only be achieved with the available equipment by changing from lateral to anterior - posterior irradiation and any potential advantages of this change would have to be balanced against a likely deterioration in patient comfort and an increase in treatment set-up times.

Water and the thermal evolution of carbonaceous chondrite parent bodies

NASA Technical Reports Server (NTRS)

Grimm, Robert E.; Mcsween, Harry Y., Jr.

1989-01-01

Two hypotheses are proposed for the aqueous alteration of carbonaceous chondrites within their parent bodies, in which respectively the alteration occurs (1) throughout the parent body interior, or (2) in a postaccretional surface regolith; both models assume an initially homogeneous mixture of ice and rock that is heated through the decay of Al-26. Water is seen to exert a powerful influence on chondrite evolution through its role of thermal buffer, permitting substitution of a low temperature aqueous alteration for high temperature recrystallization. It is quantitatively demonstrated that liquid water may be introduced by either hydrothermal circulation, vapor diffusion from below, or venting due to fracture.

Body size and premolar evolution in the early-middle eocene euprimates of Wyoming.

PubMed

Jones, Katrina E; Rose, Kenneth D; Perry, Jonathan M G

2014-01-01

The earliest euprimates to arrive in North America were larger-bodied notharctids and smaller-bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small- and increasingly mid-sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P4 displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P4 can also provide important paleoecological insights. We analyzed the P4 from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two-dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P4 than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P4 disparity and convergent evolution of the semimolariform condition in the largest omomyines. P4 morphology relates to diet in early euprimates, although patterns vary between families. Copyright © 2013 Wiley Periodicals, Inc.

Convergent evolution of sexual shape dimorphism in Diptera.

PubMed

Bonduriansky, Russell

2006-05-01

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

Million-body star cluster simulations: comparisons between Monte Carlo and direct N-body

NASA Astrophysics Data System (ADS)

Rodriguez, Carl L.; Morscher, Meagan; Wang, Long; Chatterjee, Sourav; Rasio, Frederic A.; Spurzem, Rainer

2016-12-01

We present the first detailed comparison between million-body globular cluster simulations computed with a Hénon-type Monte Carlo code, CMC, and a direct N-body code, NBODY6++GPU. Both simulations start from an identical cluster model with 106 particles, and include all of the relevant physics needed to treat the system in a highly realistic way. With the two codes `frozen' (no fine-tuning of any free parameters or internal algorithms of the codes) we find good agreement in the overall evolution of the two models. Furthermore, we find that in both models, large numbers of stellar-mass black holes (>1000) are retained for 12 Gyr. Thus, the very accurate direct N-body approach confirms recent predictions that black holes can be retained in present-day, old globular clusters. We find only minor disagreements between the two models and attribute these to the small-N dynamics driving the evolution of the cluster core for which the Monte Carlo assumptions are less ideal. Based on the overwhelming general agreement between the two models computed using these vastly different techniques, we conclude that our Monte Carlo approach, which is more approximate, but dramatically faster compared to the direct N-body, is capable of producing an accurate description of the long-term evolution of massive globular clusters even when the clusters contain large populations of stellar-mass black holes.

Does life history shape sexual size dimorphism in anurans? A comparative analysis

PubMed Central

2013-01-01

Background The evolution of sexual size dimorphism (SSD) is likely constrained by life history. Using phylogenetic comparative methods, we examined correlations between SSD among anurans and their life history traits, including egg size, clutch size, mating combat, and parental care behaviour. We used sexual dimorphism index (SDI = Body-sizefemale /Body-sizemale –1) as the measurement for SSD. Body size, life history and phylogenetic data were collected from published literature. Data were analysed at two levels: all anuran species and within individual families. Results Female-biased SSD is the predominant form in anurans. SSD decreases along with the body size increase, following the prediction of Rensch’s rule, but the magnitude of decrease is very small. More importantly, female body size is positively correlated with both fecundity related traits, egg size and clutch size, and SDI is also positively correlated with clutch size, suggesting fecundity advantage may have driven the evolution of female body size and consequently leads to the evolution of female-biased SSD. Furthermore, the presence of parental care, male parental care in particular, is negatively correlated with SDI, indicating that species with parental care tend to have a smaller SDI. A negative correlation between clutch size and parental care further suggests that parental care likely reduces the fecundity selection pressure on female body size. On the other hand, there is a general lack of significant correlation between SDI and the presence of male combat behaviour, which is surprising and contradictory to previous studies. Conclusions We find clear evidence to support the ‘fecundity advantage hypothesis’ and the ‘parental care hypothesis’ in shaping SSD in anurans. Nevertheless, the relationships of both parental care and combat behaviour to the evolution of SSD are complex in anurans and the extreme diversity of life history traits may have masked some potential interesting relationships. Our study represents the most comprehensive study of SSD in anurans to date. PMID:23368708

Modes of Brachiopod Body Size Evolution throughout the Phanerozoic Eon

NASA Astrophysics Data System (ADS)

Zhang, Z.; Payne, J.

2012-12-01

Body size correlates with numerous physiological and behavioral traits and is therefore one of the most important influences on the survival prospects of individuals and species. Patterns of body size evolution across taxa can therefore complement taxonomic diversity and geochemical proxy data in quantifying controls on long-term trends in the history of life. In contrast to widely available and synoptic taxonomic diversity data for fossil animal families and genera, however, no comprehensive size dataset exists, even for a single fossil animal phylum. For this study, we compiled a comprehensive, genus-level dataset of body sizes spanning the entire Phanerozoic for the phylum Brachiopoda. We use this dataset to examine statistical support for several possible modes of size evolution, in addition to environmental covariates: CO2, O2, and sea level. Brachiopod body size in the Phanerozoic followed two evolutionary modes: directional trend in the Early Paleozoic (Cambrian - Mississippian), and unbiased random walk from the Mississippian to the modern. We find no convincing correlation between trends in any single environmental parameter and brachiopod body size over time. The Paleozoic size increase follows Cope's Rule, and has been documented in many other marine invertebrates, while the Mesozoic size plateau has not been. This interval of size stability correlates with increased competition for resources from bivalves beginning during the Mesozoic Marine Revolution, and may be causally linked. The Late Mesozoic decline in size is an artifact of the improved sampling of smaller genera, many of which are less abundant than their Paleozoic ancestors. The Cenozoic brachiopod dataset is similarly incomplete. Biodiversity is decoupled from size dynamics even within the Paleozoic when brachiopods are on average becoming larger and more abundant, suggesting the presence of different controls. Our findings reveal that the dynamics of body size evolution changed over time in brachiopods, indicating that no single, simple model is likely to capture the true complexity of their evolutionary dynamics.

Emerging principles of regulatory evolution.

PubMed

Prud'homme, Benjamin; Gompel, Nicolas; Carroll, Sean B

2007-05-15

Understanding the genetic and molecular mechanisms governing the evolution of morphology is a major challenge in biology. Because most animals share a conserved repertoire of body-building and -patterning genes, morphological diversity appears to evolve primarily through changes in the deployment of these genes during development. The complex expression patterns of developmentally regulated genes are typically controlled by numerous independent cis-regulatory elements (CREs). It has been proposed that morphological evolution relies predominantly on changes in the architecture of gene regulatory networks and in particular on functional changes within CREs. Here, we discuss recent experimental studies that support this hypothesis and reveal some unanticipated features of how regulatory evolution occurs. From this growing body of evidence, we identify three key operating principles underlying regulatory evolution, that is, how regulatory evolution: (i) uses available genetic components in the form of preexisting and active transcription factors and CREs to generate novelty; (ii) minimizes the penalty to overall fitness by introducing discrete changes in gene expression; and (iii) allows interactions to arise among any transcription factor and downstream CRE. These principles endow regulatory evolution with a vast creative potential that accounts for both relatively modest morphological differences among closely related species and more profound anatomical divergences among groups at higher taxonomical levels.

Mississippi Curriculum Framework for Automotive Body Repair (Program CIP: 47.0603--Auto/Automotive Body Repairer). Secondary Programs.

ERIC Educational Resources Information Center

Mississippi Research and Curriculum Unit for Vocational and Technical Education, State College.

This document, which reflects Mississippi's statutory requirement that instructional programs be based on core curricula and performance-based assessment, contains outlines of the instructional units required in local instructional management plans and daily lesson plans for automotive body repair I and II. Presented first are a program…

Evolution of sexual dimorphism and Rensch’s rule in the beetle genus Limnebius (Hydraenidae): is sexual selection opportunistic?

PubMed Central

Rudoy, Andrey

2017-01-01

Sexual size dimorphism (SSD) is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch’s rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae), measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC) in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation. PMID:28286715

Evolution of sexual dimorphism and Rensch's rule in the beetle genus Limnebius (Hydraenidae): is sexual selection opportunistic?

PubMed

Rudoy, Andrey; Ribera, Ignacio

2017-01-01

Sexual size dimorphism (SSD) is widespread among animals, with larger females usually attributed to an optimization of resources in reproduction and larger males to sexual selection. A general pattern in the evolution of SSD is Rensch's rule, which states that SSD increases with body size in species with larger males but decreases when females are larger. We studied the evolution of SSD in the genus Limnebius (Coleoptera, Hydraenidae), measuring SSD and male genital size and complexity of ca. 80% of its 150 species and reconstructing its evolution in a molecular phylogeny with 71 species. We found strong support for a higher evolutionary lability of male body size, which had an overall positive allometry with respect to females and higher evolutionary rates measured over the individual branches of the phylogeny. Increases in SSD were associated to increases in body size, but there were some exceptions with an increase associated to changes in only one sex. Secondary sexual characters (SSC) in the external morphology of males appeared several times independently, generally on species that had already increased their size. There was an overall significant correlation between SSD, male body size and male genital size and complexity, although some lineages with complex genitalia had low SSD, and some small species with complex genitalia had no SSD. Our results suggest that the origin of the higher evolutionary variance of male body size may be due to lack of constraints rather than to sexual selection, that may start to act in species with already larger males due to random variation.

Foreign body in ear, nose and oropharynx: experience from a tertiary hospital.

PubMed

Tiago, Romualdo Suzano Louzeiro; Salgado, Daniel Cauduro; Corrêa, Juliano Piotto; Pio, Márcio Ricardo Barros; Lambert, Ernani Edney

2006-01-01

The occurrence of foreign bodies in otorhinolaryngology is reason of constant searches for emergency services. To value the incidence of patients with foreign body, to analyze the clinical situation and the treatment in these cases. The prospective study was realized in 81 patients with diagnosis of foreign body of nose, ear or oropharynx in the otorhinolaryngology service of the Hospital do Servidor Público Municipal de São Paulo between april/2003 and march/2005. 57 cases of foreign body of ear, 13 cases of nose and 11 of oropharynx. These patients, 51.85% were men and 48.15% were women. The age average was 23 years old. The average of the evolution time was 18.36 days, being that 38.27% these cases were taken care in less 24 hours of evolution. Inside the total of patients, 83.95% received initial attendance in the otorhinolaryngology clinic, and 16.05% came of another service after some previous removal attempt. The most common symptom of the foreign bodies cases of oropharynx it was odinofagia present in 90.91% of the cases; in the foreign bodies of nose, the unilateral rhinorrhea and cacosmia were present in 46.15 of the cases; in the foreign bodies of ear, 38.60% evolved without symptoms and 28.07 with hipoacusia. The most frequent foreign body of oropharynx it was the fish spine (54.55%); in the nose it was the paper (30.77%); and in the ear it was the cotton (31.58%). The complications resulting of the presence of foreign body or about the manipulation of these had been found in 13 cases (16.05%). Most cases of foreign body conditions, in which a non-specialist professional or a non-professional person previously handles its removal, have a bad evolution with emerging complications. Such outcomes strengthen the fact that an otorhinolaryngologist using the proper equipment must treat patients with foreign body.

Life course evolution of body size and breast cancer survival in the E3N cohort.

PubMed

His, Mathilde; Le Guélennec, Marine; Mesrine, Sylvie; Boutron-Ruault, Marie-Christine; Clavel-Chapelon, Françoise; Fagherazzi, Guy; Dossus, Laure

2018-04-15

Although adult obesity has been associated with poor breast cancer survival, data on adiposity at different periods in life and its lifelong evolution are scarce. Our aims were to assess the associations between breast cancer survival and body size during childhood, puberty and early adulthood and body size trajectories from childhood to adulthood. Self-assessed body size at age 8, at puberty, at age 20-25 and at age 35-40 and trajectories of body size of 4,662 breast cancer survivors from the prospective E3N cohort were studied in relation to risk of death from any cause, death from breast cancer and second invasive cancer event using multivariate Cox regression models. Four trajectories of body size were identified (T1 "moderate increase," T2 "stable/low increase," T3 "increase at puberty" and T4 "constantly high"). Compared with stable body size, an increase in body size during adult life was associated with an increased risk of death from any cause (HR T1 vs. T2 = 1.27; 95% CI = 1.01-1.60) and an increased risk of second invasive cancer event (HR T1 vs. T2 = 1.25; 95% CI = 1.06-1.47). Silhouettes at various ages were not associated with survival. Our results suggest that the evolution of body size from childhood to adulthood has a long-term influence on breast cancer survival. Although these results need to be confirmed, this work sheds light on the need to combine lifelong approaches to current BMI to better identify breast cancer survivors who are at higher risk of recurrence or second primary cancer, or of death. © 2017 UICC.

Fitting models of continuous trait evolution to incompletely sampled comparative data using approximate Bayesian computation.

PubMed

Slater, Graham J; Harmon, Luke J; Wegmann, Daniel; Joyce, Paul; Revell, Liam J; Alfaro, Michael E

2012-03-01

In recent years, a suite of methods has been developed to fit multiple rate models to phylogenetic comparative data. However, most methods have limited utility at broad phylogenetic scales because they typically require complete sampling of both the tree and the associated phenotypic data. Here, we develop and implement a new, tree-based method called MECCA (Modeling Evolution of Continuous Characters using ABC) that uses a hybrid likelihood/approximate Bayesian computation (ABC)-Markov-Chain Monte Carlo approach to simultaneously infer rates of diversification and trait evolution from incompletely sampled phylogenies and trait data. We demonstrate via simulation that MECCA has considerable power to choose among single versus multiple evolutionary rate models, and thus can be used to test hypotheses about changes in the rate of trait evolution across an incomplete tree of life. We finally apply MECCA to an empirical example of body size evolution in carnivores, and show that there is no evidence for an elevated rate of body size evolution in the pinnipeds relative to terrestrial carnivores. ABC approaches can provide a useful alternative set of tools for future macroevolutionary studies where likelihood-dependent approaches are lacking. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

The Origin and Diversification of Birds.

PubMed

Brusatte, Stephen L; O'Connor, Jingmai K; Jarvis, Erich D

2015-10-05

Birds are one of the most recognizable and diverse groups of modern vertebrates. Over the past two decades, a wealth of new fossil discoveries and phylogenetic and macroevolutionary studies has transformed our understanding of how birds originated and became so successful. Birds evolved from theropod dinosaurs during the Jurassic (around 165-150 million years ago) and their classic small, lightweight, feathered, and winged body plan was pieced together gradually over tens of millions of years of evolution rather than in one burst of innovation. Early birds diversified throughout the Jurassic and Cretaceous, becoming capable fliers with supercharged growth rates, but were decimated at the end-Cretaceous extinction alongside their close dinosaurian relatives. After the mass extinction, modern birds (members of the avian crown group) explosively diversified, culminating in more than 10,000 species distributed worldwide today. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Evolution of PLA's Planning Model.

ERIC Educational Resources Information Center

Elsner, Edward J.

2002-01-01

Explores the movement toward community-centered standards in public libraries. Tracks the changes of the Public Library Association's (PLA's) planning model through four incarnations, summarizes each model, and examines trends and suggests a way to use the various models together for an easier planning process. (Author/LRW)

Evolving Systems: An Outcome of Fondest Hopes and Wildest Dreams

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Balas, Mark J.

2012-01-01

New theory is presented for evolving systems, which are autonomously controlled subsystems that self-assemble into a new evolved system with a higher purpose. Evolving systems of aerospace structures often require additional control when assembling to maintain stability during the entire evolution process. This is the concept of Adaptive Key Component Control that operates through one specific component to maintain stability during the evolution. In addition, this control must often overcome persistent disturbances that occur while the evolution is in progress. Theoretical results will be presented for Adaptive Key Component control for persistent disturbance rejection. An illustrative example will demonstrate the Adaptive Key Component controller on a system composed of rigid body and flexible body modes.

Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution.

PubMed

Bell, Phil R; Campione, Nicolás E; Persons, W Scott; Currie, Philip J; Larson, Peter L; Tanke, Darren H; Bakker, Robert T

2017-06-01

Recent evidence for feathers in theropods has led to speculations that the largest tyrannosaurids, including Tyrannosaurus rex , were extensively feathered. We describe fossil integument from Tyrannosaurus and other tyrannosaurids ( Albertosaurus, Daspletosaurus, Gorgosaurus and Tarbosaurus ), confirming that these large-bodied forms possessed scaly, reptilian-like skin. Body size evolution in tyrannosauroids reveals two independent occurrences of gigantism; specifically, the large sizes in Yutyrannus and tyrannosaurids were independently derived. These new findings demonstrate that extensive feather coverings observed in some early tyrannosauroids were lost by the Albian, basal to Tyrannosauridae. This loss is unrelated to palaeoclimate but possibly tied to the evolution of gigantism, although other mechanisms exist. © 2017 The Author(s).

No evidence for directional evolution of body mass in herbivorous theropod dinosaurs

PubMed Central

Zanno, Lindsay E.; Makovicky, Peter J.

2013-01-01

The correlation between large body size and digestive efficiency has been hypothesized to have driven trends of increasing mass in herbivorous clades by means of directional selection. Yet, to date, few studies have investigated this relationship from a phylogenetic perspective, and none, to our knowledge, with regard to trophic shifts. Here, we reconstruct body mass in the three major subclades of non-avian theropod dinosaurs whose ecomorphology is correlated with extrinsic evidence of at least facultative herbivory in the fossil record—all of which also achieve relative gigantism (more than 3000 kg). Ordinary least-squares regressions on natural log-transformed mean mass recover significant correlations between increasing mass and geological time. However, tests for directional evolution in body mass find no support for a phylogenetic trend, instead favouring passive models of trait evolution. Cross-correlation of sympatric taxa from five localities in Asia reveals that environmental influences such as differential habitat sampling and/or taphonomic filtering affect the preserved record of dinosaurian body mass in the Cretaceous. Our results are congruent with studies documenting that behavioural and/or ecological factors may mitigate the benefit of increasing mass in extant taxa, and suggest that the hypothesis can be extrapolated to herbivorous lineages across geological time scales. PMID:23193135

Asteroids, Comets, Meteors 2014

NASA Astrophysics Data System (ADS)

Muinonen, K.; Penttilä, A.; Granvik, M.; Virkki, A.; Fedorets, G.; Wilkman, O.; Kohout, T.

2014-08-01

Asteroids, Comets, Meteors focuses on the research of small Solar System bodies. Small bodies are the key to understanding the formation and evolution of the Solar System, carrying signals from pre-solar times. Understanding the evolution of the Solar System helps unveil the evolution of extrasolar planetary systems. Societally, small bodies will be important future resources of minerals. The near-Earth population of small bodies continues to pose an impact hazard, whether it be small pieces of falling meteorites or larger asteroids or cometary nuclei capable of causing global environmental effects. The conference series entitled ''Asteroids, Comets, Meteors'' constitutes the leading international series in the field of small Solar System bodies. The first three conferences took place in Uppsala, Sweden in 1983, 1985, and 1989. The conference is now returning to Nordic countries after a quarter of a century. After the Uppsala conferences, the conference has taken place in Flagstaff, Arizona, U.S.A. in 1991, Belgirate, Italy in 1993, Paris, France in 1996, Ithaca, New York, U.S.A. in 1999, in Berlin, Germany in 2002, in Rio de Janeiro, Brazil in 2005, in Baltimore, Maryland, U.S.A. in 2008, and in Niigata, Japan in 2012. ACM in Helsinki, Finland in 2014 will be the 12th conference in the series.

Interspecific geographic range size-body size relationship and the diversification dynamics of Neotropical furnariid birds.

PubMed

Inostroza-Michael, Oscar; Hernández, Cristián E; Rodríguez-Serrano, Enrique; Avaria-Llautureo, Jorge; Rivadeneira, Marcelo M

2018-05-01

Among the earliest macroecological patterns documented, is the range and body size relationship, characterized by a minimum geographic range size imposed by the species' body size. This boundary for the geographic range size increases linearly with body size and has been proposed to have implications in lineages evolution and conservation. Nevertheless, the macroevolutionary processes involved in the origin of this boundary and its consequences on lineage diversification have been poorly explored. We evaluate the macroevolutionary consequences of the difference (hereafter the distance) between the observed and the minimum range sizes required by the species' body size, to untangle its role on the diversification of a Neotropical species-rich bird clade using trait-dependent diversification models. We show that speciation rate is a positive hump-shaped function of the distance to the lower boundary. The species with highest and lowest distances to minimum range size had lower speciation rates, while species close to medium distances values had the highest speciation rates. Further, our results suggest that the distance to the minimum range size is a macroevolutionary constraint that affects the diversification process responsible for the origin of this macroecological pattern in a more complex way than previously envisioned. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Coupling dynamical and collisional evolution of small bodies:. an application to the early ejection of planetesimals from the Jupiter-Saturn region

NASA Astrophysics Data System (ADS)

Charnoz, Sébastien; Morbidelli, Alessandro

2003-11-01

We present a new algorithm designed to compute the collisional erosion of a population of small bodies undergoing a complex and rapid dynamical evolution induced by strong gravitational perturbations. Usual particle-in-a-box models have been extensively and successfully used to study the evolution of asteroids or KBOs. However, they cannot track the evolution of small bodies in rapid dynamical evolution, due to their oversimplified description of the dynamics. Our code is based on both (1) a direct simulation of the dynamical evolution which is used to compute local encounter rates and (2) a classical fragmentation model. Such a code may be used to track the erosional evolution of the planetesimal disk under the action of newly formed giant-planets, a passing star or a population of massive planetary-embryos. We present here an application to a problem related to the formation of the Oort cloud. The usually accepted formation scenario is that planetesimals, originally formed in the giant planet region, have been transported to the Oort cloud by gravitational scattering. However, it has been suggested that, during the initial transport phase, the mutual large encounter velocities might have induced a rapid and intense collisional evolution of the planetesimal population, potentially causing a significant reduction of the Oort cloud formation process. This mechanism is explored with our new algorithm. Because the advantages of our new approach are better highlighted for a population undergoing a violent dynamical evolution, we concentrate in this paper on the planetesimals originally in the Jupiter-Saturn region, although it is known that they are only minor contributors to the final Oort cloud population. A wide range of parameters is explored (mass of the particle disk, initial size-distribution, material strength): depending upon the assumed parameter values, we find that from 15 to 90% of the mass contained in bodies larger than 1 km survives the collisional process; for our preferred choice of the parameters this fraction is ˜70%. It is also found that the majority of planetesimals larger than 1-10 km are pristine, and not fragments. We show also that collisional damping may not prevent planetesimals from being ejected to the outer Solar System. Thus, although the collisional activity is high during the scattering by Jupiter and Saturn, collisional grinding does not lower by orders of magnitude the mass contained in bodies larger than 1 km, originally in the Jupiter-Saturn region. These conclusions seem to support the classical collisionless scenario of Oort cloud formation, at least for the Jupiter-Saturn region.

Gaps to "Working" on the Surface of Small Bodies

NASA Astrophysics Data System (ADS)

Bellerose, J.

2012-12-01

Upcoming goals for human spaceflight include sending a crewed mission to a near-Earth asteroid (NEA) by 2025. As an alternative to this, a spacecraft could be sent to capture a small NEA, and return it to cislunar orbit where astronauts could take it apart (Brophy, 2012). In parallel, plans are also to take the next big step in resources utilization, and mine those NEAs (Lewicki, 2012). Although these exciting concepts are very different in scope, they share the same environment they will need to interact with. In this work, we discuss the required techniques for exploring and exploiting small bodies, and compare with the available tools and the current knowledge of small bodies. To support these types of missions, a number of in-situ data are required prior to start surface operations: the body shape and mass, the presence of volatiles and metals, the asteroid morphology, the internal structural properties, the surface and near-surface environments, the existence of hazards, and the time-evolution dynamics. Products obtained from remote sensing - maps, mosaics, shape models - are critical in selecting the locations to be investigated in more details, or the locations to be excavated. Composition measurements become especially important for mining, as it requires appropriate tools and techniques. Although spectrometers can be used in orbit and on the surface to determine elemental composition, the fine scale structure and mineralogical composition can only be done using surface probes or through a close-up camera. Those remote sensing images are also critical in planning the very close approaches by the spacecraft, as the small body environment is one of the most perturbed environments (Scheeres, 2000). Being able to recreate the small body dynamics is necessary to mitigate risks and to enable spacecraft docking. The navigation system, vision tools, and planning software become critical as the spacecraft will need to track features on the surface under different light conditions. Perhaps the most difficult data to obtain is the mass of the NEA, where the resolution depends on the NEA size, and the internal structure and stability of the body. It can be shown that current mass determination techniques easily result in 50% resolution on mass estimation. Secondary or surface probes released from a main spacecraft can increase resolution by one order of magnitude compared to traditional methods (Bellerose, 2012). A volume estimate combined with the overall mass of the small body results in a bulk density estimate. The bulk density is a direct insight into surface and sub-surface mechanical stability, and properties such as compaction and porosity. A number of remote sensing and surface instruments are now available for NEA applications, from past missions to new technology developments. We give a quick review of the data and instruments now available. We also identify existing gaps between the available data and requirements associated with surface interacting mission concepts. Finally, we discuss transient dynamical effects due to surface disturbances, and how these effects can put constraints on a mission concept and feed in operational strategies.

Body Size Diversity and Frequency Distributions of Neotropical Cichlid Fishes (Cichliformes: Cichlidae: Cichlinae)

PubMed Central

Steele, Sarah E.; López-Fernández, Hernán

2014-01-01

Body size is an important correlate of life history, ecology and distribution of species. Despite this, very little is known about body size evolution in fishes, particularly freshwater fishes of the Neotropics where species and body size diversity are relatively high. Phylogenetic history and body size data were used to explore body size frequency distributions in Neotropical cichlids, a broadly distributed and ecologically diverse group of fishes that is highly representative of body size diversity in Neotropical freshwater fishes. We test for divergence, phylogenetic autocorrelation and among-clade partitioning of body size space. Neotropical cichlids show low phylogenetic autocorrelation and divergence within and among taxonomic levels. Three distinct regions of body size space were identified from body size frequency distributions at various taxonomic levels corresponding to subclades of the most diverse tribe, Geophagini. These regions suggest that lineages may be evolving towards particular size optima that may be tied to specific ecological roles. The diversification of Geophagini appears to constrain the evolution of body size among other Neotropical cichlid lineages; non-Geophagini clades show lower species-richness in body size regions shared with Geophagini. Neotropical cichlid genera show less divergence and extreme body size than expected within and among tribes. Body size divergence among species may instead be present or linked to ecology at the community assembly scale. PMID:25180970

THE EFFECTS OF BODY MASS, PHYLOGENY, HABITAT, AND TROPHIC LEVEL ON MAMMALIAN AGE AT FIRST REPRODUCTION.

PubMed

Wootton, J Timothy

1987-07-01

I examined age at first reproduction of 547 mammalian species to determine the influence of diet and habitat on the evolution of life-history traits. Body mass correlated positively with age at first reproduction, explaining 56% of the variance. Habitat and trophic groups deviated significantly from the allometric curve in a pattern generally consistent with predictions from r/K selection theory and its modifications. However, mammalian orders also deviated significantly from the allometric curve, and different habitat and diet groups contained different ratios of mammalian orders. When the effects of orders were removed, residual deviations did not differ among ecological groups. Adjusting for ecological differences did not eliminate the differences between orders. These results suggest that body mass (or some correlated factor) and phylogeny strongly constrain age at first reproduction. Ecological factors appear to have little effect on the evolution of age at first reproduction. Apparent differences in weight-specific ages at first reproduction within habitats and trophic groups may be the result of ecological selection of order composition in the present, rather than ecologically driven evolution of life history in the past. © 1987 The Society for the Study of Evolution.

Evaluating Long-Term Disability Insurance Plans.

ERIC Educational Resources Information Center

Powell, Jan

1992-01-01

This report analyzes the factors involved in reviewing benefits and services of employer-sponsored group long-term disability plans for higher education institutions. Opening sections describe the evolution of disability insurance and its shape today. Further sections looks at the complex nature of "value" within a plan, relationship…

Educational Planning: A Reappraisal.

ERIC Educational Resources Information Center

Organisation for Economic Cooperation and Development, Paris (France).

This reappraisal of educational planning, implementing a decision of the Education Committee for the Organisation for Economic Cooperation and Development (OECD), has two main objectives: to review the evolution of concepts, approaches, and practices of educational planning in member countries during the past 20 years; and to identify new features…

Campus Planning.

ERIC Educational Resources Information Center

Dober, Richard P.

This book suggests ways and means by which the development of campuses can be controlled so that functional goals can be aesthetically expressed. The first section, "Prospectus," defines campus planning, illuminating through historical examples the evolution of the campus as a design form, and describes the conditions that make campus planning so…

Capture of Small Bodies After Tidal Disruption

NASA Astrophysics Data System (ADS)

Ershova, A.; Medvedev, Yu.

2017-09-01

The subject of the current work is the phisical and dynamical evolution of the small comets group formed by tidal disruption of the protocomet while passing near the large body (Sun, Jupiter). The equations of motion were integrated numericaly. In case of the Sun the evolution of the sun-grazing orbits were discussed and the typical lifetime of such comets was estimated. Nongravitational acceleration and the size reduction of fragments due to sublimation were taking into account using the Marsden formula.

Transcriptomic data from panarthropods shed new light on the evolution of insulator binding proteins in insects : Insect insulator proteins.

PubMed

Pauli, Thomas; Vedder, Lucia; Dowling, Daniel; Petersen, Malte; Meusemann, Karen; Donath, Alexander; Peters, Ralph S; Podsiadlowski, Lars; Mayer, Christoph; Liu, Shanlin; Zhou, Xin; Heger, Peter; Wiehe, Thomas; Hering, Lars; Mayer, Georg; Misof, Bernhard; Niehuis, Oliver

2016-11-03

Body plan development in multi-cellular organisms is largely determined by homeotic genes. Expression of homeotic genes, in turn, is partially regulated by insulator binding proteins (IBPs). While only a few enhancer blocking IBPs have been identified in vertebrates, the common fruit fly Drosophila melanogaster harbors at least twelve different enhancer blocking IBPs. We screened recently compiled insect transcriptomes from the 1KITE project and genomic and transcriptomic data from public databases, aiming to trace the origin of IBPs in insects and other arthropods. Our study shows that the last common ancestor of insects (Hexapoda) already possessed a substantial number of IBPs. Specifically, of the known twelve insect IBPs, at least three (i.e., CP190, Su(Hw), and CTCF) already existed prior to the evolution of insects. Furthermore we found GAF orthologs in early branching insect orders, including Zygentoma (silverfish and firebrats) and Diplura (two-pronged bristletails). Mod(mdg4) is most likely a derived feature of Neoptera, while Pita is likely an evolutionary novelty of holometabolous insects. Zw5 appears to be restricted to schizophoran flies, whereas BEAF-32, ZIPIC and the Elba complex, are probably unique to the genus Drosophila. Selection models indicate that insect IBPs evolved under neutral or purifying selection. Our results suggest that a substantial number of IBPs either pre-date the evolution of insects or evolved early during insect evolution. This suggests an evolutionary history of insulator binding proteins in insects different to that previously thought. Moreover, our study demonstrates the versatility of the 1KITE transcriptomic data for comparative analyses in insects and other arthropods.

