Epistasis occurs when the effect of a mutation depends on its carrier's genetic background. Despite increasing evidence that epistasis for fitness is common, its role during evolution is contentious. Fitness landscapes, which are mappings of genotype or phenotype to fitness, capture the full extent and complexity of epistasis. Fitness landscape theory has shown how epistasis affects the course and the outcome of evolution. Moreover, by measuring the competitive fitness of sets of tens to thousands of connected genotypes, empirical fitness landscapes have shown that epistasis is frequent and depends on the fitness measure, the choice of mutations for the landscape, and the environment in which it was measured. In this article, I review fitness landscape theory and experiments and their implications for the role of epistasis in adaptation. I discuss theoretical expectations in the light of empirical fitness landscapes and highlight open challenges and future directions toward integrating theory and data and incorporating ecological factors.

中文翻译：

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健身景观的上位性和适应

当突变的影响取决于其携带者的遗传背景时，就会发生上位性。尽管越来越多的证据表明适应性上位很常见，但它在进化过程中的作用仍然存在争议。适应度景观是基因型或表型与适应度的映射，捕捉了上位性的全部范围和复杂性。适应度景观理论表明上位性如何影响进化的过程和结果。此外，通过测量数万到数千个相连基因型组的竞争适应度，经验适应度景观表明上位性很常见，并且取决于适应度测量、景观突变的选择以及测量环境。在本文中，我回顾了适应度景观理论和实验及其对上位性在适应中的作用的影响。我根据经验适应性景观讨论了理论期望，并强调了整合理论和数据以及纳入生态因素的开放挑战和未来方向。