Conservation genetics, extinction, and taxonomic status: a case history of the regal fritillary

I investigated the phylogeography of mitochondrial DNA haplotypes in the regal fritillary (Speyeria idalia) to determine the conservation status of isolated populations in light of alternative definitions of species, subspecies, and evolutionarily significant units. A total of 1441 bases of partial cytochrome oxidase I and II genes were sequenced from 115 individuals In 18 populations located throughout the range of the species. A relatively disjunct population was differentiated with five synapomorphies, whereas all other populations had little haplotype variation and no apparent association between geographic and genetic distance. The divergence of the disjunct population may be due to either historical isolation among populations or extinction of intermediate populations within a cline. Genetic divergence due to the extinction of populations in fragmented habitat, termed anthrovicariance may be a generalizable phenomenon. Similar cases in insects have been described previously. If more cases can be elucidated, taxonomists will need to consider whether allopatry achieved through a natural vicariant event should be treated differently than that achieved via human-induced habitat loss. Mitochondrial DNA sequence divergence, along with ecological and natural-history data, suggest that the disjunct population of S. idalia is a distinct evolutionary lineage. Although taxonomic designation is not a simple task, the data indicate that the disjunct population is clearly of conservation concern.