Date of Award
Doctor of Philosophy (PhD)
The relationship between wildlife and the environment they inhabit is dependent on both spatial and temporal scales. It is therefore crucial that biological investigations account for ecological scale when analyzing patterns and processes established, particularly when such investigations inform conservation management plans. This dissertation provides extensive insight into the conservation biology of the green salamander (Aneides aeneus), a critically imperiled species in South Carolina. The green salamander is a species that exists in a patchy network of rock outcrops within mountainous forest landscapes, and most studies on habitat suitability for green salamanders have been conducted on the macrohabitat, neglecting the interaction between individuals and their immediate microhabitat. Assessments of within-habitat features can help determine habitat suitability for sites with unknown occupancy status. I evaluated within-site resource selection using logistic regression to inform the interaction between individuals and their immediate microhabitat and identified features that contribute to microclimate stability and within-habitat connectivity as significant predictors of green salamander presence. Spatial and temporal variability in population demographics were addressed by implementing a three-year population survey across upstate South Carolina. In this study, I concurrently implemented two methods of estimating abundances, a capture-mark-recapture (CMR) approach and an unmarked repeated count approach (N-mixture modeling). I surveyed twenty-one green salamanders across upstate South Carolina and implemented a two-tiered survey design to analyze the data in a robust framework that accounted for open and closed population assumptions. Survey results provided the first evidence of a green salamander migrating between two discrete rock outcrops (50 m). Our top CMR model estimated average seasonal abundances to range from 3–32 individuals across twelve sites. The top N-mixture model estimated abundances to vary from 10–51 individuals across nineteen sites throughout the three-year study period. Further, I analyzed the genetic structure within and between discrete green salamander locales across South Carolina. I used RADSeq sequencing to identify SNPS, estimate population genetic statistics including FST, FIS, HO, HS, and Ne, and used fastSTRUCTURE to detect fine-scale population patterns. Results identified no evidence of inbreeding and little genetic differentiation among sites but showed evidence of isolation by distance (IBD). To investigate the influence of landscape heterogeneity on gene flow, I evaluated the genetic structure among green salamander sites against IBD and isolation by resistance (IBR) models. We used pairwise FST values as the genetic response to evaluate resistance landscape surfaces that included water bodies and land cover features. Genetic structure was best described by the IBD model. Forested land provided little resistance to gene flow, suggesting arboreal behaviors may provide a mechanism for animal dispersal among rock outcrops. Cumulatively, this body of work provides an extensive analysis on the conservation biology within, between, and among populations of a species of conservation concern. My evaluation of the selection of microhabitat helps in identifying the threshold of features required for an overall site to be suitable. The demographic results provided the first reports of site-specific abundances. Continued monitoring practices and can help conservationists track past demographic patterns and predict future trajectories. The report of an individual migrating between sites and empirical results from our larger-scale landscape genetic analysis offer evidence of a stepping-stone dispersal network between neighboring site locales, and ultimately identified forested land cover to be a mechanism for gene flow. Results have been reported to the South Carolina Department of Natural Resources and US Forest Service to inform future species management plans.
Novak, Megan, "An Integrative Approach to Managing a Species of Conservation Concern: Resource Selection, Spatial Ecology, and Population Genetics of the Green Salamander (Aneides Aeneus)" (2023). All Dissertations. 3535.