Date of Award
Thesis open access
David O. Ribble
Michele A. Johnson
Habitat fragmentation results in smaller, more isolated populations, which experience a higher risk of extinction due to inbreeding, genetic drift, and environmental catastrophes. Wildlife populations in urban areas are frequently fragmented, but corridors connecting these areas may help conserve urban populations. In theory, corridors allow genetic diversity and relatedness of populations to be maintained through gene flow, increasing the overall fitness of otherwise isolated populations. I studied the population genetics of the Texas Spiny Lizard (Sceloporus olivaceus) in San Antonio, Texas to determine whether corridors impact the genetic diversity or genetic relatedness of lizard populations. Genetic diversity was surveyed using six microsatellite loci derived from the Eastern Fence Lizard (Sceloporus undulatus). I compared genetic diversity and relatedness between isolated, corridor, and rural localities. Individuals within a population were more closely related to one another than to individuals in any other population. There was a trend of isolation by distance over all localities (P < 0.01), but not among only the urban localities (P = 0.67). The difference in average pairwise FST for isolated localities (any pair not connected by a corridor) versus corridor localities (any pair connected by a corridor) was not statistically significant (P = 0.11). The difference in average Ho of all corridor localities versus all isolated localities was not statistically significant (P = 0.11). The samples most likely represented two clusters, based on analysis with STRUCTURE and TESS. The samples from the rural population formed one cluster, and the urban samples formed the other cluster, according to TESS. My results suggest that genetic relatedness may be higher between populations connected by a corridor, but genetic diversity is similar, when compared to isolated populations. This study demonstrates that common species, such as the Texas Spiny Lizard, can be useful model organisms for testing conservation principles in urban environments.
Fink, Alyssa A., "Are corridors effective? A genetic study of Texas Spiny Lizard populations in urban parks of San Antonio" (2015). Biology Honors Theses. 22.
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