Remold Susanna K, Lenski Richard E
Center for Microbial Ecology, Michigan State University, East Lansing, 48824, USA.
Nat Genet. 2004 Apr;36(4):423-6. doi: 10.1038/ng1324.
The effects of mutations on phenotype and fitness may depend on the environment (phenotypic plasticity), other mutations (genetic epistasis) or both. Here we examine the fitness effects of 18 random insertion mutations in E. coli in two resource environments and five genetic backgrounds. We tested each mutation for plasticity and epistasis by comparing its fitness effects across these ecological and genetic contexts. Some mutations had no measurable effect in any of these contexts. None of the mutations had effects on phenotypic plasticity that were independent of genetic background. However, half the mutations had epistatic interactions such that their effects differed among genetic backgrounds, usually in an environment-dependent manner. Also, the pattern of mutational effects across backgrounds indicated that epistasis had been shaped primarily by unique events in the evolutionary history of a population rather than by repeatable events associated with shared environmental history.
突变对表型和适应性的影响可能取决于环境（表型可塑性）、其他突变（基因上位性）或两者。在这里，我们研究了大肠杆菌中18个随机插入突变在两种资源环境和五种遗传背景下的适应性影响。我们通过比较这些生态和遗传背景下每个突变的适应性影响，测试了其可塑性和上位性。一些突变在任何这些背景下都没有可测量的影响。没有一个突变对表型可塑性有独立于遗传背景的影响。然而，一半的突变存在上位性相互作用，使得它们在不同遗传背景下的影响不同，通常以环境依赖的方式。此外，跨背景的突变效应模式表明，上位性主要是由种群进化历史中的独特事件塑造的，而不是由与共享环境历史相关的可重复事件塑造的。
