Phylogeny, evolution, and biogeography of the darter subgenus Ulocentra (genus Etheostoma, family Percidae)

The phylogenetic relationships of the 20 described species of snubnose darters, subgenus Ulocentra, and 11 members of the proposed sister subgenus Etheostoma were investigated with 1033 base pairs of mitochondrial DNA sequence data and 54 osteological characters. Three hypotheses on the interrelationships and monophyly of these two subgenera were evaluated. Monophyly for the subgenus Ulocentra was supported, but the subgenus Etheostoma appears to be polyphyletic. Mitochondrial DNA sequence data from the entire control region, tRNA Phe gene, and partial 12S rRNA gene, were analyzed for 78 population samples of species within the subgenera Ulocentra and Etheostoma, producing species-level resolution of phylogenetic relationships. Population analysis of select darter species was performed using the heteroduplex method. Phylogeography was utilized to interpret the genetic variation between populations and species of Ulocentra on maps of their geographic distributions, indicating that vicariance events from the Late Pleistocene through the Holocene were important in forming four major clades of snubnose darters. Most Ulocentra species are allopatric. Recent secondary dispersal seems to best explain the cases of the syntopic distributions.; Osteological analysis of 54 phylogenetic characters was performed on cleared and stained specimens of the subgenera Ulocentra and Etheostoma. Monophyly of the subgenus Ulocentra was supported in the strict consensus cladogram by four osteological characters. Several osteological apomorphies united members of the subgenus Ulocentra and E. histrio. Additional apomorphic characters united members of the E. simoterum species group with E. duryi and E. flavum, and were shared with E. blennioides. Many of the osteological apomorphies for Ulocentra species resulted from specialization for benthic feeding in slow moving stream habitats.; Both the molecular and morphological data sets supported the monophyly of the subgenus Ulocentra. The banded darter, E. zonale, and its sister E. lynceum, were not the closest relatives to the snubnose darters and may be best classified apart from other members of the subgenus Etheostoma by resurrecting the subgenus Nanostoma. The sister group to the subgenus Ulocentra contained a restricted assembly of species within the subgenus Etheostoma comprised of E. blennioides, E. rupestre, E. blennius , the thalassinum species group, and E. histrio.