Effects of testosterone on sexual behavior and morphology in adult female leopard geckos, Eublepharis macularius.
The leopard gecko, Eublepharis macularius, is a species in which testosterone (T) is the primary circulating sex hormone in adults of both sexes. There are, however, sex differences in T physiology. Whereas males have prolonged periods with high T levels, T levels cycle in accord with follicular development in females. Specifically, T concentration increases during vitellogenesis, drops after ovulation, and then remains at previtellogenic levels until eggs are laid and the next follicular cycle begins. To determine the function of T in females, we manipulated both the level and the duration of T elevation using Silastic implants in intact, adult female leopard geckos. Females had low ( approximately 1 ng/ml), medium ( approximately 100 ng/ml), or high ( approximately 200 ng/ml) T levels for either a short (8 days) or a long (35 days) duration. Behavior tests with males were conducted on days 1-5 in the short-duration group or on days 29-33 in the long-duration group. For both short- and long-duration groups, T treatment decreased attractivity in females with medium and high T levels compared to females with low T levels. In contrast, females with a medium T level were more receptive than females with a low T level in the short-duration group. Females in the long-duration group were unreceptive regardless of T level. Females treated for a long duration also displayed more aggression toward and evoked more aggression from males than short duration females. Short-duration T treatment had no masculinizing effect on female morphology, whereas medium and high T levels for a long duration induced development of hemipenes. Overall, these results suggest that T can both increase and decrease sexual behaviors in the female leopard gecko.
Rhen
T
T
Department of Zoology, University of Texas at Austin, Austin, Texas, 78712, USA.
Ross
J
J
Crews
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D
D000374:Aggression / Q000187:drug effects; D000818:Animals; D013196:Dihydrotestosterone / Q000097:blood; D004958:Estradiol / Q000097:blood; D005260:Female; D008116:Lizards / Q000502:physiology*; D008297:Male; D010058:Oviposition / Q000187:drug effects; D010060:Ovulation / Q000187:drug effects; D011863:Radioimmunoassay; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013739:Testosterone / Q000494:pharmacology*; D014818:Vitellogenesis / Q000187:drug effects
D013196:Dihydrotestosterone; D013739:Testosterone; D004958:Estradiol