Daniel S Fisher Stanford University
Ecological Chaos and Microbial Diversity: What Should One Be Surprised By?
One of the discoveries enabled by the DNA sequencing revolution is the enormous diversity of microbes, extending down to the finest scales of genetic differences. Remarkably, extensive diversity within a single bacterial species can coexist in the same location and time. Traditional explanations in terms of a multitude of “niches” or of “ecological neutrality” are far from sufficient. And it is known that generalized Lotka-Volterra models of many interacting strains with no niche-like assumptions have no large stable communities. We show that a broad family of such models exhibit, instead, a highly-diverse spatio-temporally chaotic “phase” that is very robust. A partially exactly solvable model, a perfectly antisymmetric interaction matrix, provides the basis for a general analysis via dynamical mean-field theory. Potential applicability to host-pathogen systems, the conditions under which such a phase could evolve, and the degree of complexity of the interactions needed for it to occur will be discussed.
Video of the lecture