Thursday, December 7, 2017, 4:30pm to 5:30pm
Program for Evolutionary Dynamics, One Brattle Square Floor 6, Cambridge
Spatial growth is at the core of many biomedical processes from disease outbreaks and tumor growth to the spread of invasive species and range shifts following an environmental change. Classically, expansions are divided into two types: pulled and pushed depending on whether intra-specific cooperation in growth or dispersal is sufficiently strong to increase the expansion velocity. I will show that this classification does not fully capture the effect of species ecology on its evolution. First, I will present a general theory of neutral evolution that describes how fixations, genetic drift, and the structure of genealogies depend of the strength of cooperative growth. This theory fully accounts for the shape and fluctuations of the expansion front and yields universal results that hold for any model of range expansions. Then, I will discuss the evolution of dispersal in pulled and pushed expansions and show that natural selection can favor both faster and slower mutants. Moreover, the change in the expansion velocity occurs through a series of ecological shifts that enable further adaptation. Overall, the talk will highlight that range expansions provide a simple context to study eco-evolutionary feedback, which plays a major role in the dynamics of natural populations.