The evolution of the Hox cluster: insights from outgroups

Two burgeoning research trends are helping to reconstruct the evolution of the Hox cluster with greater detail and clarity. First, Hox genes are being studied in a broader phylogenetic sampling of taxa: the past year has witn essed important new data from teleost fishes, onychophorans, myriapods, pol ychaetes, glossiphoniid leeches, ribbon worms, and sea anemones. Second, co mmonly accepted notions of animal relationships are being challenged by alt ernative phylogenetic hypotheses that are causing us to rethink the evoluti onary relationships of important metazoan lineages, especially arthropods, annelids, nematodes, and platyhelminthes.