Date of Award

Spring 5-1-2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Steven L. Lima

Second Advisor

Michael J. Angilletta

Third Advisor

Diana K. Hews

Abstract

Locomotory performance has been the focus of many ecological and evolutionary studies, and lizards have been a model system. While several studies have demonstrated interspecific differences in performance, few have examined intraspeciflc variation in performance and the suites of underlying physiological traits in tree lizards ( Uro.,·aurns ornatus) a species with alternative reproductive tactics that show variation in spatial use patterns. To assess the functional ecology of movement behaviors of male morphs and or females, I examined variation in exertion, plasma metabolites, plasma steroid hormones, and muscle fiber types in ornate tree lizards ( Urosaurus ornalus). In my study population, males having orange throats with a central blue patch (OB males) are territorial, and those with solid orange throats (0 males) are nonterritorial rovers or satellites. I also studied a third morph (mottled or M males), which is morphologically intermediate and behaves similarly to OB males in antipredator contexts, although their territorial behaviors are uncharacterized. I tested the hypothesis that sex and morph differences in space use are reflected in differences in exertion ability and in key physiological traits. To estimate exertion, lizards were run on a field-portable treadmill immediately after capture. The trial ended when the lizard was exhausted and no longer moved forward in response to gentle prodding on the tail base. Immediately after the trial, we obtained a blood sample and either sacrificed the lizard for further histological study or released it. To assess physiological correlations with exertion. I measured levels ol' corticosterone (CORT) and plasma metabolites. While I did not find significant sex or morph effects for exertion, CORT levels were higher after rum1ing compared to levels at capture, consistent with the role ot· CORT in energy mobilization. Also, females had significantly higher CORT and triglyceride levels than males. The second experiment tested the hypothesis that sex and morph differences in space use would be reflected in muscle fiber-type proportions in a key thigh muscle. No sex or morph differences were found. However, within individuals. the percentages of fast-oxidative-glycolytic and slow-oxidative fibers were negatively correlated, as were the percentages of fast-glycolytic and slow-oxidative fibers.

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