Bayesian sample assignment
On average, negative log-likelihood scores for the independent Structure runs increased from K = 2 through K = 13, before decreasing at K = 14 (Supplemental Appendix S1 Figure S5). Based on the ∆K method implemented in StructureHarvester, the optimal partition scheme was determined to be K = 3 (Supplemental Appendix S1 Figure S6). However additional peaks, potentially representing additional partition schemes, were detected at K = 6, K = 8, and K = 13. Individual probabilities of assignment (Q ) for major modes for values of K = 3, K = 6, K = 8, and K = 13 (Figure 2) show the clustering of the invasive populations relative to those in the native range. Major modes for values of K= 2 throughK =14 are presented in Supplemental Appendix S1 Figure S7. A summary of the biogeographic patterns based on the distance matrix analysis of the population membership coefficients (Structure “popfiles”) for K = 6, K = 8, and K = 13 are presented graphically in Supplemental Appendix S1 Figure S8, Figure 3, and Supplemental Appendix S1 Figure S9, respectively.