Evolutionary rescue in populations of Pseudomonas fluorescens across an antibiotic gradient

Environmental change represents a major threat to species persistence. When change is rapid, a population's only means of persisting may be to evolve resistance. Understanding such ‘evolutionary rescues’ is important for conservation in the face of global change, but also in the agricultural and medical sciences, where the objective is rather population control or eradication. Theory predicts that evolutionary rescue is fostered by large populations and genetic variation, but this has yet to be tested. We replicated hundreds of populations of the bacterium Pseudomonas fluorescens SBW25 submitted to a range of doses of the antibiotic streptomycin. Consistent with theory, population size, and initial genetic diversity influenced population persistence and the evolution of antibiotic resistance. Although all treated populations suffered initial declines, those experiencing the smallest decreases were most likely to be evolutionarily rescued. Our results contribute to our understanding of h...

环境变化是物种存续面临的主要威胁之一。当变化发生迅速时，种群存续的唯一途径或许是演化出抗性。理解此类‘演化拯救（evolutionary rescue）’，对于应对全球变化的物种保护工作具有重要意义，同时在以种群控制或根除为目标的农业与医学领域也同样关键。理论预测，大种群规模与遗传变异可促进演化拯救，但这一结论尚未得到实验验证。我们以荧光假单胞菌（Pseudomonas fluorescens）SBW25为研究对象，构建了数百个重复种群，并将其暴露于不同剂量的抗生素链霉素（streptomycin）环境中。实验结果与理论预测相符：种群规模与初始遗传多样性会影响种群存续能力与抗生素抗性的演化。尽管所有经处理的种群均出现了初始种群数量下降，但下降幅度最小的种群最有可能发生演化拯救。本研究结果有助于我们进一步理解……