Postdoc fellow in evolutionary biology California Institute of Technology Pasadena, California
We traced the functional co-evolution of new cell types in a multi-compound chemical defense system. The model rove beetle Dalotia coriarahas a defensive 'tergal gland' composed of unique two unique secretory cell types that synthesize three benzoquinones, an alkane and three esters. We used single cell transcriptomics (scRNAseq) of entire beetle body segments enabled us to trace how the gland cells were assembled during evolution. We found that solvent cells are a cuticular cell type that gained an expression program from ancient pheromone-producing cell type, the oenocytes, as well as in adipocyte-like ventral fat body cells (VFB). The oenocytes and adipocytes each express their own fatty acid pathways. Each contributed different branches to the solvent cell pathway (via co-option or duplication). In this way, cuticle cells between abdominal segments 6 and 7 transformed into a secretory gland that forms a chemical reservoir inside the body cavity.
