Dissertation Research: Processes of Diversification and Evolutionary History of Web-toed Salamanders (Genus Hydromantes)

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The aim of this project is to understand the evolutionary processes that have led to divergence between two species of web-toed salamanders in the Sierra Nevada. One species (Hydromantes platycephalus) is widespread and the other (H. brunus) is restricted to a small area, and the species show differences in morphology and habitat. Genetic evidence indicates that the range-restricted species may have recently diverged from the widespread species, and that different segments of the widespread species have been isolated from one another for millions of years. The relative influence of past climate changes and geological processes on genetic divergence within and between these species will be investigated using a variety of different genetic markers, in combination with distributional modeling.These salamanders offer the opportunity to study some populations with striking levels of genetic divergence but high morphological similarity, and others that are morphologically divergent but genetically similar. Examining the relative roles of climatic changes and geographic barriers in shaping the distributions and patterns of genetic divergence within these species will further our understanding of how lineages and species form, a major focus of evolutionary biology. Increased knowledge of cryptic biodiversity and species' responses to past environmental change will also be valuable for conservation efforts, especially with respect to the probable impact of future climate change.