Meeting Abstract

P1.1  Monday, Jan. 4  Genomic Basis for Sex-Role Phenotypes WOOD, Kelsey*; LANGDON, Quinn; SCHUMER, Molly; RENN, Suzy; Reed College, Portland OR renns@reed.edu

For many animals, the expression of sex-typical behavior can be plastic depending on the social environment. We use the African Julidochromis cichlid fish as a model to determine the underlying physiological and molecular mechanisms that account for differences and plasticity in expression of sex-typical behaviors. Sex-roles in most monogamous cichlids consist of territory defense by the larger male and parental care by the smaller female. Behavioral studies show that the species J. transcriptus follows these sex-role conventions. However, the sister species, J. marlieri, exhibits a reversal of these sex-roles. J. marlieri females are dominant to their mates and are clearly the aggressive sex. The reversal in sex-role behavior is size dependent. We show that experimental reversal of size ratios in both species causes a reversal from natural sex-role behavior phenotypes. In size-reversed pairs the larger mate is dominant and more aggressive towards intruders regardless of sex or species. Thus, while sex-roles in Julidochromis appear to be determined by species, they are also plastic and contingent on social context. To examine the molecular changes that accompany this heritable, yet plastic phenotype, we compare gene expression and hormone levels between species and between size-conventional and size-reversed pairs of both species. Microarray data defines modules of gene expression associated with sex-role independent of gonadal sex, and modules of gene expression associated with gonadal sex independent of sex-role. Furthermore, species-specific variation in gene expression patterns suggest that Julidochromis males and females have undergone changes in gene expression patterns on an evolutionary time-scale.