Fig. 1.

Identification of W-category genes (WA and WB) from diverse animal groups shown in a schematic phylogenetic classification of the major groups of jawed vertebrates. The schematic relative placements of major groups of jawed vertebrates (cartilaginous fish, ray-finned fish, lobe-finned fish, and tetrapods) are based on the reported phylogenetic tree of jawed vertebrates (34). Some representative names of animals or animal groups are shown in each major group. The names of animals in which we identified W-category WA and WB genes are surrounded by red lines. We experimentally identified the transcripts of W-category genes from banded houndshark, zebrafish, Mexican tetra, West African lungfish, and tiger salamander among others. The extended summary of the identification of W-category genes is shown in SI Appendix, Table S1.