Endogenous fluctuations and local mixing stabilize diverse bacteria-phage communities - Federico Ghimenti (Stanford University, USA)

The maintenance of fine-scale diversity in microbial communities is a central question in theoretical ecology. Phages are often said to promote diversity by preventing any single strain from taking over through predation, but they also cause wild fluctuations and extinctions. Whether migration across realistic spatial structure can stabilize these "kill-the-winner'' fluctuations is an open question. Here, we consider a model of phage and bacteria that interact and mix across a ring of demes, the hardest topology for repopulation by mixing. We show that, after an initial transient in which some strains go extinct, an arbitrarily large number of strains coexists in a spatiotemporally chaotic state, with a broad distribution of abundances and endogenous fluctuations whose spatial and temporal scales differ from strain to strain. We rationalize our findings by analyzing the dynamical mean field theory of a generalized Lotka-Volterra model with similar phenomenology.

Contact: Misaki Ozawa