Community formation in active-matter systems

Population genetics has undergone a major revolution over the past thirty years thanks to the development of controlled microbial experiments to test the respective roles of randomness, selection, and ecological processes in evolution.

For instance, it was shown that, when cell division drives the growth of dense bacterial colonies, fluctuations at the colony's edge generally lead to the emergence of spatial genetic segregation.

Most organisms, however, do not spread out because of cell division but instead follow complex nonequilibrium dynamics characterized by self-propulsion and motility-induced collective behaviors.

Although such nonequilibrium dynamics have been extensively studied within the new field of physics called active matter, their role in shaping microbial evolution remains largely unknown.

The aim of this proposal is to address this issue and investigate the interplay between active matter physics and spatial population genetics.

To do so, I will put forward an interdisciplinary theoretical framework that integrates coarse-grained descriptions of active-matter systems with evolutionary and ecological processes.

By combining stochastic calculus, field-theoretical methods, and numerical simulations, I will then characterize the emergent phenomenology of such systems.

To this aim, the project delves into four consecutive objectives: 1) understand the fate of genetic segregation in motile cellular colony; 2) Study the interplay of motility-induced pattern formation and genetic segregation; 3) incorporate ecological interactions in the framework developed in previous stages; 4) generalize our findings to address highly heterogeneous communities.

By achieving these tasks, I aim to unravel the complex dynamics of motile cell colonies, setting the stage for a theory of spatial eco-evolutionary changes in active populations.