MS (Master of Science)
Date of Award
Committee Chair or Co-Chairs
Timothy A. Joyner
Ingrid Luffman, Eileen Ernenwein, Blaine Schubert
North American Giant Salamanders (Cryptobranchus alleganiensis), commonly known as hellbenders, have been experiencing a population decline for decades due to human influences, such as pollution and habitat destruction. Many efforts are underway to save the hellbender but their entire potential geographical range has not been well-studied. Currently, hellbender populations are delineated by county boundaries and are on the International Union for Conservation of Nature Red List. The Genetic Algorithm for Rule-set Production, an Ecological Niche Model, was used to model the current hellbender potential distribution at a macro-scale under two different environmental scenarios. Additionally, future potential distributions were projected under two different climate change scenarios (Representative Concentration Pathways) to predict where possible habitat loss and expansion may occur in coming decades. Niche modeling was also used to evaluate the influence of environmental parameters across geography and between two sub-species of hellbender, the Eastern hellbender and the Ozark hellbender. Results showed that vegetation indices had some influence on current distribution predictions, while future models revealed that potentially large areas of currently suitable habitat may be lost, especially in the Ozark Mountains and the Southern Appalachian Mountains. Habitat expansion was predicted for several areas in the New England region of the northern Appalachian Mountains. The most influential variables were the maximum temperature of the warmest month, temperature annual range, and annual precipitation, while slope and elevation were less influential. However, areas of very high slope and elevation were not suitable for hellbenders, confirming previous descriptive habitat analyses. Current and future modeled distributions will provide conservationists with a more specific, and quantified, geographical and ecological description of where environmentally suitable areas exist for hellbenders. Micro-scale, stream-based studies provide areas of future research.
Thesis - Open Access
Roark, Selena S., "Ecological Niche Modeling of the North American Giant Salamander: Predicting Current and Future Potential Distributions and Examining Environmental Influences" (2016). Electronic Theses and Dissertations. Paper 3072. https://dc.etsu.edu/etd/3072
Copyright by the authors.