Fig. 1
From: HOX gene complement and expression in the planarian Schmidtea mediterranea
HOX complement and phylogenetic assignments in S. mediterranea. A Bayesian phylogeny of select animal HOX genes as well as caudal (Cdx), even-skipped (Evx), engrailed (En), Gsx/ind, and Xlox is shown. Genes from S. mediterranea are boxed in red. Two genes from S. mediterranea could not be placed with confidence: HOX3b and HOX4b, which are marked with red asterisks. Of note, S. mediterranea has 4 Post-2 paralogs and no Cdx, Gsx, or Xlox genes. The tree used the engrailed sub-tree as an outgroup, and only the posterior probabilities are shown for important nodes (maximum likelihood tree shown in Additional file 2: Fig. S3). Species and sequences used in the phylogeny are listed in Additional file 1: Table S1. Briefly: Smed = Schmidtea mediterranea; Ctel = Capitella teleta (polychaete annelid); Amph = Amphioxus (cephalocordate; mix of Branchiostoma species floridae and lanceolatum); Tcas = Tribolium castaneum (flour beetle); Latk = Lithobius atkinsoni (centipede); Mlig = Macrostomum lignano (basal flatworm); Smar = Strigamia maritima (centipede); Pdum = Platynereis dumerilii (polychaete annelid); Erub = Ethmostigmus rubripes (giant centipede); Hrob = Helobdella robusta (leech, annelid); Lgig = Lottia gigantea (owl limpet mollusk); Amel = Apis mellifera (honeybee); Xtro = Xenopus tropicalis (frog); Atyp = Archaster typicus (starfish, hemichordate); Esco = Euprymna scolopes (bobtail squid mollusk)