Cave-Obligate Biodiversity on the Campus of Sewanee: The University of the South, Franklin County, Tennessee


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January 2011


The southern Cumberland Plateau in Tennessee and Alabama has the greatest diversity of cave-obligate animals in the United States. The University of the South in Franklin County, TN is one of the largest private landholders on the southern Cumberland Plateau. Its 13,000-acre campus has more than 30 caves and is underlain by more than 14 km of horizontal passageways. We examined the biodiversity of cave animals on the campus at the species level and at the genetic level. Through a survey of seven caves on the campus, we identified 24 cave-obligate species, including two new county records. This total accounts for half of the cave-obligate species reported for Franklin County. For our genetic analysis, we selected six diverse taxa (two millipedes, a beetle, a fly, an aquatic isopod, and a spider) that were collected from multiple caves, and compared their mitochondrial cytochrome oxidase I gene sequences. Across the six taxa we found: (1) low genetic diversity within caves (mean nucleotide diversity within caves across all taxa: 0.25%), (2) high genetic divergence between caves (divergence between caves within taxa ranged from 2.5%–10.9%, with two exceptions), and (3) little evidence for gene flow between caves (FST between caves within taxa > 0.57, with one exception). Thus, the campus supports tremendous species diversity, and even more remarkable genetic diversity within those species on a small geographic scale (no studied caves were >7 km apart). The divergence between cave populations and lack of gene flow between them that we observed across a range of taxa highlight the importance of cave conservation on a regional scale.

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Southeastern Naturalist, Vol. 10, no. 2 (2011).