Speaker
Description
Ernesto Berríos-Caro and Hildegard Uecker
Meta-populations often exhibit complex spatial structures. Migration between environments plays a crucial role in shaping mutant dynamics. Motivated by bacterial evolution experiments, we develop a model of spatially structured populations on graphs, incorporating between-deme migration and periodic bottlenecks. We explore two key scenarios: one without mixing between demes, where bottlenecks occur independently within each deme, and another with mixing, where meta-populations from different demes are pooled together prior to bottlenecks. We find that mixing offers no advantage to mutants in the absence of interactions between wildtype and mutant sub-populations. Through a branching process approach, we demonstrate that the establishment probability is identical in both scenarios. Differences arise when interactions between sub-populations are introduced. We examine two types of interactions: competition during growth, driven by resource availability, and competition during bottlenecks, where a fixed bottleneck size limits population numbers. Notably, differences between non-mixing and mixing scenarios become apparent only when stochastic effects are considered, either in the population growth or bottlenecks. We explore approaches where one of the sources is stochastic while the other is deterministic. Our results offer insights into how spatial structure and stochastic effects shape evolutionary dynamics, opening avenues for direct experimental validation.
