Researcher ORCID Identifier

Graduation Year


Date of Submission


Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Taylor Perron

Reader 2

Branwen Williams

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Disproportionate concentrations of biodiversity in mountains worldwide suggest linkages between geologic processes and biodiversity that are not yet well understood. The Tennessee River Basin in the Blue Ridge Mountains of the southeastern U.S. is a global hotspot for freshwater fish biodiversity. To investigate drivers of biodiversity in the Tennessee River Basin, and explore links to geologic processes, I study the Greenfin Darter (Nothonotus chlorobranchius), a small fish endemic to the upper Tennessee River Basin. I use generalized linear models (GLMs) to evaluate the influence of topography, lithology, climate and land use on the distribution of the Greenfin Darter, and find that slope, elevation, geologic age, soil erosion, temperature and pasture cover drive where Greenfin Darters live. Next, I conduct additional topographic and genomic analysis to examine the hypothesis that steps in topography, or knickpoints, isolate Greenfin Darters and lead to genetic divergence. I find tentative evidence that knickpoints may play a role in geographically isolating Greenfin Darter populations and causing allopatric speciation. Finally, I analyze spatial correlations between freshwater fish species richness and anthropogenic environmental impacts and find a weak negative correlation between Superfund sites and darter species richness in the southeastern U.S. These results highlight that the unique biodiversity of the Tennessee River Basin may be at risk from climate and land use change. Furthermore, these results suggest that topographic and lithologic variation may contribute to biodiversity by creating ecological niches and causing speciation, a starting point for understanding how geologic processes shape biodiversity and evolution in mountains globally.