Literaturdatenbank
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Cureton, J. C. (2010). A future without box turtles? investigating the impact of urbanization on the population genetics of ornate box turtles, terrapene ornata. Unpublished thesis , Sam Houston State University, Huntsville, Texas.
Added by: Sarina Wunderlich (25 Jan 2011 10:31:56 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Cureton2010 View all bibliographic details  |
Categories: General Keywords: Emydidae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Terrapene, Terrapene ornata Creators: Cureton Publisher: Sam Houston State University (Huntsville, Texas) |
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| Abstract |
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Urbanization, or the development of land for human use, poses threats to wildlife because roads can fragment habitats thereby preventing gene flow between populations. As a result, populations will exhibit increased inbreeding levels and decreased genetic diversity, which is a measure of a population’s potential to adapt to diseases, pollution, or other stochastic factors. The rapid decline of ornate box turtles (Terrapene ornata) throughout their range has been attributed to personal collection and urbanization, although there is no evidence of the latter. The purpose of this thesis was to determine if urbanization is contributing to the decline of T. ornata via habitat fragmentation. I compared the genetic diversity of turtles in a natural (the Matador Wildlife Management Area; Cottle County, Texas) population to those of an urban population (Cooke and Grayson Counties, Texas) using 12 microsatellite loci (10 of which were characterized for this study) and 585 base pairs of the mitochondrial control region. I found that allelic diversity, but not observed heterozygosity, was significantly higher in the urban population than in the natural population using the microsatellites. Similarly, the number of segregating sites, but not haplotypes, in the mitochondrial control region was significantly higher in the urban population compared to the natural population. I also detected that the urban population experienced a recent genetic bottleneck, and suspect that the bottleneck was induced by the fragmentation of this population, most notably the construction of Highway 82. This four-lane highway has an average daily traffic volume of 18,222 cars and serves as a very strong gene flow barrier to T. ornata subpopulations on opposing sides of the highway. The longevity of this species has prevented significant genotypic divergence from occurring in the urban population and thus, I was unable to identify potential migrants. This data suggests that historically, the effective population size of the urban population was large, and individuals could freely move about in the habitat. Although individuals can no longer move freely (due to roads), genetic diversity is still high enough in the population that conservation measures should be implemented before diversity declines substantially due to inbreeding.
Added by: Sarina Wunderlich |