Environmental effects on morphological and genetic configuration within a phylogenetic framework

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2015-05

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Abstract

This dissertation focuses on how the environment influences the phenotypes and genotypes of species. Specifically, the primary objective is to explore how environmental factors influence morphological configuration and genetic variation at the individual and population levels in different species. This project consists of three separate studies, each employing a different model system. The first study investigates the morphological and environmental variation in the Neotropical fruit-eating bats of the genus Artibeus and whether cranial morphometric traits reflect ecological variation within a comparative phylogenetic framework. I found a strong phylogenetic signal for cranial morphometric variation that was related mainly to differences in skull size, whereas species arrangements across morphospace corresponded primarily to their levels of phylogenetic proximity. Furthermore, I found significant phylogenetic signal in clusters of variables associated with variation of temperature and precipitation, indicating that species environmental distribution might be constrained by their phylogenetic signal. The second study investigates the variation of skull configuration in the bank vole (Myodes glareolus) across individuals collected around the Chernobyl Nuclear Power Plant in Ukraine. I use the methods of geometric morphometrics to determine an increase of asymmetry in cranial dorsal, ventral and mandible lateral views of the skull associated with the geographic proximity to the Chernobyl Nuclear Power Plant and to characterize the shape variation in the symmetric and asymmetric morphometric components to evaluate the spatial distribution of patterns of variation. The results showed mixed patterns of variation of fluctuating asymmetry among cranial projections. There is a slight decrease in levels of fluctuating asymmetry as increase the geographic proximity to the Reactor 4 in cranial dorsal and ventral views. An opposite trend was shown by mandible lateral view, although association was not statistically significant. Based on these results, it is possible that the source of variation introduced by differences in imagining could bias the results. The third study analyzes the spatial patterns of genetic diversity and differentiation of Pacific giant salamander (Dicamptodon tenebrosus) from 11 headwater channels in the Pacific North West. I identified the existing population structure and addressed the levels of genetic differentiation among populations using microsatellite data. I found that the observed pattern of population differentiation was not geographically structured. Although higher levels of differentiation were observed between sites located in different geographic regions, in general levels of genetic differentiation were similar among sites located within the same drainage as among different drainages. Indeed, genetic analyses showed a lack of geographic structure and a broad range of variation across the geographic space, which might suggest high levels of gene flow across a high-disturbance landscape. My dissertation provides a greater understanding of the interactions between the phenotype, genotype and environment, and contributes to understanding how species distributions and morphological configurations are influenced by local environmental characteristics.

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Keywords

Fruit-Eating Bats, Bank Voles, Coastal Giant Salamanders, Ecomorphology, Fluctuating Asymmetry, Genetic Variation, Habitat Fragmentation, Morphometrics, Species Distribution

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