Individual variation in intensity of sexual behaviors in captive male Cnemidophorus inornatus.

The present studies investigated the source of individual variation in intensity of sexual behaviors in captive male whiptail lizards, Cnemidophorus inornatus. No correlation was found between an individual's circulating concentration of dihydrotestosterone, testosterone, or corticosterone at the time of capture or in the laboratory and their level of sexual behaviors observed in the laboratory. A large percentage of males that initially exhibited low intensity courtship remained low intensity courters, although some became more reliable courters following 6 months of acclimation to the laboratory. Similarly, following castration and androgen replacement, most low intensity courters continued to exhibit weak and infrequent sexual behaviors. The data suggest that individual variation in sexual behaviors exhibited by captive male C. inornatus is not due to (i) low circulating concentrations of androgens, (ii) elevated circulating concentrations of corticosterone, or (iii) different profiles of testicular steroidogenesis. Rather, the source of differences may lie in (i) an inability to respond to androgens, (ii) an inability to exhibit sexual behavior, or (iii) non-hormonal stress related to captivity.