Microsatellite Analysis of Genetic Population Structure and Gene Flow in Populations of the Federally Threatened Cherokee Darter, Etheostoma Scotti

Defense Date


Graduation Date

Fall 1-1-2007


Campus Only

Submission Type


Degree Name



Biological Sciences


Bayer School of Natural and Environmental Sciences

Committee Chair

Brady Porter

Committee Member

Lisa Ludvico

Committee Member

Michael Jensen-Seaman

Committee Member

Todd Katzner


population structure, conservation genetics, Percidae, gene flow, snubnose darter, Etheostoma coosae


The population structure and gene flow of the federally threatened Cherokee darter, Etheostoma scotti, were investigated by developing a novel suite of microsatellite markers that will serve future studies of E. scotti and other darter species. Physical structures in the Etowah River system where E. scotti occurs, including five pipe culverts and three small reservoirs, were examined for their potential to fragment Cherokee darter populations by decreasing or restricting gene flow. Various measures of population structure and genetic diversity were compared between populations located upstream and downstream of these potential barriers. It was determined that E. scotti populations appear to be fragmented by the aforementioned barriers, as low but significant levels of population structure were detected. In addition, Bayesian and population structure analyses revealed a phylogeographic pattern of E. scotti populations. This result was consistent with a previous mtDNA and dorsal fin coloration study of the Cherokee darter, supporting the recognition of three Evolutionary Significant Units (ESUs) of E. scotti within the Etowah River system. E. scotti and its sister species, E. coosae, which are primarily allopatric in range, were found to be occurring syntopically at a few field sites. The collection of individuals with coloration patterns that appeared intermediate between the two species suggested they may be hybridizing. The analysis of the multilocus microsatellite genotypes of individuals from the two species revealed a very narrow contact zone with limited hybridization and no clinal variation between the two species. These results permit us to accept E. scotti as a legitimate species.





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