Social context and status affect behavior, physiology and brain activity of the highly social cichlid fish, Astatotilapia burtoni

Group living confers many benefits while at the same time exposing group members to intense competition for resources and status within the group. Monitoring the social environment involves not only participating in many fast paced social interactions but also monitoring the relationships and status of other group members. In chapter 1, we use a network analysis approach to study replicate communities of the cichlid fish, Astatotilapia burtoni, which live in fast-paced social groups with a complex dominance hierarchy among males. We found several correlations between an individual’s behavior, their position in the social hierarchy and the social environment. In addition, we found that community properties are a key parameter that predicts both cortisol and testosterone levels. In chapter 2 we extend this paradigm and look at the effects of social status within a community on brain activity as measured by cytochrome oxidase histochemistry. In addition, we examined brain activity in transitioning animals as measured by cytochrome oxidase and egr-1 induction. We find that social status has a variety of subtle effects on brain activity. Finally, we tested the role of the sex steroid hormones estradiol and testosterone on social transition using an aromatase inhibitor as well as an androgen receptor antagonist. We found very few effects of blocking the nuclear androgen pathway. Blocking aromatase resulted in a hyperaggressive phenotype suggesting that estradiol plays an important role in the transition process in this species.