W.K. Kellogg Biological Station, Michigan State University, 3700 E. Gull Lake Dr., Hickory Corners, MI 49060, USA.
Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.
Proc Biol Sci. 2022 May 25;289(1975):20211955. doi: 10.1098/rspb.2021.1955.
An organism's gut microbiome can alter its fitness, yet we do not know how gut microbiomes change as their hosts evolve in the wild. We took advantage of a five-decade 'chronosequence' of translocated fish populations to examine associated changes in the gut microbiome. Populations of Trinidadian guppies have displayed parallel phenotypic convergence six times when moved from high predation (HP) to low predation (LP) environments. Across four drainages, we found microbiomes of fish translocated 5-6 years prior to sampling were already distinct from the microbiomes of their HP source populations. Changes in environmental conditions were most important in driving this shift, followed by phenotypic shifts in gut morphology. After 30-60 years in LP environments, microbiome composition was still distinct from native LP populations, but microbiome function was not. We found some evidence that nitrogen fixation enhanced gut nutrient absorption, but most functional shifts were not parallel across drainages. Stream-and drainage-specific signatures were present for both composition and function, despite our overall finding of consistent microbiome change across drainages. As we unravel the complexities of host-microbiome evolution in the wild, studies should consider environmental microbial colonization, host phenotypic plasticity in nature, and more realistic environmental conditions excluded from laboratory studies.
生物的肠道微生物组可以改变其适应性，但我们不知道随着宿主在野外进化，肠道微生物组会如何变化。我们利用了长达五十年的鱼类种群转移“时间序列”，来研究肠道微生物组的相关变化。特立尼达鳉鱼的六个种群在从高捕食（HP）环境转移到低捕食（LP）环境后，表现出了平行的表型趋同。在四个流域中，我们发现，在取样前 5-6 年转移的鱼类的微生物组已经与其 HP 来源种群的微生物组明显不同。环境条件的变化是驱动这种转变的最重要因素，其次是肠道形态的表型变化。在 LP 环境中 30-60 年后，微生物组的组成仍然与本地 LP 种群不同，但微生物组的功能没有。我们发现一些证据表明固氮作用增强了肠道营养物质的吸收，但大多数功能变化在流域之间并不平行。尽管我们在整个流域发现了一致的微生物组变化，但仍存在着组成和功能的溪流和流域特异性特征。在揭示宿主-微生物组在野外进化的复杂性时，研究应考虑环境微生物的定植、自然宿主表型的可塑性，以及实验室研究中排除的更现实的环境条件。
