Meeting Abstract

53.6  Saturday, Jan. 5  Effects of Testosterone on Sexually Dimorphic Traits in Mexican Banded Geckos (Coleonyx elegans) GOLINSKI, A.**; KRATOCHVIL, L.; JOHN-ALDER, H.; Rutgers Univ., New Brunswick; Charles Univ., Prague; Rutgers Univ., New Brunswick golinski@aesop.rutgers.edu

Eyelid geckos (Eublepharidae) exhibit genetic (GSD) and temperature-dependent (TSD) sex determination as well as sexual dimorphisms in head and body size, combativeness, and pre-cloacal pore structure. This group is well-suited for studies on proximate control of sexual dimorphisms because these traits have become evolutionary dissociated in some species. Previous work on Sceloporus spp. and other lizards has shown that the expression of sexually dimorphic traits is testosterone (T) dependent. Our present experiments on C. elegans (GSD) included 3 groups of males (intact control, surgically castrated, castrated with T replacement) and 2 groups of females (intact control, T supplemented) and were conducted over an 11-week period in the laboratory. Growth and body size were not affected by sex or treatment, but relative head width and the mass of hemipenes were increased in males and in testosterone-treated females. In common with Eublepharis macularis (TSD) (Rhen & Crews 2000), intact and T-replaced males were more combative than castrates. In contrast to E. macularis, in which precopulatory displays are strongly T-dependent, male sexual behavior, which in C. elegans is confined to mounting without precopulatory displays, was not affected by castration or T replacement. Our experiments demonstrate T-dependent expression of sexual dimorphisms in several morphological and behavioral traits in GSD and TSD eyelid geckos. However, precopulatory displays and mounting appear to be controlled by different proximate mechanisms, which could have enabled their dissociation during evolution of this group. Supported by NSF IBN-0135167 and Fulbright Program (LK).