194 research outputs found
Mammalian Enamel Prism Patterns and Enamel Deposition Rates
Enamel prism patterns and enamel deposition rates were compared for specimens representing six mammalian orders. Enamel samples were characterized by either pattern 1 or pattern 3 prisms. Each prism pattern cate-gory contained prisms from at least two mammalian orders. Enamel deposition rate was estimated for each sample by measuring prism cross striation repeat intervals. Statistical analysis of cross striation repeat intervals illustrates significant differences in deposition rate between prism patterns 1 and 3. No statistically significant differences were found in deposition rate between the higher-level taxa represented within each prism pat-tern category. That enamel deposition rate is not taxon-specific reinforces the close association between deposition rate and prism morphology. In accord with previous studies, pattern 1 enamel is deposited more slowly than is pattern 3 enamel. Correlation analyses illustrated a lack of association between enamel deposition rate and body mass, tooth size, and estimated ameloblast size. Evidence that enamel deposition rate is associated with enamel prism morphology, coupled with evidence that deposition rate is not correlated with size parameters, points to developmental homology (i.e., homogeneous deposition rate) within each prism pattern
Enamel Prism Morphology in Molar Teeth of Small Eutherian Mammals
Data summarizing enamel prism shape, sire and spacing are reported for the molar enamel of 55 species of small eutherian mammals including primates, bats, tree shrews, flying lemurs, insectivorans and representatives of a variety of fossil families. Confocal photomicrographs reveal that the subsurface enamel of most species is characterized by arc-shaped prisms. The lack of a clear distinction between pattern 2 and pattern 3 prism configurations within single specimens suggests that the broad category arc-shaped prisms is the most appropriate descriptive grouping for these species. Of the total sample, three species exhibit only circular prisms while no evidence of prismatic enamel was found in two bats. Prism shape is not an informative phylogenetic character at the ordinal level for these morphologically primitive and relatively thin-enameled taxa. Significant differences between species in several prism sire and spacing variables (central distance between prisms, prism diameter, prism area and the ratio of prism area to estimated ameloblast area) suggest the potential for further analyses of quantitative variation to document evolutionary relationships within or among family-level groups
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UMass Amherst Collections 2013
During the Campus Master Planning effort the need to better understand and plan for the UMass Amherst collections was identified and an ad-hoc committee was created to help advance a better understanding of the existing collections and how best to plan for the future. The committee was comprised of Directors/ curators of campus academic collections, Campus Planning staff and other related campus professionals. The first task of the committee was to develop a basis for creating a planning framework for the academic collections. The Committee defined existing collections and set a framework and common language that enabled the classification and quantification of collections space on campus. The UMass Amherst Collections 2013 report summarizes each collection, its mission and the contact person responsible for the collection. The term collection was defined to include all the campus holdings that are used for academic, research and outreach purposes, with the exception of the Libraries, which had recently completed a facilities Master Plan outlining strategies for future facilities
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Planning for Campus Collections 2013
During the Campus Master Planning effort the need to better understand and plan for the UMass Amherst collections was identified and an ad-hoc committee was created to help advance a better understanding of the existing collections and how best to plan for the future. The committee was comprised of Directors/ curators of campus academic collections, Campus Planning staff and other related campus professionals. The first task of the committee was to develop a basis for creating a planning framework for the academic collections. The Committee defined existing collections and set a framework and common language that enabled the classification and quantification of collections space on campus. The UMass Amherst Planning for Campus Collection 2013 report to academic Deans provides an overview of the Campus Planning Collections Study and proposes a vision for future planning efforts
Ecomorphological and phylogenetic controls on sympatry across extant bats
AimMacroecological patterns of sympatry can inform our understanding of how ecological and evolutionary processes govern species distributions. Following speciation, both intrinsic and extrinsic factors may determine how readily sympatry occurs. One possibility is that sympatry most readily occurs with ecological divergence, especially if broad‐scale co‐occurrence is mediated by niche differentiation. Time since divergence may also predict sympatry if hybridization and gene flow lead to the collapse of species boundaries between closely related taxa. Here, we test for ecological and phylogenetic predictors of sympatry across the global radiation of extant bats.LocationGlobal.TaxonBats (Order Chiroptera).MethodsWe used a combination of linear mixed‐modelling, simulations and maximum‐likelihood modelling to test whether phylogenetic and ecomorphological divergence between species predict sympatry. We further assess how these relationships vary based on biogeographic realm.ResultsWe find that time since divergence does not predict sympatry in any biogeographic realm. Morphological divergence is negatively related to sympatry in the Neotropics, but shows no relationship with sympatry elsewhere.Main conclusionsWe find that bats in most biogeographic realms co‐occur at broad spatial scales regardless of phylogenetic similarity. Neotropical bats, however, appear to co‐occur most readily when morphologically similar. To the extent that pairwise phylogenetic and morphological divergence reflect ecological differentiation, our results suggest that abiotic and environmental factors may be more important than species interactions in determining patterns of sympatry across bats.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/1/jbi13353-sup-0005-FigureS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/2/jbi13353.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/3/jbi13353-sup-0006-FigureS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/4/jbi13353-sup-0003-FigureS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/5/jbi13353-sup-0004-FigureS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/6/jbi13353_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/7/jbi13353-sup-0002-FigureS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144581/8/jbi13353-sup-0001-FigureS1.pd
