Date: November 18, 2016
Time: 3:00 pm – 4:15 pm
University of Missouri at St. Louis
The processes by which systems pass from a state of survival to a state of extinction grows ever more important in this Anthropocene Epoch, in which human-driven climate change pushes an increasing number of species toward a tipping point. With this broad motivation, we consider the dynamics of agent-based models of evolutionary dynamics on both rugged fitness landscapes and on neutral landscapes. These models show characteristics of branching and coalescing random walks, and, in the case of reproduction by bacterial fission on a neutral landscape, can be shown to exhibit nonequilibrium, absorbing phase transitions of the directed percolation universality class. Using coalescent theory, investigate the lineage structures of populations in the neighborhood of the phase transition and in the process of recovery from simulated mass extinction events. Lastly, we present preliminary experimental data in populations of S. cerevisiae suggesting the presence of a directed percolation transition when the population is subjected to a stressor such as high temperature or high salt concentration.
Refreshments will be served.