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.
Xing et al. BMC Evolutionary Biology 2013 13:69 doi:10.1186/1471-2148-13-69