Figure 3. Neutral genetic structure of the Oregon junco forms. (A) Plot of axes PC1 against PC2 (above) and PC3 (below) from a PCA based on 21,879 selectively neutral genome-wide SNPs. Percentage of explained variation is shown in parentheses. Colors match those in Fig. 1. (B) STRUCTURE analysis based on the same SNP set for K values 2 to 6. On each vertical plot, individuals are represented by horizontal bars, and colors correspond to the posterior assignment probabilities of belonging to each genetic cluster. The abbreviation n.b.s denotes UCSD individuals sampled during the non-breeding season.