Population structure
The number of genetic clusters across populations were identified using maximum likelihood hierarchical clustering via ADMIXTURE v1.3.0 as well as Principal Components Analysis, and Discriminant Analysis of Principle Components as implemented in poppr v2.9.0. ADMIXTURE was implemented with 15 iterations for each k from 1-10. Cross validation was used to identify the optimal k. Cross validation was also used to identify the optimal number of principal components via ‘xvalDapc’ in poppr, which were used to identify the number of clusters in the data via ‘find.clusters’. All data were visualized using poppr or ggplot v3.3.3 (Wickham 2016). All scripts necessary to reproduce these analyses can be found here: figshare link