Fig. 1.

Map of M. sacchariflorus and M. × giganteus individuals indicating collection sites, ploidy and genetic relationships. Each accession is represented by a pie chart showing ancestry (Q) among seven genetic clusters as determined by analysis with the software Structure using 34 605 RAD-seq SNPs. All individuals from the current study with known collection site and ploidy are plotted, including 699 M. sacchariflorus and 38 M. × giganteus. Fourteen diploid M. × giganteus found in China and Japan in previous studies (Clark et al., 2014, 2015) are also included. Elevation is shown as a grey scale. The coastline at the last glacial maximum is indicated by a brown line drawn according to Lee et al. (2008). Paleo rivers on the land that is now under the Yellow Sea are drawn according to Song et al. (2016) and Yoo et al. (2016). High-resolution maps of Structure results are available in Supplementary Data S3.