Sex steroid levels across the reproductive cycle of female leopard geckos,Eublepharis macularius, from different incubation temperatures

Incubation temperature during embryonic development determines gonadal sex in many reptiles, including the leopard gecko (Eublepharis macularius). In this study, we examined the hormonal and behavioral changes that occur duri ng the reproductive cycle of female leopard geckos from four (i.e., 26, 30, 32.5, and 34 degrees C) incubation temperatures. Controlling for reproduct ive status, plasma levels of dihydrotestosterone (DHT), testosterone (T), a nd progesterone (P) varied with incubation temperature but estradiol 17-bet a (E2) levels did not. Controlling for the effects of incubation temperatur e, DHT and T levels were low when females were previtellogenic, increased s lightly during early vitellogenesis, increased dramatically during late vit ellogenesis (i.e., prior to ovulation), and then decreased to previtellogen ic levels after ovulation. In contrast, E2 levels increased gradually from the previtellogenic stage to the early vitellogenic stage, peaked during la te vitellogenesis, and decreased to previtellogenic levels after ovulation. Levels of P increased from the previtellogenic stage to the early vitellog enic stage, remained elevated during late vitellogenesis, and then decrease d after ovulation. Moreover, we determined that females were not sexually r eceptive when previtellogenic, were somewhat receptive during early vitello genesis (similar to 20% receptive), were most receptive during late vitello genesis (similar to 80% receptive), and were again unreceptive after ovulat ion. Incubation temperature did not influence receptivity. Overall, these d ata show that hormone levels and behavior change coordinately during the re productive cycle. Although incubation temperature has persistent effects on endocrine physiology in adult female leopard geckos, these effects are mod est compared to hormonal changes across the reproductive cycle. (C) Academi c Press.