Study sites and data collection
We selected ten populations from across S. virens breeding distribution to capture range-wide genomic diversity (Figure 1). During their breeding season (April-June), we used mist nets with audio playback of conspecific song to capture S. v. virens males in Arkansas, Indiana, New York, central North Carolina, and Tennessee, as well as putative S. v. waynei males in coastal North Carolina (Table 1). For all individuals, we collected ≥50 μL of blood from the brachial vein, which was stored in either Queen’s Lysis buffer or ethanol (Seutin et al., 1991). In addition, two S. v. virenstissue samples from New York were donated by The Cornell University Museum of Vertebrates.