Predicting how new mutations alter phenotypes is difficult because mutational effects vary across genotypes and environments. Recently discovered global epistasis, in which the fitness effects of mutations scale with the fitness of the background genotype, can improve predictions, but how the environment modulates this scaling is unknown. We measured the fitness effects of ~100 insertion mutations in 42 strains of Saccharomyces cerevisiae in six laboratory environments and found that the global epistasis scaling is nearly invariant across environments. Instead, the environment tunes one global parameter, the background fitness at which most mutations switch sign. As a consequence, the distribution of mutational effects is predictable across genotypes and environments. Our results suggest that the effective dimensionality of genotype-to-phenotype maps across environments is surprisingly low.

中文翻译：

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突变效应的环境非依赖性分布来自微观上位性


预测新突变如何改变表型很困难，因为突变效应因基因型和环境而异。最近发现的全局上位性，其中突变的适应度效应与背景基因型的适应度成正比，可以改善预测，但环境如何调节这种缩放尚不清楚。我们在 6 个实验室环境中测量了 42 种酿酒酵母菌株中 ~100 个插入突变的适应度效应，发现全局上位性缩放在不同环境中几乎保持不变。相反，环境会调整一个全局参数，即大多数突变切换符号的背景适应度。因此，突变效应在基因型和环境中的分布是可预测的。我们的结果表明，跨环境的基因型到表型映射的有效维度非常低。