Meeting Abstract

S11-1.7  Monday, Jan. 7  Evolution of hermaphroditism in fishes ERISMAN, Brad; Scripps Institution of Oceanography, UC San Diego berisman@ucsd.edu

Sexual patterns in fishes are incredibly diverse compared to other vertebrates, as hermaphroditism is taxonomically widespread and takes on many forms including simultaneous, protogynous, and protandrous hermaphroditism, bi-directional sex change and androdioecy. The proximate mechanisms that influence the timing, incidence, and forms of hermaphroditism in fishes are supported by numerous theoretical and empirical studies on their mating systems and sexual patterns, but few have examined aspects of sex allocation theory within a phylogenetic context. However, comparative phylogenetic reconstructions of the evolutionary history of several families of teleost fishes have begun to emerge and are providing clues regarding the mechanisms that have shaped the evolution of sex allocation in animals. For example, evolutionary transformations from protogyny to gonochorism in groupers (Epinephelidae) are associated with equivalent transformations in mating group structure from paired to group spawning, and sperm competition is considerably higher in gonochoric species than in protogynous species. These results provide explicit phylogenetic support for predictions of the size advantage model (SAM), demonstrating that selection for protogynous sex change decreases as mating group size and sperm competition intensity increase. Comparative analyses of sex change in wrasses (Labridae) provide further support of the SAM and suggest that male size advantage drives the evolution of protogynous sex change. Finally, phylogenetic reconstructions of sexual patterns in seabasses (Serranidae) indicate that sexual patterns in fishes can evolve in several directions within single lineages and do not require functional intermediates.