Phylogenetic tree and expression patterns of the PRDM genes. (A) Phylogenetic tree of the PRDM genes in vertebrates. The reported topology is obtained with Maximum Likelihood. The branches supported with a bootstrap lower than 75 are shown in grey. On main bifurcations, the corresponding posterior probability from Bayesian inference is reported (see Methods). Different colours associated to tree branches correspond to the main subfamilies. For each subfamily, the gene structure of human PRDM ortholog is depicted. The scale refers to exons only. The tree image was produced using iTOL . (B) Evolutionary speed and gene expression of the human PRDM paralogs. PRDM genes are ordered by increasing evolutionary divergence, calculated as cumulative branch lengths from the tip to the root of the phylogenetic tree. The expression data were measured as the mean values of different assays for each gene (see Methods). The upper limit of the 2-ΔCt values was set to 10. For original values see Additional file 7.