Population Structure of Central Stoneroller (Campostoma anomalum) on the Ozark Plateau in Arkansas and Missouri

Stream fishes on the Ozark Plateau have been influenced both by historic events (i.e. vicariance versus dispersal) and ecological forces (i.e. flow regime). To examine the role of these processes, genetic structure of Central Stoneroller (Campostoma anomalum), an ecologically important omnivorous minnow with a broad distribution and elevated abundance, was evaluated across populations in the White River drainage of the Ozark Plateau in Arkansas and Missouri. Fin clips of five to eight individuals were taken at each of 20 sites (N=138 individuals; average=6.9), selected so as to represent two different flow regimes: intermittently flashy (N=10 sites; N=73 individuals; average=7.3/ site) and groundwater flashy (N=10 sites; N=65 individuals; average=6.5/ site). Two mitochondrial DNA genes (ATPase 6 and ATPase 8) were sequenced across 842 base pairs to provide comparative data. Genetic diversity within and among sites and flow regimes was evaluated using an analysis of molecular variance (AMOVA), and a Mantel test was conducted to compare genetic versus stream distance to test for isolation by distance patterns. Genetic structure was further explored through visualization with a haplotype network and a maximum likelihood analysis, where Notropis stramineus served (Sand Shiner) as outgroup. Potential historic population expansion within either flow regime was examined with a mismatch distribution. Based on the extent of genetic variability among populations, the analyses indicated that flow regime had no significant effect on genetic structure in the study species. Most sites appeared panmictic with individuals dispersing freely across the study area, at least historically, while three sites appear to be somewhat isolated. The haplotype network and ML-tree demonstrated that individuals are genetically similar. There is also a historic signal of population expansion in either flow regime. However, the presence of a rare lineage 7% diverged from Central Stoneroller indicates that diversity in the White River is more complex than originally thought, and that further studies are needed to delimit the distribution, define the species, and determine if co-occurring lineages are hybridizing