Evolutionarily independent genes and genomes and insights on genetic structure, evolution and conservation of the collis group of darters

Abstract

Comparing variation across evolutionarily independent characters, notably nuclear and mitochondrial genes, yields a more robust estimate of diversification than is generally recovered from individual characters. Patterns of variation across multiple molecular markers from the mitochondrial (16SrRNA, cytochrome b) and nuclear (ldhA6 and aldB) genomes were examined from six populations of Etheostoma collis and two populations of Etheostoma saludae, species aligned in the collis groups. Phylogenetic analyses revealed that sequence variation among individuals from the Roanoke, Tar and Neuse Rivers and the Catawba and Pee Dee Rivers, respectively, form highly supported, deeply divergent clades. Relationships of alleles sampled from Saluda River E. saludae and Cape Fear River E. collis to these lineages are unresolved, but all groups are reciprocally monophyletic for both nuclear and mtDNA loci. Phylogenetic analyses suggest that historical factors have had a strong influence on the distribution of genetic variation among populations. Genetic variation within the collis group is consistent with all previously proposed taxonomic hypotheses for the collis group, providing no taxonomic insights. From a conservation standpoint, each population of the collis group is an ESU, thereby warranting a drainage-specific management strategy.