Honors Theses

Date of Award


Document Type

Undergraduate Thesis



First Advisor

Christopher Leary

Relational Format



Circulating androgen levels can have a profound effect on the expression of elaborate male traits and courtship behaviors that are important in attracting females. For example, elevated androgens are necessary for the expression of vocal displays used by male anurans (frogs and toads) to attract mates. However, the nature of the relationship between androgen levels and the extent, or magnitude, of vocalization in male anurans is unclear. For example, androgens may have a threshold effect on vocalization wherein elevation in androgens is required for vocal expression, but elevations above threshold do not mediate an increase in the magnitude or extent of vocalization. Alternatively, androgens may have graded effects on vocalization, wherein elevations above threshold levels required for vocal expression correspond to an increase in the extent or magnitude of vocalization. Numerous androgen-based models of sexual selection propose that as testosterone levels increase, the extent and/or magnitude of elaborate male traits increases in a graded, dose-dependent (linear) manner. This relationship provides the basis for 'honest signals' (e.g., signals that confer 'good genes'). I examined how circulating androgen levels relate to vocal parameters known to be important in mate selection in male green treefrogs, Hyla cinerea. Results provided no evidence of a graded effect of testosterone on vocalization. Hence, circulating androgens do not appear to mediate changes in vocalization important in mate selection in a graded manner, contrary to the predictions of theoretical models.

Accessibility Status

Searchable text

Included in

Biology Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.