Date of Award

5-31-2018

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology/Environmental Biology

First Advisor

Liam J. Revell

Second Advisor

Robert D. Stevenson

Third Advisor

Ron J. Etter

Abstract

Urbanization is a dimension of global change with significant ecological and evolutionary consequences that will continue to grow in its importance as we increasingly transform natural areas for our use. I hypothesize that urban persistent animals, specifically neotropical lizards in the genus Anolis (anoles), face novel selection pressures leading to shifts in habitat use and phenotype. In my dissertation, I first explore how the altered urban environment has impacted habitat use. I demonstrate that of two commonly encountered urban anoles in Puerto Rico, only one (Anolis cristatellus) exploits anthropogenic habitat where it is likely exposed to unique selective pressures as it expands its niche space. Among these altered selective pressures are predation and intraspecific competition, evidenced by differences in injury rates between environments. This in turn sets the stage for rapid adaptive change. I find that urban A. cristatellus show predictable and heritable shifts in functionally relevant traits between forest and urban populations and furthermore that these traits have consequences for locomotor performance in the urban environment. This helps provide a mechanistic understanding of the natural selection that is likely responsible for measured phenotypic changes between environments. Finally, I consider responses to urbanization from a broader perspective by examining the pattern of tolerance to urban areas across all Caribbean anoles. This final analysis indicates that species adapted to hotter and drier environments may be pre-adapted to urban environments and that related species share similar tolerance to urbanization. This could result in non-random species loss as urbanization progresses. In sum, my research sheds light on the complex ecological and evolutionary ways in which tropical lizards have responded and may be adapting to anthropogenic global change.

Comments

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