"Microfluidic island biogeography"Hallatschek, OskarMicrobes often colonize spatially-constrained habitats, such as pores in the skin or crypts in the colon. The resulting micro-communities are often stable and contribute to the genetic diversity and function of our microbiomes. It is, however, unclear how spatial constraints influence microbial community assembly and evolution. By monitoring and modeling microbial populations under controlled microfluidic confinement, we find a rich spectrum of dynamical patterns that are controlled by the competition between density-dependent outflow and population growth. Our results show that density-dependent passive diffusion can drive a reproducing population to a jamming threshold, which entails a total loss of mixing and intra-species competition. The emerging sensitivity to scale may be viewed as a rigorously quantifiable in vitro version of similar effects reported in the field of island biogeography, and underscores the need to control for scale in microbial ecology experiments. Systematic, flow-adjustable length scale variations may serve as a promising strategy to elucidate further scale-dependent tipping points (conserved-noise pushed waves) and to rationally modulate the stability and resilience of microbial colonizers. |
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