Meeting Abstract

53.3  Saturday, Jan. 5  Hormonal mediation of female aggression: A possible role for androgens in the sex-role reversed pipefish, Syngnathus scovelli SCOBELL, Sunny K.*; KNAPP, Rosemary; JONES , Adam G.; 1-Texas A&M University, College Station; 2-University of Oklahoma, Norman; University of Oklahoma, Norman; Texas A&M University, College Station sscobell@bio.tamu.edu

Little is known about the hormonal mediation of female competitive aggression. One possibility is that androgens, which can mediate aggressive and sexual behaviors in many male vertebrates, also mediate these behaviors in females. Ideal species in which to study the physiological mechanisms underlying female aggression in a sexual context are sex-role reversed species where females compete for access to mates and males are choosy. One such species is the Gulf pipefish (Syngnathus scovelli) where females transfer eggs to a specialized male brood pouch for gestation. This species is the most polyandrous pipefish studied to date. Females are larger, more ornamented and more active in courtship than males. Females compete with each other in the presence or absence of males in the laboratory. In paired competitive interactions, we found that winners had higher levels of an androgen, 11β-hydroxyandrostenedione (OHA), than did losers. Winners also had a larger body depth and tended to have larger ovaries. Females with larger ovaries displayed a temporary ornament (used during competition and courtship) for a longer duration than did losers. These results suggest the duration of display of temporary ornament and trunk depth may be honest signals of reproductive potential to males and rival females. Also, OHA, which is a precursor to 11-ketotestosterone (KT, a fish androgen that mediates aggressive and courtship behavior in males), may mediate female aggression in this species. We are currently determining whether injections of OHA or KT can influence female aggressive behavior. These studies will help elucidate whether one or more androgens mediate female aggression in a sexual context in this species.