Browsing by Subject "Cichlid"

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    Social context and status affect behavior, physiology and brain activity of the highly social cichlid fish, Astatotilapia burtoni
    (2017-05) Maguire, Sean Martin; Hofmann, Hans (Hans A.); Ryan, Mike J; Phelps, Steve M; Gore, Andrea C; Crews, David P; Hoke, Kim L
    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.
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    Social Odors Conveying Dominance and Reproductive Information Induce Rapid Physiological and Neuromolecular Changes in a Cichlid Fish
    (BioMed Central, 2015-02) Simoes, Jose M.; Barata, Eduardo N.; Harris, Rayna M.; O'Connell, Lauren A.; Hofmann, Hans A.; Oliveira, Rui F.; Harris, Rayna M.; Hofmann, Hans A.
    Social plasticity is a pervasive feature of animal behavior. Animals adjust the expression of their social behavior to the daily changes in social life and to transitions between life-history stages, and this ability has an impact in their Darwinian fitness. This behavioral plasticity may be achieved either by rewiring or by biochemically switching nodes of the neural network underlying social behavior in response to perceived social information. Independent of the proximate mechanisms, at the neuromolecular level social plasticity relies on the regulation of gene expression, such that different neurogenomic states emerge in response to different social stimuli and the switches between states are orchestrated by signaling pathways that interface the social environment and the genotype. Here, we test this hypothesis by characterizing the changes in the brain profile of gene expression in response to social odors in the Mozambique Tilapia, Oreochromis mossambicus. This species has a rich repertoire of social behaviors during which both visual and chemical information are conveyed to conspecifics. Specifically, dominant males increase their urination frequency during agonist encounters and during courtship to convey chemical information reflecting their dominance status.