Neighbor-joining consensus tree of the POU gene family including deduced amino acid sequences of POU1 (pink), POU2 (red), POU3 (green), POU4 (orange), POU5 (blue), and POU6 (black) of I. notoides and selected bilaterians. All subfamilies are robustly supported. Tree nodes are supported by bootstrap values of 1,000 replicates and the consensus support (%). Branch length of the tree represents amino acid substitution per site (see scale bar for measurement). GenBank accession numbers of all sequences are itemized in caption of Figure 2 or mentioned as follows: Capitella telata: Cap-POU1: ELT90027.1, Cap-POU5: ELT90025.1; Branchiostoma floridae: Bf-POU1: ABP01321.1; Homo sapiens: Hs-POU1: NP_000297.1; Hs-POU5 isoform 1: NP_002692.2, Hs-POU5 isoform 2: NP_694948.1.