The phylogenetic tree includes 1) representatives of srsx family in C. elegans, 2) previously known srw family members from nematodes (C. elegans and P. pacificus), 3) srw like sequences identified in this study, 4) vertebrate olfactory genes (7tm_4), 5) olfactory like receptors in B. floridae, 6) olfactory like receptors in N. vectensis
[26], 7) vertebrate olfactory sequences that had significant alignment score against the 7tm_GPCR_srsx domain (see Table S2), 8) consensus representative for each NemChR families, and 9) the sequence fragments from N. vectensis (Nv_205247) and T. adhaerens (Ta_58780) that had the highest scoring alignment against the 7tm_GPCR_Srsx domain (indicated with a star symbol). Posterior probabilities and bootstrap replicates (within parenthesis) are shown as a percentage for the major nodes.