Additional file 1: Figure S1. Plots from the software STRUCTURE of A) lnP(X|K) indicating the highest probability at K = 4, and (B) graph of dK vs K from technique of Evanno et al. [7] indicating most probable population subdivisions at K = 2 and K = 4. Based on the Evanno et al [7] technique, we find 4 to be the best number of populations.