Figure 2

An example of how the ages of duplication events were estimated in the ADORA family. The neighbor-Joining phylogenetic tree (A) was constructed based on the protein sequences, and the correspondent linearized tree (B) was also calculated. The protein sequence distances (mutation per amino acid residue) were marked on the graph as the scales. The duplication events, T1–T3, were marked on the trees, and the age of the duplication events were estimated based on the linearized trees (see Methods).