Department of Evolutionary Ecology and Genetics, University of Kiel, Am Botanischen Garten 1- 9, 24118 Kiel, Germany.
Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Str. 2, Ploen, Germany.
Trends Microbiol. 2021 Sep;29(9):779-787. doi: 10.1016/j.tim.2021.02.005. Epub 2021 Mar 2.
Microbiota-host associations are ubiquitous in nature. They are often studied using a host-centered view, while microbes are assumed to have coevolved with hosts or colonize hosts as nonadapted entities. Both assumptions are often incorrect. Instead, many host-associated microbes are adapted to a biphasic life cycle in which they alternate between noncoadapted hosts and a free-living phase. Full appreciation of microbiota-host symbiosis thus needs to consider how microbes optimize fitness across this life cycle. Here, we evaluate the key stages of the biphasic life cycle and propose a new conceptual framework for microbiota-host interactions which includes an integrative measure of microbial fitness, related to the parasite fitness parameter R, and which will help in-depth assessment of the evolution of these widespread associations.
微生物组-宿主的相互关系在自然界中普遍存在。它们通常采用以宿主为中心的观点进行研究，而微生物被认为是与宿主共同进化或作为非适应实体定植于宿主。这两种假设往往是不正确的。相反，许多与宿主相关的微生物适应于一种双相生命周期，在此期间它们在非共适应宿主和自由生活阶段之间交替。因此，充分了解微生物组-宿主共生关系需要考虑微生物如何在整个生命周期中优化适应性。在这里，我们评估了双相生命周期的关键阶段，并提出了一个新的微生物组-宿主相互作用的概念框架，其中包括一个与寄生虫适应性参数 R 相关的微生物适应性综合度量，这将有助于深入评估这些广泛存在的关联的进化。
