Term of Award

Summer 2017

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 D. McBrayer

Committee Member 1

John Scott Harrison

Committee Member 2

Christian Cox

Committee Member 3

James Roberts

Committee Member 3 Email

jhroberts@georgiasouthern.edu

Abstract

Anthropogenic disturbance is known to affect biological diversity at the community, species, and genetic levels. Habitat fragmentation, in particular, has been shown to impact predator abundance and distribution, impede dispersal, and augment genetic drift. In small populations, which often result from habitat fragmentation, the effects of human disturbance may be disproportionately expressed. Small populations are more susceptible to selection pressures and random drift because genetic and phenotypic frequencies can become rapidly fixed, in comparison to larger populations. In turn, fixation of maladaptive alleles or morphs can accelerate extinction. For example, cryptic color polymorphism can be maintained by apostatic selection, where detection of prey is dependent on the relative frequencies of color morphs. In the event that a conspicuous color morph becomes fixed, the probability of detection by visual predators is likely to increase, thus increasing probability of local extinction. Furthermore, events that alter habitat structure and substrate composition may also increase exposure of cryptic animals to visual predators because crypsis is substrate-dependent. A color morph that is cryptic against one visual background may be conspicuous against a different visual background. Subpopulations of Sceloporus woodi, a cryptic species of lizard, occupy managed stands of sand pine scrub and longleaf pine habitats in the Ocala National Forest. These subpopulations are subjected to prescribe burning, fire suppression, and clear-cutting. Here, I show that habitat alteration, due to management in the Ocala National Forest, results in differential predation between sampling locations. As a result, significant variation in dorsal color is observed across the metapopulation. Furthermore, subpopulations appear to experience little genetic drift, perhaps due to gene flow facilitated by anthropogenically-maintained corridors.

Research Data and Supplementary Material

Yes

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