Hot spots become cold spots: coevolution in variable temperature environments

Antagonistic coevolution between hosts and parasites is a key process in the genesis and maintenance of biological diversity. Whereas coevolutionary dynamics show distinct patterns under favourable environmental conditions, the effects of more realistic, variable conditions are largely unknown. We investigated the impact of a fluctuating environment on antagonistic coevolution in experimental microcosms of Pseudomonas fluorescens SBW25 and lytic phage SBWΦ2. High-frequency temperature fluctuations caused no deviations from typical coevolutionary arms-race dynamics. However, coevolution was stalled during periods of high temperature under intermediate and low frequency fluctuations, generating temporary coevolutionary coldspots. Temperature variation affected population density, providing evidence that eco-evolutionary feedbacks act through variable bacteria-phage encounter rates. Our study shows that environmental fluctuations can drive antagonistic species interactions into and out of ...

宿主与寄生虫之间的拮抗共进化（antagonistic coevolution），是生物多样性起源与维持的核心过程。尽管共进化动力学在适宜环境条件下呈现出清晰的特征模式，但更贴近现实的可变环境条件所产生的影响，目前在很大程度上仍未被揭示。本研究以荧光假单胞菌SBW25（Pseudomonas fluorescens SBW25）与裂解性噬菌体SBWΦ2（lytic phage SBWΦ2）的实验微宇宙（experimental microcosms）为模型体系，探究了波动环境对拮抗共进化的影响。研究发现，高频温度波动并未使共进化军备竞赛动力学（coevolutionary arms-race dynamics）偏离典型模式。然而，在中等频率与低频温度波动条件下，高温时段会导致共进化进程停滞，进而产生暂时性的共进化冷点（coevolutionary coldspots）。温度波动会影响种群密度，这为生态-进化反馈（eco-evolutionary feedbacks）可通过改变细菌与噬菌体的接触速率发挥作用提供了证据。本研究表明，环境波动可促使拮抗物种种间交互作用进入或脱离……