Meeting Abstract

63.1  Friday, Jan. 6  Androgens and female intrasexual aggression in the sex-role reversed Gulf pipefish SCOBELL, Sunny K. *; MACKENZIE, Duncan S.; JAQUES, John T.; JONES, Adam G. ; Department of Biology, Texas A&M University, College Station; Department of Biology, Texas A&M University, College Station; Texas Veterinary Medical Diagnostic Laboratory, Texas A&M University, College Station; Department of Biology, Texas A&M University, College Station sscobell@bio.tamu.edu

Sex-role reversed species provide a unique opportunity to test the assumptions of sexual selection theory. For sex-role reversal to be an evolutionary stable strategy, females that win competitions must also be good mates. Therefore, selection that acts to increase aggressive behavior in females must do so without greatly hindering reproductive function. Little is known about the physiological mechanisms that regulate female aggression, but sex steroids are likely candidates. Several species in the family Syngnathidae (seahorses, sea dragons, and pipefish) are sex-role reversed, all species have male pregnancy, and they exhibit a range of mating systems from monogamy to polyandry. Although there is no reversal of plasma levels of the primary sex steroids in males and females, the androgen 11β-hydroxyandrostenedione is elevated in several female syngnathid species. 11-oxygenated androgens that stimulate male sexual coloration and courtship behavior in many species of fish are likely candidates for mediating sex-role reversed behavior in female syngnathids. We have conducted several studies on the role of androgens in female competitive behavior. We determined that 11-ketotestosterone affects intrasexual competitive behavior in female Gulf pipefish¸ Syngnathus scovelli. The size of the focal female, the competitive behavior of the stimulus female, and the method of hormone delivery also affect the focal female’s response to 11-ketotestosterone. Our results suggest that androgens play a role in the mediation of female intrasexual competition in this species.