Figure 4

Gene gain and loss of SRLKs and SRLCKs in the evolution of land plants. The names of internal nodes and species are abbreviated (L, Land plants; V, Vascular plants; A, Angiosperms, E, eudicots; Pt, Populus trichocarpa; At, Arabidopsis thaliana; Os, Oryza sativa; Sm, Selaginella moellendorffii; Pp, Phycomitrella patens). The numbers of common ancestors at the four internal nodes (L, V, A and E) are shown in the rectangles. Numbers after the plus signs indicate the numbers of gene gain events, whereas numbers after the minus signs indicate gene loss events.