Parallel evolution of chordate cis-regulatory code for development.

PubMed

Doglio, Laura; Goode, Debbie K; Pelleri, Maria C; Pauls, Stefan; Frabetti, Flavia; Shimeld, Sebastian M; Vavouri, Tanya; Elgar, Greg

2013-11-01

Urochordates are the closest relatives of vertebrates and at the larval stage, possess a characteristic bilateral chordate body plan. In vertebrates, the genes that orchestrate embryonic patterning are in part regulated by highly conserved non-coding elements (CNEs), yet these elements have not been identified in urochordate genomes. Consequently the evolution of the cis-regulatory code for urochordate development remains largely uncharacterised. Here, we use genome-wide comparisons between C. intestinalis and C. savignyi to identify putative urochordate cis-regulatory sequences. Ciona conserved non-coding elements (ciCNEs) are associated with largely the same key regulatory genes as vertebrate CNEs. Furthermore, some of the tested ciCNEs are able to activate reporter gene expression in both zebrafish and Ciona embryos, in a pattern that at least partially overlaps that of the gene they associate with, despite the absence of sequence identity. We also show that the ability of a ciCNE to up-regulate gene expression in vertebrate embryos can in some cases be localised to short sub-sequences, suggesting that functional cross-talk may be defined by small regions of ancestral regulatory logic, although functional sub-sequences may also be dispersed across the whole element. We conclude that the structure and organisation of cis-regulatory modules is very different between vertebrates and urochordates, reflecting their separate evolutionary histories. However, functional cross-talk still exists because the same repertoire of transcription factors has likely guided their parallel evolution, exploiting similar sets of binding sites but in different combinations.

CBCT-guided evolutive library for cervical adaptive IMRT.

PubMed

Rigaud, Bastien; Simon, Antoine; Gobeli, Maxime; Lafond, Caroline; Leseur, Julie; Barateau, Anais; Jaksic, Nicolas; Castelli, Joël; Williaume, Danièle; Haigron, Pascal; De Crevoisier, Renaud

2018-04-01

In the context of adaptive radiation therapy (ART) for locally advanced cervical carcinoma (LACC), this study proposed an original cone-beam computed tomography (CBCT)-guided "Evolutive library" and evaluated it against four other known radiotherapy (RT) strategies. For 20 patients who underwent intensity-modulated radiation therapy (IMRT) for LACC, three planning CTs [with empty (EB), intermediate (IB), and full (FB) bladder volumes], a CT scan at 20 Gy and bi-weekly CBCTs for 5 weeks were performed. Five RT strategies were simulated for each patient: "Standard RT" was based on one IB planning CT; "internal target volume (ITV)-based RT" was an ITV built from the three planning CTs; "RT with one mid-treatment replanning (MidTtReplan)" corresponded to the standard RT with a replanning at 20 Gy; "Pretreatment library ART" using a planning library based on the three planning CTs; and the "Evolutive library ART", which was the "Pretreatment library ART" strategy enriched by including some CBCT anatomies into the library when the daily clinical target volume (CTV) shape differed from the ones in the library. Two planning target volume (PTV) margins of 7 and 10 mm were evaluated. All the strategies were geometrically compared in terms of the percentage of coverage by the PTV, for the CTV and the organs at risk (OAR) delineated on the CBCT. Inadequate coverage of the CTV and OARs by the PTV was also assessed using deformable image registration. The cumulated dose distributions of each strategy were likewise estimated and compared for one patient. The "Evolutive library ART" strategy involved a number of added CBCTs: 0 for 55%; 1 for 30%; 2 for 5%; and 3 for 10% of patients. Compared with the other four, this strategy provided the highest CTV geometric coverage by the PTV, with a mean (min-max) coverage of 98.5% (96.4-100) for 10 mm margins and 96.2% (93.0-99.7) for 7 mm margins (P < 0.05). Moreover, this strategy significantly decreased the geometric coverage of the bowel. CTV undercoverage by PTV occurred in the anterior and superior uterine regions for all strategies. The dosimetric analysis at 7 mm similarly demonstrated that the "Evolutive library ART" increased the V 42.75Gy of the CTV by 27%, 20%, 13%, and 28% compared with "Standard RT", "ITV-based RT", "MidTtReplan", and "Pretreatment library ART", respectively. The dose to the bowel was also decreased by the "Evolutive library ART" compared with that by the other strategies. The "Evolutive library ART" is a personalized ART strategy that comprises a pretreatment planning library of three CT scans, enriched for half of the patients by one to three per-treatment CBCTs. This original strategy increased both the CTV coverage and bowel sparing compared with all the other tested strategies and enables us to consider a PTV margin reduction. © 2018 American Association of Physicists in Medicine.

Composition and evolution of the eucrite parent body - Evidence from rare earth elements. [extraterrestrial basaltic melts

NASA Technical Reports Server (NTRS)

Consolmagno, G. J.; Drake, M. J.

1977-01-01

Quantitative modeling of the evolution of rare earth element (REE) abundances in the eucrites, which are plagioclase-pigeonite basalt achondrites, indicates that the main group of eucrites (e.g., Juvinas) might have been produced by approximately 10% equilibrium partial melting of a single type of source region with initial REE abundances which were chondritic relative and absolute. Since the age of the eucrites is about equal to that of the solar system, extensive chemical differentiation of the eucrite parent body prior to the formation of eucrites seems unlikely. If homogeneous accretion is assumed, the bulk composition of the eucrite parent body can be estimated; two estimates are provided, representing different hypotheses as to the ratio of metal to olivine in the parent body. Since a large number of differentiated olivine meteorites, which would represent material from the interior of the parent body, have not been detected, the eucrite parent body is thought to be intact. It is suggested that the asteroid 4 Vesta is the eucrite parent body.

Head regeneration in hemichordates is not a strict recapitulation of development

PubMed Central

Luttrell, Shawn M.; Gotting, Kirsten; Ross, Eric; Alvarado, Alejandro Sánchez

2016-01-01

Background: Head or anterior body part regeneration is commonly associated with protostome, but not deuterostome invertebrates. However, it has been shown that the solitary hemichordate Ptychodera flava possesses the remarkable capacity to regenerate their entire nervous system, including their dorsal neural tube and their anterior head‐like structure, or proboscis. Hemichordates, also known as acorn worms, are marine invertebrate deuterostomes that have retained chordate traits that were likely present in the deuterostome ancestor, placing these animals in a vital position to study regeneration and chordate evolution. All acorn worms have a tripartite body plan, with an anterior proboscis, middle collar region, and a posterior trunk. The collar houses a hollow, dorsal neural tube in ptychoderid hemichordates and numerous chordate genes involved in brain and spinal cord development are expressed in a similar anterior–posterior spatial arrangement along the body axis. Results: We have examined anterior regeneration in the hemichordate Ptychodera flava and report the spatial and temporal morphological changes that occur. Additionally, we have sequenced, assembled, and analyzed the transcriptome for eight stages of regenerating P. flava, revealing significant differential gene expression between regenerating and control animals. Conclusions: Importantly, we have uncovered developmental steps that are regeneration‐specific and do not strictly follow the embryonic program. Developmental Dynamics 245:1159–1175, 2016. © 2016 The Authors. Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists PMID:27649280

Hepatocyte growth factor is crucial for development of the carapace in turtles

PubMed Central

Kawashima-Ohya, Yoshie; Narita, Yuichi; Nagashima, Hiroshi; Usuda, Ryo; Kuratani, Shigeru

2011-01-01

Turtles are characterized by their shell, composed of a dorsal carapace and a ventral plastron. The carapace first appears as the turtle-specific carapacial ridge (CR) on the lateral aspect of the embryonic flank. Accompanying the acquisition of the shell, unlike in other amniotes, hypaxial muscles in turtle embryos appear as thin threads of fibrous tissue. To understand carapacial evolution from the perspective of muscle development, we compared the development of the muscle plate, the anlage of hypaxial muscles, between the Chinese soft-shelled turtle, Pelodiscus sinensis, and chicken embryos. We found that the ventrolateral lip (VLL) of the thoracic dermomyotome of P. sinensis delaminates early and produces sparse muscle plate in the lateral body wall. Expression patterns of the regulatory genes for myotome differentiation, such as Myf5, myogenin, Pax3, and Pax7 have been conserved among amniotes, including turtles. However, in P. sinensis embryos, the gene hepatocyte growth factor (HGF), encoding a regulatory factor for delamination of the dermomyotomal VLL, was uniquely expressed in sclerotome and the lateral body wall at the interlimb level. Implantation of COS-7 cells expressing a HGF antagonist into the turtle embryo inhibited CR formation. We conclude that the de novo expression of HGF in the turtle mesoderm would have played an innovative role resulting in the acquisition of the turtle-specific body plan. PMID:21535464

Surgical Navigation: A Systematic Review of Indications, Treatments, and Outcomes in Oral and Maxillofacial Surgery.

PubMed

Azarmehr, Iman; Stokbro, Kasper; Bell, R Bryan; Thygesen, Torben

2017-09-01

This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indications are discussed. A systematic search in relevant electronic databases, journals, and bibliographies of the included articles was carried out. Clinical studies with 5 or more patients published between 2010 and 2015 were included. Traumatology, orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal were the areas of interests. The search generated 13 articles dealing with traumatology; 5, 6, 2, and 0 studies were found that dealt with the topics of orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal, respectively. The average technical system accuracy and intraoperative precision reported were less than 1 mm and 1 to 2 mm, respectively. In general, SN is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups. SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. All rights reserved.

Sign Language Planning: Pragmatism, Pessimism and Principles

ERIC Educational Resources Information Center

Turner, Graham H.

2009-01-01

This article introduces the present collection of sign language planning studies. Contextualising the analyses against the backdrop of core issues in the theory of language planning and the evolution of applied sign linguistics, it is argued that--while the sociolinguistic circumstances of signed languages worldwide can, in many respects, be…

The Texas Plan to Combat Mental Retardation.

ERIC Educational Resources Information Center

Governor's Advisory Committee on Mental Retardation Planning, Austin, TX.

The Texas state plan of action against mental retardation is presented. Aspects considered include the evolution of the plan, the role of the health services, medical aspects of retardation, education and training, vocational rehabilitation and employment, and social welfare. Also surveyed are the following: residential and day care, manpower,…

Master Plan and Chancellors Hall Southampton College.

ERIC Educational Resources Information Center

Linn, Charles

1998-01-01

Discusses a college master plan that remodeled old buildings, added new ones, and tied roads together on a campus that had experienced a haphazard evolution. The plan included splitting large parking lots into smaller ones divided by trees and plants, moving university functions of certain buildings to other locations, and strategically locating…

Tying Resource Allocation and TQM into Planning and Assessment Efforts.

ERIC Educational Resources Information Center

Mullendore, Richard H.; Wang, Li-Shing

1996-01-01

Describes the evolution of a model, developed by student affairs officials, which outlines a planning process for implementing Total Quality Management. Presents step-by-step instructions for the model's deployment and discusses such issues as transitions, planning forms, goals, and professional and personal growth needs. (RJM)

A NEW HYBRID N-BODY-COAGULATION CODE FOR THE FORMATION OF GAS GIANT PLANETS

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

Bromley, Benjamin C.; Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu

2011-04-20

We describe an updated version of our hybrid N-body-coagulation code for planet formation. In addition to the features of our 2006-2008 code, our treatment now includes algorithms for the one-dimensional evolution of the viscous disk, the accretion of small particles in planetary atmospheres, gas accretion onto massive cores, and the response of N-bodies to the gravitational potential of the gaseous disk and the swarm of planetesimals. To validate the N-body portion of the algorithm, we use a battery of tests in planetary dynamics. As a first application of the complete code, we consider the evolution of Pluto-mass planetesimals in amore » swarm of 0.1-1 cm pebbles. In a typical evolution time of 1-3 Myr, our calculations transform 0.01-0.1 M{sub sun} disks of gas and dust into planetary systems containing super-Earths, Saturns, and Jupiters. Low-mass planets form more often than massive planets; disks with smaller {alpha} form more massive planets than disks with larger {alpha}. For Jupiter-mass planets, masses of solid cores are 10-100 M{sub +}.« less

Coos, booms, and hoots: The evolution of closed-mouth vocal behavior in birds.

PubMed

Riede, Tobias; Eliason, Chad M; Miller, Edward H; Goller, Franz; Clarke, Julia A

2016-08-01

Most birds vocalize with an open beak, but vocalization with a closed beak into an inflating cavity occurs in territorial or courtship displays in disparate species throughout birds. Closed-mouth vocalizations generate resonance conditions that favor low-frequency sounds. By contrast, open-mouth vocalizations cover a wider frequency range. Here we describe closed-mouth vocalizations of birds from functional and morphological perspectives and assess the distribution of closed-mouth vocalizations in birds and related outgroups. Ancestral-state optimizations of body size and vocal behavior indicate that closed-mouth vocalizations are unlikely to be ancestral in birds and have evolved independently at least 16 times within Aves, predominantly in large-bodied lineages. Closed-mouth vocalizations are rare in the small-bodied passerines. In light of these results and body size trends in nonavian dinosaurs, we suggest that the capacity for closed-mouth vocalization was present in at least some extinct nonavian dinosaurs. As in birds, this behavior may have been limited to sexually selected vocal displays, and hence would have co-occurred with open-mouthed vocalizations. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

The island rule in large mammals: paleontology meets ecology.

PubMed

Raia, Pasquale; Meiri, Shai

2006-08-01

The island rule is the phenomenon of the miniaturization of large animals and the gigantism of small animals on islands, with mammals providing the classic case studies. Several explanations for this pattern have been suggested, and departures from the predictions of this rule are common among mammals of differing body size, trophic habits, and phylogenetic affinities. Here we offer a new explanation for the evolution of body size of large insular mammals, using evidence from both living and fossil island faunal assemblages. We demonstrate that the extent of dwarfism in ungulates depends on the existence of competitors and, to a lesser extent, on the presence of predators. In contrast, competition and predation have little or no effect on insular carnivore body size, which is influenced by the nature of the resource base. We suggest dwarfism in large herbivores is an outcome of the fitness increase resulting from the acceleration of reproduction in low-mortality environments. Carnivore size is dependent on the abundance and size of their prey. Size evolution of large mammals in different trophic levels has different underlying mechanisms, resulting in different patterns. Absolute body size may be only an indirect predictor of size evolution, with ecological interactions playing a major role.

Evolution of carbonaceous chondrite parent bodies: Insights into cometary nuclei

NASA Technical Reports Server (NTRS)

Mcsween, Harry Y., Jr.

1989-01-01

It is thought that cometary samples will comprise the most primitive materials that are able to be sampled. Although parent body alteration of such samples would not necessarily detract from scientists' interest in them, the possibility exists that modification processes may have affected cometary nuclei. Inferences about the kinds of modifications that might be encountered can be drawn from data on the evolution of carbonaceous chondrite parent bodies. Observations suggest that, of all the classes of chondrites, these meteorites are most applicable to the study of comets. If the proportion of possible internal heat sources such as Al-26 in cometary materials are similar to those in chondrites, and if the time scale of comet accretion was fast enough to permit incorporation of live radionuclides, comets might have had early thermal histories somewhat like those of carbonaceous chondrite parent bodies.

Plastic body, permanent body: Czech representations of corporeality in the early twentieth century.

PubMed

Sleigh, Charlotte

2009-12-01

In the early twentieth century, the body was seen as both an ontogenetic and a phylogenetic entity. In the former case, its individual development, it was manifestly changeable, developing from embryo to maturity and thence to a state of decay. But in the latter case, concerning its development as a species, the question was an open one. Was its phylogenetic nature a stationary snapshot of the slow process of evolution, or was this too mutable? Historians have emphasised that the question of acquired inheritance remained open into the twentieth century; this paper explores how various constructions of the individual as a phylogenetic episode--a stage in the race's evolution--related to representations of the body in the same period. A discussion of the work of the brothers Josef and Karel Capek offers a contextualised answer to the question of bodily representation. Karel Capek (1890-1938) explored the nature of the 'average man' through two different organisms, the robot and the amphibian, epitomes respectively of corporeal permanence and plasticity. Josef Capek (1887-1945), along with other members of the Group of Plastic Artists, explored visual representations of the body that challenged cubist Bergsonian norms. In so doing, he affirmed what his brother also held: that despite the constrictions imposed by the oppressive political conditions in which the Czechs found themselves, the individual body was a fragile but fluid entity, capable of effecting change upon the future evolution of humankind.

A Perfect View of Vesta: Creating Pointing Observations for the Dawn Spacecraft on Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Hay, Katrina M.

2005-01-01

The Dawn spacecraft has a timely and clever assignment in store. It will take a close look at two intact survivors from the dawn of the solar system (asteroids 4 Vesta and 1 Ceres) to understand more about solar system origin and evolution. To optimize science return, Dawn must make carefully designed observations on approach and in survey orbit, high altitude mapping orbit, and low altitude mapping orbit at each body. In this report, observations outlined in the science plan are modeled using the science opportunity analyzer program for the Vesta encounter. Specifically, I encoded Dawn's flight rules into the program, modeled pointing profiles of the optical instruments (framing camera, visible infrared spectrometer) and mapped their fields of view onto Vesta's surface. Visualization of coverage will provide the science team with information necessary to assess feasibility of alternative observation plans. Dawn launches in summer 2006 and ends its journey in 2016. Instrument observations on Vesta in 2011 will supply detailed information about Vesta's surface and internal structure. These data will be used to analyze the formation and history of the protoplanet and, therefore, complete an important step in understanding the development of our solar system.

The Near-Earth Object Camera: A Next-Generation Minor Planet Survey

NASA Astrophysics Data System (ADS)

Mainzer, Amy K.; Wright, Edward L.; Bauer, James; Grav, Tommy; Cutri, Roc M.; Masiero, Joseph; Nugent, Carolyn R.

2015-11-01

The Near-Earth Object Camera (NEOCam) is a next-generation asteroid and comet survey designed to discover, characterize, and track large numbers of minor planets using a 50 cm infrared telescope located at the Sun-Earth L1 Lagrange point. Proposed to NASA's Discovery program, NEOCam is designed to carry out a comprehensive inventory of the small bodies in the inner regions of our solar system. It address three themes: 1) quantify the potential hazard that near-Earth objects may pose to Earth; 2) study the origins and evolution of our solar system as revealed by its small body populations; and 3) identify the best destinations for future robotic and human exploration. With a dual channel infrared imager that observes at 4-5 and 6-10 micron bands simultaneously through the use of a beamsplitter, NEOCam enables measurements of asteroid diameters and thermal inertia. NEOCam complements existing and planned visible light surveys in terms of orbital element phase space and wavelengths, since albedos can be determined for objects with both visible and infrared flux measurements. NEOCam was awarded technology development funding in 2011 to mature the necessary megapixel infrared detectors.

Evolution of the snake body form reveals homoplasy in amniote Hox gene function.

PubMed

Head, Jason J; Polly, P David

2015-04-02

Hox genes regulate regionalization of the axial skeleton in vertebrates, and changes in their expression have been proposed to be a fundamental mechanism driving the evolution of new body forms. The origin of the snake-like body form, with its deregionalized pre-cloacal axial skeleton, has been explained as either homogenization of Hox gene expression domains, or retention of standard vertebrate Hox domains with alteration of downstream expression that suppresses development of distinct regions. Both models assume a highly regionalized ancestor, but the extent of deregionalization of the primaxial domain (vertebrae, dorsal ribs) of the skeleton in snake-like body forms has never been analysed. Here we combine geometric morphometrics and maximum-likelihood analysis to show that the pre-cloacal primaxial domain of elongate, limb-reduced lizards and snakes is not deregionalized compared with limbed taxa, and that the phylogenetic structure of primaxial morphology in reptiles does not support a loss of regionalization in the evolution of snakes. We demonstrate that morphometric regional boundaries correspond to mapped gene expression domains in snakes, suggesting that their primaxial domain is patterned by a normally functional Hox code. Comparison of primaxial osteology in fossil and modern amniotes with Hox gene distributions within Amniota indicates that a functional, sequentially expressed Hox code patterned a subtle morphological gradient along the anterior-posterior axis in stem members of amniote clades and extant lizards, including snakes. The highly regionalized skeletons of extant archosaurs and mammals result from independent evolution in the Hox code and do not represent ancestral conditions for clades with snake-like body forms. The developmental origin of snakes is best explained by decoupling of the primaxial and abaxial domains and by increases in somite number, not by changes in the function of primaxial Hox genes.

Force of habit: shrubs, trees and contingent evolution of wood anatomical diversity using Croton (Euphorbiaceae) as a model system

PubMed Central

van Ee, Benjamin W.; Riina, Ricarda; Berry, Paul E.; Wiedenhoeft, Alex C.

2017-01-01

Abstract Background and Aims Wood is a major innovation of land plants, and is usually a central component of the body plan for two major plant habits: shrubs and trees. Wood anatomical syndromes vary between shrubs and trees, but no prior work has explicitly evaluated the contingent evolution of wood anatomical diversity in the context of these plant habits. Methods Phylogenetic comparative methods were used to test for contingent evolution of habit, habitat and wood anatomy in the mega-diverse genus Croton (Euphorbiaceae), across the largest and most complete molecular phylogeny of the genus to date. Key Results Plant habit and habitat are highly correlated, but most wood anatomical features correlate more strongly with habit. The ancestral Croton was reconstructed as a tree, the wood of which is inferred to have absent or indistinct growth rings, confluent-like axial parenchyma, procumbent ray cells and disjunctive ray parenchyma cell walls. The taxa sampled showed multiple independent origins of the shrub habit in Croton, and this habit shift is contingent on several wood anatomical features (e.g. similar vessel-ray pits, thick fibre walls, perforated ray cells). The only wood anatomical trait correlated with habitat and not habit was the presence of helical thickenings in the vessel elements of mesic Croton. Conclusions Plant functional traits, individually or in suites, are responses to multiple and often confounding contexts in evolution. By establishing an explicit contingent evolutionary framework, the interplay between habit, habitat and wood anatomical diversity was dissected in the genus Croton. Both habit and habitat influence the evolution of wood anatomical characters, and conversely, the wood anatomy of lineages can affect shifts in plant habit and habitat. This study hypothesizes novel putatively functional trait associations in woody plant structure that could be further tested in a variety of other taxa. PMID:28065919

Force of habit: shrubs, trees and contingent evolution of wood anatomical diversity using Croton (Euphorbiaceae) as a model system.

PubMed

Arévalo, Rafael; van Ee, Benjamin W; Riina, Ricarda; Berry, Paul E; Wiedenhoeft, Alex C

2017-03-01

Wood is a major innovation of land plants, and is usually a central component of the body plan for two major plant habits: shrubs and trees. Wood anatomical syndromes vary between shrubs and trees, but no prior work has explicitly evaluated the contingent evolution of wood anatomical diversity in the context of these plant habits. Phylogenetic comparative methods were used to test for contingent evolution of habit, habitat and wood anatomy in the mega-diverse genus Croton (Euphorbiaceae), across the largest and most complete molecular phylogeny of the genus to date. Plant habit and habitat are highly correlated, but most wood anatomical features correlate more strongly with habit. The ancestral Croton was reconstructed as a tree, the wood of which is inferred to have absent or indistinct growth rings, confluent-like axial parenchyma, procumbent ray cells and disjunctive ray parenchyma cell walls. The taxa sampled showed multiple independent origins of the shrub habit in Croton , and this habit shift is contingent on several wood anatomical features (e.g. similar vessel-ray pits, thick fibre walls, perforated ray cells). The only wood anatomical trait correlated with habitat and not habit was the presence of helical thickenings in the vessel elements of mesic Croton . Plant functional traits, individually or in suites, are responses to multiple and often confounding contexts in evolution. By establishing an explicit contingent evolutionary framework, the interplay between habit, habitat and wood anatomical diversity was dissected in the genus Croton . Both habit and habitat influence the evolution of wood anatomical characters, and conversely, the wood anatomy of lineages can affect shifts in plant habit and habitat. This study hypothesizes novel putatively functional trait associations in woody plant structure that could be further tested in a variety of other taxa. Published by Oxford University Press on behalf of the Annals of Botany Company 2017. This work is written by US Government employees and is in the public domain in the US.

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte

PubMed Central

Matsunaga, Kelly K. S.; Tomescu, Alexandru M. F.

2016-01-01

Background and Aims The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Methods Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. Key Results The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. Conclusions This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that roots evolved from branches of the above-ground axial system, suggesting instead that lycophyte roots arose as a novel organ. PMID:26921730

Updating the Evidence for Oceans on Early Mars

NASA Technical Reports Server (NTRS)

Fairen, Alberto G.; Dohm, James M.; Oner, Tayfun; Ruiz, Javier; Rodriguez, Alexis P.; Schulze-Makuch, Dirk; Ormoe, Jens; McKay, Chris P.; Baker, Victor R.; Amils, Ricardo

2004-01-01

Different-sized bodies of water have been proposed to have occurred episodically in the lowlands of Mars throughout the planet's history, largely related to major stages of development of Tharsis and/or orbital obliquity. These water bodies range from large oceans in the Noachian-Early Hesperian, to a minor sea in the Late Hesperian, and dispersed lakes during the Amazonian. To evaluate the more recent discoveries regarding the oceanic possibility, here we perform a comprehensive analysis of the evolution of water on Mars, including: 1. Geological assessment of proposed shorelines; 2. A volumetric approximation to the plains-filing proposed oceans; 3. Geochemistry of the oceans and derived mineralogies; 4. Post-oceanic (i.e., Amazonian) evolution of the shorelines; and 5. Ultimate water evolution on Mars.

Directionality theory and the evolution of body size.

PubMed

Demetrius, L

2000-12-07

Directionality theory, a dynamic theory of evolution that integrates population genetics with demography, is based on the concept of evolutionary entropy, a measure of the variability in the age of reproducing individuals in a population. The main tenets of the theory are three principles relating the response to the ecological constraints a population experiences, with trends in entropy as the population evolves under mutation and natural selection. (i) Stationary size or fluctuations around a stationary size (bounded growth): a unidirectional increase in entropy; (ii) prolonged episodes of exponential growth (unbounded growth), large population size: a unidirectional decrease in entropy; and (iii) prolonged episodes of exponential growth (unbounded growth), small population size: random, non-directional change in entropy. We invoke these principles, together with an allometric relationship between entropy, and the morphometric variable body size, to provide evolutionary explanations of three empirical patterns pertaining to trends in body size, namely (i) Cope's rule, the tendency towards size increase within phyletic lineages; (ii) the island rule, which pertains to changes in body size that occur as species migrate from mainland populations to colonize island habitats; and (iii) Bergmann's rule, the tendency towards size increase with increasing latitude. The observation that these ecotypic patterns can be explained in terms of the directionality principles for entropy underscores the significance of evolutionary entropy as a unifying concept in forging a link between micro-evolution, the dynamics of gene frequency change, and macro-evolution, dynamic changes in morphometric variables.

An adaptively refined phase-space element method for cosmological simulations and collisionless dynamics

NASA Astrophysics Data System (ADS)

Hahn, Oliver; Angulo, Raul E.

2016-01-01

N-body simulations are essential for understanding the formation and evolution of structure in the Universe. However, the discrete nature of these simulations affects their accuracy when modelling collisionless systems. We introduce a new approach to simulate the gravitational evolution of cold collisionless fluids by solving the Vlasov-Poisson equations in terms of adaptively refineable `Lagrangian phase-space elements'. These geometrical elements are piecewise smooth maps between Lagrangian space and Eulerian phase-space and approximate the continuum structure of the distribution function. They allow for dynamical adaptive splitting to accurately follow the evolution even in regions of very strong mixing. We discuss in detail various one-, two- and three-dimensional test problems to demonstrate the performance of our method. Its advantages compared to N-body algorithms are: (I) explicit tracking of the fine-grained distribution function, (II) natural representation of caustics, (III) intrinsically smooth gravitational potential fields, thus (IV) eliminating the need for any type of ad hoc force softening. We show the potential of our method by simulating structure formation in a warm dark matter scenario. We discuss how spurious collisionality and large-scale discreteness noise of N-body methods are both strongly suppressed, which eliminates the artificial fragmentation of filaments. Therefore, we argue that our new approach improves on the N-body method when simulating self-gravitating cold and collisionless fluids, and is the first method that allows us to explicitly follow the fine-grained evolution in six-dimensional phase-space.

Probabilistic evaluation of the water footprint of a river basin: Accounting method and case study in the Segura River Basin, Spain.

PubMed

Pellicer-Martínez, Francisco; Martínez-Paz, José Miguel

2018-06-15

In the current study a method for the probabilistic accounting of the water footprint (WF) at the river basin level has been proposed and developed. It is based upon the simulation of the anthropised water cycle and combines a hydrological model and a decision support system. The methodology was carried out in the Segura River Basin (SRB) in South-eastern Spain, and four historical scenarios were evaluated (1998-2010-2015-2027). The results indicate that the WF of the river basin reached 5581 Mm 3 /year on average in the base scenario, with a high variability. The green component (3231 Mm 3 /year), mainly generated by rainfed crops (62%), was responsible for the great variability of the WF. The blue WF (1201 Mm 3 /year) was broken down into surface water (56%), renewable groundwater (20%) and non-renewable groundwater (24%), and it showed the generalized overexploitation of aquifers. Regarding the grey component (1150 Mm 3 /year), the study reveals that wastewater, especially phosphates (90%), was the main culprit producing water pollution in surface water bodies. The temporal evolution of the four scenarios highlighted the successfulness of the water treatment plans developed in the river basin, with a sharp decrease in the grey WF, as well as the stability of the WF and its three components in the future. So, the accounting of the three components of the WF in a basin was integrated into the management of water resources, it being possible to predict their evolution, their spatial characterisation and even their assessment in probabilistic terms. Then, the WF was incorporated into the set of indicators that usually is used in water resources management and hydrological planning. Copyright © 2018 Elsevier B.V. All rights reserved.

An Initial Strategy for Commercial Industry Awareness of the International Space Station

NASA Technical Reports Server (NTRS)

Jorgensen, Catherine A.

1999-01-01

While plans are being developed to utilize the ISS for scientific research, and human and microgravity experiments, it is time to consider the future of the ISS as a world-wide commercial marketplace developed from a government owned, operated and controlled facility. Commercial industry will be able to seize this opportunity to utilize the ISS as a unique manufacturing platform and engineering testbed for advanced technology. NASA has begun the strategic planning of the evolution and commercialization of the ISS. The Pre-Planned Program Improvement (P3I) Working Group at NASA is assessing the future ISS needs and technology plans to enhance ISS performance. Some of these enhancements will allow the accommodation of commercial applications and the Human Exploration and Development of Space mission support. As this information develops, it is essential to disseminate this information to commercial industry, targeting not only the private and public space sector but also the non-aerospace commercial industries. An approach is presented for early distribution of this information via the ISS Evolution Data book that includes ISS baseline system information, baseline utilization and operations plans, advanced technologies, future utilization opportunities, ISS evolution and Design Reference Missions (DRM). This information source and tool can be used as catalyst in the commercial world for the generation of ideas and options to enhance the current capabilities of the ISS.

