Molecular and morphological divergence in the butterfly genus Lycaeides (Lepidoptera : Lycaenidae) in North America: evidence of recent speciation

Male genital morphology, allozyme allele frequencies and mtDNA sequence var iation were surveyed in the butterfly species Lycaeides inas and L. melissa from across much of their range in North America. Despite clear difference s in male genital morphology, wing colour patterns and habitat characterist ics, genetic variation was not taxonomically or geographically structured a nd the species were not identifiable by either genetic data set. Genetic di stances (Nei's D=0.002-0.078, calculated from allozyme data) between all po pulations of both species were within the range commonly observed for consp ecific populations of other butterflies. The most frequent mtDNA haplotype was present in individuals of both species in populations from southern Cal ifornia to Wisconsin. We conclude that speciation has probably happened rec ently and the lack of genetic differentiation between the species is the pr oduct of either (1) recent or ongoing gene flow at neutral loci, and/or (2) an insufficiency of time for lineage sorting. The evolution of male genita l morphology, wing colour patterns and ecological characteristics has proce eded more rapidly than allozyme or mtDNA evolution.