Term of Award

Summer 2024

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Lance McBrayer

Committee Member 1

Steve Vives

Committee Member 2

Alan Harvey

Abstract

Selection via predation is a strong evolutionary force on small organisms, producing unique phenotypic adaptations. In cryptic species, different populations may exhibit color polymorphisms to better match multiple substrates or backgrounds. Here, I conducted a clay model study in the Ocala National Forest of Florida (USA) to test predation as a selective mechanism for color polymorphism in the Florida scrub lizard (Sceloporus woodi). Clay models were constructed to resemble light and dark morphs of S. woodi and placed on contrasting substrates in longleaf pine and Florida scrub stands. It is hypothesized Florida Scrub Jays (Aphelocoma coerulescens) are a key predator of S. woodi, so clay models were placed in scrub stands where Florida Scrub Jays were present or absent. Evidence of avian predation detected on clay models was analyzed using a generalized linear model, which found that light clay models were attacked significantly more than dark models. Furthermore, the rate of attacks on lizard clay models was significantly higher when their chromatic contrast against the substrate was lower. Apostatic selection of lizard models proposes bias through search imaging as dark morph S. woodi occur less frequently in Florida scrub where the majority of attacks occurred. Increased predation in Florida Scrub Jay-present sites suggests that predator regime has a strong effect on the maintenance of adaptive coloration and that Florida Scrub Jays may be a key predator of S. woodi.

Research Data and Supplementary Material

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