Figure 7
Duplication of 2DBD-NRs. A. Maximum Likelihood phylogenetic tree derived from sequences in the first and the second DBD of 2DBD-NRs. Phylogenetic relationship was examined by the Maximum Likelihood method as described for Fig. 3. Support values for the tree were obtained by bootstrapping a 100 replicates and are indicated above each branch. Branches under the threshold value of 45 were shown as polytomies. Bayesian inference with the same methods as in Fig. 3 running 5 million generations. The PPs are shown below each branch or after the ML bootstrapping value separated by a slash. B. Figure shows that the common ancestor gene of 2DBD-NRs underwent duplication after the split of the Arthropods, Molluscs and Platyhelminths. In Mollusks, the orthologue gene (γ) underwent a duplication giving rise to the α/β gene. In Platyhelminths, the orthologue gene (γ) underwent a duplication giving rise to a new gene, this new gene underwent a recent duplication to give birth to the two present genes (α and β genes). All three genes are present in the flatworm S. mansoni and the planarian S. mediterranea suggesting that the two rounds of 2DBD-NR duplication occurred in a common ancestor of the Platyhelminths.