Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Turk Rhen


Variation in sex ratio among clutches of eggs from different females is common in reptiles with TSD, but the mechanisms that cause this variation are unknown. In an effort to shed light on these mechanisms, we first critically review literature that examines variation in temperature-dependent sex determination (TSD) within species. Genetic variation in TSD and maternal effects on TSD are two major mechanisms that have received attention. We outline the types of experiments and data required to demonstrate that a) genetic variation, b) maternally derived steroids, or c) both factors influence variation in sex ratio among clutches. Next, we compare allele frequencies between populations of Chelydra serpentina that differ in thermosensitivity of sex determination and identify population differentiation in putative TSD genes.