Figure 3
Phylogenetic relationships among homedomains from Nematostella (red lines), human (blue lines), and fruitfly (green lines) determined by neighbor-joining [95]. Gene names are not provided in this condensed version of the tree, which is intended to convey an overview of the homeodomain radiation in metazoans. A fully labeled version of this tree is provided in Additional data file 2. All homeodomain classes that are known to be shared among cnidarians and bilaterians are indicated by colored bars (ANTP, HNF, LIM, POU, PRD, SINE, and TALE). Histograms to the right of the tree indicate the number of sequences from each species that fall within a given class (Hs, Homo sapiens; Dm, Drosophila melanogaster; Nv, Nematostella vectensis). The gray bars on the histograms provide a conservative estimate for the size of each homeodomain class in the cnidarian-bilaterian ancestor (CBA). The homeodomain tallies shown here are based solely on the phylogenetic analyses performed in this study. Additional data sources, cited in the text, would lead us to adjust the tallies for Nematostella and the CBA slightly upward.