Advisor(s)
Thane Wibbels
Committee Member(s)
Andrew Coleman
Jenny Estes
Ken Marion
Scott Rush
School
College of Arts and Sciences
Document Type
Dissertation
Department (new version)
Biology
Date of Award
9-11-2025
Abstract
For reptiles, their method of sex determination is temperature-dependent sex determination (TSD). This is where the environmental temperature directly influences the sex ratio being produced within a clutch. For sea turtles, sex is determined within a thermosensitive period (TSP) in which incubation temperatures will result in either males (cooler), females (warmer), or 50:50 even sex ratio. For this dissertation, 2 species of sea turtles were evaluated for their TSD and its implications on their ecology, evolution, and conservation: the Hawksbill sea turtle (Eretmochelys imbricata) and the Kemp’s Ridley sea turtle (Lepidochelys kempii). For the Hawksbill, a major rookery in the Western Caribbean (Pearl Cays, Nicaragua) was investigated for its cooler-than-average sand temperatures. For over 12 nesting seasons (2008 – 2019), nesting beach temperatures were consistently coo relative to pivotal, suggesting the production of a male-biased sex ratio. Additionally, the results documented an increasing trend in beach temperatures. Although the Pearl Cays are producing a male-bias currently, there could be a female bias in future decades. For the Kemp’s Ridley, a binational conservation program was created to help protect and conserve this species at its main nesting beach at Rancho Nuevo, Tamaulipas, Mexico. In this program, eggs that are laid on the primary nesting beach are translocated into the primary “egg corral” further up the beach. Over a 22-year period, results indicate a significant female bias being produced within the egg corral compared to the natural nesting beach. This program exemplifies how sex ratios can be manipulated by conservation programs in order to enhance the recovery of endangered reptiles with TSD. Further, spatial and temporal metabolic was investigated to evaluate its potential impact on TSD. Results indicate that: 1) the bottom of the nest is significantly cooler than the middle or top, 2) metabolic heating occurs during the middle and final trimester of incubation, and 3) metabolic heating is greatest in the final trimester.
ProQuest ID
Recommended Citation
Collins, Forrest William, "Temperature-Dependent Sex Determination: Implications For The Ecology, Evolution, And Conservation Of Sea Turtles" (2025). All ETDs from UAB. 7416.
https://digitalcommons.library.uab.edu/etd-collection/7416
