Estradiol facilitates mounting behavior in male green anole lizards.

Steroid hormones activate sexual behaviors across vertebrate species. In green anole lizards, testosterone is particularly important for the display of courtship and copulation by adult males. However, unlike a variety of other species, the role of its metabolite, estradiol, has been unclear. To evaluate its function and potential interaction with testosterone in the facilitation of reproductive behaviors, adult males were gonadectomized and given two treatments. The first consisted of either estradiol or its vehicle, and the second testosterone or a blank control. Parallel manipulations were done in the breeding and non-breeding seasons. Courtship and copulatory behaviors were more readily facilitated during the breeding than non-breeding season. As predicted based on previous experiments, testosterone increased the display of sexual behaviors. In addition, estradiol increased mount attempts. While this hormone did not influence the effects of subsequent testosterone exposure, the present data are consistent with the idea that it facilitates a component of reproduction in the green anole, as in species from other taxa.