Gene flow and the relationship of Plethodon stormi and P. elongatus assessed with 11 novel microsatellite loci

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.