Maximum likelihood tree of Wnt amino acid sequences in selected metazoans. Bootstrap values/poster probabilities from Maximum likelihood and Bayesian analyses respectively are given on branches. Note that support for the position of Is_Wnt16 was only found using Maximum likelihood (see also Additional file 5). Wnt amino acid sequences were used from the following species: Achaearanea tepidariorum (At), Acyrthosiphon pisum (Ap), Cupiennius salei (Cs), Daphnia pulex (Dp), Drosophila melanogaster (Dm), Glomeris marginata (Gm), Homo sapiens (Hs), Ixodes scapularis (Is), Platynereis dumerilii (Pd) and Tribolium castaneum (Tc). Bootstrap values and posterior probabilities of all branches are given in Additional files 6 and 7 respectively.