Phylogenetic relationships of North American phoxinins (Actinopterygii: Cypriniformes: Leuciscidae) as inferred from S7 nuclear DNA sequences

The phylogenetic systematics of North American (NA) phoxinins, and family Leuciscidae (formerly Cyprinidae, in part) in general, have had a very dynamic history marked by uncertainty regarding the validity of many taxonomic designations. Recent molecular studies, based on mitochondrial DNA sequences, of NA phoxinins have provided the first comprehensive hypotheses for the group and suggest that they are comprised of three major lineages: creek chub-plagopterin (CC-P), western, and open posterior myodome clades. A number of phylogenetic evaluations, using both mitochondrial and nuclear DNA sequences, of the formerly recognized family Cyprinidae (=Cyprinoidea) have failed to support the traditional subfamily designations. This study, based on sequences from the first intron of the nuclear gene S7, supports many of the findings of the earlier molecular studies of NA phoxinins, but also suggests that European Leuciscidae evolved within the NA phoxinin lineage and are most likely descended from the common ancestor of the CC-P clade. As in some other recent phylogenetic studies of the Cyprinoidea, analyses of this study fail to support the broader subfamily designations within the formerly recognized family Cyprinidae.