Phylogenetic and Population Structure
PCA (Principal Components Analysis) was carried out using the EIGENSOFT [52]. A phylogenetic tree was constructed from the SNPs data by using the neighbor-joining method in the program PHYLIP [53] and graphical demonstration was provided by using the Newick Utilities [54]. Population structure was further inferred using Admixture [55] with kinship (K ) set from 2 to 10, according to the K -values with the smallest CV (Cross-Validation) error is the optimal K values.