Adrian Corbett (Committee Member), Keith Grasman (Committee Member), Dan Krane (Advisor), James Mcdougal (Committee Member), Nicholas Reo (Committee Member)
Doctor of Philosophy (PhD)
It is generally recognized that amphibian populations declining across the globe. Habitat loss is the primary cause of decline. The salamander family Ambystomatidae has experienced significantly more rapid decline than the average for amphibians. Coefficients of Conservatism (CoC) have been developed for amphibians in Ohio. These are based primarily on habitat requirements with high CoCs for amphibians with stringent habitat requirements (e.g. vernal pools associated with large, intact, undisturbed forest), and low CoCs for amphibians with less stringent habitat requirements. Genetic diversity in five species and one hybrid complex of ambystomatid salamander in southwest Ohio were examined and compared to their respective CoC. Less gene flow across inhospitable habitat and consequently lower genetic diversity in that species would be expected compared with a species with less restrictive habitat requirements, i.e. a lower CoC. Microsatellites were used to determine conformation to Hardy Weinberg Equilibrium expectations, allelic and genotypic differences between populations, and inbreeding coefficients Fis and Fst. Genetic differences between woodlots and between ponds within a woodlot were examined. It was found that, for different species in the same habitat, species with higher CoCs have lower genetic diversity than species with lower CoCs. It was also found that habitat quality influences genetic diversity in all species. In some habitats, the genetic diversity of all species in that habitat will be lower than that of the same species in a more suitable habitat. In some cases presence of the hybrid complex (kleptogens) appears to have negatively impacted species that act as a sperm donor to the hybrid complex. In some species (e.g. smallmouth salamanders) genetic structure can be seen in different ponds within a woodlot. In other species (e.g. tiger salamanders) no such structure appears. It was also found that a railroad track acts as a barrier to marbled salamanders creating two genetically distinct populations. It was found that maternal ancestor of the kleptogens, A. barbouri, also acts as a sperm donor but does not replace the A. laterale genome in the nucleus. In addition to species specific differences in genetic diversity, habitat quality, and presence of kleptogens also influence genetic diversity in ambystomatid salamanders.
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