ROSTAL, DC; WIBBELS, T; Georgia Southern University; Univ. of Alabama at Birmingham: Temperature-dependent Sex Determination and Embryonic Development of the Gopher Tortoise (Gopherus polyphemus): A Latitudinal Investigation.

The gopher tortoise (Gopherus polyphemus) has been demonstrated to possess TSD in laboratory studies. No studies have however attempted to see how these laboratory results can be applied to understanding the process across its range from south-central Florida to South Carolina. The gopher tortoise is reported to have a pivotal temperature of approximately 29 C similar to many other emydid turtles on the east coast of the United States. However, the northernmost range of the gopher tortoise is limited to southern South Carolina. We set HOBO temperature dataloggers in sandhill habitat suitable to support gopher tortoises from central and north Florida, Georgia to South Carolina. The South Carolina site is represented by sandhill habitat but is beyond the current northern range of the gopher tortoise. In addition, field nests were monitored in Georgia and all hatchling were sexed using laparoscopy. Field nests results were compared with datalogger results from the same habitat to determine the suitability of monitoring ground temperature. Sex ratios produced were mixed with both males and females being produced in all years. Adult sex ratio from Georgia is 1:1 (n = 376). Ground temperature throughout the range were suitable for producing both males and females however, temperatures displayed greater fluctuation in the northern part of its range. Other factors such as incubation duration (80-100 days) as well as other life history traits may be a greater limiting factor to the northern distribution of gopher tortoises than TSD.