MARTIN, J.M.*; CLEMENT, T.S.; KNIER, A.L.; FERNALD, R.D.; Stanford University; Stanford University; Stanford University; Stanford Universty: Female Hormone Profile and Mate Choice in a Cichlid Fish

The African cichlid fish, Haplochromis burtoni, has proven to be a useful model for understanding the social control of behavior. In females of this species, there is substantial remodeling of the brain-pituitary-gonadal axis controlling reproduction between gravid (egg bearing) and non-gravid states (White & Fernald, 1993). Moreover, female preference for male phenotype changes during the course of the reproductive cycle (Clement, Grens & Fernald, submitted). To understand what hormonal changes are associated with the behavioral and structural changes, we measured levels of several key hormones and peptides throughout the reproductive cycle of the female and correlated these levels with ovarian stage and development. We quantified plasma levels of progesterone, testosterone and 17-&beta-estradiol using enzyme-linked immunoassays. The expression of vitellogenin, a precursor to egg-yolk proteins, and gonadotropin-releasing hormone (GnRH) were both determined using quantitative real time RT PCR. Vitellogenin expression was measured in the liver (where it is produced) and the ovaries, and expression of two GnRH receptor types was measured in the brain, pituitary and retina where GnRH is released and may act as a neuromodulator. We relate the changes in hormonal profile to female affiliation preference in order to identify internal cues that might help orchestrate the shift to preference for dominant males.