A model for the evolution of Group B Sox genes in insects following the proposal of Kirby et al (2002) for vertebrates. In this view an ancestral group B gene is duplicated during an ancient genome duplication event to generate Dichaete and SoxN. A tandem duplication of Dichaete generates Sox21a; these events would be common to the ancestor of vertebrates and invertebrates. In insects, a further duplication of Dichaete gives rise to Sox21b.
McKimmie et al. BMC Genetics 2005 6:26 doi:10.1186/1471-2156-6-26