{"title":"How Big Is Big? The Effective Population Size of Marine Bacteria","authors":"Haiwei Luo","doi":"10.1146/annurev-marine-050823-104415","DOIUrl":null,"url":null,"abstract":"Genome-reduced bacteria constitute most of the cells in surface-ocean bacterioplankton communities. Their extremely large census population sizes (Nc) have been unfoundedly translated to huge effective population sizes (Ne)—the size of an ideal population carrying as much neutral genetic diversity as the actual population. As Ne scales inversely with the strength of genetic drift, constraining the magnitude of Ne is key to evaluating whether natural selection can overcome the power of genetic drift to drive evolutionary events. Determining the Ne of extant species requires measuring the genomic mutation rate, a challenging step for most genome-reduced bacterioplankton lineages. Results for genome-reduced Prochlorococcus and CHUG are surprising—their Ne values are an order of magnitude lower than those of less abundant lineages carrying large genomes, such as Ruegeria and Vibrio. As bacterioplankton genome reduction commonly occurred in the distant past, appreciating their population genetic mechanisms requires constraining their ancient Ne values by other methods.","PeriodicalId":55508,"journal":{"name":"Annual Review of Marine Science","volume":"32 1","pages":""},"PeriodicalIF":14.3000,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annual Review of Marine Science","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1146/annurev-marine-050823-104415","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Genome-reduced bacteria constitute most of the cells in surface-ocean bacterioplankton communities. Their extremely large census population sizes (Nc) have been unfoundedly translated to huge effective population sizes (Ne)—the size of an ideal population carrying as much neutral genetic diversity as the actual population. As Ne scales inversely with the strength of genetic drift, constraining the magnitude of Ne is key to evaluating whether natural selection can overcome the power of genetic drift to drive evolutionary events. Determining the Ne of extant species requires measuring the genomic mutation rate, a challenging step for most genome-reduced bacterioplankton lineages. Results for genome-reduced Prochlorococcus and CHUG are surprising—their Ne values are an order of magnitude lower than those of less abundant lineages carrying large genomes, such as Ruegeria and Vibrio. As bacterioplankton genome reduction commonly occurred in the distant past, appreciating their population genetic mechanisms requires constraining their ancient Ne values by other methods.
减少基因组的细菌构成了海洋表层浮游细菌群落中的大部分细胞。它们极其庞大的普查种群规模(Nc)被毫无根据地转化为巨大的有效种群规模(Ne)--即理想种群的规模,其携带的中性遗传多样性与实际种群一样多。由于 Ne 与遗传漂变的强度成反比,因此限制 Ne 的大小是评估自然选择是否能克服遗传漂变驱动进化事件的关键。确定现存物种的 Ne 值需要测量基因组突变率,这对大多数基因组还原的浮游细菌系来说是一个具有挑战性的步骤。基因组还原的原绿球藻和 CHUG 的结果令人吃惊--它们的 Ne 值比 Ruegeria 和弧菌等携带大基因组的不太丰富的菌系的 Ne 值低一个数量级。由于浮游细菌基因组的减少通常发生在遥远的过去,要了解它们的种群遗传机制,就需要用其他方法来限制它们的古 Ne 值。
期刊介绍:
The Annual Review of Marine Science, published since 2009, offers a comprehensive overview of the field. It covers various disciplines, including coastal and blue water oceanography (biological, chemical, geological, and physical), ecology, conservation, and technological advancements related to the marine environment. The journal's transition from gated to open access through Annual Reviews' Subscribe to Open program ensures that all articles are available under a CC BY license, promoting wider accessibility and dissemination of knowledge.