PCA based ancestry estimation.

<p>(A) PC axis 1 (PC1) and PC2 were calculated using 2959 SNPs from 333 <i>V. vinifera</i> and 333 wild <i>Vitis</i> samples. The proportion of the variance explained by each PC is shown in parentheses along each axis. Subsequently, 1599 samples, including various <i>Vitis</i> species and hybrids, were projected onto these axes (green dots). Samples lying between the dotted vertical lines were considered hybrids for the remaining analyses. (B) Boxplots show the range of PC1 values for the two ancestral populations (<i>V. vinifera</i> and wild <i>Vitis</i>) and the hybrids identified in (A). Boxes denote upper and lower quartiles and whiskers extend to 2.7 SD. Below the boxplots, an illustration of how ancestry proportions are calculated is provided (see Methods for details).