Data from: Environmental fluctuations restrict eco-evolutionary dynamics in predator-prey system

Environmental fluctuations, species interactions and rapid evolution are all predicted to affect community structure and their temporal dynamics. Although the effects of the abiotic environment and prey evolution on ecological community dynamics have been studied separately, these factors can also have interactive effects. Here we used bacteria-ciliate microcosm experiments to test for eco-evolutionary dynamics in fluctuating environments. Specifically, we followed population dynamics and a prey defense trait over time when populations were exposed to regular changes of bottom-up or top-down stressors, or combinations of these. We found that the rate of evolution of a defense trait was significantly lower in fluctuating compared to stable environments and that the defense trait evolved to lower levels when two environmental stressors changed recurrently. The latter suggests that top-down and bottom-up changes can have additive effects constraining evolutionary response within populations. The differences in evolutionary trajectories are explained by fluctuations in population sizes of the prey and the predator, which continuously alter the supply of mutations in the prey and strength of selection through predation. Thus, it may be necessary to adopt an eco-evolutionary perspective on studies concerning the evolution of traits mediating species interactions.环境波动、物种相互作用与快速进化均被预测会对群落结构及其时间动态产生影响。尽管非生物环境（abiotic environment）与猎物进化对生态群落动态的影响已被单独研究，但这些因子亦可产生交互效应。本研究通过细菌-纤毛虫微宇宙（microcosm）实验，对波动环境下的生态进化动力学（eco-evolutionary dynamics）进行检验。具体而言，我们监测了种群暴露于上行胁迫因子（bottom-up stressors）、下行胁迫因子（top-down stressors）的周期性变化，或二者组合条件下的种群动态与猎物防御性状随时间的变化。研究发现，相较于稳定环境，波动环境下防御性状的进化速率显著更低；且当两种环境胁迫因子周期性变化时，防御性状进化至更低水平。上述结果表明，下行与上行胁迫的变化可产生加性效应，限制种群内的进化响应。进化轨迹的差异可通过猎物与捕食者的种群大小波动得到解释：这种波动持续改变了猎物的突变供应以及捕食介导的选择强度。因此，针对介导物种相互作用的性状进化研究，或许有必要采用生态进化视角。