Date of Award

Summer 8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Josiah H. Townsend

Second Advisor

Joseph E. Duchamp

Third Advisor

Jeffery L. Larkin

Fourth Advisor

Edwin R. Patterson

Abstract

The genus Plethodon are a diverse group of forest dwelling, direct-developing salamanders that play an important role in the complex food webs of temperature forests of eastern North America. Unfortunately, large population declines have been documented and many Plethodon species remain poorly understood, undermining planning for conservation and management. One understudied species is the Valley and Ridge salamander, Plethodon hoffmani. In the northern part of the Valley and Ridge salamander’s range, co-occurrence with the widespread red-backed salamander (Plethodon cinereus) is common. During the spring of 2017, I characterized microhabitat conditions for the Valley and Ridge salamander's occurrence in areas with and without the red-backed salamander co-occurring in Indiana County, Pennsylvania (n=7). Sympatric populations occupied areas with more cover objects available and higher humidity compared to allopatric P. hoffmani populations. Tissue samples were collected and mtDNA sequences were analyzed for phylogeographic structure among and within populations. Low genetic diversity and limited phylogeographic structure were recovered, suggesting a recent population bottleneck, possibly resulting from a founder effect following post-glacial range expansion. Some individuals from Blue Spruce County Park possessed morphological traits intermediate to P. hoffmani and P. cinereus, and were hypothesized to be hybrids. In the fall of 2017, Blue Spruce County Park was sampled using repeated count surveys to characterize the microhabitat for the P. hoffmani, P. cinereus, and those with intermediate morphotypes. Low detection rates of P. hoffmani and intermediates prevented robust analyses but results suggest that P. cinereus are associated with lower elevations. I collected 27 tissue samples representing each of the three morphotypes, which were sequenced for the mtDNA locus COI and the nDNA loci GAPD and POMC to detect evidence for hybridization. No first generation hybrids were detected, however incongruences among genealogies provide preliminary evidence for historical hybridization between these species. This is the first study to document ecology and hybridization for P. hoffmani populations in the Allegheny Plateau and provides critical information on Plethodon species co-occurrence in a changing climate.

Share

COinS