Combining geometric morphometrics and finite element analysis with evolutionary modeling:towards a synthesis
<p>Geometric morphometrics (GM) and finite element analysis (FEA) are increasingly common techniques for the study of form and function. We show how principles of quantitative evolution in continuous phenotypic traits can link the two techniques, allowing hypotheses about the relative importance of different functions to be tested in a phylogenetic and evolutionary framework. Finite element analysis is used to derive quantitative surfaces that describe the comparative performance of different morphologies in a morphospace derived from GM. The combination of two or more performance surfaces describes a quantitative adaptive landscape that can be used to predict the direction morphological evolution would take if a combination of functions was selected for. Predicted paths of evolution also can be derived for hypotheses about the relative importance of multiple functions, which can be tested against evolutionary pathways that are documented by phylogenies or fossil sequences. Magnitudes of evolutionary trade-offs between functions can be estimated using maximum likelihood. We apply these methods to an earlier study of carapace strength and hydrodynamic efficiency in emydid turtles. We find that strength and hydrodynamic efficiency explain about 45% of the variance in shell shape; drift and other unidentified functional factors are necessary to explain the remaining variance. Measurement of the proportional trade-off between shell strength and hydrodynamic efficiency shows that throughout the Cenozoic aquatic turtles generally sacrificed strength for streamlining and terrestrial species favored stronger shells; this suggests that the selective regime operating on small to mid-sized emydids has remained relatively static.</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Polly, P. D., C. T. Stayton, E. R. Dumont, S. E. Pierce, E. J. Rayfield, and K. D. Angielczyk. 2016. Combining geometric morphometrics and finite element analysis with evolutionary modeling: towards a synthesis. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1111225.</p
Trpc2 pseudogenization dynamics in bats reveal ancestral vomeronasal signaling, then pervasive loss
This work was supported by the National Science Foundation Graduate Research Fellowship and NSF-DEB 144214
An Efficient Method of Modeling Material Properties Using a Thermal Diffusion Analogy: An Example Based on Craniofacial Bone
The ability to incorporate detailed geometry into finite element models has allowed researchers to investigate the influence of morphology on performance aspects of skeletal components. This advance has also allowed researchers to explore the effect of different material models, ranging from simple (e.g., isotropic) to complex (e.g., orthotropic), on the response of bone. However, bone's complicated geometry makes it difficult to incorporate complex material models into finite element models of bone. This difficulty is due to variation in the spatial orientation of material properties throughout bone. Our analysis addresses this problem by taking full advantage of a finite element program's ability to solve thermal-structural problems. Using a linear relationship between temperature and modulus, we seeded specific nodes of the finite element model with temperatures. We then used thermal diffusion to propagate the modulus throughout the finite element model. Finally, we solved for the mechanical response of the finite element model to the applied loads and constraints. We found that using the thermal diffusion analogy to control the modulus of bone throughout its structure provides a simple and effective method of spatially varying modulus. Results compare favorably against both experimental data and results from an FE model that incorporated a complex (orthotropic) material model. This method presented will allow researchers the ability to easily incorporate more material property data into their finite element models in an effort to improve the model's accuracy
All You Can Eat: High Performance Capacity and Plasticity in the Common Big-Eared Bat, Micronycteris microtis (Chiroptera: Phyllostomidae)
Ecological specialization and resource partitioning are expected to be particularly high in the species-rich communities of tropical vertebrates, yet many species have broader ecological niches than expected. In Neotropical ecosystems, Neotropical leaf-nosed bats (Phyllostomidae) are one of the most ecologically and functionally diverse vertebrate clades. Resource partitioning in phyllostomids might be achieved through differences in the ability to find and process food. We selected Micronycteris microtis, a very small (5–7 g) animalivorous phyllostomid, to explore whether broad resource use is associated with specific morphological, behavioral and performance traits within the phyllostomid radiation. We documented processing of natural prey and measured bite force in free-ranging M. microtis and other sympatric phyllostomids. We found that M. microtis had a remarkably broad diet for prey size and hardness. For the first time, we also report the consumption of vertebrates (lizards), which makes M. microtis the smallest carnivorous bat reported to date. Compared to other phyllostomids, M. microtis had the highest bite force for its size and cranial shape and high performance plasticity. Bite force and cranial shape appear to have evolved rapidly in the M. microtis lineage. High performance capacity and high efficiency in finding motionless prey might be key traits that allow M. microtis, and perhaps other species, to successfully co-exist with other gleaning bats
Social mindfulness and prosociality vary across the globe
Humans are social animals, but not everyone will be mindful of others to the same extent. Individual differences have been found, but would social mindfulness also be shaped by one’s location in the world? Expecting cross-national differences to exist, we examined if and how social mindfulness differs across countries. At little to no material cost, social mindfulness typically entails small acts of attention or kindness. Even though fairly common, such low-cost cooperation has received little empirical attention. Measuring social mindfulness across 31 samples from industrialized countries and regions (n = 8,354), we found considerable variation. Among selected country-level variables, greater social mindfulness was most strongly associated with countries’ better general performance on environmental protection. Together, our findings contribute to the literature on prosociality by targeting the kind of everyday cooperation that is more focused on communicating benevolence than on providing material benefits
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