Early adaptation in a microbial community is dominated by mutualism-enhancing mutations
Early adaptation in a microbial community is dominated by mutualism-enhancing mutations
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微生物群落的早期适应主要是增强互利共生的突变
DOI：
10.1101/2021.07.07.451547
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kryazhimskiy, Sergey
中科院分区：
文献类型：
--
作者：
Venkataram, Sandeep;Kuo, Huan-Yu;Hom, Erik F.;Kryazhimskiy, Sergey
物种间的相互作用驱动着物种的进化，而进化则塑造着这些相互作用。由此产生的生态进化动力学，其结果和可重复性取决于社区成员的适应性突变如何影响适应性和生态相关性状。然而，社区成员可获得的适应性突变的多样性并没有得到很好的表征，我们不知道这种多样性是如何受到生态环境的影响。在这里，我们使用条形码血统跟踪，以解决这个差距，在一个竞争互惠的酵母SaccharomycesParaeandalgaChlamydiumreinhardtii之间。我们发现，酵母有机会获得许多适应性突变与不同的生态后果，特别是那些增加和减少两个物种的产量。酵母中的适应性突变（即，酵母在单独生长或与酵母菌一起生长之间没有适合度权衡），而是将选择转移到有利于酵母突变体的位置，所述酵母突变体增加两个物种的产量并使互惠关系更强。因此，我们发现，在酵母菌存在的情况下，酵母菌可重复地进化，变得更加合作，即使在我们的系统中，合作性并不直接受到自然选择的青睐。我们的研究结果表明，生态相互作用不仅改变了进化的轨迹，但也决定了它的可重复性，特别是，弱互惠可以重复进化变得更强。
Species interactions drive species evolution while evolution shapes these interactions. The resulting eco-evolutionary dynamics, their outcomes and their repeatability depend on how adaptive mutations available to community members affect fitness and ecologically relevant traits. However, the diversity of adaptive mutations available to community members is not well characterized, and we do not know how this diversity is affected by the ecological milieu. Here we use barcode lineage tracking to address this gap in a competitive mutualism between the yeastSaccharomyces cerevisiaeand the algaChlamydomonas reinhardtii. We find that yeast has access to many adaptive mutations with diverse ecological consequences, in particular, those that increase and reduce the yields of both species. The presence of alga does not change which mutations are adaptive in yeast (i.e., there is no fitness trade-off for yeast between growing alone or with alga), but rather shifts selection to favor yeast mutants that increase the yields of both species and make the mutualism stronger. Thus, in the presence of alga, we find that yeast repeatably evolves to become more cooperative, even though cooperativity is not directly favored by natural selection in our system. Our results demonstrate that ecological interactions not only alter the trajectory of evolution but also dictate its repeatability; in particular, weak mutualisms can repeatably evolve to become stronger.