Embryonic temperature and gonadal sex organize male-typical sexual and aggressive behavior in a lizard with temperature-dependent sex determination

Temperature during embryonic development determines gonadal sex in the leop ard gecko, Eublepharis macularius. Moreover, both embryonic temperature and gonadal sex influence adult behavior. Yet it remains unclear whether the e ffects of embryonic temperature and gonadal sex on behavior are irreversibl y organized during development. To address this question, we gonadectomized adult females and males generated from a temperature that produces mostly females (30 C) and a temperature that produces mostly males (32.5 C). Femal es and males from both temperatures were then treated with equivalent Level s of various sex steroids. We found that both embryonic temperature and gon adal sex had persistent effects on the expression of male-typical sexual an d aggressive behaviors. For example, adult females do not scent mark and di splay very little courtship and mounting behavior even when treated with le vels of hormones (primarily androgens) that activate these behaviors in mal es. In contrast, species-typical aggressive displays were less sex specific and were activated by both dihydrotestosterone and testosterone (T) in mal es and by T in females. Nevertheless, the average duration of aggressive di splays was significantly shorter in T-treated females than that in T-treate d males. With regard to submissive behavior, androgens decreased flight beh avior in males, but had no effect in females. Embryonic temperature had end uring effects on certain behaviors in males. For instance, males from a mal e-biased embryonic temperature scent-marked more than males from a female-b iased embryonic temperature when treated with dihydrotestosterone or T. Con versely, and across hormone treatments, males from a female-biased embryoni c temperature mounted more than males from a male-biased embryonic temperat ure. Finally, treatment with 17 beta-estradiol decreased submissive behavio r in males from a male-biased embryonic temperature compared with that in m ales from a female-biased embryonic temperature. Courtship and aggressive b ehavior were not influenced by temperature. These results strongly suggest that male-typical behaviors in the adult leopard gecko are permanently orga nized by both embryonic temperature and gonadal sex during development.