A) Evolution projects: Changing roles of BMP and Toll signaling during insect evolution
Research from the last decades has revealed that many developmental and cellular processes show a striking degree of conservation throughout the animal kingdom from jellyfish to mammals. Findings from invertebrate model systems like the fruit fly Drosophila melanogaster can often be directly transferred to vertebrates including humans. How can one, however, reconcile the striking diversity of body plans with the existence of highly conserved developmental mechanisms? To address this question we study the evolution of developmental mechanisms. Our focus is dorsoventral (DV) axis formation, which has been extensively studied in the fruit fly Drosophila and encompasses one of the best-known gene regulatory networks (GNR).
In Drosophila the DV axis is mostly patterned by a gradient of Toll signaling, a pathway which is not known for a patterning role in other animals, but rather for a highly conserved function in innate immunity. In contrast, the DV axis of other animals is established by a BMP signaling gradient, which in Drosophila has a more limited Toll-dependent function. In recent years our lab has shown that BMP signaling progressively replaces Toll signaling in insects which are members of more basal branches of the phylogenetic tree, like beetles, wasps and bugs. This work relates the derived mode of DV patterning in Drosophila to the more ancestral BMP-based mode found in other animals