IN SITU ACCRETION OF HYDROGEN-RICH ATMOSPHERES ON SHORT-PERIOD SUPER-EARTHS: IMPLICATIONS FOR THE KEPLER-11 PLANETS

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

Ikoma, M.; Hori, Y., E-mail: ikoma@eps.s.u-tokyo.ac.jp, E-mail: yasunori.hori@nao.ac.jp

2012-07-01

Motivated by recent discoveries of low-density super-Earths with short orbital periods, we have investigated in situ accretion of H-He atmospheres on rocky bodies embedded in dissipating warm disks, by simulating quasi-static evolution of atmospheres that connect to the ambient disk. We have found that the atmospheric evolution has two distinctly different outcomes, depending on the rocky body's mass: while the atmospheres on massive rocky bodies undergo runaway disk-gas accretion, those on light rocky bodies undergo significant erosion during disk dispersal. In the atmospheric erosion, the heat content of the rocky body that was previously neglected plays an important role. Wemore » have also realized that the atmospheric mass is rather sensitive to disk temperature in the mass range of interest in this study. Our theory is applied to recently detected super-Earths orbiting Kepler-11 to examine the possibility that the planets are rock-dominated ones with relatively thick H-He atmospheres. The application suggests that the in situ formation of the relatively thick H-He atmospheres inferred by structure modeling is possible only under restricted conditions, namely, relatively slow disk dissipation and/or cool environments. This study demonstrates that low-density super-Earths provide important clues to understanding of planetary accretion and disk evolution.« less

Convergent evolution of reduced energy demands in extremophile fish

PubMed Central

Arias-Rodriguez, Lenin; Tobler, Michael

2017-01-01

Convergent evolution in organismal function can arise from nonconvergent changes in traits that contribute to that function. Theory predicts that low resource availability and high maintenance costs in extreme environments select for reductions in organismal energy demands, which could be attained through modifications of body size or metabolic rate. We tested for convergence in energy demands and underlying traits by investigating livebearing fish (genus Poecilia) that have repeatedly colonized toxic, hydrogen sulphide-rich springs. We quantified variation in body size and routine metabolism across replicated sulphidic and non-sulphidic populations in nature, modelled total organismal energy demands, and conducted a common-garden experiment to test whether population differences had a genetic basis. Sulphidic populations generally exhibited smaller body sizes and lower routine metabolic rates compared to non-sulphidic populations, which together caused significant reductions in total organismal energy demands in extremophile populations. Although both mechanisms contributed to variation in organismal energy demands, variance partitioning indicated reductions of body size overall had a greater effect than reductions of routine metabolism. Finally, population differences in routine metabolism documented in natural populations were maintained in common-garden reared individuals, indicating evolved differences. In combination with other studies, these results suggest that reductions in energy demands may represent a common theme in adaptation to physiochemical stressors. Selection for reduced energy demand may particularly affect body size, which has implications for life history evolution in extreme environments. PMID:29077740

Evaluation of advanced propulsion options for the next manned transportation system: Propulsion evolution study

NASA Technical Reports Server (NTRS)

Spears, L. T.; Kramer, R. D.

1990-01-01

The objectives were to examine launch vehicle applications and propulsion requirements for potential future manned space transportation systems and to support planning toward the evolution of Space Shuttle Main Engine (SSME) and Space Transportation Main Engine (STME) engines beyond their current or initial launch vehicle applications. As a basis for examinations of potential future manned launch vehicle applications, we used three classes of manned space transportation concepts currently under study: Space Transportation System Evolution, Personal Launch System (PLS), and Advanced Manned Launch System (AMLS). Tasks included studies of launch vehicle applications and requirements for hydrogen-oxygen rocket engines; the development of suggestions for STME engine evolution beyond the mid-1990's; the development of suggestions for STME evolution beyond the Advanced Launch System (ALS) application; the study of booster propulsion options, including LOX-Hydrocarbon options; the analysis of the prospects and requirements for utilization of a single engine configuration over the full range of vehicle applications, including manned vehicles plus ALS and Shuttle C; and a brief review of on-going and planned LOX-Hydrogen propulsion technology activities.

Water and the Interior Structure of Terrestrial Planets and Icy Bodies

NASA Astrophysics Data System (ADS)

Monteux, J.; Golabek, G. J.; Rubie, D. C.; Tobie, G.; Young, E. D.

2018-02-01

Water content and the internal evolution of terrestrial planets and icy bodies are closely linked. The distribution of water in planetary systems is controlled by the temperature structure in the protoplanetary disk and dynamics and migration of planetesimals and planetary embryos. This results in the formation of planetesimals and planetary embryos with a great variety of compositions, water contents and degrees of oxidation. The internal evolution and especially the formation time of planetesimals relative to the timescale of radiogenic heating by short-lived 26Al decay may govern the amount of hydrous silicates and leftover rock-ice mixtures available in the late stages of their evolution. In turn, water content may affect the early internal evolution of the planetesimals and in particular metal-silicate separation processes. Moreover, water content may contribute to an increase of oxygen fugacity and thus affect the concentrations of siderophile elements within the silicate reservoirs of Solar System objects. Finally, the water content strongly influences the differentiation rate of the icy moons, controls their internal evolution and governs the alteration processes occurring in their deep interiors.

Prepaying & Saving for College: Opportunities and Issues. Policy Perspectives No. 3.

ERIC Educational Resources Information Center

Jennings, Barbara M.; Olivas, Michael A.

This publication provides an overview and discusses underlying issues of the college savings and prepaid tuition plans that are emerging in the states. Two papers offer different vantage points on college savings and prepaid plans in financing postsecondary education. The first paper, "The Evolution of State Plans" (Barbara M. Jennings),…

Evolution & Status of Approval Plans. SPEC Kit 221.

ERIC Educational Resources Information Center

Flood, Susan, Comp.

This report documents the results of a survey on the current use and management of approval plans, and compares them with similar studies published in SPEC kits in 1982 and 1988. Overall, Association of Research Libraries (ARL) institutions still consider approval plans to be efficient and cost effective. Survey results include: (1) the percentage…

Evidence for involvement of Wnt signalling in body polarities, cell proliferation, and the neuro-sensory system in an adult ctenophore.

PubMed

Jager, Muriel; Dayraud, Cyrielle; Mialot, Antoine; Quéinnec, Eric; le Guyader, Hervé; Manuel, Michaël

2013-01-01

Signalling through the Wnt family of secreted proteins originated in a common metazoan ancestor and greatly influenced the evolution of animal body plans. In bilaterians, Wnt signalling plays multiple fundamental roles during embryonic development and in adult tissues, notably in axial patterning, neural development and stem cell regulation. Studies in various cnidarian species have particularly highlighted the evolutionarily conserved role of the Wnt/β-catenin pathway in specification and patterning of the primary embryonic axis. However in another key non-bilaterian phylum, Ctenophora, Wnts are not involved in early establishment of the body axis during embryogenesis. We analysed the expression in the adult of the ctenophore Pleurobrachia pileus of 11 orthologues of Wnt signalling genes including all ctenophore Wnt ligands and Fz receptors and several members of the intracellular β-catenin pathway machinery. All genes are strongly expressed around the mouth margin at the oral pole, evoking the Wnt oral centre of cnidarians. This observation is consistent with primary axis polarisation by the Wnts being a universal metazoan feature, secondarily lost in ctenophores during early development but retained in the adult. In addition, local expression of Wnt signalling genes was seen in various anatomical structures of the body including in the locomotory comb rows, where their complex deployment suggests control by the Wnts of local comb polarity. Other important contexts of Wnt involvement which probably evolved before the ctenophore/cnidarian/bilaterian split include proliferating stem cells and progenitors irrespective of cell types, and developing as well as differentiated neuro-sensory structures.

Planning for the integration of the digital library, clinical decision support, and evidence at the point of care.

PubMed

Schwartz, Linda Matula; Iobst, Barbara

2008-01-01

Integrating knowledge-based resources at the point of care is an important opportunity for hospital library involvement. In the progression of an IAIMS planning grant, the digital library is recognized as pivotal to the success of information domain integration throughout the institution. The planning process, data collection, and evolution of the planning project are discussed.

Environmental and scale-dependent evolutionary trends in the body size of crustaceans

PubMed Central

Klompmaker, Adiël A.; Schweitzer, Carrie E.; Feldmann, Rodney M.; Kowalewski, Michał

2015-01-01

The ecological and physiological significance of body size is well recognized. However, key macroevolutionary questions regarding the dependency of body size trends on the taxonomic scale of analysis and the role of environment in controlling long-term evolution of body size are largely unknown. Here, we evaluate these issues for decapod crustaceans, a group that diversified in the Mesozoic. A compilation of body size data for 792 brachyuran crab and lobster species reveals that their maximum, mean and median body size increased, but no increase in minimum size was observed. This increase is not expressed within lineages, but is rather a product of the appearance and/or diversification of new clades of larger, primarily burrowing to shelter-seeking decapods. This argues against directional selective pressures within lineages. Rather, the trend is a macroevolutionary consequence of species sorting: preferential origination of new decapod clades with intrinsically larger body sizes. Furthermore, body size evolution appears to have been habitat-controlled. In the Cretaceous, reef-associated crabs became markedly smaller than those in other habitats, a pattern that persists today. The long-term increase in body size of crabs and lobsters, coupled with their increased diversity and abundance, suggests that their ecological impact may have increased over evolutionary time. PMID:26156761

SU-E-T-436: Feasibility of Using the 'Irregular Surface Compensator' Planning Feature of the Eclipse TPS for Total Body Irradiation (TBI) Treatment Planning.

PubMed

Ayan, A; Lu, L; Rong, Y; Cunningham, M; Weldon, M; Welliver, M; Woollard, J; Gupta, N

2012-06-01

To investigate the feasibility of using the Irregular Surface Compensator (ISC) planning feature of the Eclipse treatment planning system (TPS) for Total Body Irradiation (TBI). TBI treatments require that the whole body receives within +-10% of the prescribed dose. Different body parts with different thicknesses compared to the umbilicus separation may receive higher or lower doses compared to the prescribed dose. Another challenge is to keep the lung dose below 10Gy to avoid complications. To mitigate this problem, physical compensators and blocks are used during the treatment for different body parts and lungs. This method presents a challenge during the treatment delivery and prolongs the treatment time due to patient setup, in-vivo on-line dosimetric monitoring and the adjustment of the compensators frequently during the treatment. We investigated the use of ISC planning feature of Eclipse TPS which is an electronic compensation method that calculates a fluence map based on the body contour from the CT image. The fluence map is delivered with dynamic MLCs . This TBI treatment technique was tested using a Rando phantom in Head First Supine position with lateral beams at SSD=250cm.The calculated fluence were edited so that the lung received <∼10Gy for 12Gy prescription. A single fraction of 2Gy was delivered and the in-vivo measurements were performed in the neck, lung and the umbilicus by using OSLDs. OSLD measurements and the Eclipse TPS predictionswere 200.4/195.0, 162.2/168.9, and 196.1/208.9 cGy for the neck, lung and the umbilicus respectively. The feasibility of using the 'Irregular Surface Compensator' feature of Eclipse TPS for TBI treatment planning was demonstrated. Good agreement (<6%) between the predicted and measured doses was obtained. The proposed planning and delivery simplifies the compensation and blocking to achieve uniform dose distributions and reduces the treatment time. © 2012 American Association of Physicists in Medicine.

Chemical evolution of primitive solar system bodies

NASA Technical Reports Server (NTRS)

Oro, J.; Mills, T.

1989-01-01

Observations on organic molecules and compounds containing biogenic elements in the interstellar medium and in the primitive bodies of the solar system are reviewed. The discovery of phosphorus molecular species in dense interstellar clouds, the existence of organic ions in the dust and gas phase of the comas of Comet Halley, and the presence of presolar, deuterium-hydrogen ratios in the amino acids of carbonaceous chondrites are discussed. The relationships between comets, dark asteroids, and carbonaceous chondrites are examined. Also, consideration is given to the chemical evolution of Titan, the primitive earth, and early Mars.

Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals.

PubMed

Chen, Xi; Ling, Hong-Fei; Vance, Derek; Shields-Zhou, Graham A; Zhu, Maoyan; Poulton, Simon W; Och, Lawrence M; Jiang, Shao-Yong; Li, Da; Cremonese, Lorenzo; Archer, Corey

2015-05-18

The early diversification of animals (∼ 630 Ma), and their development into both motile and macroscopic forms (∼ 575-565 Ma), has been linked to stepwise increases in the oxygenation of Earth's surface environment. However, establishing such a linkage between oxygen and evolution for the later Cambrian 'explosion' (540-520 Ma) of new, energy-sapping body plans and behaviours has proved more elusive. Here we present new molybdenum isotope data, which demonstrate that the areal extent of oxygenated bottom waters increased in step with the early Cambrian bioradiation of animals and eukaryotic phytoplankton. Modern-like oxygen levels characterized the ocean at ∼ 521 Ma for the first time in Earth history. This marks the first establishment of a key environmental factor in modern-like ecosystems, where animals benefit from, and also contribute to, the 'homeostasis' of marine redox conditions.

Molluscan engrailed expression, serial organization, and shell evolution

NASA Technical Reports Server (NTRS)

Jacobs, D. K.; Wray, C. G.; Wedeen, C. J.; Kostriken, R.; DeSalle, R.; Staton, J. L.; Gates, R. D.; Lindberg, D. R.

2000-01-01

Whether the serial features found in some molluscs are ancestral or derived is considered controversial. Here, in situ hybridization and antibody studies show iterated engrailed-gene expression in transverse rows of ectodermal cells bounding plate field development and spicule formation in the chiton, Lepidochitona cavema, as well as in cells surrounding the valves and in the early development of the shell hinge in the clam, Transennella tantilla. Ectodermal expression of engrailed is associated with skeletogenesis across a range of bilaterian phyla, suggesting a single evolutionary origin of invertebrate skeletons. The shared ancestry of bilaterian-invertebrate skeletons may help explain the sudden appearance of shelly fossils in the Cambrian. Our interpretation departs from the consideration of canonical metameres or segments as units of evolutionary analysis. In this interpretation, the shared ancestry of engrailed-gene function in the terminal/posterior addition of serially repeated elements during development explains the iterative expression of engrailed genes in a range of metazoan body plans.

An exceptional fossil skull from South America and the origins of the archosauriform radiation

NASA Astrophysics Data System (ADS)

Pinheiro, Felipe L.; França, Marco A. G.; Lacerda, Marcel B.; Butler, Richard J.; Schultz, Cesar L.

2016-03-01

Birds, dinosaurs, crocodilians, pterosaurs and their close relatives form the highly diverse clade Archosauriformes. Archosauriforms have a deep evolutionary history, originating in the late Permian, prior to the end-Permian mass extinction, and radiating in the Triassic to dominate Mesozoic ecosystems. However, the origins of this clade and its extraordinarily successful body plan remain obscure. Here, we describe an exceptionally preserved fossil skull from the Lower Triassic of Brazil, representing a new species, Teyujagua paradoxa, transitional in morphology between archosauriforms and more primitive reptiles. This skull reveals for the first time the mosaic assembly of key features of the archosauriform skull, including the antorbital and mandibular fenestrae, serrated teeth, and closed lower temporal bar. Phylogenetic analysis recovers Teyujagua as the sister taxon to Archosauriformes, and is congruent with a two-phase model of early archosauriform evolution, in response to two mass extinctions occurring at the end of the Guadalupian and the Permian.

Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals

PubMed Central

Chen, Xi; Ling, Hong-Fei; Vance, Derek; Shields-Zhou, Graham A.; Zhu, Maoyan; Poulton, Simon W.; Och, Lawrence M.; Jiang, Shao-Yong; Li, Da; Cremonese, Lorenzo; Archer, Corey

2015-01-01

The early diversification of animals (∼630 Ma), and their development into both motile and macroscopic forms (∼575–565 Ma), has been linked to stepwise increases in the oxygenation of Earth's surface environment. However, establishing such a linkage between oxygen and evolution for the later Cambrian ‘explosion' (540–520 Ma) of new, energy-sapping body plans and behaviours has proved more elusive. Here we present new molybdenum isotope data, which demonstrate that the areal extent of oxygenated bottom waters increased in step with the early Cambrian bioradiation of animals and eukaryotic phytoplankton. Modern-like oxygen levels characterized the ocean at ∼521 Ma for the first time in Earth history. This marks the first establishment of a key environmental factor in modern-like ecosystems, where animals benefit from, and also contribute to, the ‘homeostasis' of marine redox conditions. PMID:25980960

Toward understanding the evolution of vertebrate gene regulatory networks: comparative genomics and epigenomic approaches.

PubMed

Martinez-Morales, Juan R

2016-07-01

Vertebrates, as most animal phyla, originated >500 million years ago during the Cambrian explosion, and progressively radiated into the extant classes. Inferring the evolutionary history of the group requires understanding the architecture of the developmental programs that constrain the vertebrate anatomy. Here, I review recent comparative genomic and epigenomic studies, based on ChIP-seq and chromatin accessibility, which focus on the identification of functionally equivalent cis-regulatory modules among species. This pioneer work, primarily centered in the mammalian lineage, has set the groundwork for further studies in representative vertebrate and chordate species. Mapping of active regulatory regions across lineages will shed new light on the evolutionary forces stabilizing ancestral developmental programs, as well as allowing their variation to sustain morphological adaptations on the inherited vertebrate body plan. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Urban transportation planning in the United States : an historical overview

DOT National Transportation Integrated Search

1997-09-01

The report focuses on key events in the evolution of urban transportation planning including developments in technical procedures, philosophy, processes and institutions. But, planners must also be aware of changes in legislation, policy, regulations...

The Strata-1 Regolith Dynamics Experiment: Class 1E Science on ISS

NASA Technical Reports Server (NTRS)

Fries, Marc; Graham, Lee; John, Kristen

2016-01-01

The Strata-1 experiment studies the evolution of small body regolith through long-duration exposure of simulant materials to the microgravity environment on the International Space Station (ISS). This study will record segregation and mechanical dynamics of regolith simulants in a microgravity and vibration environment similar to that experienced by regolith on small Solar System bodies. Strata-1 will help us understand regolith dynamics and will inform design and procedures for landing and setting anchors, safely sampling and moving material on asteroidal surfaces, processing large volumes of material for in situ resource utilization (ISRU) purposes, and, in general, predicting the behavior of large and small particles on disturbed asteroid surfaces. This experiment is providing new insights into small body surface evolution.

A basal dromaeosaurid and size evolution preceding avian flight.

PubMed

Turner, Alan H; Pol, Diego; Clarke, Julia A; Erickson, Gregory M; Norell, Mark A

2007-09-07

Fossil evidence for changes in dinosaurs near the lineage leading to birds and the origin of flight has been sparse. A dinosaur from Mongolia represents the basal divergence within Dromaeosauridae. The taxon's small body size and phylogenetic position imply that extreme miniaturization was ancestral for Paraves (the clade including Avialae, Troodontidae, and Dromaeosauridae), phylogenetically earlier than where flight evolution is strongly inferred. In contrast to the sustained small body sizes among avialans throughout the Cretaceous Period, the two dinosaurian lineages most closely related to birds, dromaeosaurids and troodontids, underwent four independent events of gigantism, and in some lineages size increased by nearly three orders of magnitude. Thus, change in theropod body size leading to flight's origin was not unidirectional.

Roles of NN-interaction components in shell-structure evolution

NASA Astrophysics Data System (ADS)

Umeya, Atsushi; Muto, Kazuo

2016-11-01

Since the importance of the monopole interaction was first emphasized in 1960s, roles of monopole strengths of two-body nucleon-nucleon interaction in shell structure have been discussed. Through the monopole strengths, we study the roles in shell-structure evolution, starting from explicit forms of the interaction. For the tensor component of the interaction, we show the derivation of the relation, (2j> + 1)Vjj> + (2j< + 1)Vjj< = 0, with a detailed manipulation. We show that one-body spin-orbit term appears in the multipole expansion of two-body spin-orbit interaction. Only the spin-orbit components can affect the spin-orbit energy splitting between spin-orbit partners, when the spin-orbit partner orbits are fully occupied.

Can Man Control His Biological Evolution? A Symposium on Genetic Engineering. Man's Responsibility to His Future

ERIC Educational Resources Information Center

Hoagland, Hudson

1972-01-01

Biological evolution can be carried out in the laboratory. With new knowledge available in genetics, possibilities are raised that genetic characters can be transferred in the future to embryos according to a predetermined plan. (PS)

Early crocodylomorph increases top tier predator diversity during rise of dinosaurs.

PubMed

Zanno, Lindsay E; Drymala, Susan; Nesbitt, Sterling J; Schneider, Vincent P

2015-03-19

Triassic predatory guild evolution reflects a period of ecological flux spurred by the catastrophic end-Permian mass extinction and terminating with the global ecological dominance of dinosaurs in the early Jurassic. In responding to this dynamic ecospace, terrestrial predator diversity attained new levels, prompting unique trophic webs with a seeming overabundance of carnivorous taxa and the evolution of entirely new predatory clades. Key among these was Crocodylomorpha, the largest living reptiles and only one of two archosaurian lineages that survive to the present day. In contrast to their existing role as top, semi-aquatic predators, the earliest crocodylomorphs were generally small-bodied, terrestrial faunivores, occupying subsidiary (meso) predator roles. Here we describe Carnufex carolinensis a new, unexpectedly large-bodied taxon with a slender and ornamented skull from the Carnian Pekin Formation (~231 Ma), representing one of the oldest and earliest diverging crocodylomorphs described to date. Carnufex bridges a problematic gap in the early evolution of pseudosuchians by spanning key transitions in bauplan evolution and body mass near the origin of Crocodylomorpha. With a skull length of >50 cm, the new taxon documents a rare instance of crocodylomorphs ascending to top-tier predator guilds in the equatorial regions of Pangea prior to the dominance of dinosaurs.

Human Evolution: The Real Cause for Birth Palsy

PubMed Central

Sreekanth, R; Thomas, BP

2015-01-01

ABSTRACT Objective: Birth palsy, otherwise known as obstetric brachial plexus paralysis (OBPP), is a closed stretch injury to the brachial plexus of nerves during the birth process resulting in varying degree of paralysis and contractures of the upper limb. The study aimed to find out the susceptibility of humans and small-bodied primates to birth palsy. Method: A comparative study on parturition in modern humans, hominoids, hominids, small-bodied primates and great apes was done to determine if changes in the female pelvis and neonatal head and shoulder during human evolution is the real cause for OBPP. Results: During evolution, the morphology of the female pelvis and birth canal changed into a narrow and twisted one and also the size of the fetal head increased. Thus, the narrow and twisted pelvis of the mother, and the relatively large head and broad shoulders of the newborn has made the birthing process of modern human and small bodied primates a precarious fine-tuned act with a very narrow margin for error. This has necessitated proper obstetric care to reduce or even at times obviate the incidence of birth injuries like OBPP. Conclusion: Human evolution has made human babies susceptible to birth palsy and thus is the real cause of birth palsy. PMID:26624599

Early crocodylomorph increases top tier predator diversity during rise of dinosaurs

PubMed Central

Zanno, Lindsay E.; Drymala, Susan; Nesbitt, Sterling J.; Schneider, Vincent P.

2015-01-01

Triassic predatory guild evolution reflects a period of ecological flux spurred by the catastrophic end-Permian mass extinction and terminating with the global ecological dominance of dinosaurs in the early Jurassic. In responding to this dynamic ecospace, terrestrial predator diversity attained new levels, prompting unique trophic webs with a seeming overabundance of carnivorous taxa and the evolution of entirely new predatory clades. Key among these was Crocodylomorpha, the largest living reptiles and only one of two archosaurian lineages that survive to the present day. In contrast to their existing role as top, semi-aquatic predators, the earliest crocodylomorphs were generally small-bodied, terrestrial faunivores, occupying subsidiary (meso) predator roles. Here we describe Carnufex carolinensis a new, unexpectedly large-bodied taxon with a slender and ornamented skull from the Carnian Pekin Formation (~231 Ma), representing one of the oldest and earliest diverging crocodylomorphs described to date. Carnufex bridges a problematic gap in the early evolution of pseudosuchians by spanning key transitions in bauplan evolution and body mass near the origin of Crocodylomorpha. With a skull length of >50 cm, the new taxon documents a rare instance of crocodylomorphs ascending to top-tier predator guilds in the equatorial regions of Pangea prior to the dominance of dinosaurs. PMID:25787306

Efficient determination of the Markovian time-evolution towards a steady-state of a complex open quantum system

NASA Astrophysics Data System (ADS)

Jonsson, Thorsteinn H.; Manolescu, Andrei; Goan, Hsi-Sheng; Abdullah, Nzar Rauf; Sitek, Anna; Tang, Chi-Shung; Gudmundsson, Vidar

2017-11-01

Master equations are commonly used to describe time evolution of open systems. We introduce a general computationally efficient method for calculating a Markovian solution of the Nakajima-Zwanzig generalized master equation. We do so for a time-dependent transport of interacting electrons through a complex nano scale system in a photon cavity. The central system, described by 120 many-body states in a Fock space, is weakly coupled to the external leads. The efficiency of the approach allows us to place the bias window defined by the external leads high into the many-body spectrum of the cavity photon-dressed states of the central system revealing a cascade of intermediate transitions as the system relaxes to a steady state. The very diverse relaxation times present in the open system, reflecting radiative or non-radiative transitions, require information about the time evolution through many orders of magnitude. In our approach, the generalized master equation is mapped from a many-body Fock space of states to a Liouville space of transitions. We show that this results in a linear equation which is solved exactly through an eigenvalue analysis, which supplies information on the steady state and the time evolution of the system.

Miocene small-bodied ape from Eurasia sheds light on hominoid evolution.

PubMed

Alba, David M; Almécija, Sergio; DeMiguel, Daniel; Fortuny, Josep; Pérez de los Ríos, Miriam; Pina, Marta; Robles, Josep M; Moyà-Solà, Salvador

2015-10-30

Miocene small-bodied anthropoid primates from Africa and Eurasia are generally considered to precede the divergence between the two groups of extant catarrhines—hominoids (apes and humans) and Old World monkeys—and are thus viewed as more primitive than the stem ape Proconsul. Here we describe Pliobates cataloniae gen. et sp. nov., a small-bodied (4 to 5 kilograms) primate from the Iberian Miocene (11.6 million years ago) that displays a mosaic of primitive characteristics coupled with multiple cranial and postcranial shared derived features of extant hominoids. Our cladistic analyses show that Pliobates is a stem hominoid that is more derived than previously described small catarrhines and Proconsul. This forces us to reevaluate the role played by small-bodied catarrhines in ape evolution and provides key insight into the last common ancestor of hylobatids (gibbons) and hominids (great apes and humans). Copyright © 2015, American Association for the Advancement of Science.

Deformation Failure Characteristics of Coal Body and Mining Induced Stress Evolution Law

PubMed Central

Wen, Zhijie; Wen, Jinhao; Shi, Yongkui; Jia, Chuanyang

2014-01-01

The results of the interaction between coal failure and mining pressure field evolution during mining are presented. Not only the mechanical model of stope and its relative structure division, but also the failure and behavior characteristic of coal body under different mining stages are built and demonstrated. Namely, the breaking arch and stress arch which influence the mining area are quantified calculated. A systematic method of stress field distribution is worked out. All this indicates that the pore distribution of coal body with different compressed volume has fractal character; it appears to be the linear relationship between propagation range of internal stress field and compressed volume of coal body and nonlinear relationship between the range of outburst coal mass and the number of pores which is influenced by mining pressure. The results provide theory reference for the research on the range of mining-induced stress and broken coal wall. PMID:24967438

PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS.

PubMed

Dehant, V; Asael, D; Baland, R M; Baludikay, B K; Beghin, J; Belza, J; Beuthe, M; Breuer, D; Chernonozhkin, S; Claeys, Ph; Cornet, Y; Cornet, L; Coyette, A; Debaille, V; Delvigne, C; Deproost, M H; De WInter, N; Duchemin, C; El Atrassi, F; François, C; De Keyser, J; Gillmann, C; Gloesener, E; Goderis, S; Hidaka, Y; Höning, D; Huber, M; Hublet, G; Javaux, E J; Karatekin, Ö; Kodolanyi, J; Revilla, L Lobo; Maes, L; Maggiolo, R; Mattielli, N; Maurice, M; McKibbin, S; Morschhauser, A; Neumann, W; Noack, L; Pham, L B S; Pittarello, L; Plesa, A C; Rivoldini, A; Robert, S; Rosenblatt, P; Spohn, T; Storme, J -Y; Tosi, N; Trinh, A; Valdes, M; Vandaele, A C; Vanhaecke, F; Van Hoolst, T; Van Roosbroek, N; Wilquet, V; Yseboodt, M

2016-11-01

The Interuniversity Attraction Pole (IAP) 'PLANET TOPERS' (Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their Reservoirs) addresses the fundamental understanding of the thermal and compositional evolution of the different reservoirs of planetary bodies (core, mantle, crust, atmosphere, hydrosphere, cryosphere, and space) considering interactions and feedback mechanisms. Here we present the first results after 2 years of project work.

Thermal evolution of a partially differentiated H chondrite parent body

NASA Astrophysics Data System (ADS)

Abrahams, J. N. H.; Bryson, J. F. J.; Weiss, B. P.; Nimmo, F.

2016-12-01

It has traditionally been assumed that planetesimals either melted entirely or remained completely undifferentiated as they accreted. The unmelted textures and cooling histories of chondrites have been used to argue that these meteorites originated from bodies that never differentiated. However, paleomagnetic measurements indicate that some chondrites (e.g., the H chondrite Portales Valley and several CV chondrites) were magnetized by a core dynamo magnetic field, implying that their parent bodies were partially differentiated. It has been unclear, however, whether planetesimal histories consistent with dynamo production can also be consistent with the diversity of chondrite cooling rates and ages. To address this, we modeled the thermal evolution of the H chondrite parent body, considering a variety of accretion histories and parent body radii. We considered partial differentiation using two-stage accretion involving the initial formation and differentiation of a small body, followed by the later addition of low thermal conductivity chondritic material that remains mostly unmelted. We were able to reproduce the measured thermal evolution of multiple H chondrites for a range of parent body parameters, including initial radii from 70-150 km, chondritic layer thicknesses from 50 km to over 100 km, and second stage accretion times of 2.5-3 Myr after solar system formation. Our predicted rates of core cooling and crystallization are consistent with dynamo generation by compositional convection beginning 60-200 Myr after solar system formation and lasting for at least tens of millions of years. This is consistent with magnetic studies of Portales Valley [Bryson et al., this meeting]. In summary, we find that thermal models of partial differentiation are consistent the radiometric ages, magnetization, and cooling rates of a diversity H chondrites.

Empirical tests of harvest-induced body-size evolution along a geographic gradient in Australian macropods.

