Meeting Abstract
In most systems, the sex determination mechanism of a species has evolved to maintain a 50:50 sex ratio, but an even mix of males and females in every brood is not required. In species with environmental sex determination, it may be advantageous for parents to produce more males at one time of year and more females at another, as environmental conditions change. 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 has an affect on phenotype within a sex: There are (at least) two common male morphs that differ in color and reproductive behavior, and the expression of these alternate phenotypes is also influenced by pH. Methylation of the gonadal aromatase gene (cyp19a1A), which converts testosterone to estrogen, has been linked with temperature sex determination in other teleost species, but has not been investigated as a mechanism for pH dependent sex determination. We will report on gonadal as well as brain (cyp19a1B) aromatase methylation status in P. pulcher. We demonstrate an experimental paradigm for a detailed temporal study to identify the critical period for environmentally sensitive aromatase methylation, focusing on P. pulcher fry development over the first 60 days of life. We compare fish raised in acidic and neutral conditions.
