FIG 6.

Ploidy variation is observed in other heterothallic Phytophthora species. Histograms showing the major and minor allele frequency observed for individuals. Samples of P. infestans are diploid or triploid. The hybrid taxon P. andina appeared predominantly diploid. Note that the y axis indicates many more heterozygous positions in these samples relative to the other species. The clade 1 species P. parasitica is diploid. However, note the “shoulder” peaks at the 3× expectation for samples P10297and P1569. The clade 2 species P. capsici demonstrated a predominance of diploidy, with the single sample Pc389 being triploid. The x axis ticks mark 0, 1/5, 1/4, 1/3, 1/2, 2/3, 3/4, 4/5, and 1 mark our expectations for pentaploid, tetraploid, triploid, and diploid. The y axis ticks in the histograms are in units of 10,000 heterozygous sites. Phylogeny adapted from Martin et al. (49). Larger histograms are presented in Text Files S6 and S7 in the supplemental material (53).