PubMed

Prowse, Thomas A A; Correll, Rachel A; Johnson, Christopher N; Prideaux, Gavin J; Brook, Barry W

2015-01-01

Life-history theory predicts the progressive dwarfing of animal populations that are subjected to chronic mortality stress, but the evolutionary impact of harvesting terrestrial herbivores has seldom been tested. In Australia, marsupials of the genus Macropus (kangaroos and wallabies) are subjected to size-selective commercial harvesting. Mathematical modelling suggests that harvest quotas (c. 10-20% of population estimates annually) could be driving body-size evolution in these species. We tested this hypothesis for three harvested macropod species with continental-scale distributions. To do so, we measured more than 2000 macropod skulls sourced from wildlife collections spanning the last 130 years. We analysed these data using spatial Bayesian models that controlled for the age and sex of specimens as well as environmental drivers and island effects. We found no evidence for the hypothesized decline in body size for any species; rather, models that fit trend terms supported minor body size increases over time. This apparently counterintuitive result is consistent with reduced mortality due to a depauperate predator guild and increased primary productivity of grassland vegetation following European settlement in Australia. Spatial patterns in macropod body size supported the heat dissipation limit and productivity hypotheses proposed to explain geographic body-size variation (i.e. skull size increased with decreasing summer maximum temperature and increasing rainfall, respectively). There is no empirical evidence that size-selective harvesting has driven the evolution of smaller body size in Australian macropods. Bayesian models are appropriate for investigating the long-term impact of human harvesting because they can impute missing data, fit nonlinear growth models and account for non-random spatial sampling inherent in wildlife collections. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Multiple origins of gigantism in stem baleen whales

NASA Astrophysics Data System (ADS)

Tsai, Cheng-Hsiu; Kohno, Naoki

2016-12-01

Living baleen whales (Mysticeti) include the world's largest animals to have ever lived—blue whales ( Balaenoptera musculus) can reach more than 30 m. However, the gigantism in baleen whales remains little explored. Here, we compiled all published stem mysticetes from the Eocene and Oligocene and then mapped the estimated body size onto different phylogenies that suggest distinct evolutionary histories of baleen whales. By assembling all known stem baleen whales, we present three novel findings in early mysticete evolution. Results show that, regardless of different phylogenetic scenarios, large body size (more than 5-m long) evolved multiple times independently in their early evolutionary history. For example, the earliest known aetiocetid ( Fucaia buelli, 33-31 Ma) was small in size, about 2 m, and a later aetiocetid ( Morawanocetus-like animal, 26-23 Ma) can reach 8-m long—almost four times the size of Fucaia buelli—suggesting an independent gigantism in the aetiocetid lineage. In addition, our reconstruction of ancestral state demonstrates that the baleen whales originated from small body size (less than 5 m) rather than large body size as previously acknowledged. Moreover, reconstructing the evolution of body size in stem baleen whales suggests that the initial pulse of mysticete gigantism started at least back to the Paleogene and in turn should help to understand the origin, pattern, and process of the extreme gigantism in the crown baleen whales. This study illustrates that Cope's rule is insufficient to explain the evolution of body size in a group that comprises the largest animals in the history of life, although currently the lack of exact ancestor-descendant relationships remains to fully reveal the evolutionary history of body size.

Multiple origins of gigantism in stem baleen whales.

PubMed

Tsai, Cheng-Hsiu; Kohno, Naoki

2016-12-01

Living baleen whales (Mysticeti) include the world's largest animals to have ever lived-blue whales (Balaenoptera musculus) can reach more than 30 m. However, the gigantism in baleen whales remains little explored. Here, we compiled all published stem mysticetes from the Eocene and Oligocene and then mapped the estimated body size onto different phylogenies that suggest distinct evolutionary histories of baleen whales. By assembling all known stem baleen whales, we present three novel findings in early mysticete evolution. Results show that, regardless of different phylogenetic scenarios, large body size (more than 5-m long) evolved multiple times independently in their early evolutionary history. For example, the earliest known aetiocetid (Fucaia buelli, 33-31 Ma) was small in size, about 2 m, and a later aetiocetid (Morawanocetus-like animal, 26-23 Ma) can reach 8-m long-almost four times the size of Fucaia buelli-suggesting an independent gigantism in the aetiocetid lineage. In addition, our reconstruction of ancestral state demonstrates that the baleen whales originated from small body size (less than 5 m) rather than large body size as previously acknowledged. Moreover, reconstructing the evolution of body size in stem baleen whales suggests that the initial pulse of mysticete gigantism started at least back to the Paleogene and in turn should help to understand the origin, pattern, and process of the extreme gigantism in the crown baleen whales. This study illustrates that Cope's rule is insufficient to explain the evolution of body size in a group that comprises the largest animals in the history of life, although currently the lack of exact ancestor-descendant relationships remains to fully reveal the evolutionary history of body size.

Integrating conservation and development at the National Marine Park of Alonissos, Northern Sporades, Greece: perception and practice.

PubMed

Oikonomou, Zoi-Sylvia; Dikou, Angela

2008-11-01

Available information on the socioeconomic implications of marine protected areas (MPAs) for the socioculturally diverse Mediterranean region is scant. The National Marine Park of Alonissos, Northern Sporades (NMPANS), Greece was established in 1992 as a foundation for the conservation of the endangered Mediterranean monk seal Monachus monachus. The evolution of the degree of acceptance of and satisfaction from the NMPANS by involved stakeholder groups (fishermen, tourism operators, hoteliers and owners of rooms to let, governmental bodies, nongovernmental bodies, students, domestic and foreign tourists) were investigated 13 years after its establishment using written questionnaires delivered during personal interviews. The initial positive attitude of local professionals for the NMPANS has eroded due to the unsatisfactory fulfillment of expectations for socioeconomic development. Fishermen expressed dissatisfaction with, mistrust toward, and a reluctancy to communicate with the NMPANS's management body. They believe that the fishery areas have decreased in actual geographic area because of the prohibitive measures; fish stocks are declining; compensation for damage to fishery equipment by the Mediterranean monk seal and for the prohibitive measures should be provided; and stricter enforcement of regulations should take place. On the other hand, tourism operators, who organize trips for tourists to the NMPANS, unanimously reported direct economic benefits. Furthermore, there was a disparity in the perception of socioeconomic benefits derived from the NMPANS between governmental bodies and local stakeholders. The governmental bodies and the nongovernmental organization MOm-Hellenic Society for the Study and Protection of the Monk Seal postulated that there had been considerable socioeconomic benefits for the local community of Alonissos due to the establishment of the NMPANS, whereas the local nongovernmental organization Ecological and Cultural Movement of Alonissos claimed benefits were scant. Tourists (domestic and foreign) believe that the NMPANS is not the main attraction to Alonissos Island but is part of a composite, including serenity, aesthetic beauty, and small-scale tourism development, which can turn Alonissos Island into an ideal eco-tourism destination; a common aspiration for both the tourists and the local community by general consensus. The aim of the NMPANS to integrate conservation and development lies in (1) the effectiveness of the NMPANS management body in formulating a strategic management plan that would accommodate stakeholders' interests and aspirations and (2) a national policy of conservation and enhancement of natural resources with consistency and continuity. Quantitative assessment of the socioeconomic effectiveness of the Mediterranean MPAs using a common methodology would facilitate the identification of intraregional variation and better planning for the network of MPAs in the Mediterranean.

Integrating Conservation and Development at the National Marine Park of Alonissos, Northern Sporades, Greece: Perception and Practice

NASA Astrophysics Data System (ADS)

Oikonomou, Zoi-Sylvia; Dikou, Angela

2008-11-01

Available information on the socioeconomic implications of marine protected areas (MPAs) for the socioculturally diverse Mediterranean region is scant. The National Marine Park of Alonissos, Northern Sporades (NMPANS), Greece was established in 1992 as a foundation for the conservation of the endangered Mediterranean monk seal Monachus monachus. The evolution of the degree of acceptance of and satisfaction from the NMPANS by involved stakeholder groups (fishermen, tourism operators, hoteliers and owners of rooms to let, governmental bodies, nongovernmental bodies, students, domestic and foreign tourists) were investigated 13 years after its establishment using written questionnaires delivered during personal interviews. The initial positive attitude of local professionals for the NMPANS has eroded due to the unsatisfactory fulfillment of expectations for socioeconomic development. Fishermen expressed dissatisfaction with, mistrust toward, and a reluctancy to communicate with the NMPANS’s management body. They believe that the fishery areas have decreased in actual geographic area because of the prohibitive measures; fish stocks are declining; compensation for damage to fishery equipment by the Mediterranean monk seal and for the prohibitive measures should be provided; and stricter enforcement of regulations should take place. On the other hand, tourism operators, who organize trips for tourists to the NMPANS, unanimously reported direct economic benefits. Furthermore, there was a disparity in the perception of socioeconomic benefits derived from the NMPANS between governmental bodies and local stakeholders. The governmental bodies and the nongovernmental organization MOm-Hellenic Society for the Study and Protection of the Monk Seal postulated that there had been considerable socioeconomic benefits for the local community of Alonissos due to the establishment of the NMPANS, whereas the local nongovernmental organization Ecological and Cultural Movement of Alonissos claimed benefits were scant. Tourists (domestic and foreign) believe that the NMPANS is not the main attraction to Alonissos Island but is part of a composite, including serenity, aesthetic beauty, and small-scale tourism development, which can turn Alonissos Island into an ideal eco-tourism destination; a common aspiration for both the tourists and the local community by general consensus. The aim of the NMPANS to integrate conservation and development lies in (1) the effectiveness of the NMPANS management body in formulating a strategic management plan that would accommodate stakeholders’ interests and aspirations and (2) a national policy of conservation and enhancement of natural resources with consistency and continuity. Quantitative assessment of the socioeconomic effectiveness of the Mediterranean MPAs using a common methodology would facilitate the identification of intraregional variation and better planning for the network of MPAs in the Mediterranean.

A virtual tour of the Galilean Satellites

NASA Astrophysics Data System (ADS)

Schenk, Paul

2010-01-01

Galileo's imagination was quick to comprehend the importance of the 4 starry objects he observed near Jupiter in January 1610, not only for himself as a scientist but for our common understanding of the place of the Earth and our species in the cosmos. Even he, however, could not have imagined what those four objects would actually look like once humans got their first good look. Some 369 years the fast traveling Voyager 1 and 2 spacecraft provided that first good look during 1979, followed by an even closer look from the Galileo Orbiter beginning in 1996 through 2001. The following mosaics represent some of the best of those views. They include views of impact craters young and ancient, icy terrains that have been intensely faulted, eroded or disrupted, mountains towering 10 or more kilometers high, and volcanic eruptions hotter than those on Earth. Each of the four Galilean satellites is geologically distinct, betraying very diverse global histories and evolutions. Images and other observations of these 4 objects revealed the importance of tidal heating and subsurface water oceans in planetary evolution, but mapping is very incomplete. New missions to explore these planetary bodies are being planned and the images and observations of the missions that went before will lay the groundwork for these new explorations as we begin the 5th Galilean century.

The Lateral Somitic Frontier in Ontogeny and Phylogeny*

PubMed Central

SHEARMAN, REBECCA MARIE; BURKE, ANN CAMPBELL

2010-01-01

The vertebrate musculoskeletal system comprises the axial and appendicular systems. The postcranial axial system consists of the vertebrae, ribs and associated muscles, and the appendicular system comprises the muscles and skeleton of the paired appendages and their respective girdles. The morphology, proportions, and arrangements of these parts have undergone tremendous variation during vertebrate history. Despite this vertebrate diversity, the cells that form all of the key parts of the musculoskeletal system during development arise from two populations of embryonic mesoderm, the somites and somatic lateral plate. Nowicki et al. (2003. Mech Dev 120:227–240) identified two dynamic domains in the developing chick embryo. The primaxial domain is populated exclusively by cells from the somites. The abaxial domain includes muscle and bone that develop within lateral plate-derived connective tissue. The boundary between the two domains is the lateral somitic frontier. We hypothesize that the primaxial and abaxial domains are patterned independently and that morphological evolution of the musculoskeletal system is facilitated by partially independent developmental changes in the abaxial and primaxial domain. Here we present our hypothesis in detail and review recent experimental and comparative studies that use the concept of the lateral somitic frontier in the analysis of the evolution of the highly derived chelonian and limbless squamate body plans. PMID:19021255

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science

NASA Technical Reports Server (NTRS)

Cooper, John F.

2011-01-01

We often look "through a glass, darkly" at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers are radiation crusts on cometary nuclei and iogenic components of sulfate hydrate deposits on the trailing hemisphere of Europa. Weathering processes include plasma ion implantation into surfaces, sputtering by charged particles and solar ultraviolet photons, photolytic chemistry driven by UV irradiation, and radiolytic chemistry evolving from products of charged particle irradiation. Regolith structure from impacts, and underlying deeper structures from internal evolution, affects efficacy of certain surface interactions, e.g. sputtering as affected by porosity and surface irradiation dosage as partly attenuated by local topographic shielding. These processes should be regarded for mission science planning as potentially enabling, e.g. since direct surface sputtering, and resultant surface-bound exospheres, can provide in-situ samples of surface composition to ion and neutral mass spectrometers on orbital spacecraft. Sample return for highest sensitivity compOSitional and structural analyses at Earth will usually be precluded by limited range of surface sampling, long times for return, and high cost. Targeted advancements in instrument technology would be more cost efficient for local remote and in-situ sample analysis. More realistic laboratory simulations, e.g. for bulk samples, are needed to interpret mission science observations of weathered surfaces. Space environment effects on mission spacecraft and science operations must also be specified and mitigated from the hourly to monthly changes in space weather and from longer term (e.g., solar cycle) evolution of space climate. Capable instrumentation on planetary missions can and should be planned to contribute to knowledge of interplanetary space environments. Evolving data system technologies such as virtual observatories should be explored for more interdisciplinary application to the science of planetary surface, atmospheric, magnetospheric, and interplanetary interactions.

THE EVOLUTION OF SCHOOL MATHEMATICS.

ERIC Educational Resources Information Center

DAVIS, ROBERT B.

ACTION AND PLANS OF THE MADISON PROJECT TO GIVE RATIONAL GUIDANCE TO EVOLUTIONARY CHANGES IN SCHOOL MATHEMATICS ARE DESCRIBED. THE PROJECT ATTEMPTS TO CONTRIBUTE TO RATIONAL GUIDANCE OF EDUCATIONAL EVOLUTION BY MAKING "THRUSTS AND PROBES" INTO THE UNKNOWN POTENTIAL OF MATHEMATICS LEARNING. EXAMPLES ARE--INTRODUCING THE ARITHMETIC OF…

Flight Planning for the International Space Station-Levitation Observation of Dendrite Evolution in Steel Ternary Alloy Rapid Solidification

NASA Technical Reports Server (NTRS)

Flemings, M. C.; Matson, D. M.; Loser, W.; Hyers, R. W.; Rogers, J. R.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The paper is an overview of the status and science for the LODESTARS research project. The program is aimed at understanding how melt convection influences phase selection and the evolution of rapid solidification microstructures

Development of an Operational Model for the Application of Planning-Programming-Budgeting Systems in Local School Districts. Program Budgeting Note 1, Introduction to Program Budgeting.

ERIC Educational Resources Information Center

State Univ. of New York, Buffalo. Western New York School Study Council.

Although the public is best served by governmental agencies which have integrated the major functions of planning, managing, and budgeting, it can be asserted that the planning function is paramount. A review of the evolution of public agency administration in the U.S. reveals that until recent years the planning function has been largely…

The influence of body size and net diversification rate on molecular evolution during the radiation of animal phyla

PubMed Central

Fontanillas, Eric; Welch, John J; Thomas, Jessica A; Bromham, Lindell

2007-01-01

Background Molecular clock dates, which place the origin of animal phyla deep in the Precambrian, have been used to reject the hypothesis of a rapid evolutionary radiation of animal phyla supported by the fossil record. One possible explanation of the discrepancy is the potential for fast substitution rates early in the metazoan radiation. However, concerted rate variation, occurring simultaneously in multiple lineages, cannot be detected by "clock tests", and so another way to explore such variation is to look for correlated changes between rates and other biological factors. Here we investigate two possible causes of fast early rates: change in average body size or diversification rate of deep metazoan lineages. Results For nine genes for phylogenetically independent comparisons between 50 metazoan phyla, orders, and classes, we find a significant correlation between average body size and rate of molecular evolution of mitochondrial genes. The data also indicate that diversification rate may have a positive effect on rates of mitochondrial molecular evolution. Conclusion If average body sizes were significantly smaller in the early history of the Metazoa, and if rates of diversification were much higher, then it is possible that mitochondrial genes have undergone a slow-down in evolutionary rate, which could affect date estimates made from these genes. PMID:17592650

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

PubMed

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

2017-11-15

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

Size-dependent selective mechanisms on males and females and the evolution of sexual size dimorphism in frogs.

PubMed

Nali, Renato C; Zamudio, Kelly R; Haddad, Célio F B; Prado, Cynthia P A

2014-12-01

Sexual size dimorphism (SSD) varies in animals from male biased to female biased. The evolution of SSD is potentially influenced by a number of factors, such as territoriality, fecundity, and temporal breeding patterns (explosive vs. prolonged). In general, frogs show female-biased SSD with broad variance among species. Using comparative methods, we examine how different selective forces affect male and female sizes, and we test hypotheses about size-dependent mechanisms shaping SSD in frogs. Male size was weakly associated with SSD in all size classes, and we found no significant association among SSD, male size, temporal breeding pattern, and male territoriality. In contrast, female size best explained SSD variation across all size classes but especially for small-bodied species. We found a stronger evolutionary association between female body size and fecundity, and this fecundity advantage was highest in explosively breeding species. Our data indicate that the fecundity advantage associated with female body size may not be linear, such that intermediate and large females benefit less with body size increases. Therefore, size-dependent selection in females associated with fecundity and breeding patterns is an important mechanism driving SSD evolution in frogs. Our study underscores the fact that lineage-specific ecology and behavior should be incorporated in comparative analyses of animal SSD.

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

PubMed

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

2017-02-01

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

Changes in body composition of high competition rugby players during the phases of a regular season; influence of diet and exercise load.

PubMed

García, M; Martínez-Moreno, J M; Reyes-Ortiz, A; Suarez Moreno-Arrones, L; García A, A; Garcíacaballero, M

2014-04-01

Top athletes are subjected to intense training to achieve high performance. There are factors such as diet and strenuous exercise that affects body composition and can modify the performance. The aim of the study was to evaluate the effect of a personalized plan of diet and training on body composition. We studied the body composition of 18 professional rugby players using Kinanthropometry parameters. The study was conducted from the preseason to the end of the season taking into account the position of the player for measuring exercise intensity, and developing a personalized nutritional and training plan to each player. At baseline the players were away from the internationally recommended body composition, with high percentages of body fat. Appropriate and personalized diet plans and training custom achieved fat percentages close to those recommended. The personalized program of diet and training directed has adequate leverage to improve all parameters studied them bringing them as close to the ideal. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Schooling the Dancer: The Evolution of an Identity as a Ballet Dancer

ERIC Educational Resources Information Center

Pickard, Angela

2012-01-01

This paper explores how young ballet dancers' bodies are constructed and narrated through their desire to become performing ballet dancers. The schooling of the balletic body engages the young dancer in embodying the discipline of ballet and in developing a particular belief in a performing body. The embodied set of acquired dispositions that are…

Feminist Pedagogy, Body Image, and the Dance Technique Class

ERIC Educational Resources Information Center

Barr, Sherrie; Oliver, Wendy

2016-01-01

This paper investigates the evolution of feminist consciousness in dance technique class as related to body image, the myth of the perfect body, and the development of feminist pedagogy. Western concert dance forms have often been taught in a manner where imitating the teacher is primary in the learning process. In this traditional scenario,…

Comparison between whole-body and head and neck neurovascular coils for 3-T magnetic resonance proton resonance frequency shift thermography guidance in the head and neck region.

PubMed

Ginat, Daniel Thomas; Anthony, Gregory J; Christoforidis, Gregory; Oto, Aytekin; Dalag, Leonard; Sammet, Steffen

2018-02-01

The purpose of this study is to compare the image quality of magnetic resonance (MR) treatment planning images and proton resonance frequency (PRF) shift thermography images and inform coil selection for MR-guided laser ablation of tumors in the head and neck region. Laser ablation was performed on an agar phantom and monitored via MR PRF shift thermography on a 3-T scanner, following acquisition of T1-weighted (T1W) planning images. PRF shift thermography images and T2-weighted (T2W) planning images were also performed in the neck region of five normal human volunteers. Signal-to-noise ratios (SNR) and temperature uncertainty were calculated and compared between scans acquired with the quadrature mode body integrated coil and a head and neck neurovascular coil. T1W planning images of the agar phantom produced SNRs of 4.0 and 12.2 for the quadrature mode body integrated coil and head and neck neurovascular coil, respectively. The SNR of the phantom MR thermography magnitude images obtained using the quadrature mode body integrated coil was 14.4 versus 59.6 using the head and neck coil. The average temperature uncertainty for MR thermography performed on the phantom with the quadrature mode body integrated coil was 1.1 versus 0.3 °C with the head and neck coil. T2W planning images of the neck in five human volunteers produced SNRs of 28.3 and 91.0 for the quadrature mode body integrated coil and head and neck coil, respectively. MR thermography magnitude images of the neck in the volunteers obtained using the quadrature mode body integrated coil had a signal-to-noise ratio of 8.3, while the SNR using the head and neck coil was 16.1. The average temperature uncertainty for MR thermography performed on the volunteers with the body coil was 2.5 versus 1.6 °C with the head and neck neurovascular coil. The quadrature mode body integrated coil provides inferior image quality for both basic treatment planning sequences and MR PRF shift thermography compared with a neurovascular coil, but may nevertheless be adequate for clinical purposes.

Developing biology teachers' pedagogical content knowledge through learning study: the case of teaching human evolution

NASA Astrophysics Data System (ADS)

Bravo, Paulina; Cofré, Hernán

2016-11-01

This work explores how pedagogical content knowledge (PCK) on evolution was modified by two biology teachers who participated in a professional development programme (PDP) that included a subsequent follow-up in the classroom. The PDP spanned a semester and included activities such as content updates, collaborative lesson planning, and the presentation of planned lessons. In the follow-up part, the lessons were videotaped and analysed, identifying strategies, activities, and conditions based on student learning about the theory of evolution. Data were collected in the first round with an interview before the training process, identifying these teachers' initial content representation (CoRe) for evolution. Then, a group interview was conducted after the lessons, and, finally, an interview of stimulated recall with each teacher was conducted regarding the subject taught to allow teachers to reflect on their practice (final CoRe). This information was analysed by the teachers and the researchers, reflecting on the components of the PCK, possible changes, and the rationale behind their actions. The results show that teachers changed their beliefs and knowledge about the best methods and strategies to teach evolution, and about students' learning obstacles and misconceptions on evolution. They realised how a review of their own practices promotes this transformation.

Composite Agency: Semiotics of Modularity and Guiding Interactions.

PubMed

Sharov, Alexei A

2017-07-01

Principles of constructivism are used here to explore how organisms develop tools, subagents, scaffolds, signs, and adaptations. Here I discuss reasons why organisms have composite nature and include diverse subagents that interact in partially cooperating and partially conflicting ways. Such modularity is necessary for efficient and robust functionality, including mutual construction and adaptability at various time scales. Subagents interact via material and semiotic relations, some of which force or prescribe actions of partners. Other interactions, which I call "guiding", do not have immediate effects and do not disrupt the evolution and learning capacity of partner agents. However, they modify the extent of learning and evolutionary possibilities of partners via establishment of scaffolds and constraints. As a result, subagents construct reciprocal scaffolding for each other to rebalance their communal evolution and learning. As an example, I discuss guiding interactions between the body and mind of animals, where the pain system adjusts mind-based learning to the physical and physiological constraints of the body. Reciprocal effects of mind and behaviors on the development and evolution of the body includes the effects of Lamarck and Baldwin.

Evolution of a proto-neutron star with a nuclear many-body equation of state: Neutrino luminosity and gravitational wave frequencies

DOE PAGES

Camelio, Giovanni; Lovato, Alessandro; Gualtieri, Leonardo; ...

2017-08-30

In a core-collapse supernova, a huge amount of energy is released in the Kelvin-Helmholtz phase subsequent to the explosion, when the proto-neutron star cools and deleptonizes as it loses neutrinos. Most of this energy is emitted through neutrinos, but a fraction of it can be released through gravitational waves. We model the evolution of a proto-neutron star in the Kelvin-Helmholtz phase using a general relativistic numerical code, and a recently proposed finite temperature, many-body equation of state; from this we consistently compute the diffusion coefficients driving the evolution. To include the many-body equation of state, we develop a new fittingmore » formula for the high density baryon free energy at finite temperature and intermediate proton fraction. Here, we estimate the emitted neutrino signal, assessing its detectability by present terrestrial detectors, and we determine the frequencies and damping times of the quasinormal modes which would characterize the gravitational wave signal emitted in this stage.« less

Evolution of a proto-neutron star with a nuclear many-body equation of state: Neutrino luminosity and gravitational wave frequencies

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

Camelio, Giovanni; Lovato, Alessandro; Gualtieri, Leonardo

In a core-collapse supernova, a huge amount of energy is released in the Kelvin-Helmholtz phase subsequent to the explosion, when the proto-neutron star cools and deleptonizes as it loses neutrinos. Most of this energy is emitted through neutrinos, but a fraction of it can be released through gravitational waves. We model the evolution of a proto-neutron star in the Kelvin-Helmholtz phase using a general relativistic numerical code, and a recently proposed finite temperature, many-body equation of state; from this we consistently compute the diffusion coefficients driving the evolution. To include the many-body equation of state, we develop a new fittingmore » formula for the high density baryon free energy at finite temperature and intermediate proton fraction. Here, we estimate the emitted neutrino signal, assessing its detectability by present terrestrial detectors, and we determine the frequencies and damping times of the quasinormal modes which would characterize the gravitational wave signal emitted in this stage.« less

Effects of Combined Stellar Feedback on Star Formation in Stellar Clusters

NASA Astrophysics Data System (ADS)

Wall, Joshua Edward; McMillan, Stephen; Pellegrino, Andrew; Mac Low, Mordecai; Klessen, Ralf; Portegies Zwart, Simon

2018-01-01

We present results of hybrid MHD+N-body simulations of star cluster formation and evolution including self consistent feedback from the stars in the form of radiation, winds, and supernovae from all stars more massive than 7 solar masses. The MHD is modeled with the adaptive mesh refinement code FLASH, while the N-body computations are done with a direct algorithm. Radiation is modeled using ray tracing along long characteristics in directions distributed using the HEALPIX algorithm, and causes ionization and momentum deposition, while winds and supernova conserve momentum and energy during injection. Stellar evolution is followed using power-law fits to evolution models in SeBa. We use a gravity bridge within the AMUSE framework to couple the N-body dynamics of the stars to the gas dynamics in FLASH. Feedback from the massive stars alters the structure of young clusters as gas ejection occurs. We diagnose this behavior by distinguishing between fractal distribution and central clustering using a Q parameter computed from the minimum spanning tree of each model cluster. Global effects of feedback in our simulations will also be discussed.

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

PubMed

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

2018-05-17

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

SU-E-T-540: Volumetric Modulated Total Body Irradiation Using a Rotational Lazy Susan-Like Immobilization System

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

Gu, X; Hrycushko, B; Lee, H

2014-06-01

Purpose: Traditional extended SSD total body irradiation (TBI) techniques can be problematic in terms of patient comfort and/or dose uniformity. This work aims to develop a comfortable TBI technique that achieves a uniform dose distribution to the total body while reducing the dose to organs at risk for complications. Methods: To maximize patient comfort, a lazy Susan-like couch top immobilization system which rotates about a pivot point was developed. During CT simulation, a patient is immobilized by a Vac-Lok bag within the body frame. The patient is scanned head-first and then feet-first following 180° rotation of the frame. The twomore » scans are imported into the Pinnacle treatment planning system and concatenated to give a full-body CT dataset. Treatment planning matches multiple isocenter volumetric modulated arc (VMAT) fields of the upper body and multiple isocenter parallel-opposed fields of the lower body. VMAT fields of the torso are optimized to satisfy lung dose constraints while achieving a therapeutic dose to the torso. The multiple isocenter VMAT fields are delivered with an indexed couch, followed by body frame rotation about the pivot point to treat the lower body isocenters. The treatment workflow was simulated with a Rando phantom, and the plan was mapped to a solid water slab phantom for point- and film-dose measurements at multiple locations. Results: The treatment plan of 12Gy over 8 fractions achieved 80.2% coverage of the total body volume within ±10% of the prescription dose. The mean lung dose was 8.1 Gy. All ion chamber measurements were within ±1.7% compared to the calculated point doses. All relative film dosimetry showed at least a 98.0% gamma passing rate using a 3mm/3% passing criteria. Conclusion: The proposed patient comfort-oriented TBI technique provides for a uniform dose distribution within the total body while reducing the dose to the lungs.« less

Early bursts of body size and shape evolution are rare in comparative data.

PubMed

Harmon, Luke J; Losos, Jonathan B; Jonathan Davies, T; Gillespie, Rosemary G; Gittleman, John L; Bryan Jennings, W; Kozak, Kenneth H; McPeek, Mark A; Moreno-Roark, Franck; Near, Thomas J; Purvis, Andy; Ricklefs, Robert E; Schluter, Dolph; Schulte Ii, James A; Seehausen, Ole; Sidlauskas, Brian L; Torres-Carvajal, Omar; Weir, Jason T; Mooers, Arne Ø

2010-08-01

George Gaylord Simpson famously postulated that much of life's diversity originated as adaptive radiations-more or less simultaneous divergences of numerous lines from a single ancestral adaptive type. However, identifying adaptive radiations has proven difficult due to a lack of broad-scale comparative datasets. Here, we use phylogenetic comparative data on body size and shape in a diversity of animal clades to test a key model of adaptive radiation, in which initially rapid morphological evolution is followed by relative stasis. We compared the fit of this model to both single selective peak and random walk models. We found little support for the early-burst model of adaptive radiation, whereas both other models, particularly that of selective peaks, were commonly supported. In addition, we found that the net rate of morphological evolution varied inversely with clade age. The youngest clades appear to evolve most rapidly because long-term change typically does not attain the amount of divergence predicted from rates measured over short time scales. Across our entire analysis, the dominant pattern was one of constraints shaping evolution continually through time rather than rapid evolution followed by stasis. We suggest that the classical model of adaptive radiation, where morphological evolution is initially rapid and slows through time, may be rare in comparative data.

Kennedy Space Center Orion Processing Team Planning for Ground Operations

NASA Technical Reports Server (NTRS)

Letchworth, Gary; Schlierf, Roland

2011-01-01

Topics in this presentation are: Constellation Ares I/Orion/Ground Ops Elements Orion Ground Operations Flow Orion Operations Planning Process and Toolset Overview, including: 1 Orion Concept of Operations by Phase 2 Ops Analysis Capabilities Overview 3 Operations Planning Evolution 4 Functional Flow Block Diagrams 5 Operations Timeline Development 6 Discrete Event Simulation (DES) Modeling 7 Ground Operations Planning Document Database (GOPDb) Using Operations Planning Tools for Operability Improvements includes: 1 Kaizen/Lean Events 2 Mockups 3 Human Factors Analysis

Comparing Common Origins: Using Biotechnology To Teach Evolution.

ERIC Educational Resources Information Center

McLaughlin, John; Glasson, George

2001-01-01

Presents an innovative, inquiry-oriented lesson plan for using biotechnology to teach evolution. Using acrylamide gel electrophoresis, students learn how to isolate and compare different proteins from the muscle tissue of readily available seafood specimens to determine phylogenetic relationships. Uses a 5E (engagement, exploration, explanation,…

Evolution and advanced technology. [of Flight Telerobotic Servicer

NASA Technical Reports Server (NTRS)

Ollendorf, Stanford; Pennington, Jack E.; Hansen, Bert, III

1990-01-01

The NASREM architecture with its standard interfaces permits development and evolution of the Flight Telerobotic Servicer to greater autonomy. Technologies in control strategies for an arm with seven DOF, including a safety system containing skin sensors for obstacle avoidance, are being developed. Planning and robotic execution software includes symbolic task planning, world model data bases, and path planning algorithms. Research over the last five years has led to the development of laser scanning and ranging systems, which use coherent semiconductor laser diodes for short range sensing. The possibility of using a robot to autonomously assemble space structures is being investigated. A control framework compatible with NASREM is being developed that allows direct global control of the manipulator. Researchers are developing systems that permit an operator to quickly reconfigure the telerobot to do new tasks safely.

A prototype for understanding the effects of TMDL standards: Tying property values to sediment loads in the Lake Tahoe Basin

USGS Publications Warehouse

Tracy, J.C.; Bernknopf, R.; Forney, W.; Hill, K.

