All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Ken Marion

David C Rostal

Robert W Thacker

Jeanette Wyneken

Document Type

Dissertation

Date of Award

2009

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

This dissertation examines the arribada, or group nesting, phenomenon of ridley turtles and its' ecological and evolutionary significance regarding certain aspects of reproduction such as egg survival, hatchling survival, and sex ratios. The initial two chapters test the role of non-steady moisture or temperature on sex ratios produced by the arribada nesting behavior. The first chapter addresses the potential effects of a nest's hydric environment on sex ratios using the red-eared slider, Trachemys scripta, as a laboratory model since it possesses a temperature-dependent sex determination (TSD) pattern similar to that of sea turtles. The results indicate that daily water treatments significantly influenced sex ratios by increasing the production of males when temperatures were near pivotal. The second chapter addresses the effects of fluctuating environmental temperatures on TSD by again using the red-eared slider as a laboratory model. The sex ratios produced in the fluctuating temperature experiments were not significantly different from sex ratios of control groups produced at constant incubation temperatures. The third chapter represents the most comprehensive evaluation to date of the effects of specific temperatures on sex ratios in the Kemp's ridley sea turtle, giving a more refined estimate of the transitional range of temperatures (TRT) and pivotal temperature for the Kemp's ridley. The fourth chapter evaluates sex ratios produced in the Kemp's Ridley Recovery Program during the 2005-2008 nesting seasons. This included sex ratio predictions for every nest in the main egg corral for 2007 and 2008. The results indicate an approximate 75% female bias being produced in the egg corral. The results also indicate that in situ nests were cooler than egg corral nests but still produced an overall female bias. The fifth chapter addressed the effects of arribada nesting behavior on sex ratios and survival of eggs and hatchlings. The results indicate that arribada nesting enhances the survival of eggs and hatchlings through the confusing and satiation of predators. Additionally, the arribada significantly affected sex ratios and may be advantageous for increasing seasonal and yearly variability in sex ratios.

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