WADE, M.J.; SHUSTER, S.M.; Indiana University; Northern Arizona University: Don\’t Throw Bateman Out With the Bathwater!

Darwin recognized two patterns in nature and used them to frame the central questions of sexual selection: (1) Why do males and females of the same species differ from one another, with males exhibiting morphological and behavioral phenotypes more exaggerated than those of females? (2) Why do the males of closely related species exhibit much greater differences in morphology and behavior than the females of closely related species? These macroevolutionary patterns suggest the existence of a rapid and powerful evolutionary force. Yet microevolutionary analyses, as well as Darwin�s own assessment of sexual selection, suggest that sexual selection�s evolutionary effects are slow and weak. We call this conflict the Quantitative Paradox of sexual selection. Bateman identified variation in mate numbers as the fundamental cause of sexual selection. We show how sexual selection, although restricted to one sex and opposed by natural selection in the in the other, is indeed one of the strongest and fastest of all evolutionary forces. Thus, Bateman�s observations allow us to resolve the Quantitative Paradox and explain Darwin�s central questions of sexual selection.