Emergent behaviors in microbial communities

Abstract

Physics of systems around us are often emergent, shaped by not only the fundamental constituents but their interactions, structures, and symmetries at larger scales. Microbial communities, which play indispensable roles in nature, are complex active systems that naturally pushes us to the unexplored frontier of emergent phenomena. During my PhD, I studied how some behaviors of microbial communities can be simple at emergent level despite the underlying complexity at microscopic level. First, I demonstrated that competition for resources may lead to the experimentally observed simplicity in community assembly. Even without microscopic information on the traits of microbes, trio and larger community assembly is often predictable from collections of pairwise competitions. Second, I demonstrated that slow mutants can take over expanding fronts and the resulting large-scale spatial pattern can be predicted without microscopic information. Overall, my works illustrate that, beyond qualitative explanations, we can make precise predictions for the behaviors of microbial communities without any information about microscopic details of the systems. This lens of emergent behavior allows us to discover simple descriptions of microbial communities at large scales unhindered by their complexities at small scales.