Institution: University of Oklahoma
Title of Talk: "Hormonal mediation of a condition-dependent sexually-selected trait: stress, attractiveness, and sexually-parasitic male toads."
The effects of gonadal steroids on sexually dimorphic traits suggest that individual variation in sex-steroid levels can play a major role in sexual selection. However, in the Great Plains toad, Bufo cognatus, males producing the longest advertisement calls do not have significantly higher levels of circulating androgens than individuals producing shorter calls. Rather, I show through a series of studies that males with the lowest circulating levels of the stress hormone corticosterone produce the longest calls that are preferred by females. Therefore, selection should favor males with traits that maintain relatively low corticosterone levels or that buffer against glucocorticoid-mediated stress responses. However, my results also suggest that males with the longest calls experience a reduction in reproductive success by attracting sexually-parasitic conspecific satellite males. Hence, directional selection on preferred male traits via female choice may be countered by host selection via male s practicing alternative mating tactics and appears to be mediated by a hormone reflecting the calling males' physiological condition.
Recent Articles:
http://beheco.oxfordjournals.org/cgi/content/abstract/15/2/313