Biophysics Program, Stanford University, Stanford, CA, USA.
Department of Applied Physics, Stanford University, Stanford, CA, USA.
Nat Ecol Evol. 2024 Nov;8(11):2085-2096. doi: 10.1038/s41559-024-02527-0. Epub 2024 Sep 11.
Mutations can alter the short-term fitness of an organism, as well as the rates and benefits of future mutations. While numerous examples of these evolvability modifiers have been observed in rapidly adapting microbial populations, existing theory struggles to predict when they will be favoured by natural selection. Here we develop a mathematical framework for predicting the fates of genetic variants that modify the rates and benefits of future mutations in linked genomic regions. We derive analytical expressions showing how the fixation probabilities of these variants depend on the size of the population and the diversity of competing mutations. We find that competition between linked mutations can dramatically enhance selection for modifiers that increase the benefits of future mutations, even when they impose a strong direct cost on fitness. However, we also find that modest direct benefits can be sufficient to drive evolutionary dead ends to fixation. Our results suggest that subtle differences in evolvability could play an important role in shaping the long-term success of genetic variants in rapidly evolving microbial populations.
突变可以改变生物体的短期适应性，以及未来突变的速度和收益。虽然在快速适应的微生物群体中已经观察到了许多这种可进化性修饰因子的例子，但现有的理论难以预测它们何时会被自然选择所青睐。在这里，我们开发了一个数学框架，用于预测在连锁基因组区域中改变未来突变速度和收益的遗传变异的命运。我们推导出了分析表达式，展示了这些变体的固定概率如何取决于种群大小和竞争突变的多样性。我们发现，连锁突变之间的竞争可以极大地增强对增加未来突变收益的修饰因子的选择，即使它们对适应性造成很强的直接成本。然而，我们还发现，适度的直接收益就足以促使进化死胡同固定下来。我们的研究结果表明，细微的可进化性差异可能在塑造快速进化的微生物群体中遗传变异的长期成功方面发挥重要作用。
