All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Ken Marion

David Nelson

Willem Roosenburg

Daniel Warner

R Douglas Watson

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Temperature-dependent sex determination has significant implications for the ecology, evolution, and conservation of reptiles because it can affect sex ratios, reproduction and fitness in a population. The studies presented in this dissertation characterized the impact of temperature on sex determination using both laboratory- and field-based experiments. The effects of fluctuating temperature on sex ratio, incubation duration, and hatchling phenotype were examined at 28.2 ± 5°C and 31 ± 3°C. Fluctuating incubation temperature was found to extend incubation duration, relative to constant incubation temperatures, in both cases and resulted in a significant difference in sex ratio when eggs were incubated at 28.2 ± 5°C compared to constant 28.2°C. The effects of incubation temperature on the duration of the TSP were examined and the results indicate that the temperature potency, as well as, the specific incubation temperature affects the duration of the TSP. Our results suggest that there may be other factors contributing to the duration of the TSP in addition to the effects of temperature potency. The effects of metabolic heating during incubation on sex determination and embryonic development were examined. The results indicate that metabolic heating can significantly increase incubation temperature during the TSP and significantly affect sex determination. This should be taken into consideration when attempting to predict sex ratios based on beach temperatures. A surrogate species was utilized to evaluate sex ratios produced on natural nesting beaches of the diamond-backed terrapin in Alabama. The results indicated strong female biases and provide insight on the “quality” of terrapin nesting beaches. Finally, the reproductive ecology, abundance, and morphology of adult female terrapin utilizing Cedar Point Marsh (CPM) nesting beach were evaluated. Our results indicate that there are approximately 222 - 263 individuals with a clutch size of 7.6 ± 2.1 utilizing CPM nesting beach. Additionally, radio tracking indicates that this beach is nesting habitat for turtles residing in several marshes in Heron Bay. Collectively, the results of this dissertation provide a basis to generate and test hypotheses related to TSD as well as baseline data important for the development of a conservation management strategy for the terrapin in Alabama.

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