Figure 3. Lack of differentiation between eastern and western monarchs. (A) Genetic clustering was based on principal component analysis (PCA) of SNPs covered in all the samples of eastern and western monarchs, generated using SNPrealte (Zheng et al. , 2012). Each point represents one sample in the data set (black: eastern monarchs; red: western monarchs). Although there are a few outliers from the western population, we did not observe any clear clustering patterns of eastern and western monarchs (top 5 Principle components are given in Figure S5). (B) Admixture plot for eastern and western monarchs with values of ‘K’ set to 2, 3 and 4. No specific pattern of clustering was observed between eastern and western monarchs.