Honors Theses

Date of Award


Document Type

Undergraduate Thesis



First Advisor

Christopher Leary

Relational Format



Condition-dependent male alternative tactics are often driven by competition among males for females. The expression of alternative male mating tactics can be influenced by the external social environment as well as internal physiological state. Recent models predict that circulating levels of stress hormones (i.e., glucocorticoids) and androgens may be particularly important in determining mating tactic expression under varying social circumstances. This study intergrates both components to investigate the cause of alternative tactic adoption in male green tree frogs, Hyla cinerea. Males of this species produce acoustic signals that are critical for attracting females and male vocalizations stimulate production of the stress hormone corticosterone (CORT) in rival males, suggesting that CORT plays a pivotal role in male-male competition. By administering CORT to calling male H. cinerea, I show that increased circulating levels of glucocorticoids significantly decrease vocal attractiveness of males and increase the probability of non-calling satellite behavior when males are challenged by another male, these effects occurred independently of changes in circulating androgen levels. My results suggest that males of this species attempt to manipulate the stress physiology of males competitors during vocal contests in ways that decrease the probability of acquiring mates.

Included in

Biology Commons



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