Dissertation Research: Linking Ecology to Phylogeography: The Desmognathus Salamander Assemblage

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9801305 Wilbur To conserve biodiversity it is essential to understand and document patterns of genetic variation in natural populations. Much work by community ecologists has shown that species interactions can influence spatial variation in population sizes and dispersal rates, two factors known to impact the magnitude of genetic variation in populations. Population geneticists, however, have given less emphasis to how species interactions influence levels of population differentiation and speciation. There is a need to bridge this gap by utilizing a system in which a mechanistic understanding of the factors influencing movement patterns and population sizes can be developed. The salamander genus Desmognathus in the eastern United States is a model system for examining species interactions and their possible role in the evolution of terrestriality. The southern Appalachians support the world center of salamander diversity. Streams commonly support four Desmognathus species that form an ecological continuum from a large, more fully aquatic species to a small, predominately terrestrial species. The Eastern Continental Divide separates streams that contain D. quadramaculatus from those that do not. The mere presence of this large, predaceous salamander is known to affect the distribution and abundance of the other more terrestrial Desmognathus species. In this doctoral dissertation research, Henry M. Wilbur and student Leslie J. Rissler will utilize modern genetic techniques employing mitochondrial DNA markers to address the spatial scale of genetic variation within these Desmognathus species. Work emphasizes the contributions of both ecological and genetic tools to determine (1) the major biogeographic boundaries for each of the four Desmognathus species which exhibit varying degrees of terrestriality and (2) the influence of species interactions in structuring the extent of genetic variation in populations.