Our view of genome size in Archaea and Bacteria has remained skewed as the data used to paint its picture has been dominated by genomes of microorganisms that can be cultivated under laboratory settings. However, the continuous effort to catalog the genetic make-up of Earth’s microbiomes specifically propelled by recent extensive work on uncultivated microorganisms, provides a unique opportunity to revise our perspective on genome size distribution. Capitalizing on a recently released extensive catalog of tens of thousands of metagenome-assembled genomes, we provide a comprehensive overview of genome size distributions. We observe that the known phylogenetic diversity of environmental microorganisms possesses significantly smaller genomes than the collection of laboratory isolated microorganisms. Aquatic microorganisms average 3.1 Mb, host-associated microbial genomes average 3.0 Mb, terrestrial microorganism average 3.7 Mb and isolated microorganisms average 4.3 Mb. While the environment where the microorganisms live can certainly be linked to genome size, in some cases, evolutionary phylogenetic history can be a stronger predictor. Moreover, ecological strategies such as auxotrophies have a direct impact on genome size. To better understand the ecological drivers of genome size, we expand on the known and the overlooked factors that influence genome size in different environments, phylogenetic groups and trophic strategies.

中文翻译：

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地球微生物组的基因组观点表明，古细菌和细菌的基因组大小与生态系统类型和营养策略有关

我们对古细菌和细菌基因组大小的看法仍然存在偏差，因为用于描绘其图景的数据主要是可以在实验室环境下培养的微生物基因组。然而，最近对未培养微生物的广泛研究特别推动了对地球微生物组的遗传组成进行编目的持续努力，为我们修改对基因组大小分布的看法提供了独特的机会。利用最近发布的数万个宏基因组组装基因组的广泛目录，我们提供了基因组大小分布的全面概述。我们观察到，与实验室分离的微生物集合相比，环境微生物的已知系统发育多样性具有明显更小的基因组。水生微生物平均 3.1 Mb，宿主相关微生物基因组平均 3.0 Mb，陆生微生物平均 3.7 Mb，分离微生物平均 4.3 Mb。虽然微生物生存的环境肯定与基因组大小有关，但在某些情况下，进化系统发育历史可以成为更强的预测因子。此外，营养缺陷等生态策略对基因组大小有直接影响。为了更好地了解基因组大小的生态驱动因素，我们扩展了影响不同环境、系统发育群体和营养策略中基因组大小的已知和被忽视的因素。进化系统发育历史可以是一个更强的预测因子。此外，营养缺陷等生态策略对基因组大小有直接影响。为了更好地了解基因组大小的生态驱动因素，我们扩展了影响不同环境、系统发育群体和营养策略中基因组大小的已知和被忽视的因素。进化系统发育历史可以是一个更强的预测因子。此外，营养缺陷等生态策略对基因组大小有直接影响。为了更好地了解基因组大小的生态驱动因素，我们扩展了影响不同环境、系统发育群体和营养策略中基因组大小的已知和被忽视的因素。