2004-01-01

The Federal Clean Water Act (Section 303(d)) mandates that states develop Total Maximum Daily Load (TMDL) plans for water bodies that are on the Section 303(d) list. To be placed on the 303(d) list, a water body must be found to have water quality conditions that limit its ability to meet its designated beneficial uses. The TMDL for a water body is defined in 40 CFR 130 as the sum of waste load allocations from identified points sources and non-point sources within the water body's watershed. The TMDL plan for a listed water body should identify the current waste loads to the water body, the waste load capacity of the water body and then allocate the waste load capacity to the known point and non-point sources of pollution within the water body's watershed. Copyright 2004 ASCE.

The Evolution of Morphospace in Phytophagous Scarab Chafers: No Competition - No Divergence?

PubMed Central

Eberle, Jonas; Myburgh, Renier; Ahrens, Dirk

2014-01-01

Body shape reflects species' evolution and mediates its role in the environment as it integrates gene expression, life style, and structural morphology. Its comparative analysis may reveal insight on what shapes shape, being a useful approach when other evidence is lacking. Here we investigated evolutionary patterns of body shape in the highly diverse phytophagous chafers (Scarabaeidae: Pleurosticti), a polyphagous group utilizing different parts of angiosperms. Because the reasons of their successful diversification are largely unknown, we used a phylogenetic tree and multivariate analysis on twenty linear measurements of body morphology including all major Pleurosticti lineages to infer patterns of morphospace covariation and divergence. The chafer's different feeding types resulted to be not distinguishable in the described morphospace which was largely attributed to large occupancy of the morphospace of some feeding types and to multiple convergences of feeding behavior (particularly of anthophagy). Low correlation between molecular and morphological rates of evolution, including significant rate shifts for some lineages, indicated directed selection within feeding types. This is supported by morphospace divergence within feeding types and convergent evolution in Australian Melolonthinae. Traits driving morphospace divergence were extremities and traits linked with locomotion behavior, but also body size. Being highly adaptive for burrowing and locomotion these traits showed major changes in the evolution of pleurostict scarabs. These activities also affected another trait, the metacoxal length, which is highly influenced by key innovations of the metacoxa (extended mesal process, secondary closure) particularly in one lineage, the Sericini. Significant shape divergence between major lineages and a lack of strong differentiation among closely related lineages indicated that the question about the presence or absence of competition-derived directed selection needs to be addressed for different time scales. Striking divergence between some sister lineages at their origin revealed strong driven selection towards morphospace divergence, possibly linked with resource partitioning. PMID:24875856

Interworking evolution of mobile satellite and terrestrial networks

NASA Technical Reports Server (NTRS)

Matyas, R.; Kelleher, P.; Moller, P.; Jones, T.

1993-01-01

There is considerable interest among mobile satellite service providers in interworking with terrestrial networks to provide a universal global network. With such interworking, subscribers may be provided a common set of services such as those planned for the Public Switched Telephone Network (PSTN), the Integrated Services Digital Network (ISDN), and future Intelligent Networks (IN's). This paper first reviews issues in satellite interworking. Next the status and interworking plans of terrestrial mobile communications service providers are examined with early examples of mobile satellite interworking including a discussion of the anticipated evolution towards full interworking between mobile satellite and both fixed and mobile terrestrial networks.

The evolution of inducible defence.

PubMed

Harvell, C D

1990-01-01

Defences against parasites are characterized by inducible, amplifiable responses, often with a memory component. Inducible defences with similar properties are common in a variety of other types of interactions, for example many aquatic invertebrates produce inducible structural defences against their predators and competitors. Most inducible defences have the following properties: (1) a threshold of activation; (2) an amplification of response with increasing stimulus; (3) a memory component. Specificity, amplification and memory are the basis for defining a defence as 'immune' (Klein, 1982), and these properties are present in both the vertebrate and invertebrate internal defence responses to pathogens. Invertebrates differ in the absence of immunoglobulins and therefore in reduced specificity. Although the reduced specificity of invertebrate internal defence systems is often viewed as proof of their 'primitiveness', the differences in defence systems of vertebrates and invertebrates may be more related to their respective selection regimes than to phylogeny. The syngeneic recognition system of vertebrates functions to recognize small departures from self, such as would arise from neoplasia. Are vertebrates under more intense selection from neoplasia, perhaps due to a greater incidence of hormonal imbalance or hypersensitivity reactions? The invertebrate internal defence systems are all less discriminating than the vertebrate, but there are marked differences in degree of discrimination depending on whether the group is colonial or not. Even the phyla of colonial animals with quite simple body plans, the sponges and cnidarians, have a more discriminating recognition system than the phyla of solitary animals with more complex body plans, such as the molluscs and arthropods. The primary effectors of all invertebrate responses to parasites are encapsulation and phagocytosis, although in some phyla there are specific antibacterial proteins than can also be induced.(ABSTRACT TRUNCATED AT 250 WORDS)

Robot body self-modeling algorithm: a collision-free motion planning approach for humanoids.

PubMed

Leylavi Shoushtari, Ali

2016-01-01

Motion planning for humanoid robots is one of the critical issues due to the high redundancy and theoretical and technical considerations e.g. stability, motion feasibility and collision avoidance. The strategies which central nervous system employs to plan, signal and control the human movements are a source of inspiration to deal with the mentioned problems. Self-modeling is a concept inspired by body self-awareness in human. In this research it is integrated in an optimal motion planning framework in order to detect and avoid collision of the manipulated object with the humanoid body during performing a dynamic task. Twelve parametric functions are designed as self-models to determine the boundary of humanoid's body. Later, the boundaries which mathematically defined by the self-models are employed to calculate the safe region for box to avoid the collision with the robot. Four different objective functions are employed in motion simulation to validate the robustness of algorithm under different dynamics. The results also confirm the collision avoidance, reality and stability of the predicted motion.

Can Foraging Ecology Drive the Evolution of Body Size in a Diving Endotherm?

PubMed Central

Cook, Timothée R.; Lescroël, Amélie; Cherel, Yves; Kato, Akiko; Bost, Charles-André

2013-01-01

Within a single animal species, different morphs can allow for differential exploitation of foraging niches between populations, while sexual size dimorphism can provide each sex with access to different resources. Despite being potentially important agents of evolution, resource polymorphisms, and the way they operate in wild populations, remain poorly understood. In this study, we examine how trophic factors can select for different body sizes between populations and sexes in a diving endotherm. Dive depth and duration are positively related to body size in diving birds and mammals, a relationship explained by a lower mass-specific metabolic rate and greater oxygen stores in larger individuals. Based on this allometry, we predict that selection for exploiting resources situated at different depths can drive the evolution of body size in species of diving endotherms at the population and sexual level. To test this prediction, we studied the foraging ecology of Blue-eyed Shags, a group of cormorants with male-biased sexual size dimorphism from across the Southern Ocean. We found that mean body mass and relative difference in body mass between sexes varied by up to 77% and 107% between neighbouring colonies, respectively. Birds from colonies with larger individuals dived deeper than birds from colonies with smaller individuals, when accounting for sex. In parallel, males dived further offshore and deeper than females and the sexual difference in dive depth reflected the level of sexual size dimorphism at each colony. We argue that body size in this group of birds is under intense selection for diving to depths of profitable benthic prey patches and that, locally, sexual niche divergence selection can exaggerate the sexual size dimorphism of Blue-eyed Shags initially set up by sexual selection. Our findings suggest that trophic resources can select for important geographic micro-variability in body size between populations and sexes. PMID:23409169

Can foraging ecology drive the evolution of body size in a diving endotherm?

PubMed

Cook, Timothée R; Lescroël, Amélie; Cherel, Yves; Kato, Akiko; Bost, Charles-André

2013-01-01

Within a single animal species, different morphs can allow for differential exploitation of foraging niches between populations, while sexual size dimorphism can provide each sex with access to different resources. Despite being potentially important agents of evolution, resource polymorphisms, and the way they operate in wild populations, remain poorly understood. In this study, we examine how trophic factors can select for different body sizes between populations and sexes in a diving endotherm. Dive depth and duration are positively related to body size in diving birds and mammals, a relationship explained by a lower mass-specific metabolic rate and greater oxygen stores in larger individuals. Based on this allometry, we predict that selection for exploiting resources situated at different depths can drive the evolution of body size in species of diving endotherms at the population and sexual level. To test this prediction, we studied the foraging ecology of Blue-eyed Shags, a group of cormorants with male-biased sexual size dimorphism from across the Southern Ocean. We found that mean body mass and relative difference in body mass between sexes varied by up to 77% and 107% between neighbouring colonies, respectively. Birds from colonies with larger individuals dived deeper than birds from colonies with smaller individuals, when accounting for sex. In parallel, males dived further offshore and deeper than females and the sexual difference in dive depth reflected the level of sexual size dimorphism at each colony. We argue that body size in this group of birds is under intense selection for diving to depths of profitable benthic prey patches and that, locally, sexual niche divergence selection can exaggerate the sexual size dimorphism of Blue-eyed Shags initially set up by sexual selection. Our findings suggest that trophic resources can select for important geographic micro-variability in body size between populations and sexes.

Phylogenetic analyses suggest that diversification and body size evolution are independent in insects.

PubMed

Rainford, James L; Hofreiter, Michael; Mayhew, Peter J

2016-01-08

Skewed body size distributions and the high relative richness of small-bodied taxa are a fundamental property of a wide range of animal clades. The evolutionary processes responsible for generating these distributions are well described in vertebrate model systems but have yet to be explored in detail for other major terrestrial clades. In this study, we explore the macro-evolutionary patterns of body size variation across families of Hexapoda (insects and their close relatives), using recent advances in phylogenetic understanding, with an aim to investigate the link between size and diversity within this ancient and highly diverse lineage. The maximum, minimum and mean-log body lengths of hexapod families are all approximately log-normally distributed, consistent with previous studies at lower taxonomic levels, and contrasting with skewed distributions typical of vertebrate groups. After taking phylogeny and within-tip variation into account, we find no evidence for a negative relationship between diversification rate and body size, suggesting decoupling of the forces controlling these two traits. Likelihood-based modeling of the log-mean body size identifies distinct processes operating within Holometabola and Diptera compared with other hexapod groups, consistent with accelerating rates of size evolution within these clades, while as a whole, hexapod body size evolution is found to be dominated by neutral processes including significant phylogenetic conservatism. Based on our findings we suggest that the use of models derived from well-studied but atypical clades, such as vertebrates may lead to misleading conclusions when applied to other major terrestrial lineages. Our results indicate that within hexapods, and within the limits of current systematic and phylogenetic knowledge, insect diversification is generally unfettered by size-biased macro-evolutionary processes, and that these processes over large timescales tend to converge on apparently neutral evolutionary processes. We also identify limitations on available data within the clade and modeling approaches for the resolution of trees of higher taxa, the resolution of which may collectively enhance our understanding of this key component of terrestrial ecosystems.

NASA evolution of exploration architectures

NASA Technical Reports Server (NTRS)

Roberts, Barney B.

1991-01-01

A series of charts and diagrams is used to provide a detailed overview of the evolution of NASA space exploration architectures. The pre-Apollo programs including the Werner von Braun feasibility study are discussed and the evolution of the Apollo program itself is treated in detail. The post-Apollo era is reviewed and attention is given to the resurgence of strategic planning exemplified by both ad hoc and formal efforts at planning. Results of NASA's study of the main elements of the Space Exploration Initiative which examined technical scenarios, science opportunities, required technologies, international considerations, institutional strengths and needs, and resource estimates are presented. The 90-day study concludes that, among other things, major investments in challenging technologies are required, the scientific opportunities provided by the program are considerable, current launch capabilities are inadequate, and Space Station Freedom is essential.

On the Coplanar Integrable Case of the Twice-Averaged Hill Problem with Central Body Oblateness

NASA Astrophysics Data System (ADS)

Vashkov'yak, M. A.

2018-01-01

The twice-averaged Hill problem with the oblateness of the central planet is considered in the case where its equatorial plane coincides with the plane of its orbital motion relative to the perturbing body. A qualitative study of this so-called coplanar integrable case was begun by Y. Kozai in 1963 and continued by M.L. Lidov and M.V. Yarskaya in 1974. However, no rigorous analytical solution of the problem can be obtained due to the complexity of the integrals. In this paper we obtain some quantitative evolution characteristics and propose an approximate constructive-analytical solution of the evolution system in the form of explicit time dependences of satellite orbit elements. The methodical accuracy has been estimated for several orbits of artificial lunar satellites by comparison with the numerical solution of the evolution system.

How useful is the `mean stream' in discussing meteoroid stream evolution?

NASA Astrophysics Data System (ADS)

Williams, I. P.; Jones, D. C.

2007-02-01

The current model for meteoroid formation involves particles being ejected from parent objects, usually comets and sometimes asteroids. The orbital speed of any body in the Solar system is much larger than any potential ejection speed of small particles from the body, hence the initial orbit of any meteoroid is fairly similar to that of the parent. However, with the passage of time the effects of gravitational perturbations from the planets and solar radiation will cause the orbits of the meteoroids to evolve away from the parent's orbit. Initially this may cause a meteor shower to occur, but eventually will lead to the dissipation of the stream. When modelling meteoroid streams, it is usually more convenient to use the average orbital elements of all the meteoroids to study their evolution. In this paper, we consider the evolution of the orbits of several sets of meteoroids comparing the effectiveness of using the mean and median values for a stream when modelling the overall evolution. We conclude that although both mean and median provide a good match to the evolution of the real meteoroids for most of the time interval studied, the mean orbit remains more consistently close to the stream.

Exponential Stellar Disks in Low Surface Brightness Galaxies: A Critical Test of Viscous Evolution

NASA Astrophysics Data System (ADS)

Bell, Eric F.

2002-12-01

Viscous redistribution of mass in Milky Way-type galactic disks is an appealing way of generating an exponential stellar profile over many scale lengths, almost independent of initial conditions, requiring only that the viscous timescale and star formation timescale are approximately equal. However, galaxies with solid-body rotation curves cannot undergo viscous evolution. Low surface brightness (LSB) galaxies have exponential surface brightness profiles, yet have slowly rising, nearly solid-body rotation curves. Because of this, viscous evolution may be inefficient in LSB galaxies: the exponential profiles, instead, would give important insight into initial conditions for galaxy disk formation. Using star formation laws from the literature and tuning the efficiency of viscous processes to reproduce an exponential stellar profile in Milky Way-type galaxies, I test the role of viscous evolution in LSB galaxies. Under the conservative and not unreasonable condition that LSB galaxies are gravitationally unstable for at least a part of their lives, I find that it is impossible to rule out a significant role for viscous evolution. This type of model still offers an attractive way of producing exponential disks, even in LSB galaxies with slowly rising rotation curves.

Experimental evolution in Drosophila melanogaster: interaction of temperature and food quality selection regimes.

PubMed

Bochdanovits, Zoltán; de Jong, Gerdien

2003-08-01

In Drosophila, both the phenotypic and evolutionary effect of temperature on adult size involves alterations to larval resource processing and affects other life-history traits, that is, development time but most notably, larval survival. Therefore, thermal evolution of adult body size might not be independent of simultaneous adaptation of larval traits to resource availability. Using experimental evolution lines adapted to high and low temperatures at different levels of food, we show that selection pressures interact in shaping larval resource processing. Evolution on poor food invariably leads to lower resource acquisition suggesting a cost to feeding behavior. However, following low temperature selection, lower resource acquisition led to a higher adult body size, probably by more efficient allocation to growth. In contrast, following high temperature selection, low resource acquisition benefited larval survival, possibly by reducing feeding-associated costs. We show that evolved differences to larval resource processing provide a possible proximate mechanism to variation in a suite of correlated life-history traits during adaptation to different climates. The implication for natural populations is that in nature, thermal evolution drives populations to opposite ends of an adult size versus larval survival trade-off by altering resource processing, if resource availability is limited.

REBOUND-ing Off Asteroids: An N-body Particle Model for Ejecta Dynamics on Small Bodies

NASA Astrophysics Data System (ADS)

Larson, Jennifer; Sarid, Gal

2017-10-01

Here we describe our numerical approach to model the evolution of ejecta clouds. Modeling with an N-body particle method enables us to study the micro-dynamics while varying the particle size distribution. A hydrodynamic approach loses many of the fine particle-particle interactions included in the N-body particle approach (Artemieva 2008).We use REBOUND, an N-body integration package (Rein et al. 2012) developed to model various dynamical systems (planetary orbits, ring systems, etc.) with high resolution calculations at a lower performance cost than other N-body integrators (Rein & Tamayo 2017). It offers both symplectic (WHFast) and non-symplectic (IAS15) methods (Rein & Spiegel 2014, Rein & Tamayo 2015). We primarily use the IAS15 integrator due to its robustness and accuracy with short interaction distances and non-conservative forces. We implemented a wrapper (developed in Python) to handle changes in time step and integrator at different stages of ejecta particle evolution.To set up the system, each particle is given a velocity away from the target body’s surface at a given angle within a defined ejecta cone. We study the ejecta cloud evolution beginning immediately after an impact rather than the actual impact itself. This model considers effects such as varying particle size distribution, radiation pressure, perturbations from a binary component, particle-particle collisions and non-axisymmetric gravity of the target body. Restrictions on the boundaries of the target body’s surface define the physical shape and help count the number of particles that land on the target body. Later, we will build the central body from individual particles to allow for a wider variety of target body shapes and topographies.With our particle modeling approach, individual particle trajectories are tracked and predicted on short, medium and long timescales. Our approach will be applied to modeling of the ejecta cloud produced during the Double Asteroid Redirection Test (DART) impact (Cheng et al. 2016, Schwartz et al. 2016). We will present some preliminary results of our applied model and possible applications to other asteroid impact events and Centaur ring formation mechanisms.

Investigating Island Evolution: A Galapagos-Based Lesson Using the 5E Instructional Model.

ERIC Educational Resources Information Center

DeFina, Anthony V.

2002-01-01

Introduces an inquiry-based lesson plan on evolution and the Galapagos Islands. Uses the 5E instructional model which includes phases of engagement, exploration, explanation, elaboration, and evaluation. Includes information on species for exploration and elaboration purposes, and a general rubric for student evaluation. (YDS)

A spatial analysis of hierarchical waste transport structures under growing demand.

PubMed

Tanguy, Audrey; Glaus, Mathias; Laforest, Valérie; Villot, Jonathan; Hausler, Robert

2016-10-01

The design of waste management systems rarely accounts for the spatio-temporal evolution of the demand. However, recent studies suggest that this evolution affects the planning of waste management activities like the choice and location of treatment facilities. As a result, the transport structure could also be affected by these changes. The objective of this paper is to study the influence of the spatio-temporal evolution of the demand on the strategic planning of a waste transport structure. More particularly this study aims at evaluating the effect of varying spatial parameters on the economic performance of hierarchical structures (with one transfer station). To this end, three consecutive generations of three different spatial distributions were tested for hierarchical and non-hierarchical transport structures based on costs minimization. Results showed that a hierarchical structure is economically viable for large and clustered spatial distributions. The distance parameter was decisive but the loading ratio of trucks and the formation of clusters of sources also impacted the attractiveness of the transfer station. Thus the territories' morphology should influence strategies as regards to the installation of transfer stations. The use of spatial-explicit tools such as the transport model presented in this work that take into account the territory's evolution are needed to help waste managers in the strategic planning of waste transport structures. © The Author(s) 2016.

Treating Type 2 Diabetes

MedlinePlus

... of the treatment plan. Exercise helps improve the body's response to insulin, which helps to control blood sugar levels. It also helps the body burn more calories, which can reduce excess body ...

3-D orbital evolution model of outer asteroid belt

NASA Technical Reports Server (NTRS)

Solovaya, Nina A.; Gerasimov, Igor A.; Pittich, Eduard M.

1992-01-01

The evolution of minor planets in the outer part of the asteroid belt is considered. In the framework of the semi-averaged elliptic restricted three-dimensional three-body model, the boundary of regions of the Hill's stability is found. As was shown in our work, the Jacobian integral exists.

Supporting Source Code Comprehension during Software Evolution and Maintenance

ERIC Educational Resources Information Center

Alhindawi, Nouh

2013-01-01

This dissertation addresses the problems of program comprehension to support the evolution of large-scale software systems. The research concerns how software engineers locate features and concepts along with categorizing changes within very large bodies of source code along with their versioned histories. More specifically, advanced Information…

The Evolution and Effectiveness of Graduated Licensing.

ERIC Educational Resources Information Center

Simpson, Herb M.

2003-01-01

Traces the history and evolution of graduated driver licensing in the United States and elsewhere. Considers the extent to which graduated licensing achieves its objective of reducing collisions. Discusses a growing body of research that shows the effectiveness of the program. (Contains 2 tables and 47 references.) (AUTHOR/WFA)

SU-E-T-106: Development of a Collision Prediction Algorithm for Determining Problematic Geometry for SBRT Treatments Using a Stereotactic Body Frame

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

Wagar, M; Friesen, S; Mannarino, E

2014-06-01

Purpose: Collision between the gantry and the couch or patient during Radiotherapy is not a common concern for conventional RT (static fields or arc). With the increase in the application of stereotactic planning techniques to the body, collisions have become a greater concern. Non-coplanar beam geometry is desirable in stereotatic treatments in order to achieve sharp gradients and a high conformality. Non-coplanar geometry is less intuitive in the body and often requires an iterative process of planning and dry runs to guarantee deliverability. Methods: Purpose written software was developed in order to predict the likelihood of collision between the headmore » of the gantry and the couch, patient or stereotatic body frame. Using the DICOM plan and structures set, exported by the treatment planning system, this software is able to predict the possibility of a collision. Given the plan's isocenter, treatment geometry and exterior contours, the software is able to determine if a particular beam/arc is clinically deliverable or if collision is imminent. Results: The software was tested on real world treatment plans with untreatable beam geometry. Both static non-coplanar and VMAT plans were tested. Of these, the collision prediction software could identify all as having potentially problematic geometry. Re-plans of the same cases were also tested and validated as deliverable. Conclusion: This software is capable of giving good initial indication of deliverability for treatment plans that utilize complex geometry (SBRT) or have lateral isocenters. This software is not intended to replace the standard pre-treatment QA dry run. The effectiveness is limited to those portions of the patient and immobilization devices that have been included in the simulation CT and contoured in the planning system. It will however aid the planner in reducing the iterations required to create complex treatment geometries necessary to achieve ideal conformality and organ sparing.« less

Physical aspects of total-body irradiation at the Middlesex Hospital (UCL group of hospitals), London 1988-1993: I. Phantom measurements and planning methods.

PubMed

Planskoy, B; Bedford, A M; Davis, F M; Tapper, P D; Loverock, L T

1996-11-01

This paper, which is divided into parts I and II, describes the physical aspects of work on total-body irradiation (TBI) at the Middlesex Hospital, London, from 1988 to 1993. Irradiation is fractionated and bi-lateral with horizontal accelerator photon beams of 8 MV (1988-1992) at a source-surface distance (SSD) of 3.36 m and 10 MV (1992-1993) at an SSD of 4.62 m. The main aims were maximum patient comfort, a simple, accurate set-up with overall times per fraction of 30 min or less, dose homogeneity throughout the body within +/- 10 to +/- 15%, pre-irradiation treatment planning on nine CT slices using our commercial IGE RTplan (1988-1992) and Target 2 (1992-1993) treatment planning systems and, most important, verification of the plans by in vivo dosimetry to within +/- 5%. Verification of the planned lung doses, which are distributed over five CT slices, was given special attention. In part I of this paper we describe the preliminary work, most of which was done prior to patient treatment. This consisted of standard dosimetric measurements (central axis depth doses, beam profiles at several depths, build-up and build-down curves, beam output calibrations, effect of body compensators, etc), in evaluating silicon diode dosimeters for in vivo dosimetry and of adapting and verifying the methods of treatment planning for TBI conditions. The results obtained with phantoms, including a Rando body phantom, showed that, in principle, our aims could be achieved. The final proof depended, however, on an analysis of the results of the in vivo work and this forms the subject of part II of this paper.

Dynamical evolution of differentiated asteroid families

NASA Astrophysics Data System (ADS)

Martins-Filho, W. S.; Carvano, J.; Mothe-Diniz, T.; Roig, F.

2014-10-01

The project aims to study the dynamical evolution of a family of asteroids formed from a fully differentiated parent body, considering family members with different physical properties consistent with what is expected from the break up of a body formed by a metallic nucleus surrounded by a rocky mantle. Initially, we study the effects of variations in density, bond albedo, and thermal inertia in the semi-major axis drift caused by the Yarkovsky effect. The Yarkovsky effect is a non-conservative force caused by the thermal re-radiation of the solar radiation by an irregular body. In Solar System bodies, it is known to cause changes in the orbital motions (Peterson, 1976), eventually bringing asteroids into transport routes to near-Earth space, such as some mean motion resonances. We expressed the equations of variation of the semi-major axis directly in terms of physical properties (such as the mean motion, frequency of rotation, conductivity, thermal parameter, specific heat, obliquity and bond albedo). This development was based on the original formalism for the Yarkovsky effect (i.e., Bottke et al., 2006 and references therein). The derivation of above equations allowed us to closely study the variation of the semi-major axis individually for each physical parameter, clearly showing that the changes in semi-major axis for silicate bodies is twice or three times greater than for metal bodies. The next step was to calculate the orbital elements of a synthetic family after the break-up. That was accomplished assuming that the catastrophic disruption energy is given by the formalism described by Stewart and Leinhardt (2009) and assuming an isotropic distribution of velocities for the fragments of the nucleus and the mantle. Finally, the orbital evolution of the fragments is implemented using a simpletic integrator, and the result compared with the distribution of real asteroid families.

A longitudinal study about the body image and psychosocial adjustment of breast cancer patients during the course of the disease.

PubMed

Moreira, Helena; Canavarro, Maria Cristina

2010-09-01

The research of body image among breast cancer patients is characterized by some limitations, such as the lack of longitudinal studies or the absence of a multidimensional perspective of body image. This study intends to overcome these limitations, by examining the evolution of body image dimensions (investment, emotions and evaluations) from the period of surgery (T1) to 6-months after the treatment's ending (T2). It also aims to explore the predictors of body image at T2 and, simultaneously, the predictive role of initial body image to psychosocial adjustment at T2. A total of 56 breast cancer patients participated in both assessments and completed a battery of instruments that included measures of body image dimensions (appearance investment, self-consciousness of appearance, shame and appearance satisfaction) and psychosocial adjustment (quality of life and emotional distress). Within the dimensions of body image, only shame increased over time. In general, initial levels of investment predicted subsequent body image dimensions and having a mastectomy done was associated with higher shame and lower appearance satisfaction at T2. Initial body image did not predict later adjustment, with the exception of depression, where appearance investment played a relevant role. Our findings contributed to the advance of knowledge in this area, providing relevant data about the evolution of body image dimensions, its predictors and its predictive role on psychosocial adjustment among breast cancer patients. This study also suggested some clinical implications that can assist health professionals to implement strategies focused on body image throughout the disease.

A modeling framework for optimal long-term care insurance purchase decisions in retirement planning.

PubMed

Gupta, Aparna; Li, Lepeng

2004-05-01

The level of need and costs of obtaining long-term care (LTC) during retired life require that planning for it is an integral part of retirement planning. In this paper, we divide retirement planning into two phases, pre-retirement and post-retirement. On the basis of four interrelated models for health evolution, wealth evolution, LTC insurance premium and coverage, and LTC cost structure, a framework for optimal LTC insurance purchase decisions in the pre-retirement phase is developed. Optimal decisions are obtained by developing a trade-off between post-retirement LTC costs and LTC insurance premiums and coverage. Two-way branching models are used to model stochastic health events and asset returns. The resulting optimization problem is formulated as a dynamic programming problem. We compare the optimal decision under two insurance purchase scenarios: one assumes that insurance is purchased for good and other assumes it may be purchased, relinquished and re-purchased. Sensitivity analysis is performed for the retirement age.

Spots and stripes: ecology and colour pattern evolution in butterflyfishes

PubMed Central

Kelley, Jennifer L.; Fitzpatrick, John L.; Merilaita, Sami

2013-01-01

The incredible diversity of colour patterns in coral reef fishes has intrigued biologists for centuries. Yet, despite the many proposed explanations for this diversity in coloration, definitive tests of the role of ecological factors in shaping the evolution of particular colour pattern traits are absent. Patterns such as spots and eyespots (spots surrounded by concentric rings of contrasting colour) have often been assumed to function for predator defence by mimicking predators' enemies' eyes, deflecting attacks or intimidating predators, but the evolutionary processes underlying these functions have never been addressed. Striped body patterns have been suggested to serve for both social communication and predator defence, but the impact of ecological constraints remains unclear. We conducted the first comparative analysis of colour pattern diversity in butterflyfishes (Family: Chaetodontidae), fishes with conspicuous spots, eyespots and wide variation in coloration. Using a dated molecular phylogeny of 95 species (approx. 75% of the family), we tested whether spots and eyespots have evolved characteristics that are consistent with their proposed defensive function and whether the presence of spots and body stripes is linked with species' body length, dietary complexity, habitat diversity or social behaviour. Contrary to our expectations, spots and eyespots appeared relatively recently in butterflyfish evolution and are highly evolutionarily labile, suggesting that they are unlikely to have played an important part in the evolutionary history of the group. Striped body patterns showed correlated evolution with a number of ecological factors including habitat type, sociality and dietary complexity. Our findings question the prevailing view that eyespots are an evolutionary response to predation pressure, providing a valuable counter example to the role of these markings as revealed in other taxa. PMID:23427170

The Interior and Orbital Evolution of Charon as Preserved in Its Geologic Record

NASA Technical Reports Server (NTRS)

Rhoden, Alyssa Rose; Henning, Wade; Hurford, Terry A.; Hamilton, Douglas P.

2014-01-01

Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital evolution of Pluto and Charon and by the interior structure and rheology of each body. As the secondary, Charon would have experienced a larger tidal response than Pluto, which may have manifested as observable tectonism. Unfortunately, there are few constraints on the interiors of Pluto and Charon. In addition, the pathway by which Charon came to occupy its present orbital state is uncertain. If Charon's orbit experienced a high-eccentricity phase, as suggested by some orbital evolution models, tidal effects would have likely been more significant. Therefore, we determine the conditions under which Charon could have experienced tidally-driven geologic activity and the extent to which upcoming New Horizons spacecraft observations could be used to constrain Charon's internal structure and orbital evolution. Using plausible interior structure models that include an ocean layer, we find that tidally-driven tensile fractures would likely have formed on Charon if its eccentricity were on the order of 0.01, especially if Charon were orbiting closer to Pluto than at present. Such fractures could display a variety of azimuths near the equator and near the poles, with the range of azimuths in a given region dependent on longitude; east-west-trending fractures should dominate at mid-latitudes. The fracture patterns we predict indicate that Charon's surface geology could provide constraints on the thickness and viscosity of Charon's ice shell at the time of fracture formation.

Pre-Bilaterian Origins of the Hox Cluster and the Hox Code: Evidence from the Sea Anemone, Nematostella vectensis

PubMed Central

Ryan, Joseph F.; Mazza, Maureen E.; Pang, Kevin; Matus, David Q.; Baxevanis, Andreas D.; Martindale, Mark Q.; Finnerty, John R.

