Division of Evolution, Infection and Genomics, School of Biological Sciences, University of Manchester, Manchester, United Kingdom.
Department of Environmental and Earth Sciences, School of Natural Sciences, University of Manchester, Manchester, United Kingdom.
PLoS Biol. 2024 Apr 12;22(4):e3002580. doi: 10.1371/journal.pbio.3002580. eCollection 2024 Apr.
Endosymbiosis drives evolutionary innovation and underpins the function of diverse ecosystems. The mechanistic origins of symbioses, however, remain unclear, in part because early evolutionary events are obscured by subsequent evolution and genetic drift. This Essay highlights how experimental studies of facultative, host-switched, and synthetic symbioses are revealing the important role of fitness trade-offs between within-host and free-living niches during the early-stage evolution of new symbiotic associations. The mutational targets underpinning such trade-offs are commonly regulatory genes, such that single mutations have major phenotypic effects on multiple traits, thus enabling and reinforcing the transition to a symbiotic lifestyle.
共生关系推动了进化创新，是多样化生态系统功能的基础。然而，共生关系的机械起源仍不清楚，部分原因是早期进化事件被后续进化和遗传漂变所掩盖。本文强调了如何通过对兼性、宿主转换和人工合成共生关系的实验研究，揭示了在新共生关系的早期进化过程中，宿主内和自由生活小生境之间的适应性权衡在共生关系中的重要作用。这种权衡的突变靶点通常是调节基因，因此单个突变对多个性状有重大表型效应，从而使向共生生活方式的转变成为可能并得到加强。
