Phylogeography and population structure of the Rock Darter species complex, Etheostoma rupestre (Teleostomi: Percidae) across the Mobile River Basin

Despite the high diversity and endemism in the Mobile River Basin, analyses of molecular phylogeographic patterns of freshwater fishes in this system are lacking. Using cytochrome b (cyt b) and S7 ribosomal intron-1, this study compares the phylogeography and population structure of Etheostoma rupestre Rock Darter with a disjunct distribution throughout the Mobile River Basin. For cyt b, parsimony, Bayesian, and Species Delimitation analyses showed a split between the Tombigbee, Alabama, and Coosa/Tallapoosa Rivers, potentially representing previously undescribed species. In addition, there is evidence of limited gene flow between the lower Tombigbee/Sipsey River populations and other populations. Hierarchical comparison showed that there is genetic divergence between the major rivers of the Mobile River Basin. The lack of structure within the tributaries of the river system may indicate that Rock Darter is capable of further dispersal than typical for a darter species. The structure identified across the basin may be due to historic sea-level fluctuations and/or contemporary structure, but fine-scale, within-river analyses would be necessary to further unravel the phylogenetic relationships of the Rock Darter species complex. This study is relevant to establishing conservation guidelines for the biodiversity in the Mobile River Basin.

Automated summary

This study compares the phylogeography and population structure of Rock Darter in the Mobile River Basin. The results show genetic divergence between major rivers, potentially representing previously undescribed species. Limited gene flow was also observed between lower Tombigbee/Sipsey River populations and others. This study has important implications for establishing conservation guidelines for biodiversity in the Mobile River Basin.