Androgen-glucocorticoid Mediation of Behavioral Variation

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

Understanding the physiological bases of behavioral and morphological variation is a major goal in biology. However, the continuous nature of much of the variation among individuals often makes such study difficult. This research will use sunfish to exploit the existence of two distinct types of males: a "typical" parental male type and a cuckolder male that exhibits a mosaic of male- and female-typical characters. Morphological differences between the two types of males are tightly correlated with divergence in reproductive behavior and both types of males are reproductively competent. This project will begin a systematic biochemical and behavioral examination of the role of androgens and glucocorticoids, and their interactions, in the expression of male behavioral and morphological variation. These hormones are known across vertebrates to be important mediators of reproductive behavior and to play a central role in transducing information from various environmental stimuli. These studies will test hypotheses that differences in behavior between the two types of males are related to differences in two important components of steroid hormone action. The studies will determine 1) the activity of a major enzyme involved in androgen and glucocorticoid metabolism, 2) document morph and sex differences in tissue-specific activity of this and a related enzyme, 3) document in the brain and other tissues the expression of androgen and glucocorticoid receptors and these two steroidogenic enzymes, and 4) determine whether morphs differ in their sensitivity to a standardized stressor. Because many neuroendocrine mechanisms underlying behavior are conserved, the findings from the proposed studies of sunfish should be broadly applicable across vertebrates. The project will provide research training for students in a research program that integrates neuroendocrine studies with studies of behavior of animals in the field to understand the evolution of physiological mechanisms underlying behavior.