2007-01-01

Background Hox genes were critical to many morphological innovations of bilaterian animals. However, early Hox evolution remains obscure. Phylogenetic, developmental, and genomic analyses on the cnidarian sea anemone Nematostella vectensis challenge recent claims that the Hox code is a bilaterian invention and that no “true” Hox genes exist in the phylum Cnidaria. Methodology/Principal Findings Phylogenetic analyses of 18 Hox-related genes from Nematostella identify putative Hox1, Hox2, and Hox9+ genes. Statistical comparisons among competing hypotheses bolster these findings, including an explicit consideration of the gene losses implied by alternate topologies. In situ hybridization studies of 20 Hox-related genes reveal that multiple Hox genes are expressed in distinct regions along the primary body axis, supporting the existence of a pre-bilaterian Hox code. Additionally, several Hox genes are expressed in nested domains along the secondary body axis, suggesting a role in “dorsoventral” patterning. Conclusions/Significance A cluster of anterior and posterior Hox genes, as well as ParaHox cluster of genes evolved prior to the cnidarian-bilaterian split. There is evidence to suggest that these clusters were formed from a series of tandem gene duplication events and played a role in patterning both the primary and secondary body axes in a bilaterally symmetrical common ancestor. Cnidarians and bilaterians shared a common ancestor some 570 to 700 million years ago, and as such, are derived from a common body plan. Our work reveals several conserved genetic components that are found in both of these diverse lineages. This finding is consistent with the hypothesis that a set of developmental rules established in the common ancestor of cnidarians and bilaterians is still at work today. PMID:17252055

Electronic compensation technique to deliver a total body dose

NASA Astrophysics Data System (ADS)

Lakeman, Tara E.

Purpose: Total body irradiation (TBI) uses large parallel-opposed radiation fields to suppress the patient's immune system and eradicate the residual cancer cells in preparation of recipient for bone marrow transplant. The manual placement of lead compensators has been conventionally used to compensate for the varying thickness throughout the body in large-field TBI. The goal of this study is to pursue utilizing the modern electronic compensation technique to more accurately and efficiently deliver dose to patients in need of TBI. Method: Treatment plans utilizing the electronic compensation to deliver a total body dose were created retrospectively for patients for whom CT data had been previously acquired. Each treatment plan includes two pair of parallel opposed fields. One pair of large fields is used to encompass the majority of the patient's anatomy. The other pair are very small open fields focused only on the thin bottom portion of the patient's anatomy, which requires much less radiation than the rest of the body to reach 100% of the prescribed dose. A desirable fluence pattern was manually painted within each of the larger fields for each patient to provide a more uniform distribution. Results: Dose-volume histograms (DVH) were calculated for evaluating the electronic compensation technique. In the electronically compensated plans, the maximum body doses calculated from the DVH were reduced from the conventionally-compensated plans by an average of 15%, indicating a more uniform dose. The mean body doses calculated from the electronically compensated DVH remained comparable to that of the conventionally-compensated plans, indicating an accurate delivery of the prescription dose using electronic compensation. All calculated monitor units were within clinically acceptable limits. Conclusion: Electronic compensation technique for TBI will not increase the beam on time beyond clinically acceptable limits while it can substantially reduce the compensator setup time and the potential risk of errors in manually placing lead compensators.

Potential dosimetric benefit of dose-warping based 4D planning compared to conventional 3D planning in liver stereotactic body radiotherapy (SBRT)

NASA Astrophysics Data System (ADS)

Yeo, U. J.; Taylor, M. L.; Kron, T.; Pham, D.; Siva, S.; Franich, R. D.

2013-06-01

Respiratory motion induces dosimetric uncertainties for thoracic and abdominal cancer radiotherapy (RT) due to deforming and moving anatomy. This study investigates the extent of dosimetric differences between conventional 3D treatment planning and path-integrated 4D treatment planning in liver stereotactic body radiotherapy (SBRT). Respiratory-correlated 4DCT image sets with 10 phases were acquired for patients with liver tumours. Path-integrated 4D dose accumulation was performed using dose-warping techniques based on deformable image registration. Dose-volume histogram analysis demonstrated that the 3D planning approach overestimated doses to targets by up to 24% and underestimated dose to normal liver by ~4.5%, compared to the 4D planning methodology. Therefore, 4D planning has the potential to quantify such issues of under- and/or over-dosage and improve treatment accuracy.

Brain mechanisms of perceiving tools and imagining tool use acts: a functional MRI study.

PubMed

Wadsworth, Heather M; Kana, Rajesh K

2011-06-01

The ability to conceptualize and manipulate tools in a complex manner is a distinguishing characteristic of humans, and forms a promising milestone in human evolution. While using tools is a motor act, proposals for executing such acts may be evoked by the mere perception of a tool. Imagining an action using a tool may invoke mental readjustment of body posture, planning motor movements, and matching such plans with the model action. This fMRI study examined the brain response in 32 healthy adults when they either viewed a tool or imagined using it. While both viewing and imagining tasks recruited similar regions, imagined tool use showed greater activation in motor areas, and in areas around the bilateral temporoparietal junction. Viewing tools, on the other hand, produced robust activation in the inferior frontal, occipital, parietal, and ventral temporal areas. Analysis of gender differences indicated males recruiting medial prefrontal and anterior cingulate cortices and females, left supramarginal gyrus and left anterior insula. While tool viewing seems to generate prehensions about using them, the imagined action using a tool mirrored brain responses underlying functional use of it. The findings of this study may suggest that perception and imagination of tools may form precursors to overt actions. Published by Elsevier Ltd.

ROSETTA: How to archive more than 10 years of mission

NASA Astrophysics Data System (ADS)

Barthelemy, Maud; Heather, D.; Grotheer, E.; Besse, S.; Andres, R.; Vallejo, F.; Barnes, T.; Kolokolova, L.; O'Rourke, L.; Fraga, D.; A'Hearn, M. F.; Martin, P.; Taylor, M. G. G. T.

2018-01-01

The Rosetta spacecraft was launched in 2004 and, after several planetary and two asteroid fly-bys, arrived at comet 67P/Churyumov-Gerasimenko in August 2014. After escorting the comet for two years and executing its scientific observations, the mission ended on 30 September 2016 through a touch down on the comet surface. This paper describes how the Planetary Science Archive (PSA) and the Planetary Data System - Small Bodies Node (PDS-SBN) worked with the Rosetta instrument teams to prepare the science data collected over the course of the Rosetta mission for inclusion in the science archive. As Rosetta is an international mission in collaboration between ESA and NASA, all science data from the mission are fully archived within both the PSA and the PDS. The Rosetta archiving process, supporting tools, archiving systems, and their evolution throughout the mission are described, along with a discussion of a number of the challenges faced during the Rosetta implementation. The paper then presents the current status of the archive for each of the science instruments, before looking to the improvements planned both for the archive itself and for the Rosetta data content. The lessons learned from the first 13 years of archiving on Rosetta are finally discussed with an aim to help future missions plan and implement their science archives.

The Worldwide Hospice Palliative Care Alliance.

PubMed

Connor, Stephen R; Gwyther, Elizabeth

2018-02-01

The Worldwide Hospice Palliative Care Alliance (WHPCA) is an international non-governmental organization registered as a charity in England and Wales that was established in 2008 following a series of international gatherings that highlighted the important need for palliative care to be included in global policy and health planning. The vision of the WHPCA is a world with universal access to hospice and palliative care. Its mission is to foster, promote and influence the delivery of affordable, quality palliative care. This article describes the evolution of the WHPCA and what it has been able to accomplish in the eight years since its formation. These accomplishments include effective advocacy with United Nations bodies, acceptance as a non-governmental organization in official relations with the World Health Organization and the UN Economic and Social Council, publication of many position papers on critical aspects of palliative care, publication of the Global Atlas of Palliative Care at the End of Life, development of toolkits for palliative care development, publication of the international edition of ehospice, and management of World Hospice and Palliative Care Day each year. Some of the many challenges to the growth and development of palliative care globally are described along with future plans. Copyright © 2017 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Evolving directions in NASA's planetary rover requirements and technology

NASA Technical Reports Server (NTRS)

Weisbin, C. R.; Montemerlo, Mel; Whittaker, W.

1993-01-01

The evolution of NASA's planning for planetary rovers (that is robotic vehicles which may be deployed on planetary bodies for exploration, science analysis, and construction) and some of the technology that was developed to achieve the desired capabilities is reviewed. The program is comprised of a variety of vehicle sizes and types in order to accommodate a range of potential user needs. This includes vehicles whose weight spans a few kilograms to several thousand kilograms; whose locomotion is implemented using wheels, tracks, and legs; and whose payloads vary from microinstruments to large scale assemblies for construction. Robotic vehicles and their associated control systems, developed in the late 1980's as part of a proposed Mars Rover Sample Return (MRSR) mission, are described. Goals suggested at the time for such a MRSR mission included navigating for one to two years across hundreds of kilometers of Martian surface; traversing a diversity of rugged, unknown terrain; collecting and analyzing a variety of samples; and bringing back selected samples to the lander for return to Earth. Current plans (considerably more modest) which have evolved both from technological 'lessons learned' in the previous period, and modified aspirations of NASA missions are presented. Some of the demonstrated capabilities of the developed machines and the technologies which made these capabilities possible are described.

Physiological variation as a mechanism for developmental caste-biasing in a facultatively eusocial sweat bee.

PubMed

Kapheim, Karen M; Smith, Adam R; Ihle, Kate E; Amdam, Gro V; Nonacs, Peter; Wcislo, William T

2012-04-07

Social castes of eusocial insects may have arisen through an evolutionary modification of an ancestral reproductive ground plan, such that some adults emerge from development physiologically primed to specialize on reproduction (queens) and others on maternal care expressed as allo-maternal behaviour (workers). This hypothesis predicts that variation in reproductive physiology should emerge from ontogeny and underlie division of labour. To test these predictions, we identified physiological links to division of labour in a facultatively eusocial sweat bee, Megalopta genalis. Queens are larger, have larger ovaries and have higher vitellogenin titres than workers. We then compared queens and workers with their solitary counterparts-solitary reproductive females and dispersing nest foundresses-to investigate physiological variation as a factor in caste evolution. Within dyads, body size and ovary development were the best predictors of behavioural class. Queens and dispersers are larger, with larger ovaries than their solitary counterparts. Finally, we raised bees in social isolation to investigate the influence of ontogeny on physiological variation. Body size and ovary development among isolated females were highly variable, and linked to differences in vitellogenin titres. As these are key physiological predictors of social caste, our results provide evidence for developmental caste-biasing in a facultatively eusocial bee.

Physiological variation as a mechanism for developmental caste-biasing in a facultatively eusocial sweat bee

PubMed Central

Kapheim, Karen M.; Smith, Adam R.; Ihle, Kate E.; Amdam, Gro V.; Nonacs, Peter; Wcislo, William T.

2012-01-01

Social castes of eusocial insects may have arisen through an evolutionary modification of an ancestral reproductive ground plan, such that some adults emerge from development physiologically primed to specialize on reproduction (queens) and others on maternal care expressed as allo-maternal behaviour (workers). This hypothesis predicts that variation in reproductive physiology should emerge from ontogeny and underlie division of labour. To test these predictions, we identified physiological links to division of labour in a facultatively eusocial sweat bee, Megalopta genalis. Queens are larger, have larger ovaries and have higher vitellogenin titres than workers. We then compared queens and workers with their solitary counterparts—solitary reproductive females and dispersing nest foundresses—to investigate physiological variation as a factor in caste evolution. Within dyads, body size and ovary development were the best predictors of behavioural class. Queens and dispersers are larger, with larger ovaries than their solitary counterparts. Finally, we raised bees in social isolation to investigate the influence of ontogeny on physiological variation. Body size and ovary development among isolated females were highly variable, and linked to differences in vitellogenin titres. As these are key physiological predictors of social caste, our results provide evidence for developmental caste-biasing in a facultatively eusocial bee. PMID:22048951

An archaic crested plesiosaur in opal from the Lower Cretaceous high-latitude deposits of Australia

PubMed Central

Kear, Benjamin P; Schroeder, Natalie I; Lee, Michael S.Y

2006-01-01

Umoonasaurus demoscyllus gen. et sp. nov. is a new small-bodied (approx. 2.5 m) pliosauroid plesiosaur from the Lower Cretaceous (Aptian–Albian) of southern Australia. It is represented by several partial skeletons (one with a near complete skull is the most complete opalized vertebrate fossil yet known), and is unique in having large crests on the skull midline and above the orbits. Umoonasaurus is surprisingly archaic despite its relatively late age (approx. 115 Myr ago)—being simultaneously the most basal (primitive) and last surviving rhomaleosaurid. Notably, it lacks the ‘pliosauromorph’ features (large head, short neck, gigantism) typically characterizing many more derived Jurassic rhomaleosaurids; thus, reinforcing the suspected convergent evolution of the ‘pliosauromorph’ hypercarnivore body plan. Umoonasaurus inhabited an Early Cretaceous high-latitude (approx. 70° S) inland seaway subject to seasonally near-freezing climatic conditions. This extreme environment supported a diverse range of plesiosaur taxa, suggesting that these marine reptiles might have possessed adaptations (e.g. heightened metabolic levels) to cope with cold-water temperatures. Indeed, survival of ancient endemic lineages such as Umoonasaurus is a common phenomenon in Australian Cretaceous vertebrate assemblages and might have been facilitated by isolation in low-temperature high-latitude regions. PMID:17148303

Ediacaran developmental biology

PubMed Central

Liu, Alexander G.; Donoghue, Philip C. J.

2017-01-01

ABSTRACT Rocks of the Ediacaran System (635–541 Ma) preserve fossil evidence of some of the earliest complex macroscopic organisms, many of which have been interpreted as animals. However, the unusual morphologies of some of these organisms have made it difficult to resolve their biological relationships to modern metazoan groups. Alternative competing phylogenetic interpretations have been proposed for Ediacaran taxa, including algae, fungi, lichens, rhizoid protists, and even an extinct higher‐order group (Vendobionta). If a metazoan affinity can be demonstrated for these organisms, as advocated by many researchers, they could prove informative in debates concerning the evolution of the metazoan body axis, the making and breaking of axial symmetries, and the appearance of a metameric body plan. Attempts to decipher members of the enigmatic Ediacaran macrobiota have largely involved study of morphology: comparative analysis of their developmental phases has received little attention. Here we present what is known of ontogeny across the three iconic Ediacaran taxa Charnia masoni, Dickinsonia costata and Pteridinium simplex, together with new ontogenetic data and insights. We use these data and interpretations to re‐evaluate the phylogenetic position of the broader Ediacaran morphogroups to which these taxa are considered to belong (rangeomorphs, dickinsoniomorphs and erniettomorphs). We conclude, based on the available evidence, that the affinities of the rangeomorphs and the dickinsoniomorphs lie within Metazoa. PMID:29105292

Radar-Sounding of Icy Mantles and Comets Using Natural Radio Noise

NASA Astrophysics Data System (ADS)

Winebrenner, D. P.; Sahr, J. D.

2011-10-01

Radar-sounding of ice sheets on Earth yields crucial information on ice history and dynamics, including discoveries of subglacial lakes beneath 3-4 km of ice [1]. Mars Express and the Mars Reconnaissance Orbiter (MRO) have now demonstrated the corresponding power of orbital radar sounding for planetary exploration, in particular by imaging structures within and beneath kilometers of Martian water ice [2-4]. Based on this experience, a sophisticated orbital radar sounder is planned for a flagship mission to Europa, with the aim of imaging stratigraphy, faults, diapirs and other geological structure in the upper few kilometers of the water-ice mantle there, and possibly even detecting the upper surface of the (likely) underlying ocean [5]. Recent modeling of the formation and evolution of volatilerich bodies suggests that oceans or lakes of liquid water occur beneath water-ice mantles in a surprising variety of places, including Ceres in the outer asteroid belt [6], 3 of the 4 Galilean moons of Jupiter as well as Enceladus and Titan in the Saturnian system [7], and possibly even Pluto [8]. Thus there is now a wide scope for low-cost missions to bodies of exceptional interest, and for radar sounding of icy mantles to image near-surface structural geology related to underlying water (whether past or present).

EVOLUTION. A four-legged snake from the Early Cretaceous of Gondwana.

PubMed

Martill, David M; Tischlinger, Helmut; Longrich, Nicholas R

2015-07-24

Snakes are a remarkably diverse and successful group today, but their evolutionary origins are obscure. The discovery of snakes with two legs has shed light on the transition from lizards to snakes, but no snake has been described with four limbs, and the ecology of early snakes is poorly known. We describe a four-limbed snake from the Early Cretaceous (Aptian) Crato Formation of Brazil. The snake has a serpentiform body plan with an elongate trunk, short tail, and large ventral scales suggesting characteristic serpentine locomotion, yet retains small prehensile limbs. Skull and body proportions as well as reduced neural spines indicate fossorial adaptation, suggesting that snakes evolved from burrowing rather than marine ancestors. Hooked teeth, an intramandibular joint, a flexible spine capable of constricting prey, and the presence of vertebrate remains in the guts indicate that this species preyed on vertebrates and that snakes made the transition to carnivory early in their history. The structure of the limbs suggests that they were adapted for grasping, either to seize prey or as claspers during mating. Together with a diverse fauna of basal snakes from the Cretaceous of South America, Africa, and India, this snake suggests that crown Serpentes originated in Gondwana. Copyright © 2015, American Association for the Advancement of Science.

The Search for Extraterrestrial Life

NASA Astrophysics Data System (ADS)

Peter, Ulmschneider

Looking at the nature, origin, and evolution of life on Earth is one way of assessing whether extraterrestrial life exists on Earth-like planets elsewhere (see Chaps. 5 and 6). A more direct approach is to search for favorable conditions and traces of life on other celestial bodies, both in the solar system and beyond. Clearly, there is little chance of encountering nonhuman intelligent beings in the solar system. But there could well be primitive life on Mars, particularly as in the early history of the solar system the conditions on Mars were quite similar to those on Earth. In addition, surprisingly favorable conditions for life once existed on the moons of Jupiter. Yet even if extraterrestrial life is not encountered in forthcoming space missions, it would be of utmost importance to recover fossils of past organisms as such traces would greatly contribute to our basic understanding of the formation of life. In addition to the planned missions to Mars and Europa, there are extensive efforts to search for life outside the solar system. Rapid advances in the detection of extrasolar planets, outlined in Chap. 3, are expected to lead to the discovery of Earth-like planets in the near future. But how can we detect life on these distant bodies?

Long-term evolution of a planetesimal swarm in the vicinity of a protoplanet

NASA Technical Reports Server (NTRS)

Kary, David M.; Lissauer, Jack J.

1991-01-01

Many models of planet formation involve scenarios in which one or a few large protoplanets interact with a swarm of much smaller planetesimals. In such scenarios, three-body perturbations by the protoplanet as well as mutual collisions and gravitational interactions between the swarm bodies are important in determining the velocity distribution of the swarm. We are developing a model to examine the effects of these processes on the evolution of a planetesimal swarm. The model consists of a combination of numerical integrations of the gravitational influence of one (or a few) massive protoplanets on swarm bodies together with a statistical treatment of the interactions between the planetesimals. Integrating the planetesimal orbits allows us to take into account effects that are difficult to model analytically or statistically, such as three-body collision cross-sections and resonant perturbations by the protoplanet, while using a statistical treatment for the particle-particle interactions allows us to use a large enough sample to obtain meaningful results.

Intraspecific competition and high food availability are associated with insular gigantism in a lizard.

PubMed

Pafilis, Panayiotis; Meiri, Shai; Foufopoulos, Johannes; Valakos, Efstratios

2009-09-01

Resource availability, competition, and predation commonly drive body size evolution. We assess the impact of high food availability and the consequent increased intraspecific competition, as expressed by tail injuries and cannibalism, on body size in Skyros wall lizards (Podarcis gaigeae). Lizard populations on islets surrounding Skyros (Aegean Sea) all have fewer predators and competitors than on Skyros but differ in the numbers of nesting seabirds. We predicted the following: (1) the presence of breeding seabirds (providing nutrients) will increase lizard population densities; (2) dense lizard populations will experience stronger intraspecific competition; and (3) such aggression, will be associated with larger average body size. We found a positive correlation between seabird and lizard densities. Cannibalism and tail injuries were considerably higher in dense populations. Increases in cannibalism and tail loss were associated with large body sizes. Adult cannibalism on juveniles may select for rapid growth, fuelled by high food abundance, setting thus the stage for the evolution of gigantism.

The carotid rete and artiodactyl success.

PubMed

Mitchell, G; Lust, A

2008-08-23

Since the Eocene, the diversity of artiodactyls has increased while that of perissodactyls has decreased. Reasons given for this contrasting pattern are that the evolution of a ruminant digestive tract and improved locomotion in artiodactyls were adaptively advantageous in the highly seasonal post-Eocene climate. We suggest that evolution of a carotid rete, a structure highly developed in artiodactyls but absent in perissodactyls, was at least as important. The rete confers an ability to regulate brain temperature independently of body temperature. The net effect is that in hot ambient conditions artiodactyls are able to conserve energy and water, and in cold ambient conditions they are able to conserve body temperature. In perissodactyls, brain and body temperature change in parallel and thermoregulation requires abundant food and water to warm/cool the body. Consequently, perissodactyls occupy habitats of low seasonality and rich in food and water, such as tropical forests. Conversely, the increased thermoregulatory flexibility of artiodactyls has facilitated invasion of new adaptive zones ranging from the Arctic Circle to deserts and tropical savannahs.

Stability and Evolution of Multiple Planet and Satellite Systems

NASA Astrophysics Data System (ADS)

Quillen, Alice

Numerous multiple planet systems have recently been discovered with the Kepler Mission, suggesting that multiple planet systems are common. Multiple- body nearly coplanar satellite systems are also found in the Solar system. Multiple planet and satellite systems exhibit rich dynamics as they are affected by three-body and secular resonances affecting short timescale behavior and long timescale stability. Interactions with debris disks and planetesimal belts and tidal interactions can both reduce and induce instability. Using both numerical and analytical studies, we propose to develop a broadly applicable framework to estimate diffusion rates and stability regimes both in resonant and non- resonant configurations. Understanding of resonant dynamics is needed to understand each of these systems and a broader general theory would cover scenarios and mechanisms that are relevant for all of them. Architectures and dynamical mechanisms will be used to test scenarios for formation and evolution of multiple body systems and constrain poorly known quantities such as masses, eccentricities, inclinations, radii, and the existence of undetected bodies.

BOOK REVIEW: The Gravitational Million-Body Problem: A Multidisciplinary Approach to Star Cluster Dynamics

NASA Astrophysics Data System (ADS)

Heggie, D.; Hut, P.

2003-10-01

The gravitational N-body problem is to describe the evolution of an isolated system of N point masses interacting only through Newtonian gravitational forces. For N =2 the solution is due to Newton. For N =3 there is no general analytic solution, but the problem has occupied generations of illustrious physicists and mathematicians including Laplace, Lagrange, Gauss and Poincaré, and inspired the modern subjects of nonlinear dynamics and chaos theory. The general gravitational N-body problem remains one of the oldest unsolved problems in physics. Many-body problems can be simpler than few-body problems, and many physicists have attempted to apply the methods of classical equilibrium statistical mechanics to the gravitational N-body problem for N gg 1. These applications have had only limited success, partly because the gravitational force is too strong at both small scales (the interparticle potential energy diverges) and large scales (energy is not extensive). Nevertheless, we now understand a rich variety of behaviour in large-N gravitating systems. These include the negative heat capacity of isolated, gravitationally bound systems, which is the basic reason why nuclear burning in the Sun is stable; Antonov's discovery that an isothermal, self-gravitating gas in a container is located at a saddle point, rather than a maximum, of the entropy when the gas is sufficiently dense and hence is unstable (the 'gravothermal catastrophe'); the process of core collapse, in which relaxation induces a self-similar evolution of the central core of the system towards (formally) infinite density in a finite time; and the remarkable phenomenon of gravothermal oscillations, in which the central density undergoes periodic oscillations by factors of a thousand or more on the relaxation timescale - but only if N gtrsim 104. The Gravitational Million-Body Problem is a monograph that describes our current understanding of the gravitational N-body problem. The authors have chosen to focus on N = 106 for two main reasons: first, direct numerical integrations of N-body systems are beginning to approach this threshold, and second, globular star clusters provide remarkably accurate physical instantiations of the idealized N-body problem with N = 105 - 106. The authors are distinguished contributors to the study of star-cluster dynamics and the gravitational N-body problem. The book contains lucid and concise descriptions of most of the important tools in the subject, with only a modest bias towards the authors' own interests. These tools include the two-body relaxation approximation, the Vlasov and Fokker-Planck equations, regularization of close encounters, conducting fluid models, Hill's approximation, Heggie's law for binary star evolution, symplectic integration algorithms, Liapunov exponents, and so on. The book also provides an up-to-date description of the principal processes that drive the evolution of idealized N-body systems - two-body relaxation, mass segregation, escape, core collapse and core bounce, binary star hardening, gravothermal oscillations - as well as additional processes such as stellar collisions and tidal shocks that affect real star clusters but not idealized N-body systems. In a relatively short (300 pages plus appendices) book such as this, many topics have to be omitted. The reader who is hoping to learn about the phenomenology of star clusters will be disappointed, as the description of their properties is limited to only a page of text; there is also almost no discussion of other, equally interesting N-body systems such as galaxies(N approx 106 - 1012), open clusters (N simeq 102 - 104), planetary systems, or the star clusters surrounding black holes that are found in the centres of most galaxies. All of these omissions are defensible decisions. Less defensible is the uneven set of references in the text; for example, nowhere is the reader informed that the classic predecessor to this work was Spitzer's 1987 monograph, Dynamical Evolution of Globular Clusters, or that the standard reference on the observational properties of stellar systems is Binney and Merrifield's Galactic Astronomy. A minor irritation is that many concepts are discussed several times before they are defined, and the index provides no pointer to the primary discussion; thus, for example, there are ten index entries for 'phase mixing' and no indication that the fourth of these refers to the actual definition. The book is intended as a graduate textbook but more likely it will be used mainly in other contexts: by theoretical researchers, as an indispensable reference on the dynamics of gravitational N-body systems; by observational astronomers, as a readable summary of the theory of star cluster evolution; and by physicists seeking a well-written and accessible introduction to a simple problem that remains fascinating and incompletely understood after three centuries. Scott Tremaine

Nature and evolution of the meteorite parent bodies: Evidence from petrology and metallurgy

NASA Technical Reports Server (NTRS)

Wood, J. A.

1978-01-01

The physical as well as chemical properties of the meteorite parent bodies are reviewed and it is concluded that many differentiated meteorites were likely formed in asteroidal-sized parents. A new model is developed for the formation of pallasites at the interface between an iron core and olivine mantle in differentiated bodies only about 10 km in diameter, which are later incorporated into a second generation of larger (100 km) parent bodies.

Body size evolution of a shell-brooding cichlid fish from Lake Tanganyika.

PubMed

Takahashi, T; Ota, K

2016-12-01

The substrate-brooding cichlid fish Telmatochromis temporalis in Lake Tanganyika demonstrates a simple example of ecological speciation between normal and dwarf morphs through divergent natural selection on body size. The dwarf morph most likely evolved from the ancestral normal morph; therefore, elucidating the evolution of its small body size is a key to understanding this ecological speciation event. Previous studies suggest that the small body size of the dwarf morph is an adaptation to the use of empty snail shells as shelters (males) and spawning sites (females), but this idea has not been fully evaluated. Combining original and previously published information, this study compared likelihood values to determine the primary factor that would be responsible for regulating the body size of the dwarf morph. Male body size is most likely regulated by the ability to turn within shells, which may influence the predation avoidance of adult fish. Females are smaller than males, and their body size is most likely regulated by the ability to lay eggs in the small spaces within shells close to the shell apices where predation risk on eggs is lower. This study provides new evidence supporting the hypothesis that different natural selection factors affected body size of the different sexes of the dwarf morph, which has not been reported in other animal species. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Nucleolar evolution and coiled bodies during meiotic prophase in Olea europaea: differential localization of nucleic acids.

PubMed

Olmedilla, A; de Dios Alché, J; Rodríguez-García, M I

1997-10-01

We studied the ultrastructural evolution of the nucleolus during meiotic prophase in olive microsporocytes. During prophase, nuclear bodies morphologically similar to coiled bodies were observed. The nucleic acid composition of these bodies was examined in microsporocytes using electron microscopic techniques with EDTA preferential ribonucleoprotein staining, anti-DNA immunolabeling, the in situ terminal deoxynucleotidyl transferase-immunogold technique, and in situ hybridization with 18S rRNA and U3 snoRNA digoxigenin-labeled probes. The ultrastructural appearance of the meiocyte nucleolus indicated a low level of activity from the early prophase stage: the granular component was practically absent and nucleoli were constituted almost exclusively by dense fibrillar component containing large fibrillar centers that lacked chromatin inclusions. However, the appearance of reactivation vacuoles in the nucleolus during zygotene and high levels of rRNA in the nucleoplasm during pachytene support the presence of a peak in rRNA synthesis. Our results also show that the nuclear bodies that appear during prophase I are ribonucleoproteinaceous in nature; neither DNA nor ribosomal RNA were detected. The presence of U3 snoRNA, as shown by in situ hybridization in nuclear bodies from plant material, is also evidence that these structures are coiled bodies. We suggest that coiled bodies are involved not only in pre- and post-splicing events but also in the storage, transport or recycling of rRNA maturation elements.

Mutual gravitational potential, force, and torque of a homogeneous polyhedron and an extended body: an application to binary asteroids

NASA Astrophysics Data System (ADS)

Shi, Yu; Wang, Yue; Xu, Shijie

2017-11-01

Binary systems are quite common within the populations of near-Earth asteroids, main-belt asteroids, and Kuiper belt asteroids. The dynamics of binary systems, which can be modeled as the full two-body problem, is a fundamental problem for their evolution and the design of relevant space missions. This paper proposes a new shape-based model for the mutual gravitational potential of binary asteroids, differing from prior approaches such as inertia integrals, spherical harmonics, or symmetric trace-free tensors. One asteroid is modeled as a homogeneous polyhedron, while the other is modeled as an extended rigid body with arbitrary mass distribution. Since the potential of the polyhedron is precisely described in a closed form, the mutual gravitational potential can be formulated as a volume integral over the extended body. By using Taylor expansion, the mutual potential is then derived in terms of inertia integrals of the extended body, derivatives of the polyhedron's potential, and the relative location and orientation between the two bodies. The gravitational forces and torques acting on the two bodies described in the body-fixed frame of the polyhedron are derived in the form of a second-order expansion. The gravitational model is then used to simulate the evolution of the binary asteroid (66391) 1999 KW4, and compared with previous results in the literature.

An improved artificial bee colony algorithm based on balance-evolution strategy for unmanned combat aerial vehicle path planning.

PubMed

Li, Bai; Gong, Li-gang; Yang, Wen-lun

2014-01-01

Unmanned combat aerial vehicles (UCAVs) have been of great interest to military organizations throughout the world due to their outstanding capabilities to operate in dangerous or hazardous environments. UCAV path planning aims to obtain an optimal flight route with the threats and constraints in the combat field well considered. In this work, a novel artificial bee colony (ABC) algorithm improved by a balance-evolution strategy (BES) is applied in this optimization scheme. In this new algorithm, convergence information during the iteration is fully utilized to manipulate the exploration/exploitation accuracy and to pursue a balance between local exploitation and global exploration capabilities. Simulation results confirm that BE-ABC algorithm is more competent for the UCAV path planning scheme than the conventional ABC algorithm and two other state-of-the-art modified ABC algorithms.

Evolution of body weight parameters up to 3 years after solid organ transplantation: The prospective Swiss Transplant Cohort Study.

