Changing fitness effects of mutations through long-term bacterial evolution

• 成果类型: Article
• 署名作者: Couce, Alejandro; Limdi, Anurag; Magnan, Melanie; Owen, Sian V.; Herren, Cristina M.; Lenski, Richard E.; Tenaillon, Olivier; Baym, Michael
• 署名单位: Institut National de la Sante et de la Recherche Medicale (Inserm); Universite Paris Cite; Institut National de la Sante et de la Recherche Medicale (Inserm); Universite Paris Cite; Imperial College London; Universidad Politecnica de Madrid; Harvard University; Harvard Medical School; Harvard University; Harvard Medical School; Northeastern University; Michigan State University; Michigan State University; Institut National de la Sante et de la Recherche Medicale (Inserm); Universite Paris Cite
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8382
• DOI: 10.1126/science.add1417
• 发表日期: 2024-01-26
• 关键词: escherichia-coli; beneficial mutations; molecular evolution; neutral theory; adaptation; selection; epistasis; genes; populations; divergence

摘要

The distribution of fitness effects of new mutations shapes evolution, but it is challenging to observe how it changes as organisms adapt. Using Escherichia coli lineages spanning 50,000 generations of evolution, we quantify the fitness effects of insertion mutations in every gene. Macroscopically, the fraction of deleterious mutations changed little over time whereas the beneficial tail declined sharply, approaching an exponential distribution. Microscopically, changes in individual gene essentiality and deleterious effects often occurred in parallel; altered essentiality is only partly explained by structural variation. The identity and effect sizes of beneficial mutations changed rapidly over time, but many targets of selection remained predictable because of the importance of loss-of-function mutations. Taken together, these results reveal the dynamic-but statistically predictable-nature of mutational fitness effects.