Fig. 6

Phylogenetic tree to illustrate the evolution of Tektin-1 in bilaterian species. This phylogenetic analysis includes the Tektin-1 sequences identified in bilaterian species. The 23 spiralians include six mollusks (Ac, Bg, Ob, Lg, Cg, Pf), 12 platyhelminthes (Cs, Ov, Sch, Scm, Scj, Eg, Emu, Taa, Tas. Hmi, Sme, and Mli), three annelids (Pd, Ct, Hr), and one brachiopod (La). The ecdysozoans include many insects, two chelicerates (Pt, Smi), one myriapod (Sma), one crustacean (Dp), one dicyemid (Dj), one tardigrade (Hd), and one priapulid (Pc). The invertebrate deuterostomes are represented by one echinoderm (Sp), one hemichordate (Sk), one cephalochordate (Bf), and one urochordate (Ci). The vertebrate deuterostomes are represented by three teleost fish (Dr, Tr, and Ch), one holostei fish (Lo), one chondrichthyes (Cm), one sarcopterygian fish (Lc), three amphibian (Xl, Amb, Nvi), one reptile (Cpb) two avians (Ap, Gg), and three mammal species (Oa, Mm, Hs). In addition, Tektin-4 sequences from C. gigas, P. dumerilii, S. kowalevskii, D. rerio and H. sapiens were included as an outgroup. The tree was rooted with N. vectensis Tektin-1/4/3/5A. Both Bayesian and Maximum Likelihood analyses were performed using Mr. Bayes and RAxML, respectively. The Bayesian tree topology is shown. Node support is shown for non-terminal nodes. Posterior probability values from Mr. Bayes and bootstrap values from RAxML are shown above or below each node, respectively. Diamonds indicate support less than 80%. “X” under a node indicates that this node was not recovered in the RAxML maximum likelihood tree. The large colored boxes group Tektin-1 sequences of the three major bilaterian branches, the spiralians (green), the ecdysozoans (blue), and the deuterostomes (orange). Note that tektin-1 exists as a single copy gene in most extant species with only two duplicate tektin-1 genes observed in two spiralian species, a leech (Hr) and a planarian (Sme). Species abbreviations and accession numbers for each sequence are provided in Additional file 5