Nutrient-rich spatial refuges buffer against extinction and promote evolutionary rescue in evolving microbial populations

Microbial populations are often exposed to long-term chemical disturbances, which can reduce population viability and cause local extinction. Eco-evolutionary theory suggests that spatial refuges can facilitate persistence and evolutionary rescue. However, one drawback of spatial refuges is reduced exposure to nutrients such as carbon and oxygen, suggesting the protective effect of refuges depends on the interplay between environmental conditions and the degree of stress. Here, we tested this general idea using mathematical modelling, and experimental evolution of the model bacterium Pseudomonas fluorescens SBW25 under salinity stress.