Abstract:
Plethodontid salamanders are model organisms for studying evolutionary
questions of gene flow, restricted ranges, and speciation. Plethodon, a diverse
genus within Plethodontidae, is widely distributed in eastern and western North
America. Much research has been based in the eastern United States where
diversity of these salamanders is high. Because of their morphological
conservatism, genetic analysis has often been used to address the questions of
population structure, speciation, and gene flow. The majority of these analyses
have relied on allozyme and mtDNA markers. However, these markers have their
shortcomings in resolving differentiation on a small geographic scale. To date no
researchers have used nuclear microsatellites to address systematic questions in
plethodontid salamanders.
I developed 11 nuclear microsatellite loci to address evolutionary
questions in two western members of the genus Plethodon, the sister species
Plethodon elongatus and P. storni. The taxonomic status of these salamanders
has been a source of contention. Although recent mtDNA analyses reveal the
presence of a third species previously included as P. storini in the Scott River
drainage, no samples from this possible new species are included in this thesis.
Substructure inferred from the mtDNA analyses within the range of P. stormi is
assessed, as well as gene flow between P. elongatus and P. stormi. My results
provide strong support for treating P. elongatus and P. stormi as separate species.
