Figure 2.

Phylogenetic relationship of 13 representative chordates analyzed and number variation of RP genes. 1R, 2R, 3R and 4R indicate the four rounds of WGD that occurred during vertebrate evolution. Slash indicates no homologous gene detected, probably due to secondary loss or incomplete genome sequences. * indicates two isoforms of RPS4 located on the human X and Y chromosomes. Cin, Ciona intestinalis; Pma, Petromyzon marinus; Lch, Latimeria chalumnae; Hsa, Homo sapiens; Mmu, Mus musculus; Loc, Lepisosteus oculatus; Dre, Danio rerio; Cca, Cyprinus carpio; Ipu, Ictalurus punctatus; Ssa, Salmo salar; Ola, Oryzias latipes; Oni, Oreochromis niloticus; Tru, Takifugu rubripes.