Phylogeography of Hydromantes shastae: Implications for Management

Robert E. Bingham

Department of Integrative Biology

University of California, Berkeley, CA

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ABSTRACT

BINGHAM, ROBERT E.
Department of Integrative Biology, University of California, Berkeley, CA, rbingham@berkeley.edu

Phylogeography of Hydromantes shastae: Implications for Management

The utility of phylogeographic analyses in conservation and management has increased dramatically with the development of molecular and analytic methods. When different molecular markers and statistical approaches yield congruent results, we are able to properly characterize distinct evolutionary lineages and identify divergent populations for management. One application of phylogeography to management is to identify species with restricted ranges and high levels of genetic divergence between lineages, indicating significant isolation. The Shasta Salamander, Hydromantes shastae, is a geographically restricted plethodontid species exhibiting remarkable evolutionary diversification at small spatial scales. New and previously collected tissue samples from throughout the known range of the species were sequenced for the mitochondrial cytochrome b and 16S genes. Bayesian phylogenetic analyses showed statistically supported clades with large divergences between lineages. In two different pairwise comparisons, samples two miles apart were 4.5% divergent in the cytochrome b gene, indicating remarkably high levels of genetic differentiation. Unpublished allozyme data were previously collected for a subset of these populations, and have now been analyzed using multidimensional scaling and population structure software. With relatively high estimates of Nei’s genetic distance and fixed allozyme differences, the nuclear data strongly support significant isolation and diversification at small spatial scales. Analyses of both mitochondrial and nuclear markers show Hydromantes shastae to be strongly structured across its restricted range, and highlight several divergent populations and lineages that should be of high priority in management actions aimed at preserving evolutionary history and potential in this unique species.