Developmental control of animal size: mechanisms and evolution

How do organs reach their appropriate size during animal development? Unravelling organ size control is key to understanding growth pathologies such as cancer and fulfilling the potential of regenerative medicine. Although we know many signals that can modulate developmental growth, we lack a coherent model of how growth ceases at the correct time. Furthermore, although differences in body size and proportions across species are among the most striking aspects of animal evolution, the cellular and molecular bases for these differences remain little explored. Here, we exploit the unique live- imaging and genetic tractability of the fruit fly Drosophila melanogaster abdominal epidermis to ask how growth is terminated at the appropriate size in a developing system. We will combine rigorous quantitative biology with temporal genomics and a candidate approach to identify the signals that ensure the robust control of tissue size during development (Aim 1). We will take advantage of the broad variation in abdomen sizes across the Drosophila genus and the precision of our quantitative approach to developmental growth in the abdominal epidermis to explore tissue size control in differently sized Drosophila species. We will ask what cellular behaviours and molecular mechanisms underpin the evolution of organ size (Aim 2).