PubMed

Beckmann, Sonja; Nikolic, Nataša; Denhaerynck, Kris; Binet, Isabelle; Koller, Michael; Boely, Elsa; De Geest, Sabina

2017-03-01

Obesity and weight gain are serious concerns after solid organ transplantation (Tx); however, no unbiased comparison regarding body weight parameter evolution across organ groups has yet been performed. Using data from the prospective nationwide Swiss Transplant Cohort Study, we compared the evolution of weight parameters up to 3 years post-Tx in 1359 adult kidney (58.3%), liver (21.7%), lung (11.6%), and heart (8.4%) recipients transplanted between May 2008 and May 2012. Changes in mean weight and body mass index (BMI) category were compared to reference values from 6 months post-Tx. At 3 years post-Tx, compared to other organ groups, liver Tx recipients showed the greatest weight gain (mean 4.8±10.4 kg), 57.4% gained >5% body weight, and they had the highest incidence of obesity (38.1%). After 3 years, based on their BMI categories at 6 months, normal weight and obese liver Tx patients, as well as underweight kidney, lung and heart Tx patients had the highest weight gains. Judged against international Tx patient data, the majority of our Swiss Tx recipients' experienced lower post-Tx weight gain. However, our findings show weight gain pattern differences, both within and across organ Tx groups that call for preventive measures. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Selection on an extreme weapon in the frog-legged leaf beetle (Sagra femorata).

PubMed

O'Brien, Devin M; Katsuki, Masako; Emlen, Douglas J

2017-11-01

Biologists have been fascinated with the extreme products of sexual selection for decades. However, relatively few studies have characterized patterns of selection acting on ornaments and weapons in the wild. Here, we measure selection on a wild population of weapon-bearing beetles (frog-legged leaf beetles: Sagra femorata) for two consecutive breeding seasons. We consider variation in both weapon size (hind leg length) and in relative weapon size (deviations from the population average scaling relationship between hind leg length and body size), and provide evidence for directional selection on weapon size per se and stabilizing selection on a particular scaling relationship in this population. We suggest that whenever growth in body size is sensitive to external circumstance such as nutrition, then considering deviations from population-level scaling relationships will better reflect patterns of selection relevant to evolution of the ornament or weapon than will variation in trait size per se. This is because trait-size versus body-size scaling relationships approximate underlying developmental reaction norms relating trait growth with body condition in these species. Heightened condition-sensitive expression is a hallmark of the exaggerated ornaments and weapons favored by sexual selection, yet this plasticity is rarely reflected in the way we think about-and measure-selection acting on these structures in the wild. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Contrasting magmatic structures between small plutons and batholiths emplaced at shallow crustal level (Sierras de Córdoba, Argentina)

NASA Astrophysics Data System (ADS)

Pinotti, Lucio P.; D'Eramo, Fernando J.; Weinberg, Roberto F.; Demartis, Manuel; Tubía, José María; Coniglio, Jorge E.; Radice, Stefania; Maffini, M. Natalia; Aragón, Eugenio

2016-11-01

Processes like injection, magma flow and differentiation and influence of the regional strain field are here described and contrasted to shed light on their role in the formation of small plutons and large batholiths their magmatic structures. The final geometric and compositional arrangement of magma bodies are a complex record of their construction and internal flow history. Magma injection, flow and differentiation, as well as regional stresses, all control the internal nature of magma bodies. Large magma bodies emplaced at shallow crustal levels result from the intrusion of multiple magma batches that interact in a variety of ways, depending on internal and external dynamics, and where the early magmatic, growth-related structures are commonly overprinted by subsequent history. In contrast, small plutons emplaced in the brittle-ductile transition more likely preserve growth-related structures, having a relatively simple cooling history and limited internal magma flow. Outcrop-scale magmatic structures in both cases record a rich set of complementary information that can help elucidate their evolution. Large and small granitic bodies of the Sierra Pampeanas preserve excellent exposures of magmatic structures that formed as magmas stepped through different rheological states during pluton growth and solidification. These structures reveal not only the flow pattern inside magma chambers, but also the rheological evolution of magmas in response to temperature evolution.

Altitudinal divergence in maternal thermoregulatory behaviour may be driven by differences in selection on offspring survival in a viviparous lizard.

PubMed

Uller, Tobias; While, Geoffrey M; Cadby, Chloe D; Harts, Anna; O'Connor, Katherine; Pen, Ido; Wapstra, Erik

2011-08-01

Plastic responses to temperature during embryonic development are common in ectotherms, but their evolutionary relevance is poorly understood. Using a combination of field and laboratory approaches, we demonstrate altitudinal divergence in the strength of effects of maternal thermal opportunity on offspring birth date and body mass in a live-bearing lizard (Niveoscincus ocellatus). Poor thermal opportunity decreased birth weight at low altitudes where selection on body mass was negligible. In contrast, there was no effect of maternal thermal opportunity on body mass at high altitudes where natural selection favored heavy offspring. The weaker effect of poor maternal thermal opportunity on offspring development at high altitude was accompanied by a more active thermoregulation and higher body temperature in highland females. This may suggest that passive effects of temperature on embryonic development have resulted in evolution of adaptive behavioral compensation for poor thermal opportunity at high altitudes, but that direct effects of maternal thermal environment are maintained at low altitudes because they are not selected against. More generally, we suggest that phenotypic effects of maternal thermal opportunity or incubation temperature in reptiles will most commonly reflect weak selection for canalization or selection on maternal strategies rather than adaptive plasticity to match postnatal environments. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Adaptive evolution toward larger size in mammals

PubMed Central

Baker, Joanna; Meade, Andrew; Pagel, Mark; Venditti, Chris

2015-01-01

The notion that large body size confers some intrinsic advantage to biological species has been debated for centuries. Using a phylogenetic statistical approach that allows the rate of body size evolution to vary across a phylogeny, we find a long-term directional bias toward increasing size in the mammals. This pattern holds separately in 10 of 11 orders for which sufficient data are available and arises from a tendency for accelerated rates of evolution to produce increases, but not decreases, in size. On a branch-by-branch basis, increases in body size have been more than twice as likely as decreases, yielding what amounts to millions and millions of years of rapid and repeated increases in size away from the small ancestral mammal. These results are the first evidence, to our knowledge, from extant species that are compatible with Cope’s rule: the pattern of body size increase through time observed in the mammalian fossil record. We show that this pattern is unlikely to be explained by several nonadaptive mechanisms for increasing size and most likely represents repeated responses to new selective circumstances. By demonstrating that it is possible to uncover ancient evolutionary trends from a combination of a phylogeny and appropriate statistical models, we illustrate how data from extant species can complement paleontological accounts of evolutionary history, opening up new avenues of investigation for both. PMID:25848031

Dynamics of Three-Body Correlations in Quenched Unitary Bose Gases

NASA Astrophysics Data System (ADS)

Colussi, V. E.; Corson, J. P.; D'Incao, J. P.

2018-03-01

We investigate dynamical three-body correlations in the Bose gas during the earliest stages of evolution after a quench to the unitary regime. The development of few-body correlations is theoretically observed by determining the two- and three-body contacts. We find that the growth of three-body correlations is gradual compared to two-body correlations. The three-body contact oscillates coherently, and we identify this as a signature of Efimov trimers. We show that the growth of three-body correlations depends nontrivially on parameters derived from both the density and Efimov physics. These results demonstrate the violation of scaling invariance of unitary bosonic systems via the appearance of log-periodic modulation of three-body correlations.

Reconstructing the Initial Relaxation Time of Young Star Clusters in the Large Magellanic Cloud: The Evolution of Star Clusters

NASA Astrophysics Data System (ADS)

Portegies Zwart, S. F.; Chen, H.-C.

2008-06-01

We reconstruct the initial two-body relaxation time at the half mass radius for a sample of young ⪉ 300 Myr star clusters in the Large Magellanic cloud. We achieve this by simulating star clusters with 12288 to 131072 stars using direct N-body integration. The equations of motion of all stars are calculated with high precision direct N-body simulations which include the effects of the evolution of single stars and binaries. We find that the initial relaxation times of the sample of observed clusters in the Large Magellanic Cloud ranges from about 200 Myr to about 2 Gyr. The reconstructed initial half-mass relaxation times for these clusters have a much narrower distribution than the currently observed distribution, which ranges over more than two orders of magnitude.

The 25 kW power module evolution study. Part 3: Conceptual designs for power module evolution. Volume 4: Design analyses

NASA Technical Reports Server (NTRS)

1979-01-01

Topics covered include growth options evaluation, mass properties, attitude control and structural dynamics, contamination evaluation, berthing concepts, orbit reboost options and growth kit concepts. Systems support elements and space support equipment are reviewed with emphasis on power module operations and technology planning.

Alcohol's Effects on the Body

MedlinePlus

... Council Strategic Plan 2017-2021 Our Work Our Funding Our Staff Jobs & Training Our Location Contact Us You are here Home » Alcohol & Your Health » Alcohol's Effects on the Body Alcohol's Effects on the Body ...

CryoSat Ice Processor: Known Processor Anomalies and Potential Future Product Evolutions

NASA Astrophysics Data System (ADS)

Mannan, R.; Webb, E.; Hall, A.; Bouffard, J.; Femenias, P.; Parrinello, T.; Bouffard, J.; Brockley, D.; Baker, S.; Scagliola, M.; Urien, S.

2016-08-01

Launched in 2010, CryoSat was designed to measure changes in polar sea ice thickness and ice sheet elevation. To reach this goal the CryoSat data products have to meet the highest performance standards and are subjected to a continual cycle of improvement achieved through upgrades to the Instrument Processing Facilities (IPFs). Following the switch to the Baseline-C Ice IPFs there are already planned evolutions for the next processing Baseline, based on recommendations from the Scientific Community, Expert Support Laboratory (ESL), Quality Control (QC) Centres and Validation campaigns. Some of the proposed evolutions, to be discussed with the scientific community, include the activation of freeboard computation in SARin mode, the potential operation of SARin mode over flat-to-slope transitory land ice areas, further tuning of the land ice retracker, the switch to NetCDF format and the resolution of anomalies arising in Baseline-C. This paper describes some of the anomalies known to affect Baseline-C in addition to potential evolutions that are planned and foreseen for Baseline-D.

Migrate small, sound big: functional constraints on body size promote tracheal elongation in cranes.

PubMed

Jones, M R; Witt, C C

2014-06-01

Organismal traits often represent the outcome of opposing selection pressures. Although social or sexual selection can cause the evolution of traits that constrain function or survival (e.g. ornamental feathers), it is unclear how the strength and direction of selection respond to ecological shifts that increase the severity of the constraint. For example, reduced body size might evolve by natural selection to enhance flight performance in migratory birds, but social or sexual selection favouring large body size may provide a countervailing force. Tracheal elongation is a potential outcome of these opposing pressures because it allows birds to convey an auditory signal of exaggerated body size. We predicted that the evolution of migration in cranes has coincided with a reduction in body size and a concomitant intensification of social or sexual selection for apparent large body size via tracheal elongation. We used a phylogenetic comparative approach to examine the relationships among migration distance, body mass and trachea length in cranes. As predicted, we found that migration distance correlated negatively with body size and positively with proportional trachea length. This result was consistent with our hypothesis that evolutionary reductions in body size led to intensified selection for trachea length. The most likely ultimate causes of intensified positive selection on trachea length are the direct benefits of conveying a large body size in intraspecific contests for mates and territories. We conclude that the strength of social or sexual selection on crane body size is linked to the degree of functional constraint. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Quantum power functional theory for many-body dynamics

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

Schmidt, Matthias, E-mail: Matthias.Schmidt@uni-bayreuth.de

2015-11-07

We construct a one-body variational theory for the time evolution of nonrelativistic quantum many-body systems. The position- and time-dependent one-body density, particle current, and time derivative of the current act as three variational fields. The generating (power rate) functional is minimized by the true current time derivative. The corresponding Euler-Lagrange equation, together with the continuity equation for the density, forms a closed set of one-body equations of motion. Space- and time-nonlocal one-body forces are generated by the superadiabatic contribution to the functional. The theory applies to many-electron systems.

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

PubMed

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

2018-03-01

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

Inference of ecological and social drivers of human brain-size evolution.

PubMed

González-Forero, Mauricio; Gardner, Andy

2018-05-01

The human brain is unusually large. It has tripled in size from Australopithecines to modern humans 1 and has become almost six times larger than expected for a placental mammal of human size 2 . Brains incur high metabolic costs 3 and accordingly a long-standing question is why the large human brain has evolved 4 . The leading hypotheses propose benefits of improved cognition for overcoming ecological 5-7 , social 8-10 or cultural 11-14 challenges. However, these hypotheses are typically assessed using correlative analyses, and establishing causes for brain-size evolution remains difficult 15,16 . Here we introduce a metabolic approach that enables causal assessment of social hypotheses for brain-size evolution. Our approach yields quantitative predictions for brain and body size from formalized social hypotheses given empirical estimates of the metabolic costs of the brain. Our model predicts the evolution of adult Homo sapiens-sized brains and bodies when individuals face a combination of 60% ecological, 30% cooperative and 10% between-group competitive challenges, and suggests that between-individual competition has been unimportant for driving human brain-size evolution. Moreover, our model indicates that brain expansion in Homo was driven by ecological rather than social challenges, and was perhaps strongly promoted by culture. Our metabolic approach thus enables causal assessments that refine, refute and unify hypotheses of brain-size evolution.

Enriching Planning through Industry Analysis

ERIC Educational Resources Information Center

Martinez, Mario; Wolverton, Mimi

2009-01-01

Strategic planning is an important tool, but the sole dependence on it across departments and campuses has resulted in the underutilization of equally important methods of analysis. The evolution of higher and postsecondary education necessitates a systemic industry analysis, as the combination of new providers and delivery mechanisms and changing…

Feather development genes and associated regulatory innovation predate the origin of Dinosauria.

PubMed

Lowe, Craig B; Clarke, Julia A; Baker, Allan J; Haussler, David; Edwards, Scott V

2015-01-01

The evolution of avian feathers has recently been illuminated by fossils and the identification of genes involved in feather patterning and morphogenesis. However, molecular studies have focused mainly on protein-coding genes. Using comparative genomics and more than 600,000 conserved regulatory elements, we show that patterns of genome evolution in the vicinity of feather genes are consistent with a major role for regulatory innovation in the evolution of feathers. Rates of innovation at feather regulatory elements exhibit an extended period of innovation with peaks in the ancestors of amniotes and archosaurs. We estimate that 86% of such regulatory elements and 100% of the nonkeratin feather gene set were present prior to the origin of Dinosauria. On the branch leading to modern birds, we detect a strong signal of regulatory innovation near insulin-like growth factor binding protein (IGFBP) 2 and IGFBP5, which have roles in body size reduction, and may represent a genomic signature for the miniaturization of dinosaurian body size preceding the origin of flight. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Parallel evolution of sexual isolation in sticklebacks.

PubMed

Boughman, Janette Wenrick; Rundle, Howard D; Schluter, Dolph

2005-02-01

Mechanisms of speciation are not well understood, despite decades of study. Recent work has focused on how natural and sexual selection cause sexual isolation. Here, we investigate the roles of divergent natural and sexual selection in the evolution of sexual isolation between sympatric species of threespine sticklebacks. We test the importance of morphological and behavioral traits in conferring sexual isolation and examine to what extent these traits have diverged in parallel between multiple, independently evolved species pairs. We use the patterns of evolution in ecological and mating traits to infer the likely nature of selection on sexual isolation. Strong parallel evolution implicates ecologically based divergent natural and/or sexual selection, whereas arbitrary directionality implicates nonecological sexual selection or drift. In multiple pairs we find that sexual isolation arises in the same way: assortative mating on body size and asymmetric isolation due to male nuptial color. Body size and color have diverged in a strongly parallel manner, similar to ecological traits. The data implicate ecologically based divergent natural and sexual selection as engines of speciation in this group.

Vestibular evidence for the evolution of aquatic behaviour in early cetaceans.

PubMed

Spoor, F; Bajpai, S; Hussain, S T; Kumar, K; Thewissen, J G M

2002-05-09

Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton. Here we assess the evolution of cetacean locomotor behaviour from an independent perspective by looking at the semicircular canal system, one of the main sense organs involved in neural control of locomotion. Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times smaller than in other mammals. This reduces the sensitivity of the canal system, most plausibly to match the fast body rotations that characterize cetacean behaviour. Eocene fossils show that the new sensory regime, incompatible with terrestrial competence, developed quickly and early in cetacean evolution, as soon as the taxa are associated with marine environments. Dedicated agile swimming of cetaceans thus appeared to have originated as a rapid and fundamental shift in locomotion rather than as the gradual transition suggested by postcranial evidence. We hypothesize that the unparalleled modification of the semicircular canal system represented a key 'point of no return' event in early cetacean evolution, leading to full independence from life on land.

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

PubMed

Holman, Luke; Bro-Jørgensen, Jakob

2016-08-01

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

Dinosaur evolution. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds.

PubMed

Lee, Michael S Y; Cau, Andrea; Naish, Darren; Dyke, Gareth J

2014-08-01

Recent discoveries have highlighted the dramatic evolutionary transformation of massive, ground-dwelling theropod dinosaurs into light, volant birds. Here, we apply Bayesian approaches (originally developed for inferring geographic spread and rates of molecular evolution in viruses) in a different context: to infer size changes and rates of anatomical innovation (across up to 1549 skeletal characters) in fossils. These approaches identify two drivers underlying the dinosaur-bird transition. The theropod lineage directly ancestral to birds undergoes sustained miniaturization across 50 million years and at least 12 consecutive branches (internodes) and evolves skeletal adaptations four times faster than other dinosaurs. The distinct, prolonged phase of miniaturization along the bird stem would have facilitated the evolution of many novelties associated with small body size, such as reorientation of body mass, increased aerial ability, and paedomorphic skulls with reduced snouts but enlarged eyes and brains. Copyright © 2014, American Association for the Advancement of Science.

Evolution of large body size in abalones (Haliotis): Patterns and implications

USGS Publications Warehouse

Estes, J.A.; Lindberg, D.R.; Wray, C.

2005-01-01

Kelps and other fleshy macroalgae - dominant reef-inhabiting organisms in cool - seasmay have radiated extensively following late Cenozoic polar cooling, thus triggering a chain of evolutionary change in the trophic ecology of nearshore temperate ecosystems. We explore this hypothesis through an analysis of body size in the abalones (Gastropoda; Haliotidae), a widely distributed group in modern oceans that displays a broad range of body sizes and contains fossil representatives from the late Cretaceous (60-75 Ma). Geographic analysis of maximum shell length in living abalones showed that small-bodied species, while most common in the Tropics, have a cosmopolitan distribution, whereas large-bodied species occur exclusively in cold-water ecosystems dominated by kelps and other macroalgae. The phylogeography of body size evolution in extant abalones was assessed by constructing a molecular phylogeny in a mix of large and small species obtained from different regions of the world. This analysis demonstrates that small body size is the plesiomorphic state and largeness has likely arisen at least twice. Finally, we compiled data on shell length from the fossil record to determine how (slowly or suddenly) and when large body size arose in the abalones. These data indicate that large body size appears suddenly at the Miocene/Pliocene boundary. Our findings support the view that fleshy-algal dominated ecosystems radiated rapidly in the coastal oceans with the onset of the most recent glacial age. We conclude with a discussion of the broader implications of this change. ?? 2005 The Paleontological Society. All rights reserved.

Sea shell diversity and rapidly evolving secretomes: insights into the evolution of biomineralization.

PubMed

Kocot, Kevin M; Aguilera, Felipe; McDougall, Carmel; Jackson, Daniel J; Degnan, Bernard M

2016-01-01

An external skeleton is an essential part of the body plan of many animals and is thought to be one of the key factors that enabled the great expansion in animal diversity and disparity during the Cambrian explosion. Molluscs are considered ideal to study the evolution of biomineralization because of their diversity of highly complex, robust and patterned shells. The molluscan shell forms externally at the interface of animal and environment, and involves controlled deposition of calcium carbonate within a framework of macromolecules that are secreted from the dorsal mantle epithelium. Despite its deep conservation within Mollusca, the mantle is capable of producing an incredible diversity of shell patterns, and macro- and micro-architectures. Here we review recent developments within the field of molluscan biomineralization, focusing on the genes expressed in the mantle that encode secreted proteins. The so-called mantle secretome appears to regulate shell deposition and patterning and in some cases becomes part of the shell matrix. Recent transcriptomic and proteomic studies have revealed marked differences in the mantle secretomes of even closely-related molluscs; these typically exceed expected differences based on characteristics of the external shell. All mantle secretomes surveyed to date include novel genes encoding lineage-restricted proteins and unique combinations of co-opted ancient genes. A surprisingly large proportion of both ancient and novel secreted proteins containing simple repetitive motifs or domains that are often modular in construction. These repetitive low complexity domains (RLCDs) appear to further promote the evolvability of the mantle secretome, resulting in domain shuffling, expansion and loss. RLCD families further evolve via slippage and other mechanisms associated with repetitive sequences. As analogous types of secreted proteins are expressed in biomineralizing tissues in other animals, insights into the evolution of the genes underlying molluscan shell formation may be applied more broadly to understanding the evolution of metazoan biomineralization.

Automatic Substitute Computed Tomography Generation and Contouring for Magnetic Resonance Imaging (MRI)-Alone External Beam Radiation Therapy From Standard MRI Sequences

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

Dowling, Jason A., E-mail: jason.dowling@csiro.au; University of Newcastle, Callaghan, New South Wales; Sun, Jidi

Purpose: To validate automatic substitute computed tomography CT (sCT) scans generated from standard T2-weighted (T2w) magnetic resonance (MR) pelvic scans for MR-Sim prostate treatment planning. Patients and Methods: A Siemens Skyra 3T MR imaging (MRI) scanner with laser bridge, flat couch, and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole-pelvis MRI scan (1.6 mm 3-dimensional isotropic T2w SPACE [Sampling Perfection with Application optimized Contrasts using different flip angle Evolution] sequence) was acquired. Three additional small field of view scans were acquired: T2w, T2*w, and T1wmore » flip angle 80° for gold fiducials. Patients received a routine planning CT scan. Manual contouring of the prostate, rectum, bladder, and bones was performed independently on the CT and MR scans. Three experienced observers contoured each organ on MRI, allowing interobserver quantification. To generate a training database, each patient CT scan was coregistered to their whole-pelvis T2w using symmetric rigid registration and structure-guided deformable registration. A new multi-atlas local weighted voting method was used to generate automatic contours and sCT results. Results: The mean error in Hounsfield units between the sCT and corresponding patient CT (within the body contour) was 0.6 ± 14.7 (mean ± 1 SD), with a mean absolute error of 40.5 ± 8.2 Hounsfield units. Automatic contouring results were very close to the expert interobserver level (Dice similarity coefficient): prostate 0.80 ± 0.08, bladder 0.86 ± 0.12, rectum 0.84 ± 0.06, bones 0.91 ± 0.03, and body 1.00 ± 0.003. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same dose prescription was found to be 0.3% ± 0.8%. The 3-dimensional γ pass rate was 1.00 ± 0.00 (2 mm/2%). Conclusions: The MR-Sim setup and automatic sCT generation methods using standard MR sequences generates realistic contours and electron densities for prostate cancer radiation therapy dose planning and digitally reconstructed radiograph generation.« less

Oxygen no longer plays a major role in Body Size Evolution

NASA Astrophysics Data System (ADS)

Datta, H.; Sachson, W.; Heim, N. A.; Payne, J.

2015-12-01

When observing the long-term relationship between atmospheric oxygen and the maximum size in organisms across the Geozoic (~3.8 Ga - present), it appears that as oxygen increases, organism size grows. However, during the Phanerozoic (541 Ma - Present) oxygen levels varied, so we set out to test the hypothesis that oxygen levels drive patterns marine animal body size evolution. Expected decreases in maximum size due to a lack of oxygen do not occur, and instead, body size continues to increase regardless. In the oxygen data, a relatively low atmospheric oxygen percentage can support increasing body size, so our research tries to determine whether lifestyle affects body size in marine organisms. The genera in the data set were organized based on their tiering, motility, and feeding, such as a pelagic, fully-motile, predator. When organisms fill a certain ecological niche to take advantage of resources, they will have certain life modes, rather than randomly selected traits. For example, even in terrestrial environments, large animals have to constantly feed themselves to support their expensive terrestrial lifestyle which involves fairly consistent movement, and the structural support necessary for that movement. Only organisms with access to high energy food sources or large amounts of food can support themselves, and that is before they expend energy elsewhere. Organisms that expend energy frugally when active or have slower metabolisms in comparison to body size have a more efficient lifestyle and are generally able to grow larger, while those who have higher energy demands like predators are limited to comparatively smaller sizes. Therefore, in respect to the fossil record and modern measurements of animals, the metabolism and lifestyle of an organism dictate its body size in general. With this further clarification on the patterns of evolution, it will be easier to observe and understand the reasons for the ecological traits of organisms today.

Conceptualizing 2000: Proactive Planning.

ERIC Educational Resources Information Center

Angel, Dan, Ed.; DeVault, Mike, Ed.

As community, technical, and junior colleges approach the 21st century, faculty shortages, an increasingly diverse student body, dwindling financial resources, and accountability mandates will require careful, action-oriented college planning. This two-part book presents 10 articles on the dynamics of planning and specific planning models, and…

Planning Education: Exchanging Approaches to Teaching Practice-Based Skills

ERIC Educational Resources Information Center

Ritchie, Heather; Sheppard, Adam; Croft, Nick; Peel, Deborah

2017-01-01

Planning curricula have continually evolved to meet changing societal needs, technological change and employer expectations. The professional accrediting body in the United Kingdom, the Royal Town Planning Institute, stipulates the core planning skills required, differentiating between formal classroom-based learning and professional competencies,…

Proximate determinants of bite force in Anolis lizards.

PubMed

Wittorski, Antoine; Losos, Jonathan B; Herrel, Anthony

2016-01-01

Performance measures associated with the vertebrate jaw system may provide important insights into vertebrate ecology and evolution because of their importance in many ecologically relevant tasks. Previous studies have shown that in many taxa, evolution toward higher bite force has gone hand in hand with the evolution of larger body size. However, independent of differences in overall body size, bite force may vary depending on head size and shape as well. Moreover, the underlying musculature may also drive variation in bite force. Here, we investigate the proximate determinants of bite force in lizards of the genus Anolis. We dissected the jaw muscles and quantified muscle mass, fibre length, and cross-sectional area. Data were analysed for both sexes independently given the sexual dimorphism detected in the dataset. Our results show that the traits that explain bite force are similar in both males and females with overall body size and muscle mass being the principal determinants. Among the different muscles examined, the adductor externus and the pseudotemporalis groups were the best determinants of bite force. However, models run for males predicted the variation in bite force better than models for females, suggesting that selection on morphology improving bite force may be stronger in males. © 2015 Anatomical Society.

Convergent evolution in mechanical design of lamnid sharks and tunas.

PubMed

Donley, Jeanine M; Sepulveda, Chugey A; Konstantinidis, Peter; Gemballa, Sven; Shadwick, Robert E

2004-05-06

The evolution of 'thunniform' body shapes in several different groups of vertebrates, including whales, ichthyosaurs and several species of large pelagic fishes supports the view that physical and hydromechanical demands provided important selection pressures to optimize body design for locomotion during vertebrate evolution. Recognition of morphological similarities between lamnid sharks (the most well known being the great white and the mako) and tunas has led to a general expectation that they also have converged in their functional design; however, no quantitative data exist on the mechanical performance of the locomotor system in lamnid sharks. Here we examine the swimming kinematics, in vivo muscle dynamics and functional morphology of the force-transmission system in a lamnid shark, and show that the evolutionary convergence in body shape and mechanical design between the distantly related lamnids and tunas is much more than skin deep; it extends to the depths of the myotendinous architecture and the mechanical basis for propulsive movements. We demonstrate that not only have lamnids and tunas converged to a much greater extent than previously known, but they have also developed morphological and functional adaptations in their locomotor systems that are unlike virtually all other fishes.

Functional modularity in lake-dwelling characin fishes of Mexico

PubMed Central

Bautista, Amando; Herder, Fabian; Doadrio, Ignacio

2017-01-01

Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi, which are differentiated by their trophic habits. Two different datasets were analyzed: (1) skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi) to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2) a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi). Skull shape showed significant differences among species and sex (P < 0.001), where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body), being significant only for A. caballeroi. PMID:28951817

Functional modularity in lake-dwelling characin fishes of Mexico.

PubMed

Ornelas-García, Claudia Patricia; Bautista, Amando; Herder, Fabian; Doadrio, Ignacio

2017-01-01

Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi , which are differentiated by their trophic habits. Two different datasets were analyzed: (1) skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi ) to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2) a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi ). Skull shape showed significant differences among species and sex ( P  < 0.001), where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body), being significant only for A. caballeroi .

Evolution of gigantism in nine-spined sticklebacks.

PubMed

Herczeg, Gábor; Gonda, Abigél; Merilä, Juha

2009-12-01

The relaxation of predation and interspecific competition are hypothesized to allow evolution toward "optimal" body size in island environments, resulting in the gigantism of small organisms. We tested this hypothesis by studying a small teleost (nine-spined stickleback, Pungitius pungitius) from four marine and five lake (diverse fish community) and nine pond (impoverished fish community) populations. In line with theory, pond fish tended to be larger than their marine or lake conspecifics, sometimes reaching giant sizes. In two geographically independent cases when predatory fish had been introduced into ponds, fish were smaller than those in nearby ponds lacking predators. Pond fish were also smaller when found in sympatry with three-spined stickleback (Gasterosteus aculeatus) than those in ponds lacking competitors. Size-at-age analyses demonstrated that larger size in ponds was achieved by both increased growth rates and extended longevity of pond fish. Results from a common garden experiment indicate that the growth differences had a genetic basis: pond fish developed two to three times higher body mass than marine fish during 36 weeks of growth under similar conditions. Hence, reduced risk of predation and interspecific competition appear to be chief forces driving insular body size evolution toward gigantism.

[Body image among obese women: consequences and degree of body dissatisfaction, relationship with low self-esteem and coping strategies].

PubMed

Brytek-Matera, Anna

2010-01-01

Definition of factors influencing negative body image among obese women and analysis of the relationship between body dissatisfaction and personality variables. 63 patients participated in this study. The mean age of the obese subjects was 41.90 years (SD +/- 12.23) and the mean body mass index (BMI) was 37.09 kg/m2 (SD +/- 8.09). The control group consisted of 60 women with normal body weight. The Body Dissatisfaction Scale of EDI (Garner et al., 1984), the Self-Esteem Inventory (Coopersmith, 1983) and the Brief COPE (Carver, 1997) were used in the study. In the clinical sample of women suffering from obesity, we have found a correlation between body dissatisfaction and behavioural disengagement, four dimensions of self-esteem (general, social, family and professional) and coping strategies focused on planning and positive reinterpretation. The regression analysis revealed that use of emotional support, planning and general self-esteem were predictive factors for the body dissatisfaction in obesity. Body dissatisfaction seriously influences the social, professional and emotional obese women's self.

A diploblastic radiate animal at the dawn of cambrian diversification with a simple body plan: distinct from Cnidaria?

PubMed

Yasui, Kinya; Reimer, James D; Liu, Yunhuan; Yao, Xiaoyong; Kubo, Daisuke; Shu, Degan; Li, Yong

2013-01-01

Microfossils of the genus Punctatus include developmental stages such as blastula, gastrula, and hatchlings, and represent the most complete developmental sequence of animals available from the earliest Cambrian. Despite the extremely well-preserved specimens, the evolutionary position of Punctatus has relied only on their conical remains and they have been tentatively assigned to cnidarians. We present a new interpretation of the Punctatus body plan based on the developmental reconstruction aided by recent advances in developmental biology. Punctatus developed from a rather large egg, gastrulated in a mode of invagination from a coeloblastura, and then formed a mouth directly from the blastopore. Spiny benthic hatchlings were distinguishable from swimming or crawling ciliate larvae found in cnidarians and sponges. A mouth appeared at the perihatching embryonic stage and was renewed periodically during growth, and old mouths transformed into the body wall, thus elongating the body. Growing animals retained a small blind gut in a large body cavity without partitioning by septa and did not form tentacles, pedal discs or holdfasts externally. A growth center at the oral pole was sufficient for body patterning throughout life, and the body patterning did not show any bias from radial symmetry. Contrary to proposed cnidarian affinity, the Punctatus body plan has basic differences from that of cnidarians, especially concerning a spacious body cavity separating ectoderm from endoderm. The lack of many basic cnidarian characters in the body patterning of Punctatus leads us to consider its own taxonomic group, potentially outside of Cnidaria.

