BACKGROUND The relatively fast selection of symbiotic bacteria within hosts and the potential transmission of these bacteria across generations of hosts raise the question of whether interactions between host and bacteria support emergent adaptive capabilities beyond those of germ-free hosts. RESULTS To investigate possibilities for emergent adaptations that may distinguish composite host-microbiome systems from germ-free hosts, we introduce a population genetics model of a host-microbiome system with vertical transmission of bacteria. The host and its bacteria are jointly exposed to a toxic agent, creating a toxic stress that can be alleviated by selection of resistant individuals and by secretion of a detoxification agent ("detox"). We show that toxic exposure in one generation of hosts leads to selection of resistant bacteria, which in turn, increases the toxic tolerance of the host's offspring. Prolonged exposure to toxin over many host generations promotes anadditional form of emergent adaptation due to selection of hosts based on detox produced by their bacterial community as a whole (as opposed to properties of individual bacteria). CONCLUSIONS These findings show that interactions between pure Darwinian selections of host and its bacteria can give rise to emergent adaptive capabilities, including Lamarckian-like adaptation of the host-microbiome system. REVIEWERS This article was reviewed by Eugene Koonin, Yuri Wolf and Philippe Huneman.

中文翻译：

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宿主和细菌的达尔文选择支持整个系统的Lamarckian式适应。

背景技术宿主内共生细菌的相对较快的选择以及这些细菌跨代宿主的潜在传播提出了一个问题，即宿主与细菌之间的相互作用是否支持除无菌宿主之外的新兴适应能力。结果为了研究可能发生的适应性变化（可能将复合宿主-微生物组系统与无菌宿主区分开）的可能性，我们引入了细菌垂直传播的宿主-微生物组系统的种群遗传模型。宿主及其细菌共同暴露于毒性剂，产生毒性应激，该应激可通过选择抗性个体和分泌排毒剂（“排毒”）来缓解。我们证明了一代人宿主的有毒暴露会导致选择抗药性细菌，反过来，增加宿主后代的毒性耐受性。由于宿主是根据整个细菌群落产生的排毒来选择宿主（与个别细菌的特性相反），因此在许多宿主世代中长时间接触毒素会促进紧急适应的其他形式。结论这些发现表明，宿主的纯达尔文选择与其细菌之间的相互作用可产生紧急适应能力，包括宿主微生物组系统的类似拉马克适应性。审阅者本文由Eugene Koonin，Yuri Wolf和Philippe Huneman审阅。由于宿主是根据整个细菌群落产生的排毒来选择宿主（与个别细菌的特性相反），因此在许多宿主世代中长时间接触毒素会促进紧急适应的其他形式。结论这些发现表明，宿主的纯达尔文选择与其细菌之间的相互作用可产生紧急适应能力，包括宿主微生物组系统的类似拉马克适应性。审阅者本文由Eugene Koonin，Yuri Wolf和Philippe Huneman审阅。由于宿主是根据整个细菌群落产生的排毒来选择宿主（与个别细菌的特性相反），因此在许多宿主世代中长时间接触毒素会促进紧急适应的其他形式。结论这些发现表明，宿主的纯达尔文选择与其细菌之间的相互作用可产生紧急适应能力，包括宿主微生物组系统的类似拉马克适应性。审阅者本文由Eugene Koonin，Yuri Wolf和Philippe Huneman审阅。包括宿主微生物组系统的类似Lamarckian的适应方法。审阅者本文由Eugene Koonin，Yuri Wolf和Philippe Huneman审阅。包括宿主微生物组系统的类似Lamarckian的适应方法。审阅者本文由Eugene Koonin，Yuri Wolf和Philippe Huneman审阅。