Master's Theses

Document Type

Thesis

Date of Award

Spring 2012

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Recent studies in behavioral ecology have suggested environmental pressures might influence sexual selection dynamics to the extent that sexually-selected signals reflect local adaptation. I experimentally tested this hypothesis by manipulating a potential male ornament and observing the sexual selection dynamics in a Smoky Hills population of eastern collared lizards (Crotaphytus collaris). Sexual selection dynamics were investigated by characterizing habitat structure, describing individual lizard spatial distribution, and investigating morphological predictors of adult male territorial success. Habitat occupied by lizards had significantly different and higher percentages of rock cover, and significantly different and lower percentages of vegetation cover, than unoccupied habitat. No differences in habitat structure were detected between areas occupied by both sexes and areas occupied only by males. Experimental enlargement of the male gular ornament did not affect the spatial distribution of sexually mature lizards. Potential male fitness was estimated using several indices, which were then used to predict which morphological characters might affect male intrasexual success. Measures of body size, particularly mass, snout-vent length, and head width, were the strongest predictors of successful territory defense in adult males. The potential for sexual selection for this population is analyzed with respect to previous studies of sexual selection in C. collaris. This study supports previous observations of geographic variation in behavior in this species, and constitutes one of the first behavioral studies of C. collaris in the Smoky Hills portion of its range.

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Rights

© 2012 Katherine Talbott

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