Morphological and genetic investigation of Pennsylvania populations of the channel shiner

The channel shiner, Notropis wickliffi, is listed as a vulnerable species in Pennsylvania due largely to taxonomic confusion with a closely related minnow species, the mimic shiner, N. volucellus. Previous taxonomic studies have been performed in several drainage systems; however, due to regional variation in morphology, key identification characters from other studies might be problematic when applied to Pennsylvania populations. Sequences of the mitochondrial cytochrome b gene from mimic, channel and ghost shiners (N. buchanani) separated specimens into only two phylogenetic clades. Morphologically identified mimic and ghost shiners clustered together in the same mtDNA clade and were not reciprocally monophyletic.  Rampant unidirectional hybridization and backcrossing has likely occurred between mimic and ghost shiners in Pennsylvania and Ohio.  Channel shiners formed a second monophyletic clade, separated from the mimic/ghost clade by an average 6.2% sequence divergence.  Three pigmentation patterns were highly correlated to the haplotype clade assignment for the mimic and channel shiners, which will prove helpful in their field identification. Sheared principal component analysis revealed statistical morphological differentiation between all three species.  Bayesian analysis from eight microsatellite loci resulted in the unique assignment of ghost shiners, but only minor assignment differences between mimic and channel shiner samples.