The evolution of chemoreceptor genes in coelacanths. (A) The neighbor-joining tree of vertebrate V1R genes. The evolutionary distances were computed using the JTT matrix-based method and are presented in amino acid substitutions per site as shown by the scale bar. Bootstrap values (10,000 replicates) >60 are shown in the tree. The species are indicated as follows: gray, cow (Bos taurus); green, frog (Xenopus tropicalis); red, coelacanth (L. chalumnae); blue, five teleost fishes—zebrafish (D. rerio), stickleback (G. aculeatus), fugu (T. rubripes), pufferfish (T. nigroviridis), and medaka (O. latipes). (B) Comparison of the copy numbers of the OR genes belonging to subfamilies α and γ among vertebrates. Blue, yellow, and red bars indicate the genes that were annotated as intact, truncated (because of the incompleteness of the draft genome), and pseudogenes, respectively.
