Figure 6

NRPD2/E2 gene lineage phylogeny versus organism phylogeny of Allexis and Viola. Unbroken lines denote putatively expressed paralogs, broken lines denote pseudogenes, and thick lines branches that have undergone positive selection (cf. Figure 5). Dots indicate events of pseudogenization or gene death. Truncated gray branches indicate the three (presumably extinct) lineages that contributed genomes to the four paleopolyploid Viola sections Chilenium, Erpetion, Melanium and Viola. Putative allopolyploidization events are indicated by diagonal NRPD2/E2 lines connecting the organism lineages. For simplificity, the sections Melanium and Viola are shown as derived from the same allopolyploidization event, and secondary gene duplications within section Melanium have been omitted.