Many animals display physiological and behavioral plasticity in response to changes in their social environment. A particularly remarkable example of these phenomena is the African cichlid fish Astatotilapia burtoni. This species forms social hierarchies that consist of two male phenotypes: 1) dominant (DOM) males, which are typically larger in size and have large testes, high circulating steroid hormone levels, and bright coloration, and 2) non-dominant (ND) males, which are typically smaller in size and have small testes, low circulating steroid levels, and drab coloration. While DOM males possess a territory which they use to court and mate with females and defend from other males, ND males lack a territory. However, these social hierarchies are fluid; ND males actively survey their environment in search of an opportunity to rise in social rank and become a DOM individual, a process called social ascent. Social ascent is associated with profound changes in steroid hormones and social behavior, including a surge of circulating testosterone and increased aggressive and reproductive behaviors.
As a postdoctoral fellow, I am investigating the neuroendocrine and molecular mechanisms underlying aggressive and reproductive behaviors in A. burtoni. Currently, I am investigating the role of neural androgen receptors (ARα and ARβ) in regulating aggression in males using CRISPR-Cas9 gene editing and pharmacological manipulations. In addition, I am examining how these mechanisms are affected by social status and social experience.
Image credit: Karen Maruska, Louisiana State University.