Data from: Widespread genetic incompatibilities between first-step mutations during parallel adaptation of Saccharomyces cerevisiae to a common environment

AbstractIndependently evolving populations may adapt to similar selection pressures via different genetic changes. The interactions between such changes, such as in a hybrid individual, can inform us about what course adaptation may follow and allow us to determine whether gene flow would be facilitated or hampered following secondary contact. We used Saccharomyces cerevisiae to measure the genetic interactions between first-step mutations that independently evolved in the same biosynthetic pathway following exposure to the fungicide nystatin. We found that genetic interactions are prevalent and predominantly negative, with the majority of mutations causing lower growth when combined in a double mutant than when alone as a single mutant (sign epistasis). The prevalence of sign epistasis is surprising given the small number of mutations tested and runs counter to expectations for mutations arising in a single biosynthetic pathway in the face of a simple selective pressure. Furthermore, in one third of pairwise interactions, the double mutant grew less well than either single mutant (reciprocal sign epistasis). The observation of reciprocal sign epistasis among these first adaptive mutations arising in the same genetic background indicates that partial postzygotic reproductive isolation could evolve rapidly between populations under similar selective pressures, even with only a single genetic change in each. The nature of the epistatic relationships was sensitive, however, to the level of drug stress in the assay conditions, as many double mutants became fitter than the single mutants at higher concentrations of nystatin. We discuss the implications of these results both for our understanding of epistatic interactions among beneficial mutations in the same biochemical pathway and for speciation., Usage notesData package about incompatibilities between adaptive mutations in yeastThis package contains files and scripts related to the publication \"Widespread Genetic Incompatibilities Between First-Step Mutations During Parallel Adaptation of Saccharomyces cerevisiae to a Common Environment\". Raw data and analyses are included.DryadSubmission.zip摘要 独立演化的种群在面临相似选择压力时，可通过不同的遗传改变实现适应性演化。此类遗传改变之间的相互作用（例如在杂交个体中）可帮助我们预判适应的演化路径，并能判断：种群发生次生接触后，基因流会得到促进还是受阻。本研究以酿酒酵母（Saccharomyces cerevisiae）为实验材料，测定了暴露于杀菌剂制霉菌素（nystatin）后，同一生物合成通路中独立演化出的一阶突变之间的遗传相互作用。研究结果显示，遗传相互作用普遍存在且以负相互作用为主：多数突变以双突变体形式组合时的生长状态，相较于单突变体单独存在时更差，即符号上位性（sign epistasis）。尽管本次实验仅测试了少量突变，但符号上位性的普遍程度仍超出预期，这与单一生物合成通路中的突变在简单选择压力下的演化预期相悖。此外，在三分之一的成对相互作用中，双突变体的生长状态差于任一单突变体，即互反符号上位性（reciprocal sign epistasis）。在同一遗传背景下产生的这些适应性一阶突变中观察到互反符号上位性，这表明：即使每个种群仅发生单一遗传改变，在相似选择压力下的种群之间也可快速演化出不完全的合子后生殖隔离（postzygotic reproductive isolation）。不过，上位性相互作用的性质会受到实验条件中药物胁迫水平的影响：在制霉菌素浓度更高的条件下，许多双突变体的适应度反而高于单突变体。本研究将讨论这些结果的双重意义：一是深化我们对同一生化通路中有益突变间上位性相互作用的认知，二是为物种形成相关研究提供参考。 使用说明 本数据集包聚焦酵母适应性突变间的不相容性问题。本数据包包含与论文《酿酒酵母平行适应同一环境时一阶突变间广泛存在的遗传不相容性》（Widespread Genetic Incompatibilities Between First-Step Mutations During Parallel Adaptation of Saccharomyces cerevisiae to a Common Environment）相关的文件与脚本，其中涵盖原始数据与分析内容。DryadSubmission.zip