Thermococcales has a strong adaptability to extreme environments, which is of profound interest in explaining how complex life forms emerge on earth. However, their gene composition, thermal stability and evolution in hyperthermal environments are still little known. Here, we characterized the pan-genome architecture of 30 Thermococcales species to gain insight into their genetic properties, evolutionary patterns and specific metabolisms adapted to niches. We revealed an open pan-genome of Thermococcales comprising 6070 gene families that tend to increase with the availability of additional genomes. The genome contents of Thermococcales were flexible, with a series of genes experienced gene duplication, progressive divergence, or gene gain and loss events exhibiting distinct functional features. These archaea had concise types of heat shock proteins, such as HSP20, HSP60 and prefoldin, which were constrained by strong purifying selection that governed their conservative evolution. Furthermore, purifying selection forced genes involved in enzyme, motility, secretion system, defence system and chaperones to differ in functional constraints and their disparity in the rate of evolution may be related to adaptation to specific niche. These results deepened our understanding of genetic diversity and adaptation patterns of Thermococcales, and provided valuable research models for studying the metabolic traits of early life forms.

中文翻译：

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Thermococcales 的泛基因组研究揭示了嗜热适应的广泛遗传多样性和遗传证据

Thermococcales对极端环境具有很强的适应性，这对于解释地球上复杂的生命形式如何出现具有深远的意义。然而，它们的基因组成、热稳定性和在超高温环境中的进化仍然鲜为人知。在这里，我们表征了 30 个 Thermococcales 物种的泛基因组结构，以深入了解它们的遗传特性、进化模式和适应生态位的特定代谢。我们揭示了 Thermococcales 的开放泛基因组，包括 6070 个基因家族，这些基因家族随着额外基因组的可用性而增加。Thermococcales 的基因组内容是灵活的，一系列基因经历了基因重复、渐进分歧或基因获得和丢失事件，表现出不同的功能特征。这些古细菌具有简明类型的热休克蛋白，例如 HSP20、HSP60 和前折叠蛋白，它们受到控制其保守进化的强纯化选择的限制。此外，纯化选择迫使涉及酶、运动、分泌系统、防御系统和分子伴侣的基因在功能限制方面不同，它们在进化速度上的差异可能与对特定生态位的适应有关。这些结果加深了我们对热球菌的遗传多样性和适应模式的理解，并为研究早期生命形式的代谢特征提供了有价值的研究模型。分泌系统、防御系统和伴侣在功能限制方面的不同及其进化速度的差异可能与对特定生态位的适应有关。这些结果加深了我们对热球菌的遗传多样性和适应模式的理解，并为研究早期生命形式的代谢特征提供了有价值的研究模型。分泌系统、防御系统和伴侣在功能限制方面的不同及其进化速度的差异可能与对特定生态位的适应有关。这些结果加深了我们对热球菌的遗传多样性和适应模式的理解，并为研究早期生命形式的代谢特征提供了有价值的研究模型。