Drivers of Spatial Structure in Social Microbial Communities

Abstract

Microbes are social organisms, interacting primarily through secreted biomolecules. Many traits have evolved based solely on their effects upon other community members, yet even individually beneficial traits often create social side effects that are mediated by spatial population structure. Predicting the evolution of many microbial traits thus requires a comprehensive understanding of their social consequences. In this review, we examine the critical role of population spatial structure in microbial social evolution. We briefly review key mechanisms structuring microbial communities, focusing primarily on the universal roles of cellular death and reproduction. Finally, we explain how spatial assortment can be efficiently calculated in twodimensional, surface-attached populations.

The Evolution of Mutualistic Dependence

“…The bacterial strains repeatedly evolved traits for the costly production of resources, which ultimately fueled the formation of a cooperative partnership. This dependence, however, required high spatial structuring of the community, a context well known to promote cooperation in microbial communities (Drescher et al 2014, Yanni et al 2019.…”

The role of spatial structure in the evolution of viral innate immunity evasion: A diffusion-reaction cellular automaton model

“…Because indirect effects depend on other members of the viral and cellular populations, tackling the evolution of innate immunity evasion requires considering the spatial structure and the dynamics of viral spread and IFN-mediated responses. In general, the term spatial structure refers to a non-random arrangement of individuals in space, and can originate from physical barriers, limited dispersal, a tendency to aggregate, demographical history, and other processes related to population dynamics [7]. For instance, in viral infections, host-to-host transmission and intra-host dissemination is limited by anatomical barriers.…”

Cooperation in Microbial Populations: Theory and Experimental Model Systems

“…However, the explicit consideration of space is an important aspect of microbial life as many microbes on our planet occur in the form of dense microbial communities like colonies and biofilms [251,87], quite distinct from a well-mixed scenario. Even more, spatial extension and arrangement can strongly affect evolutionary dynamics [389]. In this section, we thus give a short overview of experimental and theoretical work on the public good dilemma in spatially extended systems.…”