A Diploblastic Radiate Animal at the Dawn of Cambrian Diversification with a Simple Body Plan: Distinct from Cnidaria?

PubMed Central

Yasui, Kinya; Reimer, James D.; Liu, Yunhuan; Yao, Xiaoyong; Kubo, Daisuke; Shu, Degan; Li, Yong

2013-01-01

Background Microfossils of the genus Punctatus include developmental stages such as blastula, gastrula, and hatchlings, and represent the most complete developmental sequence of animals available from the earliest Cambrian. Despite the extremely well-preserved specimens, the evolutionary position of Punctatus has relied only on their conical remains and they have been tentatively assigned to cnidarians. We present a new interpretation of the Punctatus body plan based on the developmental reconstruction aided by recent advances in developmental biology. Results Punctatus developed from a rather large egg, gastrulated in a mode of invagination from a coeloblastura, and then formed a mouth directly from the blastopore. Spiny benthic hatchlings were distinguishable from swimming or crawling ciliate larvae found in cnidarians and sponges. A mouth appeared at the perihatching embryonic stage and was renewed periodically during growth, and old mouths transformed into the body wall, thus elongating the body. Growing animals retained a small blind gut in a large body cavity without partitioning by septa and did not form tentacles, pedal discs or holdfasts externally. A growth center at the oral pole was sufficient for body patterning throughout life, and the body patterning did not show any bias from radial symmetry. Conclusions Contrary to proposed cnidarian affinity, the Punctatus body plan has basic differences from that of cnidarians, especially concerning a spacious body cavity separating ectoderm from endoderm. The lack of many basic cnidarian characters in the body patterning of Punctatus leads us to consider its own taxonomic group, potentially outside of Cnidaria. PMID:23840375

National Training Course. Emergency Medical Technician. Paramedic. Instructor's Lesson Plans. Module III. Shock and Fluid Therapy.

ERIC Educational Resources Information Center

National Highway Traffic Safety Administration (DOT), Washington, DC.

This instructor's lesson plan guide on shock and fluid therapy is one of fifteen modules designed for use in the training of emergency medical technicians (paramedics). Six units of study are presented: (1) body fluids, electrolytes and their effect on the body, and the general principles of fluid and acid base balances; (2) characteristics of…

Technical-Oriented Enterprise Resource Planning (ERP) Body of Knowledge for Information Systems Programs: Content and Implementation

ERIC Educational Resources Information Center

Boyle, Todd A.

2007-01-01

In this article, the author proposes a body of knowledge that the educators can use to incorporate the technical aspects of enterprise resource planning (ERP) into an information systems (IS) program, encapsulated as the ERP technical knowledge framework. To illustrate the application of this framework, the author discusses a course sequence that…

Ascidians and the plasticity of the chordate developmental program.

PubMed

Lemaire, Patrick; Smith, William C; Nishida, Hiroki

2008-07-22

Little is known about the ancient chordates that gave rise to the first vertebrates, but the descendants of other invertebrate chordates extant at the time still flourish in the ocean. These invertebrates include the cephalochordates and tunicates, whose larvae share with vertebrate embryos a common body plan with a central notochord and a dorsal nerve cord. Tunicates are now thought to be the sister group of vertebrates. However, research based on several species of ascidians, a diverse and wide-spread class of tunicates, revealed that the molecular strategies underlying their development appear to diverge greatly from those found in vertebrates. Furthermore, the adult body plan of most tunicates, which arises following an extensive post-larval metamorphosis, shows little resemblance to the body plan of any other chordate. In this review, we compare the developmental strategies of ascidians and vertebrates and argue that the very divergence of these strategies reveals the surprising level of plasticity of the chordate developmental program and is a rich resource to identify core regulatory mechanisms that are evolutionarily conserved in chordates. Further, we propose that the comparative analysis of the architecture of ascidian and vertebrate gene regulatory networks may provide critical insight into the origin of the chordate body plan.

Biophysics, environmental stochasticity, and the evolution of thermal safety margins in intertidal limpets.

PubMed

Denny, M W; Dowd, W W

2012-03-15

As the air temperature of the Earth rises, ecological relationships within a community might shift, in part due to differences in the thermal physiology of species. Prediction of these shifts - an urgent task for ecologists - will be complicated if thermal tolerance itself can rapidly evolve. Here, we employ a mechanistic approach to predict the potential for rapid evolution of thermal tolerance in the intertidal limpet Lottia gigantea. Using biophysical principles to predict body temperature as a function of the state of the environment, and an environmental bootstrap procedure to predict how the environment fluctuates through time, we create hypothetical time-series of limpet body temperatures, which are in turn used as a test platform for a mechanistic evolutionary model of thermal tolerance. Our simulations suggest that environmentally driven stochastic variation of L. gigantea body temperature results in rapid evolution of a substantial 'safety margin': the average lethal limit is 5-7°C above the average annual maximum temperature. This predicted safety margin approximately matches that found in nature, and once established is sufficient, in our simulations, to allow some limpet populations to survive a drastic, century-long increase in air temperature. By contrast, in the absence of environmental stochasticity, the safety margin is dramatically reduced. We suggest that the risk of exceeding the safety margin, rather than the absolute value of the safety margin, plays an underappreciated role in the evolution of thermal tolerance. Our predictions are based on a simple, hypothetical, allelic model that connects genetics to thermal physiology. To move beyond this simple model - and thereby potentially to predict differential evolution among populations and among species - will require significant advances in our ability to translate the details of thermal histories into physiological and population-genetic consequences.

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte.

PubMed

Matsunaga, Kelly K S; Tomescu, Alexandru M F

2016-04-01

The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian-Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant-substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that roots evolved from branches of the above-ground axial system, suggesting instead that lycophyte roots arose as a novel organ. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Departmental Planning Team: A Bridge to the Future.

ERIC Educational Resources Information Center

Cross, Cynthia S.; And Others

1989-01-01

One of the primary vehicles for coordinating information technology services at the University of Michigan is the Departmental Planning Team, a joint effort of the administrative and academic computing units of the University's Information Technology Division. The evolution of this group and its activities are described. (Author/MLW)

75 FR 13643 - ITS Joint Program Office; Intelligent Transportation Systems Program Advisory Committee; Notice...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-22

... Advisory Committee; Notice of Meeting AGENCY: Research and Innovative Technology Administration, U.S... Plan; (5) Evolution of IntelliDrive\\SM\\; (6) ITS Strategic Research Plan, 2010-2014; (7) University... Technology Administration, ITS Joint Program Office, Attention: Stephen Glasscock, 1200 New Jersey Avenue, SE...

The Foundations and Evolution of Institutional Research

ERIC Educational Resources Information Center

Volkwein, J. Fredericks

2008-01-01

What is institutional research (IR)? One of the most widely definition of the institutional research is by Joe Saupe, who emphasized institutional research as a set of activities that support institutional planning, policy formation, and decision making. Institutional researchers and IR functions are embedded in the offices of strategic planning,…

Health Care Marketing: Role Evolution of the Community Health Educator.

ERIC Educational Resources Information Center

Syre, Thomas R.; Wilson, Richard W.

1990-01-01

This article discusses role delineation in the health education profession, defines and presents principles of health care marketing, describes marketing plan development, and examines major ethical issues associated with health care marketing when utilized by community health educators. A marketing plan format for community health education is…

Support for the reproductive ground plan hypothesis of social evolution and major QTL for ovary traits of Africanized worker honey bees (Apis mellifera L.)

PubMed Central

2011-01-01

Background The reproductive ground plan hypothesis of social evolution suggests that reproductive controls of a solitary ancestor have been co-opted during social evolution, facilitating the division of labor among social insect workers. Despite substantial empirical support, the generality of this hypothesis is not universally accepted. Thus, we investigated the prediction of particular genes with pleiotropic effects on ovarian traits and social behavior in worker honey bees as a stringent test of the reproductive ground plan hypothesis. We complemented these tests with a comprehensive genome scan for additional quantitative trait loci (QTL) to gain a better understanding of the genetic architecture of the ovary size of honey bee workers, a morphological trait that is significant for understanding social insect caste evolution and general insect biology. Results Back-crossing hybrid European x Africanized honey bee queens to the Africanized parent colony generated two study populations with extraordinarily large worker ovaries. Despite the transgressive ovary phenotypes, several previously mapped QTL for social foraging behavior demonstrated ovary size effects, confirming the prediction of pleiotropic genetic effects on reproductive traits and social behavior. One major QTL for ovary size was detected in each backcross, along with several smaller effects and two QTL for ovary asymmetry. One of the main ovary size QTL coincided with a major QTL for ovary activation, explaining 3/4 of the phenotypic variance, although no simple positive correlation between ovary size and activation was observed. Conclusions Our results provide strong support for the reproductive ground plan hypothesis of evolution in study populations that are independent of the genetic stocks that originally led to the formulation of this hypothesis. As predicted, worker ovary size is genetically linked to multiple correlated traits of the complex division of labor in worker honey bees, known as the pollen hoarding syndrome. The genetic architecture of worker ovary size presumably consists of a combination of trait-specific loci and general regulators that affect the whole behavioral syndrome and may even play a role in caste determination. Several promising candidate genes in the QTL intervals await further study to clarify their potential role in social insect evolution and the regulation of insect fertility in general. PMID:21489230

Knowledge Infrastructures for Solar Cities

ERIC Educational Resources Information Center

Vanderburg, Willem H.

2006-01-01

The evolution of contemporary cities into solar cities will be affected by the decisions of countless specialists according to an established intellectual and professional division of labor. These specialists belong to groups responsible for advancing and applying a body of knowledge, and jointly, these bodies of knowledge make up a knowledge…

A Middle Triassic stem-turtle and the evolution of the turtle body plan.

PubMed

Schoch, Rainer R; Sues, Hans-Dieter

2015-07-30

The origin and early evolution of turtles have long been major contentious issues in vertebrate zoology. This is due to conflicting character evidence from molecules and morphology and a lack of transitional fossils from the critical time interval. The ∼220-million-year-old stem-turtle Odontochelys from China has a partly formed shell and many turtle-like features in its postcranial skeleton. Unlike the 214-million-year-old Proganochelys from Germany and Thailand, it retains marginal teeth and lacks a carapace. Odontochelys is separated by a large temporal gap from the ∼260-million-year-old Eunotosaurus from South Africa, which has been hypothesized as the earliest stem-turtle. Here we report a new reptile, Pappochelys, that is structurally and chronologically intermediate between Eunotosaurus and Odontochelys and dates from the Middle Triassic period (∼240 million years ago). The three taxa share anteroposteriorly broad trunk ribs that are T-shaped in cross-section and bear sculpturing, elongate dorsal vertebrae, and modified limb girdles. Pappochelys closely resembles Odontochelys in various features of the limb girdles. Unlike Odontochelys, it has a cuirass of robust paired gastralia in place of a plastron. Pappochelys provides new evidence that the plastron partly formed through serial fusion of gastralia. Its skull has small upper and ventrally open lower temporal fenestrae, supporting the hypothesis of diapsid affinities of turtles.

An organismal concept for Sengelia radicans gen. et sp. nov. – morphology and natural history of an Early Devonian lycophyte

PubMed Central

Tomescu, Alexandru M. F.

2017-01-01

Abstract Background and Aims Fossil plants are found as fragmentary remains and understanding them as natural species requires assembly of whole-organism concepts that integrate different plant parts. Such concepts are essential for incorporating fossils in hypotheses of plant evolution and phylogeny. Plants of the Early Devonian are crucial to reconstructing the initial radiation of tracheophytes, yet few are understood as whole organisms. Methods This study assembles a whole-plant concept for the Early Devonian lycophyte Sengelia radicans gen. et sp. nov., based on morphometric data and taphonomic observations from >1000 specimens collected in the Beartooth Butte Formation (Wyoming, USA). Key Results Sengelia radicans occupies a key position between stem-group and derived lycophyte lineages. Sengelia had a rooting system of downward-growing root-bearing stems, formed dense monotypic mats of prostrate shoots in areas that experienced periodic flooding, and was characterized by a life-history strategy adapted for survival after floods, dominated by clonality, and featuring infrequent sexual reproduction. Conclusions Sengelia radicans is the oldest among the very few early tracheophytes for which a detailed, rigorous whole-plant concept integrates morphology, growth habit, life history and growth environment. This plant adds to the diversity of body plans documented among lycophytes and may help elucidate patterns of morphological evolution in the clade. PMID:28334100

Characteristic density contrasts in the evolution of superclusters. The case of A2142 supercluster

NASA Astrophysics Data System (ADS)

Gramann, Mirt; Einasto, Maret; Heinämäki, Pekka; Teerikorpi, Pekka; Saar, Enn; Nurmi, Pasi; Einasto, Jaan

2015-09-01

Context. The formation and evolution of the cosmic web in which galaxy superclusters are the largest relatively isolated objects is governed by a gravitational attraction of dark matter and antigravity of dark energy (cosmological constant). Aims: We study the characteristic density contrasts in the spherical collapse model for several epochs in the supercluster evolution and their dynamical state. Methods: We analysed the density contrasts for the turnaround, future collapse, and zero gravity in different ΛCDM models and applied them to study the dynamical state of the supercluster A2142 with an almost spherical main body, making it a suitable test object to apply a model that assumes sphericity. Results: We present characteristic density contrasts in the spherical collapse model for different cosmological parameters. The analysis of the supercluster A2142 shows that its high-density core has already started to collapse. The zero-gravity line outlines the outer region of the main body of the supercluster. In the course of future evolution, the supercluster may split into several collapsing systems. Conclusions: The various density contrasts presented in our study and applied to the supercluster A2142 offer a promising way to characterise the dynamical state and expected future evolution of galaxy superclusters.

Evolution of male coloration during a post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi).

PubMed

Martin, Ryan A; Riesch, Rüdiger; Heinen-Kay, Justa L; Langerhans, R Brian

2014-02-01

Sexual signal evolution can be complex because multiple factors influence the production, transmission, and reception of sexual signals, as well as receivers' responses to them. To grasp the relative importance of these factors in generating signal diversity, we must simultaneously investigate multiple selective agents and signaling traits within a natural system. We use the model system of the radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes to test the effects of resource availability, male body size and other life-history traits, key aspects of the transmission environment, sex ratio, and predation risk on variation in multiple male color traits. Consistent with previous work examining other traits in this system, several color traits have repeatedly diverged between predation regimes, exhibiting greater elaboration in the absence of predators. However, other factors proved influential as well, with variation in resource levels, body size, relative testes size, and background water color being especially important for several color traits. For one prominent signaling trait, orange dorsal fins, we further confirmed a genetic basis underlying population differences using a laboratory common-garden experiment. We illustrate a promising approach for gaining a detailed understanding of the many contributing factors in the evolution of multivariate sexual signals. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Asynchronous evolution of physiology and morphology in Anolis lizards.

PubMed

Hertz, Paul E; Arima, Yuzo; Harrison, Alexis; Huey, Raymond B; Losos, Jonathan B; Glor, Richard E

2013-07-01

Species-rich adaptive radiations typically diversify along several distinct ecological axes, each characterized by morphological, physiological, and behavioral adaptations. We test here whether different types of adaptive traits share similar patterns of evolution within a radiation by investigating patterns of evolution of morphological traits associated with microhabitat specialization and of physiological traits associated with thermal biology in Anolis lizards. Previous studies of anoles suggest that close relatives share the same "structural niche" (i.e., use the same types of perches) and are similar in body size and shape, but live in different "climatic niches" (i.e., use habitats with different insolation and temperature profiles). Because morphology is closely tied to structural niche and field active body temperatures are tied to climatic niches in Anolis, we expected phylogenetic analyses to show that morphology is more evolutionarily conservative than thermal physiology. In support of this hypothesis, we find (1) that thermal biology exhibits more divergence among recently diverged Anolis taxa than does morphology; and (2) diversification of thermal biology among all species often follows diversification in morphology. These conclusions are remarkably consistent with predictions made by anole biologists in the 1960s and 1970s. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

BOOSTED TIDAL DISRUPTION BY MASSIVE BLACK HOLE BINARIES DURING GALAXY MERGERS FROM THE VIEW OF N -BODY SIMULATION

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

Li, Shuo; Berczik, Peter; Spurzem, Rainer

Supermassive black hole binaries (SMBHBs) are productions of the hierarchical galaxy formation model. There are many close connections between a central SMBH and its host galaxy because the former plays very important roles on galaxy formation and evolution. For this reason, the evolution of SMBHBs in merging galaxies is a fundamental challenge. Since there are many discussions about SMBHB evolution in a gas-rich environment, we focus on the quiescent galaxy, using tidal disruption (TD) as a diagnostic tool. Our study is based on a series of numerical, large particle number, direct N -body simulations for dry major mergers. According tomore » the simulation results, the evolution can be divided into three phases. In phase I, the TD rate for two well separated SMBHs in a merging system is similar to that for a single SMBH in an isolated galaxy. After two SMBHs approach close enough to form a bound binary in phase II, the disruption rate can be enhanced by ∼2 orders of magnitude within a short time. This “boosted” disruption stage finishes after the SMBHB evolves to a compact binary system in phase III, corresponding to a reduction in disruption rate back to a level of a few times higher than in phase I. We also discuss how to correctly extrapolate our N -body simulation results to reality, and the implications of our results to observations.« less

Evolution in health and medicine Sackler colloquium: Making evolutionary biology a basic science for medicine.

PubMed

Nesse, Randolph M; Bergstrom, Carl T; Ellison, Peter T; Flier, Jeffrey S; Gluckman, Peter; Govindaraju, Diddahally R; Niethammer, Dietrich; Omenn, Gilbert S; Perlman, Robert L; Schwartz, Mark D; Thomas, Mark G; Stearns, Stephen C; Valle, David

2010-01-26

New applications of evolutionary biology in medicine are being discovered at an accelerating rate, but few physicians have sufficient educational background to use them fully. This article summarizes suggestions from several groups that have considered how evolutionary biology can be useful in medicine, what physicians should learn about it, and when and how they should learn it. Our general conclusion is that evolutionary biology is a crucial basic science for medicine. In addition to looking at established evolutionary methods and topics, such as population genetics and pathogen evolution, we highlight questions about why natural selection leaves bodies vulnerable to disease. Knowledge about evolution provides physicians with an integrative framework that links otherwise disparate bits of knowledge. It replaces the prevalent view of bodies as machines with a biological view of bodies shaped by evolutionary processes. Like other basic sciences, evolutionary biology needs to be taught both before and during medical school. Most introductory biology courses are insufficient to establish competency in evolutionary biology. Premedical students need evolution courses, possibly ones that emphasize medically relevant aspects. In medical school, evolutionary biology should be taught as one of the basic medical sciences. This will require a course that reviews basic principles and specific medical applications, followed by an integrated presentation of evolutionary aspects that apply to each disease and organ system. Evolutionary biology is not just another topic vying for inclusion in the curriculum; it is an essential foundation for a biological understanding of health and disease.

Evolution of asteroidal orbits with high inclinations

NASA Astrophysics Data System (ADS)

Solovaya, Nina A.; Pittich, Eduard M.

1993-10-01

The 20,000 years orbital evolution of massless fictitious asteroid located at a border of the Hill's gravitational sphere has been investigated. The eleven orbits with the eccentricities from 0.0 to 0.4 in five groups of inclinations from 40 deg to 80 deg were numerically integrated with planetary perturbations of six major planets, using the numerical integration n-body program with the Everhart's integrator RA 15. For each group time evolution of orbital elements of the asteroids is presented.

Catastrophic Disruption of Asteroids: First Simulations with Explicit Formation of Spinning Rigid and Semi-rigid Aggregates

NASA Astrophysics Data System (ADS)

Michel, Patrick; Richardson, D. C.

2007-10-01

We have made major improvements in simulations of asteroid disruption by computing explicitly aggregate formations during the gravitational reaccumulation of small fragments, allowing us to obtain information on their spin and shape. First results will be presented taking as examples asteroid families that we reproduced successfully with previous less sophisticated simulations. In the last years, we have simulated successfully the formation of asteroid families using a SPH hydrocode to compute the fragmentation following the impact of a projectile on the parent body, and the N-body code pkdgrav to compute the mutual interactions of the fragments. We found that fragments generated by the disruption of a km-size asteroid can have large enough masses to be attracted by each other during their ejection. Consequently, many reaccumulations take place. Eventually most large fragments correspond to gravitational aggregates formed by reaccumulation of smaller ones. Moreover, formation of satellites occurs around the largest and other big remnants. In these previous simulations, when fragments reaccumulate, they merge into a single sphere whose mass is the sum of their masses. Thus, no information is obtained on the actual shape of the aggregates, their spin, ... For the first time, we have now simulated the disruption of a family parent body by computing explicitly the formation of aggregates, along with the above-mentioned properties. Once formed these aggregates can interact and/or collide with each other and break up during their evolution. We will present these first simulations and their possible implications on properties of asteroids generated by disruption. Results can for instance be compared with data provided by the Japanese space mission Hayabusa of the asteroid Itokawa, a body now understood to be a reaccumulated fragment from a larger parent body. Acknowledgments: PM and DCR acknowledge supports from the French Programme National de Planétologie and grants NSF AST0307549&AST0708110.

Parasitoidism, not sociality, is associated with the evolution of elaborate mushroom bodies in the brains of hymenopteran insects.

PubMed

Farris, Sarah M; Schulmeister, Susanne

2011-03-22

The social brain hypothesis posits that the cognitive demands of social behaviour have driven evolutionary expansions in brain size in some vertebrate lineages. In insects, higher brain centres called mushroom bodies are enlarged and morphologically elaborate (having doubled, invaginated and subcompartmentalized calyces that receive visual input) in social species such as the ants, bees and wasps of the aculeate Hymenoptera, suggesting that the social brain hypothesis may also apply to invertebrate animals. In a quantitative and qualitative survey of mushroom body morphology across the Hymenoptera, we demonstrate that large, elaborate mushroom bodies arose concurrent with the acquisition of a parasitoid mode of life at the base of the Euhymenopteran (Orussioidea + Apocrita) lineage, approximately 90 Myr before the evolution of sociality in the Aculeata. Thus, sociality could not have driven mushroom body elaboration in the Hymenoptera. Rather, we propose that the cognitive demands of host-finding behaviour in parasitoids, particularly the capacity for associative and spatial learning, drove the acquisition of this evolutionarily novel mushroom body architecture. These neurobehavioural modifications may have served as pre-adaptations for central place foraging, a spatial learning-intensive behaviour that is widespread across the Aculeata and may have contributed to the multiple acquisitions of sociality in this taxon.

Cytodifferentiation of hair cells during the development of a basal chordate.

PubMed

Gasparini, Fabio; Caicci, Federico; Rigon, Francesca; Zaniolo, Giovanna; Burighel, Paolo; Manni, Lucia

2013-10-01

Tunicates are unique animals for studying the origin and evolution of vertebrates because they are considered vertebrates' closest living relatives and share the vertebrate body plan and many specific features. Both possess neural placodes, transient thickenings of the cranial ectoderm that give rise to various types of sensory cells, including axonless secondary mechanoreceptors. In vertebrates, these are represented by the hair cells of the inner ear and the lateral line, which have an apical apparatus typically bearing cilia and stereovilli. In tunicates, they are found in the coronal organ, which is a mechanoreceptor located at the base of the oral siphon along the border of the velum and tentacles and is formed of cells bearing a row of cilia and short microvilli. The coronal organ represents the best candidate homolog for the vertebrate lateral line. To further understand the evolution of secondary sensory cells, we analysed the development and cytodifferentiation of coronal cells in the tunicate ascidian Ciona intestinalis for the first time. Here, coronal sensory cells can be identified as early as larval metamorphosis, before tentacles form, as cells with short cilia and microvilli. Sensory cells gradually differentiate, acquiring hair cell features with microvilli containing actin and myosin VIIa; in the meantime, the associated supporting cells develop. The coronal organ grows throughout the animal's lifespan, accompanying the growth of the tentacle crown. Anti-phospho Histone H3 immunostaining indicates that both hair cells and supporting cells can proliferate. This finding contributes to the understanding of the evolution of secondary sensory cells, suggesting that both ancestral cell types were able to proliferate and that this property was progressively restricted to supporting cells in vertebrates and definitively lost in mammals. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparative anatomy and histology of developmental and parasitic stages in the life cycle of the lined sea anemone Edwardsiella lineata.

PubMed

Reitzel, Adam M; Daly, Marymegan; Sullivan, James C; Finnerty, John R

2009-02-01

The evolution of parasitism is often accompanied by profound changes to the developmental program. However, relatively few studies have directly examined the developmental evolution of parasitic species from free-living ancestors. The lined sea anemone Edwardsiella lineata is a relatively recently evolved parasite for which closely related free-living outgroups are known, including the starlet sea anemone Nematostella vectensis. The larva of E. lineata parasitizes the ctenophore Mnemiopsis leidyi, and, once embedded in its host, the anemone assumes a novel vermiform body plan. That we might begin to understand how the developmental program of this species has been transformed during the evolution of parasitism, we characterized the gross anatomy, histology, and cnidom of the parasitic stage, post-parasitic larval stage, and adult stage of the E. lineata life cycle. The distinct parasitic stage of the life cycle differs from the post-parasitic larva with respect to overall shape, external ciliation, cnida frequency, and tissue architecture. The parasitic stage and planula both contain holotrichs, a type of cnida not previously reported in Edwardsiidae. The internal morphology of the post-parasitic planula is extremely similar to the adult morphology, with a complete set of mesenterial tissue and musculature despite this stage having little external differentiation. Finally, we observed 2 previously undocumented aspects of asexual reproduction in E. lineata: (1) the parasitic stage undergoes transverse fission via physal pinching, the first report of asexual reproduction in a pre-adult stage in the Edwardsiidae; and (2) the juvenile polyp undergoes transverse fission via polarity reversal, the first time this form of fission has been reported in E. lineata.

The Physical Origin of Galaxy Morphologies and Scaling Laws

NASA Technical Reports Server (NTRS)

Steinmetz, Matthias; Navarro, Julio F.

2002-01-01

We propose a numerical study designed to interpret the origin and evolution of galaxy properties revealed by space- and ground-based imaging and spectroscopical surveys. Our aim is to unravel the physical processes responsible for the development of different galaxy morphologies and for the establishment of scaling laws such as the Tully-Fisher relation for spirals and the Fundamental Plane of ellipticals. In particular, we plan to address the following major topics: (1) The morphology and observability of protogalaxies, and in particular the relationship between primordial galaxies and the z approximately 3 'Ly-break' systems identified in the Hubble Deep Field and in ground-based searches; (2) The origin of the disk and spheroidal components in galaxies, the timing and mode of their assembly, the corresponding evolution in galaxy morphologies and its sensitivity to cosmological parameters; (3) The origin and redshift evolution of the scaling laws that link the mass, luminosity size, stellar content, and metal abundances of galaxies of different morphological types. This investigation will use state-of-the-art N-body/gasdynamical codes to provide a spatially resolved description of the galaxy formation process in hierarchically clustering universes. Coupled with population synthesis techniques. our models can be used to provide synthetic 'observations' that can be compared directly with observations of galaxies both nearby and at cosmologically significant distances. This study will thus provide insight into the nature of protogalaxies and into the formation process of galaxies like our own Milky Way. It will also help us to assess the cosmological significance of these observations within the context of hierarchical theories of galaxy formation and will supply a theoretical context within which current and future observations can be interpreted.

Family planning in Guinea: a need for better public commitment.

PubMed

Delamou, Alexandre; Koivogui, Akoi; Dubourg, Dominique; Delvaux, Thérèse

2014-01-01

To describe the evolution of family planning (FP) in Guinea and to identify strengths, weaknesses, opportunities and threats of the current FP programme. Descriptive study of the evolution of FP in Guinea between 1992 and 2010. First, national laws as well as health policies and strategic plans related to reproductive health and family planning were reviewed. Second, FP indicators were extracted from the Guinean Demographic and Health Surveys (1992, 1999 and 2005). Third, FP services, sources of supply and data on FP funding were analysed. Laws, policies and strategic plans in Guinea are supportive of FP programme and services. Public and private actors are not sufficiently coordinated. The general government expenditure on health has remained stable at 6-7% between 2005 and 2011 despite a doubling of total expenditures on health, and contraceptives are supplied by foreign aid. Modern contraceptive prevalence slightly increased from 1.5% in 1992 to 6.8% in 2005 among women aged 15-49. A stronger national engagement in favour of repositioning FP should result in improved government funding of the FP programme and the promotion of long-acting and permanent methods. © 2013 John Wiley & Sons Ltd.

A Generalized National Planning Approach for Admission Capacity in Higher Education: A Nonlinear Integer Goal Programming Model with a Novel Differential Evolution Algorithm

PubMed Central

El-Qulity, Said Ali; Mohamed, Ali Wagdy

2016-01-01

This paper proposes a nonlinear integer goal programming model (NIGPM) for solving the general problem of admission capacity planning in a country as a whole. The work aims to satisfy most of the required key objectives of a country related to the enrollment problem for higher education. The system general outlines are developed along with the solution methodology for application to the time horizon in a given plan. The up-to-date data for Saudi Arabia is used as a case study and a novel evolutionary algorithm based on modified differential evolution (DE) algorithm is used to solve the complexity of the NIGPM generated for different goal priorities. The experimental results presented in this paper show their effectiveness in solving the admission capacity for higher education in terms of final solution quality and robustness. PMID:26819583

A Generalized National Planning Approach for Admission Capacity in Higher Education: A Nonlinear Integer Goal Programming Model with a Novel Differential Evolution Algorithm.

PubMed

El-Qulity, Said Ali; Mohamed, Ali Wagdy

2016-01-01

This paper proposes a nonlinear integer goal programming model (NIGPM) for solving the general problem of admission capacity planning in a country as a whole. The work aims to satisfy most of the required key objectives of a country related to the enrollment problem for higher education. The system general outlines are developed along with the solution methodology for application to the time horizon in a given plan. The up-to-date data for Saudi Arabia is used as a case study and a novel evolutionary algorithm based on modified differential evolution (DE) algorithm is used to solve the complexity of the NIGPM generated for different goal priorities. The experimental results presented in this paper show their effectiveness in solving the admission capacity for higher education in terms of final solution quality and robustness.

Evolution of the regions of the 3D particle motion in the regular polygon problem of (N+1) bodies with a quasi-homogeneous potential

NASA Astrophysics Data System (ADS)

Fakis, Demetrios; Kalvouridis, Tilemahos

2017-09-01

The regular polygon problem of (N+1) bodies deals with the dynamics of a small body, natural or artificial, in the force field of N big bodies, the ν=N-1 of which have equal masses and form an imaginary regular ν -gon, while the Nth body with a different mass is located at the center of mass of the system. In this work, instead of considering Newtonian potentials and forces, we assume that the big bodies create quasi-homogeneous potentials, in the sense that we insert to the inverse square Newtonian law of gravitation an inverse cube corrective term, aiming to approximate various phenomena due to their shape or to the radiation emitting from the primaries. Based on this new consideration, we apply a general methodology in order to investigate by means of the zero-velocity surfaces, the regions where 3D motions of the small body are allowed, their evolutions and parametric variations, their topological bifurcations, as well as the existing trapping domains of the particle. Here we note that this process is definitely a fundamental step of great importance in the study of many dynamical systems characterized by a Jacobian-type integral of motion in the long way of searching for solutions of any kind.