Thane Wibbels

Research Description:

My research interests center on the comparative reproductive physiology of vertebrates with an emphasis on temperature-dependent sex determination (TSD) in reptiles. The research that my students and I are conducting is multidisciplinary and includes studies on the molecular physiology underlying TSD. Further, this research has applied aspects in which we are developing and implementing nonlethal methods for estimating hatchling sex ratios in sea turtles conservation programs.

Many reptiles (including all sea turtles) possess TSD, in which sex is determined by the temperature at which the egg is incubated. For physiological studies, TSD provides several advantages not available in other vertebrate sex determination systems, including the ability to manipulate sex by both temperature and steroid hormones. We have characterized TSD in the slider turtle system so that it can be used as a model system for elucidating the physiology underlying sex determination and gonadal differentiation. We are now using this system to pursue putative sex factors which control these events in sexual development.

In regards to sea turtle conservation, we are developing and validating nonlethal sexing techniques for hatchlings sea turtles. These methods can be used to enhance the recovery of endangered sea turtles populations. We are currently examining hatchling sex ratios in sea turtle programs ranging from St. Croix, U.S. Virgin Islands (in collaboration with the National Park Service) to the French Frigate Shoals in the Hawaiian archipelago (in collaboration with the National Marine Fisheries Service).

Representative Publications:

Wibbels, T. (1999). Diagnosing the sex of sea turtles in foraging habitats. In: Research and Management Techniques for the Conservation of Sea Turtles. K. Eckert, K. Bjorndal, and A. Abreu, M. Donnelly (eds), IUCN/SSC Marine Turtle Specialist Group Publication No. 4.

Fleming, A., Wibbels, T., Skipper, J., and Crews, D. (1999). Developmental expression of steroidogenic factor 1 mRNA in the red-eared slider turtle, a species with temperature-dependent sex determination. General and Comparative Endocrinology (in press)

Wibbels, T., Hillis-Starr, Z-M., and Phillips, B. (1999) Female-biased sex ratios of hatchling hawksbill sea turtles from a Caribbean nesting beach. Journal of Herpetology 33: 142-144.

Wibbels, T., Wilson, C., and Crews, D. (1999) Mullerian duct development and regression in a turtle with temperature-dependent sex determination. Journal of Herpetology 33:149-152.

Wibbels, T., Cowan, J., and LeBoeuf, R. (1998) Temperature-dependent sex determination in the red-eared slider turtle,Trachemys scripta. Journal of Experimental Zoology. 281: 409-416.

Wibbels, T., Rostal, D., and Byles, R. (1998) High pivotal temperature in the sex determination of the olive ridley sea turtle from Playa Nancite, Costa Rica. Copeia 1998: 1086-1088.

Hanson, J., Wibbels, T., and Martin, R. E. (1998) Predicted female bias in hatchling sex ratios of loggerhead sea turtles from a Florida nesting beach. Canadian Journal of Zoology 76:1850-1851.

Wibbels, T., Hanson, J, Balazs, G., Hillis-Starr, Z-M., Phillips, B. (1998) Blood sampling techniques for hatchling cheloniid sea turtles. Herpetological Review 29: 218-220.

Bergeron, J.M., Gahr, M., Horan, K., Wibbels, T., and Crews. (1998) Cloning and in situ hybridization in the developing gonads of the red-eared slider turtle, a species with temperature-dependent sex determination. Development, Growth, and Differentiation 40: 243-254.

Hines, G.A., , Boots, L.R., Wibbels, T., and Watts, S.A.. (1998) Steroid levels and steroid metabolism in relation to early gonadal development in the tilapia Oreochromis niloticus (Teleostei: Cyprinoidei). General and Comparative Endocrinology 114: 235-248.

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