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Mutability of demographic noise in microbial range expansions
The ISME Journal ( IF 11.0 ) Pub Date : 2021-03-21 , DOI: 10.1038/s41396-021-00951-9
QinQin Yu 1 , Matti Gralka 1, 2 , Marie-Cécilia Duvernoy 1, 3 , Megan Sousa 1 , Arbel Harpak 4, 5 , Oskar Hallatschek 1, 3
Affiliation  

Demographic noise, the change in the composition of a population due to random birth and death events, is an important driving force in evolution because it reduces the efficacy of natural selection. Demographic noise is typically thought to be set by the population size and the environment, but recent experiments with microbial range expansions have revealed substantial strain-level differences in demographic noise under the same growth conditions. Many genetic and phenotypic differences exist between strains; to what extent do single mutations change the strength of demographic noise? To investigate this question, we developed a high-throughput method for measuring demographic noise in colonies without the need for genetic manipulation. By applying this method to 191 randomly-selected single gene deletion strains from the E. coli Keio collection, we find that a typical single gene deletion mutation decreases demographic noise by 8% (maximal decrease: 81%). We find that the strength of demographic noise is an emergent trait at the population level that can be predicted by colony-level traits but not cell-level traits. The observed differences in demographic noise from single gene deletions can increase the establishment probability of beneficial mutations by almost an order of magnitude (compared to in the wild type). Our results show that single mutations can substantially alter adaptation through their effects on demographic noise and suggest that demographic noise can be an evolvable trait of a population.



中文翻译:

微生物范围扩展中人口统计噪声的可变性

人口噪声是由于随机出生和死亡事件而导致的人口组成变化,是进化的重要驱动力,因为它降低了自然选择的功效。人口噪声通常被认为是由种群规模和环境决定的,但最近的微生物范围扩展实验揭示了在相同生长条件下人口噪声的显着菌株水平差异。菌株之间存在许多遗传和表型差异;单一突变在多大程度上改变了人口统计噪音的强度?为了研究这个问题,我们开发了一种高通量方法来测量菌落中的人口统计噪音,而无需进行基因操作。通过将这种方法应用到 191 个随机选择的单基因缺失菌株大肠杆菌Keio 收集,我们发现典型的单基因缺失突变将人口统计噪声降低了 8%(最大降低:81%)。我们发现人口噪声的强度是群体水平的一种新兴特征,可以通过菌落水平的特征而不是细胞水平的特征来预测。观察到的来自单基因缺失的人口统计噪声差异可以将有益突变的建立概率提高几乎一个数量级(与野生型相比)。我们的研究结果表明,单个突变可以通过其对人口噪声的影响来显着改变适应,并表明人口噪声可以是人口的可进化特征。

更新日期:2021-03-22
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