Data from: 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 how evolution may or may not save populations and species from extinction.

环境变化是物种存续面临的核心威胁之一。当环境变化速率较快时，种群得以存续的唯一途径或许是演化出抗性。理解这类‘演化拯救（evolutionary rescue）’现象，不仅对于应对全球变化的物种保护工作至关重要，在以种群控制或清除为目标的农业与医学领域同样具有重要应用价值。现有理论预测，大型种群与遗传变异可促进演化拯救，但该结论尚未得到实验验证。本研究以荧光假单胞菌（Pseudomonas fluorescens）SBW25为实验对象，构建了数百个重复种群，并将其暴露于一系列梯度剂量的链霉素（streptomycin）抗生素环境中。实验结果与理论预测一致：种群规模与初始遗传多样性会显著影响种群存续能力与抗生素抗性的演化过程。尽管所有经抗生素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。本研究结果有助于进一步明晰演化在何种情境下能够拯救种群与物种免于灭绝，又在何种情境下无法发挥该保护作用。