Organization and activation of sexual and agonistic behavior in the leopard gecko, Eublepharis macularius

Gonadal sex is determined by the temperature experienced during incubation in the leopard gecko (Euble-pharis macularius). furthermore, both factors, incubation temperature and gonadal sex, influence adult sexual and agonisti c behavior in this species. Yet it is unclear whether such differences in b ehavior are irreversibly organized during development or are mediated by di fferences in hormone levels in adulthood. To address this question, we gona dectomized adult females and males generated from a female-biased (30 degre es C) and a male-biased (32.5 degrees C) incubation temperature and treated them with equivalent levels of various sex steroids. We found that 17 beta -estradiol (E-2) activated sexual receptivity in females but not males, sug gesting an organized sex difference in behavioral sensitivity to E-2. There were also organized and activated sex differences in attractivity to stimu lus males. Although females were more attractive than males when treated wi th E-2, both sexes were equally unattractive when treated with dihydrotesto sterone (DHT) or testosterone (T). Likewise, sex differences in aggressive and submissive behavior were organized and activated. Attacks on stimulus m ales were activated by T in males but not in females. In contrast, hormones did not influence flight behavior in males but did affect female submissiv eness. Overall, males also evoked more attacks by stimulus males than did f emales. Nevertheless, females and males treated with androgens evoked more attacks than animals of the same sex that were treated with cholesterol or E-2. Incubation temperature had some weak effects on certain behaviors and no effect on others. This suggests that temperature effects in gonadally in tact geckos may be due primarily to differences in circulating levels of ho rmones in adulthood. We conclude that gonadal sex has both organizational a nd activational effects on various behaviors in the leopard gecko. Copyrigh t (C) 2000 S. Karger AG, Basel.