Meeting Abstract
The sex determination mechanism of most species has evolved to maintain a 50:50 sex ratio, but an even mix of males and females in every brood is not required. The Charnov-Bull model predicts that environmental sex determination should be selected for when early life environmental conditions differentially impact males and females. In the African cichlid fish Pelvicachromis pulcher, sex determination is influenced by water pH during the first 30 days of life, producing a male bias at lower (acidic) pH and a female bias at neutral pH. pH also impacts ratios of the two common male morphs, which differ in color and reproductive behavior. Methylation of the gonadal aromatase gene (cyp19a1A) has been linked with temperature sex determination in other teleost species, but has not previously been investigated as a mechanism for pH dependent sex determination. We report that methylation of the cyp19a1A promoter differs between fish raised in acidic and neutral conditions, consistent with a role in pH sex determination. In addition, we report on tissue-specific methylation exhibited by the cyp19a1A gene promoter as well as the brain aromatase (cyp19a1B) gene promoter.
