Shane Ritchea

Defense Date

7-24-2006

Graduation Date

Summer 2006

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Environmental Science and Management (ESM)

Committee Chair

Brady A. Porter

Committee Member

Daniel K. Donnelly

Committee Member

Robert D. Volkmar

Keywords

control region, mitochondrial DNA, ND2, Nothonotus, phylogenetics

Abstract

The Etowah darter is a recently described member of the Etheostoma (Nothonotus) jordani species group believed to be geographically restricted to the Upper Etowah River in Georgia. Small population sizes and restricted range present potential risks to the continued existence of this endangered species. The most geographically proximal records of the relatively abundant greenbreast darter, E. jordani, were reported from Stamp Creek (a tributary to the middle section of the Etowah River); however, in recent surveys Nothonotus individuals have been documented from intermediate localities and appear to be morphological mixtures of E. jordani and E. etowahae. Two alternative hypotheses may explain these findings: these newly discovered localities may indicate syntopy and/or hybridization between these two species, or alternatively, morphological characters promoted in the formal species description of E. etowahae may be problematic and incapable of definitively identifying all Nothonotus specimens from the Etowah River. Either call raises questions as to the classification status of these newly documented populations and the true geographic ranges of these sister species. In this study we have sequenced 2020bp of mtDNA from 123 Nothonotus specimens to provide a means for genetic identification of E. etowahae, examine population structure, and redefine geographic distributions for each species. Phylogeographic analysis documents E. etowahae haplotypes in areas approximately 110 river kilometers downstream from where it was first described in 1993. Surprisingly, little phylogeographic structure is found within either of these species throughout their respective ranges.

Format

PDF

Language

English

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