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.理解生物物种的起源，对于阐明地球生命的演化进程至关重要。近期的生物信息学分析揭示，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。已知病毒的遗传交换频率极高，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相近的噬菌体进行分析，鉴定出三种限制二者间遗传交换的关键因素：1）类核区室（nucleus-like compartment）：通过物理分隔正在复制的噬菌体基因组，从而在共感染过程中限制噬菌体间的重组；2）微管蛋白纺锤体（tubulin-based spindle）：调控噬菌体的复制过程，并可形成无功能的杂合聚合物；3）核不相容因子（nuclear incompatibility factor）：可降低噬菌体的适合度。上述三类性状通过两种机制维持物种间的差异：一是亚细胞遗传隔离（Subcellular Genetic Isolation）——共感染阶段病毒基因组被物理分隔；二是病毒发生不相容性（Virogenesis Incompatibility）——跨物种组分的相互作用会干扰病毒的组装与产生。