Molecular phylogenetics of North American phoxinins (Actinopterygii: Cypriniformes: Leuciscidae) based on RAG1 and S7 nuclear DNA sequence data

Most molecular phylogenetic hypotheses for North American (NA) phoxinins are based on mitochondrial DNA sequences (mtDNA) and the resulting hypotheses are rather variable, though there is general support for three major lineages of NA phoxinins: western, creek chub-plagopterin (CC-P), and open posterior myodome (OPM) clades. Support for a monophyletic NA phoxinin group has varied among studies. This study utilizes nuclear DNA (nDNA) sequences from the RAG1 (exon 3) and S7 (intron 1) gene regions to evaluate the phylogenetic relationships and monophyly of NA phoxinins. Results from the nDNA analyses provide overall support for the western, CC-P, and OPM clades. The CC-P clade had the best overall resolution and support in the individual and combined analyses of the nDNA data. Resolution of the western clade was fairly good, with most analyses recovering a monophyletic Gila clade. The OPM clade demonstrated the highest degree of topological variability among the analyses. The RAG1 analyses failed to recover a monophyletic NA phoxinin group by resolving the European leuciscins, inclusive Notemigonus crysoleucas, within the NA phoxinin topology. Most analyses recovered a strongly supported shiner clade though, similar to several mtDNA studies; there was a high degree of topological variability among the results.