Term of Award

Fall 2023

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

J. Checo Colon-Gaud

Committee Member 1

Scott Harrison

Committee Member 2

Lance McBrayer

Committee Member 3

Christian Cox

Committee Member 3 Email



Amphibians are valuable organisms in our ecosystems. They are mid-level predators and can act as an indicator species for ecosystem disruptions, such as environmental toxicity and salinity intrusion. Amphiuma means, or the Two-toed amphiuma, is an aquatic salamander native to the southeast United States that primarily inhabits freshwater wetlands. Along the coast, A. means may be exposed to different environmental conditions compared to more inland populations. Additionally, several populations of A. means have been spatially isolated on barrier islands for thousands of years. The purpose of this study was to investigate environmental, morphological, and genetic variation between mainland and a barrier island population of A. means. I predicted that the different environmental conditions on Sapelo Island would have an impact on A. means size, and I predicted that being spatially isolated from mainland populations would result in a decrease in genetic diversity on Sapelo Island. Mean head size between the two populations did not differ. However, Sapelo Island A. means were larger in body size on average. The sole environmental factor that differed between the two locations was conductivity, a proxy for salinity, which was to be expected. The genetic diversity of Sapelo Island was lower than the mainland population, specifically for mitochondrial DNA. The results suggest that while the Sapelo Island A. means population morphology is different than the mainland population, it is not clear that it is due to exposure to different environmental conditions. Results support that genetic diversity on Sapelo Island is lower than on mainland Georgia.

OCLC Number


Research Data and Supplementary Material