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Master of Science in Biology (M.S.)
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Thesis (open access)
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This work is licensed under a Creative Commons Attribution 4.0 License.
Department of Biology
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To date, most genetic studies on the American alligator (Alligator mississippiensis) have focused on population genetics and multiple paternity. There have not been any studies looking at how relatedness affects alligator behavior and movement. This study focused on three main questions: 1) what is the genetic diversity among alligators in this location? 2) can parentage be accurately defined among parents and offspring? and 3) how does individual relatedness affect their spatial distribution? We examined the relatedness of 174 unique individuals from the Okefenokee Swamp Park, in South Georgia, USA. In addition, we placed Telonics® satellite tags on 10 adult alligators and created home ranges for these animals. We extracted DNA from tissue, bone, and egg samples, screened multiple microsatellites via PCR, and characterized each individual’s genotype. Mean Pairwise Relatedness (MPR) was used to determine the upper and lower 95% confidence limits to describe the expected random deviations of MPR if random mating occurred among sites. The data were categorized into six groups based on the sex and age classes of the alligators. The MPR was calculated among individuals with known GPS capture locations and tracking movement data to examine the effect of relatedness on spatial distribution. By including the GPS locations, it was possible to test if animals with overlapping, or disjunct home ranges differed in genetic relatedness. Observational field data and MPR were also used to test relatedness among all sampled alligators. Since alligators had known age classes and sex, the MPR was integrated with the known physical data to assign hatchlings and juveniles to a parent pair. Overall hatchlings and juvenile males trended slightly towards inbreeding, while adult males trended slightly toward outbreeding. I was able to determine parentage for three nests, one nest was consistent with multiple paternity, while the other two were consistent with having only a single sire, but all three nests were at least partially sired by the dominant male. Spatial data combined with MPR showed that non-related individuals are significantly more likely to have overlapping territories than related individuals. Specifically, non-related individuals had 5.3 times more hectares of overlap than related individuals.
Hoog, Mark, "The Effect of Genetic Relatedness on Mate Selection and Spatial Distribution in the American Alligator, Alligator mississippiensis" (2023). Electronic Theses and Dissertations. 2619.
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