Traces of polyploidy events in the Brassica 'A' and 'C' genomes. (a-g) Distributions of Ks values were obtained from comparisons of sets of paralogous EST sequences in Br (a), Bo (b), and Bna (c) and comparisons of putative orthologous EST sequences between the genomes (d-g). The vertical axes indicate the frequency of paired sequences, and the horizontal axes denote Ks values at 0.05 (a-f) or 0.02 (g) intervals. The black bars indicate the positions of the modes of Ks distributions obtained from comparisons of orthologous or paralogous gene pairs. Bna, B. napus; Bo, B. oleracea; Br, B. rapa.