Out from under the wing: reconceptualizing the insect wing gene regulatory network as a versatile, general module for body-wall lobes in arthropods

Body plan evolution often occurs through the differentiation of serially homologous body parts, particularly in the evolution of arthropod body plans. Recently, homeotic transformations resulting from experimental manipulation of gene expression have been interpreted as evidence that portions of dorsal and lateral arthropod body-wall are serially homologous to wings. These results, along with comparative data on the expression and function of genes in the wing regulatory network, provided a new perspective on an old question in insect evolution—how did the insect wing, evolve? A proposed ancestral role for the wing regulatory network in patterning body-wall margins motivated a broader comparison of gene function in wings and body-wall. We investigated the roles of a suite of ten wing- and body-wall related genes in a hemimetabolous insect, Oncopeltus fasciatus. Our results indicate that genes involved in wing development in O. fasciatus play similar roles in the development of adult body-wall flattened cuticular evaginations. We found extensive functional similarity between the development of wings and other bilayered evaginations of the body wall. Overall, our results support the existence of a versatile development module for building bilayered cuticular epithelial structures, which may have played a central role in the evolution of wings.