Specimen collection and identification
Specimens were collected using aerial nets and were either preserved in ethanol or frozen at -20°C until DNA was extracted from each sample. Following Campbell et al. (2019), morphological identifications to subspecies were made using multiple sources, including range information (Moeck 1975), field markings (Bird et al. 1995; Brock & Kaufman 2003; Dunford 2009; Warren et al. 2012), and comparison to specimens in the Bean Museum collection at Brigham Young University or the personal reference collection of E. Gage. In addition to specimens of S. atlantis and S. hesperis , we included several specimens of S. zerene to test for both ancient and contemporary admixture, since SNP-based Structure analysis by Campbellet al. (2019) indicated limited putative hybridization betweenS. zerene and S. hesperis , and phylogenetic analyses additionally showed mito-nuclear discordance in relationships amongS. hesperis, S. atlantis, and S. zerene . The total dataset was comprised of 113 specimens in 14 subspecies of S. hesperis,19 specimens in three subspecies of S. atlantis, 18 specimens in four subspecies of S. zerene , and for phylogenetic analysis, two outgroup specimens of S. cybele cybele (Fabricius, 1775) (Table S1).