Viral_Speciation_NatComms_2020

Abstract Understanding how biological species arise is critical for understanding the evolution of life on Earth. Bioinformatic analyses have recently revealed that viruses, like multicellular life, form reproductively isolated biological species. Viruses are known to share high rates of genetic exchange, so how do they evolve genetic isolation? Here we evaluate two related bacteriophages and describe three factors that limit genetic exchange between them: 1) A nucleus-like compartment that physically separates replicating phage genomes, thereby limiting inter-phage recombination during co-infection. 2) A tubulin-based spindle that orchestrates phage replication and forms nonfunctional hybrid polymers. 3) A nuclear incompatibility factor that reduces phage fitness. Together these traits maintain species differences through “Subcellular Genetic Isolation” where viral genomes are physically separated during co-infection, and “Virogenesis Incompatibility” in which the interaction of cross-species components interferes with virus production.摘要 理解生物物种的起源，是解析地球上生命演化历程的关键所在。近期的生物信息学分析显示，病毒与多细胞生物一样，能够形成具有生殖隔离特性的生物物种。已知病毒的基因交流频率极高，那么它们是如何演化出遗传隔离机制的？ 本研究对两种亲缘关系较近的噬菌体（bacteriophages）展开评估，阐明了三类可限制噬菌体间基因交流的关键因素：1） 类细胞核区室，可物理分隔复制中的噬菌体基因组，从而限制共感染（co-infection）过程中的噬菌体间重组；2） 基于微管蛋白（tubulin）的纺锤体，负责调控噬菌体的复制过程，且会形成无功能的杂合多聚体；3） 细胞核不相容因子，可降低噬菌体的适配度。 上述三类性状通过两种机制维持物种间的差异：其一为**亚细胞遗传隔离（Subcellular Genetic Isolation）**，即共感染阶段病毒基因组被物理分隔；其二为**病毒发生不相容性（Virogenesis Incompatibility）**，即跨物种组分的相互作用会干扰病毒的产生过程。