TY - JOUR TI - Changes in BMP and EGFR signaling components underlie the evolution of Drosophila eggshell morphologies DO - https://doi.org/doi:10.7282/T37S7M09 PY - 2014 AB - A fundamental requirement for understanding the evolution of tissue morphogenesis involves exploring underlying changes in cell signaling amongst species. We used the magnificent diversity of Drosophila eggshell morphologies to investigate mechanisms guiding morphological variation. Drosophila eggshell structures, including the dorsal appendages (DAs) and the dorsal ridge (DR), are formed during oogenesis when a 2D monolayer of follicle cells (FCs) overlying the oocyte is instructed by numerous cell signaling pathways to form the eggshell. Here, we focus on the bone morphogenetic protein (BMP) signaling in reference to DAs formation, and the epidermal growth factor receptor (EGFR) in reference to DR formation. BMP signaling in the FCs is initiated when the anteriorly secreted transforming growth factor-β-like Decepentaplegic (DPP) activates a uniform and then patterned type I BMP receptor Thickveins (TKV). We found that the pattern of BMP signaling is dynamic and spatially diverse in species with different DAs morphologies. Using computational modeling and experimental validation, we found that qualitative and quantitative changes in TKV can account for different BMP signaling outputs across species. The DR is a lumen-like structure along the dorsal-most side on eggshells of numerous species and absent from D. melanogaster eggshells. We developed a binary matrix to analyze 180 2D expression patterns of a family of structural proteins, the Chorion proteins, in species with and without a DR and associate DR patterns to domains of known regulation. The DR domain clusters with EGFR regulated domains and thus, we focused on EGFR and DR formation. EGFR activation begins when the transforming growth factor-α-like ligand, Gurken (GRK), is secreted from the oocyte and creates a dorsal-ventral activation gradient. We found that DR morphologies correlate with EGFR signaling and GRK patterns in the DR domain. In the DR species D. willistoni, we successfully perturbed EGFR signaling and DR formation by genetically perturbing GRK levels. Expression of D. willistoni GRK (wGRK) in D. melanogaster rescues the GRK null phenotype and in some cases, wGRK is sufficient to produce a ridge-like structure on D. melanogaster eggshells. Our results support the idea that changes in major components of developmental pathways underlie the evolution of morphologies. KW - Computational and Integrative Biology KW - Drosophila--Morphogenesis KW - Bone morphogenetic proteins LA - eng ER -