Data from: Bacterial adaptation to sublethal antibiotic gradients can change the ecological properties of multitrophic microbial communities

Antibiotics leak constantly into environments due to widespread use in agriculture and human therapy. Although sublethal concentrations are well known to select for antibiotic-resistant bacteria, little is known about how bacterial evolution cascades through food webs, having indirect effect on species not directly affected by antibiotics (e.g. via population dynamics or pleiotropic effects). Here, we used an experimental evolution approach to test how temporal patterns of antibiotic stress, as well as migration within metapopulations, affect the evolution and ecology of microcosms containing one prey bacterium, one phage, and two protist predators.We found that environmental variability, autocorrelation and migration had only subtle effects for population and evolutionary dynamics. However, and unexpectedly, bacteria evolved greatest fitness increases to both antibiotics and enemies when the sublethal levels of antibiotics were highest, indicating positive pleiotropy. Crucially, bacterial adaptation cascaded through the food web leading to reduced predator-to-prey abundance ratio, lowered predator community diversity and increased instability of populations.Our results showthat the presence of natural enemies canmodify and even reverse the effects of antibiotics on bacteria and that antibiotic selection can change the ecological properties of multitrophic microbial communities by having indirect effects on species not directly affected by antibiotics.

抗生素因在农业与人类治疗中的广泛应用，持续向环境中泄漏。尽管已知亚致死浓度会筛选出抗生素耐药菌，但学界对细菌演化如何在食物网中级联传播，并对未直接暴露于抗生素的物种产生间接影响（例如通过种群动态或多效性效应）的认知仍较为匮乏。本研究采用实验进化方法，探究抗生素胁迫的时间模式以及集合种群（metapopulations）内的迁移，如何影响包含1种猎物细菌、1种噬菌体（phage）与2种原生生物捕食者（protist predators）的微宇宙系统（microcosms）的演化与生态特性。研究结果显示，环境变异性、自相关性与迁移对种群动态与演化过程仅存在微弱影响。但出乎意料的是，当抗生素处于最高亚致死浓度水平时，细菌对各类抗生素与天敌的适合度提升最为显著，这表明存在正向多效性效应（pleiotropic effects）。至关重要的是，细菌的适应性演化在食物网中产生级联效应，导致捕食者-猎物丰度比降低、捕食者群落多样性下降，以及种群不稳定性升高。本研究结果表明，自然天敌的存在可以改变甚至逆转抗生素对细菌的作用效果；而抗生素选择压力可通过对未直接暴露于抗生素的物种产生间接效应，改变多营养级微生物群落的生态属性。