小柯机器人

美国哈佛大学Michael M. Desai研究团队发现了高分辨率谱系追踪技术能够揭示实验室酵母的适应行波。这一研究成果2019年11月13日在线发表在国际学术期刊《自然》上。

研究人员引入一种可再生条形码系统，以高分辨率观察实验室芽殖酵母的进化动态。研究发现即使在低频下，干扰和搭乘的嵌套模式也是如此。这些事件是由不断出现的新突变驱动的，这些突变会在现有谱系达到高频率之前对其命运进行修改。他们观察人口中的适应性分布如何随时间变化，并找到理论预测的适应行波。他们证明了克隆竞争会产生动态的“富者更富”效应：在进化的早期获得的适应性优势推动了克隆的扩展，从而增加了获得新突变的机会。但是，适应性较弱的谱系通常也会超过适应性强的谱系。结果表明，在现有的进化动力学模型中，没有考虑到的因素组合对于确定适应的速率、可预测性以及分子基础至关重要。

研究人员表示，在快速适应的无性种群中，包括许多微生物病原体和病毒，许多突变谱系通常在种群竞争中占优势。这些复杂的进化动力学决定了适应的结果，但是很难直接观察到。先前的研究已经使用全基因组测序来跟踪分子适应性；但是，这些方法在微生物种群中的分辨率有限。

附：英文原文

Title: High-resolution lineage tracking reveals travelling wave of adaptation in laboratory yeast

Author: Alex N. Nguyen Ba

Issue&Volume: 2019-11-13

Abstract: In rapidly adapting asexual populations, including many microbial pathogens and viruses, numerous mutant lineages often compete for dominance within the population15. These complex evolutionary dynamics determine the outcomes of adaptation, but have been difficult to observe directly. Previous studies have used whole-genome sequencing to follow molecular adaptation610; however, these methods have limited resolution in microbial populations. Here we introduce a renewable barcoding system to observe evolutionary dynamics at high resolution in laboratory budding yeast. We find nested patterns of interference and hitchhiking even at low frequencies. These events are driven by the continuous appearance of new mutations that modify the fates of existing lineages before they reach substantial frequencies. We observe how the distribution of fitness within the population changes over time, and find a travelling wave of adaptation that has been predicted by theory1117. We show that clonal competition creates a dynamical rich-get-richer effect: fitness advantages that are acquired early in evolution drive clonal expansions, which increase the chances of acquiring future mutations. However, less-fit lineages also routinely leapfrog over strains of higher fitness. Our results demonstrate that this combination of factors, which is not accounted for in existing models of evolutionary dynamics, is critical in determining the rate, predictability and molecular basis of adaptation. A renewable barcoding system reveals the evolutionary dynamics of laboratory budding yeast, showing that fitness changes over time in a travelling wave of adaptation that can fluctuate owing to leapfrogging events.

DOI: 10.1038/s41586-019-1749-3

Source:https://www.nature.com/articles/s41586-019-1749-3

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html