Meeting Abstract
The Julidochromis genus of African Rift Lake cichlids provides an excellent opportunity to investigate differences in social role between closely-related taxa. Previous work has been focused on describing the social roles of two species in the genus; J. marlieri females are socially and reproductively dominant, whereas J. transcriptus females display the reverse social pattern. Based on work done in non-fish systems that showed differences in genitalia based on social role, we performed a morphometric analysis on the genital papillae of both sexes of J. marlieri and J. transcriptus, to determine if the differences in social roles were reflected in genital morphology. We performed the same analysis on the lekking species Astatotilapia burtoni, which was used as an outgroup for taxonomic distance and behavior. J. marlieri displayed clear dimorphism between the sexes, while J. transcriptus displayed ambiguous genital structures; the strong dimorphism in J. marlieri may not be true sex role reversal, but suggests that sexual selection might be occurring within this species. A. burtoni genital morphology appeared to change based on position in the social hierarchy. To the best of our knowledge, this is the first time plasticity in external genital papillae has been documented in fish that do not change sex.
