Fig. 1

Phylogenetic analyses Phylogenetic trees of T-box genes A, Mox genes B and Blimp genes C. Bayesian analyses using MrBayes [39] applying 0.75 million cycles (T-box Tree), 1 million cycles (Mox tree), and 0.3 million cycles (Blimp tree) for the Metropolis-Coupled Markov Chain Monte Carlo (MCMCMC). The scale bars represent the amino acid substitutions rate per site. Orthologs of Mox proteins are compared with Eve genes and Hox genes B. Orthologs of Blimp genes are compared with the most closely related genes of these species, many of them representing previously uncharacterized genes C. Support values represent posterior probabilities. Species abbreviations: Ci; Ciona intestinalis (Chordata); Dm, Drosophila melanogaster (Arthropoda: Insecta); Dp, Daphnia pulex (Arthropoda: Branchiopoda); Ek, Euperipatoides kanangrensis (Onychophora); Gm, Glomeris marginata (Arthropoda: Myriapoda); Hs, Halicryptus spinulosus (Priapulida); He, Hydroides elegans (Polychaeta); Lg, Lottia gigantea (Mollusca); Mm, Mus musculus (Vertebrata); Nv, Nematostella vectensis (Cnidaria); Pc, Priapulus caudatus (Priapulida); Parasteatoda tepidariorum (Arthropoda: Chelicerata); Sp, Strongylocentrotus purpuratus (Echinodermata); Ta, Trichoplax adhaerens (Placozoa); Tc, Tribolium castaneum (Arthropoda: Insecta); Xl, Xenopus laevis (Vertebrata). Accession numbers are listed in (Additional file 7: Supplementary File 7)