title: The history and geography of diversification within the butterfly genus Lycaeides in North America.
abstract: The Lycaeides butterfly species complex in North America consists of two nominal, morphologically defined species. These butterflies are ecologically diverse and appear to be distributed as a geographically complex mosaic of locally differentiated populations that may be undergoing adaptive radiation. We asked whether patterns of molecular genetic variation within the species complex are congruent with currently recognized morphological species and whether the distribution of molecular variation is consistent with the hypothesis that Pleistocene climate changes contributed to the process of differentiation within the genus. Variation in the form of the genitalia from 726 males from 59 populations clearly distinguishes both species with only six populations containing morphologically intermediate or ambiguous individuals. However, partitioning of molecular variance in a 236 bp section of the mitochondrial AT-rich region from 628 individuals (57 populations) surveyed using single strand conformation polymorphism analysis (SSCP) indicates that only 26% of the total genetic variation is distributed along nominal species boundaries as defined by morphology. Instead, three phylogeographical groups were detected, represented by three major haplotype clades, which account for 90% of the total genetic variance. Pleistocene glaciations appear to have fostered divergence during glacial maxima, while post-glacial range expansions created opportunities for gene exchange and reticulation along suture zones between geographical groups. Data presented here allow us to make inferences about the history of the species complex. However, evidence of ancestral polymorphism and reticulation limit our ability to define species boundaries based on mitochondrial DNA sequence variation.
authors.affiliation: Department of Biology, Texas State University--San Marcos, 601 University Dr., San Marcos, Texas 78666, USA. ccnice@txstate.edu
authors.forename: Chris C
authors.initials: CC
authors.lastname: Nice
authors.forename: Nicola
authors.initials: N
authors.lastname: Anthony
authors.forename: Greg
authors.initials: G
authors.lastname: Gelembiuk
authors.forename: Denise
authors.initials: D
authors.lastname: Raterman
authors.forename: Richard
authors.initials: R
authors.lastname: Ffrench-Constant
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D002080:Butterflies / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics*; D016000:Cluster Analysis; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics; D003710:Demography; D014644:Genetic Variation; D005828:Genetics, Population; D005837:Genitalia, Male / Q000033:anatomy & histology*; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009656:North America; D018807:Polymorphism, Single-Stranded Conformational; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial