Systematics, ecomorphology, and morphometrics of the Etheostoma blennioides complex (Teleostomi: Percidae)
Description
The greenside darter, Etheostoma blennioides (Teleostomi: Percidae), is a wide-ranging polytypic taxon that occurs throughout Eastern North America. A prior morphological study recognized that E. blennioides was comprised of four subspecies, several morphological races, and three zones of morphological intergradation. This dissertation uses complete sequences from the mitochondrial cytochrome b gene to estimate phylogenetic relationships for 28 populations within the complex. The results from this portion of the dissertation suggest that taxonomic rearrangement is needed, as the currently recognized taxa do not conform to distinct evolutionary lineages. The taxa in the E. blennioides occupy distinctive habitats, including large rivers, upland streams, and shorelines of the Great Lakes. Ecological (microhabitat) and morphological (fin size) data were gathered from 19 populations of greenside darters from across the range of the complex. One of the four equally parsimonious phylogenies generated in Chapter II was used to examine the relationship between ecology and morphology in a phylogenetic context. Fin sizes, morphological characters considered most sensitive to environmental conditions in these fishes, were utilized in a phylogenetic comparative analysis (spatial autocorrelation). The results indicated that no significant phylogenetic constraint exists for fins. Results from a canonical correlation analysis indicated that there was a significant relationship between microhabitat and morphological phenotype for females, but not for males. Factors associated with morphological and ecological diversification of the complex are discussed. Finally, a previous study of geographic variation of the E. blennioides complex failed to address differences in body shape. Therefore, modern geometric morphometric techniques were applied to examine differences in body shape across the range of E. blennioides . Based on landmark-based methods of analysis, the results indicate that there are significant differences in body shape among the taxa in the complex. These shape differences further strengthen the conclusion of species recognition for the genetically unique taxa identified in Chapter II