Evolution of the fantail darter, Etheostoma flabellare (Percidae: Catonotus): Systematics, phylogeography, and population history

Etheostoma flabellare has a long history of taxonomic confusion due to complex patterns of morphological variation. Four or five subspecies are currently recognized. Alternative hypotheses suggest species-level descriptions are warranted. No studies have tested the morphology-based taxonomy and phylogenetic relationships have not been proposed. Relationships within the E. flabellare species group of Catonotus are also problematic.;Genetic markers are used to generate phylogenies to test alternate taxonomic hypotheses for E. flabellare by examining patterns of lineage diversification and the monophyly of subspecies. Phylogenies are also used to examine relationships within the species group and test hypotheses associated with Central Highlands Vicariance Biogeography. Mitochondrial haplotypes are used to examine population genetic structure and test the predicted limited dispersal ability of E. flabellare. Associations between phylogeny and geography of haplotypes are examined with nested clade analysis (NCA) to infer historic and ongoing population-level processes that have been important in the evolutionary history of the species and in shaping genetic structure. NCA fragmentation events are re-examined in a phylogenetic context and to identify evolutionary lineages that warrant species-level recognition.;Phylogenies recover each subspecies as paraphyletic, providing no support for the current taxonomy. High genetic divergence among geographically-concordant monophyletic clades suggests that species-level designations more accurately describe diversity and highlight the need for taxonomic revision. Relationships recovered for E. flabellare species group members suggest species group designations within Catonotus require revision. Phylogeographic patterns illustrate that current clade distributions and diversity in E. flabellare require vicariant and dispersal explanations. Population-level genetic structure shows that E. flabellare is subdivided at broad and fine spatial scales, supporting limited dispersal ability as predicted by intrinsic and extrinsic features of the species. NCA revealed significant non-random associations between the phylogeny and geographic distribution of haplotypes, rejecting the hypothesis of panmixia in E. flabellare populations. NCA recovered several population processes, including historic fragmentation, restricted gene flow, and range expansions, highlighting the complexity of events associated with the history of the species and its genetic diversity. Most inferred fragmentation events corresponded to populations that also formed exclusive phylogenetic clades, further supporting unrecognized species-level diversity in E. flabellare.