Liaghat Armun, Guillemet Martin, Whitaker Rachel, Gandon Sylvain, Pascual Mercedes
Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, USA.
Department of Biology, New York University, New York, New York, USA.
Ecol Lett. 2025 Jun;28(6):e70153. doi: 10.1111/ele.70153.
Microbial host populations evolve traits conferring specific resistance to viral predators via various defence mechanisms, while viruses reciprocally evolve traits to evade these defences. Such coevolutionary dynamics often involve diversification promoted by negative frequency-dependent selection. However, microbial traits conferring competitive asymmetries can induce directional selection, opposing diversification. Despite extensive research on microbe-virus coevolution, the combined effect of both host trait types and associated selection remains unclear. Using a CRISPR-mediated coevolutionary system, we examine how the co-occurrence of both trait types impacts viral evolution and persistence, previously shown to be transient and nonstationary in computational models. A stochastic model incorporating host competitive asymmetries via variation of intrinsic growth rates reveals that competitively advantaged host clades generate the majority of immune diversity. Greater asymmetries extend viral extinction times, accelerate viral adaptation locally in time and augment long-term local adaptation. These findings align with previous experiments and provide further insights into long-term coevolutionary dynamics.
微生物宿主种群通过各种防御机制进化出赋予对病毒捕食者特定抗性的性状，而病毒则相互进化出逃避这些防御的性状。这种协同进化动态通常涉及由负频率依赖选择促进的多样化。然而，赋予竞争不对称性的微生物性状可诱导定向选择，与多样化相反。尽管对微生物-病毒协同进化进行了广泛研究，但这两种宿主性状类型及其相关选择的综合影响仍不清楚。我们使用一个CRISPR介导的协同进化系统，研究这两种性状类型的共存如何影响病毒进化和持久性，此前在计算模型中已证明这是短暂且非平稳的。一个通过内在生长率变化纳入宿主竞争不对称性的随机模型表明，具有竞争优势的宿主进化枝产生了大部分免疫多样性。更大的不对称性延长了病毒灭绝时间，在局部时间加速了病毒适应，并增强了长期局部适应。这些发现与之前的实验一致，并为长期协同进化动态提供了进一步的见解。
