Document Details

Document Type:   Thesis
Title:   Distribution of Woodland Salamanders of the Valley and Ridge in West Virginia
Author:   Horace Reid Downer
College:   Science
Degree Program:   Biological Sciences, M.S.
Degree:   Master of Science
Committee Director:   Thomas K. Pauley, PhD
Document Availability:   Document available for World-Wide access.
Date of Defense:   24 April 2008

Two terrestrial woodland salamanders of the genus Plethodon, P. punctatus and P. virginia, are endemic to the Valley and Ridge Physiographic Province in West Virginia and Virginia and occupy limited geographic ranges. Two common and widespread species, P. cylindraceus and P. cinereus, also inhabit this region. To evaluate the distribution and habitat of these terrestrial salamanders I surveyed wooded ridges and slopes throughout the geographic range of the two endemic species by conducting daytime cover object searches and nocturnal visual encounter surveys. From March through November 2008, I recorded the presence of 321 woodland salamanders at 91 sites. I used two types of modeling to evaluate the distributions of these species with site occupancy data. I used logistic regression to evaluate a priori models that were developed with presence-absence data and associated environmental variables from 2008 surveys and ranked them with Akaikes Information Criterion corrected for small sample size (AICc). I then used historic and current presence data to model the distribution of each species with the software program Maxent with WorldClim climatic variables. Logistic regression models revealed that P. punctatus and P. cinereus had positive associations with elevation, P. virginia was negatively associated with relative humidity, and P. cylindraceus occurrence was negatively associated with elevation and positively associated with ambient temperature and relative humidity. Maxent distribution models were evaluated and suggested that the distributions of woodland salamanders are likely shaped by both climatic factors as well as biological factors, possibly in the form of competition. These results suggest that P. punctatus is associated with rocky substrates primarily among or near talus at high elevations. Plethodon virginia inhabits relatively dry ridges and slopes at all elevations. Plethodon cylindraceus is widespread throughout habitat types at lower elevations, while P. cinereus is largely limited to mesic habitats in this region. 

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