Group sex, sex change, and parasitic males: sexual strategies among the fishes and their neurobiological correlates.

Sexual selection, in the form of intrasexual competition and mate choice, has driven the evolution of a variety of sexual phenotypes amongst the vertebrates (Andersson, 1994). As a result, vertebrate species utilize many different approaches to acquire fertilizations. Humans and other primates show a wide range of sexual behaviors, but this range is dwarfed by the remarkable variation seen in advanced fishes. The goals of this review are (a) to acquaint the reader with the tremendous sexual diversity exhibited by fishes, (b) to demonstrate how this diversity provides unique opportunities to examine the neurobiological correlates of vertebrate sexual strategies, and (c) to highlight the parallels between the neuroendocrine correlates of the sexual strategies of fish with the mechanisms underlying sexual phenotypes in other vertebrates, showing the utility of fish studies for understanding sexual variation in general.