Sex determination is of central importance to the propagation of a species. During this step, differentiation of males and females is initiated in the embryo. There is a remarkable diversity of mechanisms by which sex determination can be accomplished. Two means by which sex determination can be done are genetic sex determination (GSD) and environmental sex determination (ESD). GSD is dependent on the genetic factors that are located on sex chromosomes, while ESD is dependent on epigenetic factors. Species where sex differentiation is dependent on the specific temperature at which the eggs are incubated is called temperature-dependent sex determination (TSD), which is a type of ESD. Reptiles with TSD include all crocodilians, most turtles, and some lizards; however, they do not include snakes. The effects on sex-determination by specific temperature ranges vary widely throughout these species, even between closely related species. (Many studies have been done in laboratories using both fluctuating and stable temperatures in order to understand the effects of temperature ranges. However, the effect of varying temperatures that occur in natural nests still remains unknown. While a single origin, adaptation, and evolutionary implication of reptilian species with TSD has not been confirmed, this paper strives to synthesize and compare the current perspectives within this scientific issue.
"The Evolutionary Significance of Temperature-Dependent Sex Determination in Reptiles,"
Rollins Undergraduate Research Journal: Vol. 2
, Article 5.
Available at: http://scholarship.rollins.edu/rurj/vol2/iss1/5