Date of Award
9-22-2025
Document Type
Thesis
Degree Name
Biology, MS
First Advisor
Brook Fluker
Committee Members
Andrew Sweet; Kyle Gustafson
Abstract
The Cumberland Darter (Etheostoma susanae) is an endangered species of freshwater fish endemic to the tributaries of the Cumberland River above the Cumberland Falls in Kentucky and Tennessee. Once recognized as a subspecies of Johnny Dater (E. nigrum), E. susanae was elevated to species level based on morphological and mtDNA variation. Habitat degradation and modification is a primary concern for the species with its preference for slow-flow streams. Fragmented populations increase the risk of disrupting historic gene flow between tributaries which could potentially result in genetically distinct populations. In 2011, E. susanae was listed under the Endangered Species Act by US Fish & Wildlife Service. Furthermore, a comprehensive genetic evaluation was needed to resolve its complicated origin. Here, we present the first range-wide population genomic study of E. susanae, integrating microsatellites, RADSeq, and mitochondrial DNA to evaluate phylogenetic relationships, population structure, genetic diversity, and potential hybridization with its sister species, E. nigrum. Phylogenetic analyses recovered all E. susanae populations as monophyletic and sister to E. nigrum, with no evidence of recent or ongoing hybridization between species, including in historically identified contact zones such as the Poor Fork. Population genetic structure was strong, with 8 genetically distinct populations corresponding to 8 of the 9 Management Units defined in the recovery plan for E. susanae. There was no evidence for reduced measures of genetic diversity for populations of E. susanae when compared to populations of its more broadly distributed sister species, E. nigrum. However, the high degree of genetic structuring among populations of E. susanae, despite its relatively small geographic range, has important implications for conservation. These findings provide critical baseline data for future genetic monitoring and conservation management strategies for E. susanae.
Rights Management
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Recommended Citation
Canada, Hilary, "Population Genomic Assessment of the Endangered Cumberland Darter (Etheostoma Susanae)" (2025). Student Theses and Dissertations. 1109.
https://arch.astate.edu/all-etd/1109
