Date of Award:

8-2024

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Susannah S. French

Committee

Susannah S. French

Committee

Julie K. Young

Committee

Alan H. Savitzky

Abstract

Urbanization can alter wildlife, requiring species to adjust to anthropogenic changes via life history strategies. Reptiles are particularly vulnerable to these changes, as ectotherms directly rely on their environment to maintain their optimal homeostatic state. As urbanization changes the landscape, reptiles will have to adapt to anthropogenic change, but it is unclear what behaviors may be aiding in this adaptation and whether there are morphological tradeoffs existing to support this change. To analyze the impact of urbanization and anthropogenic disturbances on reptile behavior and morphology, I conducted three research studies on two different species – the common side-blotched lizard and the Colorado checkered whiptail (Aspidoscelis neotesselatus).

In my first chapter, I characterized differences in side-blotched lizard body condition, aggressive behaviors, and thermoregulatory behaviors between urban sites experiencing an urban heat island effect, and rural field sites in St. George, UT, USA. Although temperature differences were recorded, there were minimal behavioral differenced between sites, yet a strong trade-off between thermoregulatory and aggressive behaviors, regardless of site type.

In my second chapter, I analyzed the impacts of military aircraft noise at Fort Carson Military Base in Colorado Springs, CO, USA on the behavior, stress, and metabolism of the Colorado checkered whiptail. During the flyovers, corticosterone and ketone bodies were upregulated, while lizards spent a greater portion of their time eating, not moving, to help buffer the effect of the flyovers.

Because I detected considerable variation in behavior within sites studied in my first chapter, I investigated morphological and behavioral differences between side-blotched lizards within an urban site for my third chapter. At one of my urban sites, Interstate 15 bisects lizard habitat and introduces anthropogenic disturbances via noise pollution and an increased predator abundance. I observed poor body condition closer to the interstate but detected no difference in exploratory or anti-predator behavior by proximity to the interstate, though lizards fled faster and farther from a simulated aerial predator than the terrestrial model. A higher proportion of lizards fled from the terrestrial model, highlighting the potential for urban lizards to adjust their behavior based on predator type.

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