Meeting Abstract
Mitochondrial markers have been widely used over the past 30 years to study phylogeography and infer species boundaries. The utility of these markers for such studies is based on the premise that variation within mitochondrial genes is largely neutral. However, evidence that different mitochondrial haplotypes within species confer differential fitness, and thus undergo selection, challenges this assumption. This, along with other factors, such as sex-biased dispersal and mitochondrial introgression across species, can lead to discordant genetic structure between mitochondrial and nuclear genomes. Mitonuclear discordance has been increasingly observed in a wide range of organisms, calling into question mitochondrial-based inferences of species boundaries. Here, we use a cytochrome-b sequence fragment and nuclear SNPs to investigate the presence of mitonuclear discordance in the North American corn snakes (Pantherophis guttatus), a complex that has been taxonomically defined by mitochondrial genetic structure. We identified five geographically partitioned mitochondrial haplotypes, indicating greater mitochondrial diversity than was previously recognized. However, only two of these haplotypes were monophyletic in our nuclear SNP phylogeny, which differed in topology from the mitochondrial tree. Further, population structure analyses using nuclear SNPs showed little evidence of reproductive barriers across haplotype boundaries.
