Frequency distributions of membership in the clusters defined by the reference population for <i>C. japonica</i>.

<p>(a) natural population (n = 181). Black bar represents the reference samples for STRUCTURE analysis. Q>0.8 indicates reference samples for Pacific Ocean side, while Q<0.2 those for Japan Sea side. (b) core collection (n = 456), (c) plus tree individuals in Kanto Breeding region (n = 367).</p>