PILGER, J. F. *; MARTINDALE, M. Q.: Hox and ParaHox Genes in the Echiura and Sipuncula

Molecular phylogeny has provided an additional lens through which we can study animal evolution. Based primarily on 18S rRNA these studies have resulted in changes to the anatomically based phylogenies including, among others, the division of the protostomes into two large clades, the Ecdysozoa and Lophotrochozoa. Hox genes, widely regarded as playing a key role in anterior-posterior patterning in bilaterians, support that phylogeny. We have surveyed two key lophotrochozoan taxa, echiurans and sipunculans, for the Hox and ParaHox genes. Our results show a close alignment of these two taxa with polychaete annelids. Future studies will determine how these genes are deployed during development in these understudied protostomes.