Data from: Field measurements of genotype by environment interaction for fitness caused by spontaneous mutations in Arabidopsis thaliana.

As the ultimate source of genetic diversity, spontaneous mutation is critical to the evolutionary process. The fitness effects of spontaneous mutations are almost always studied under controlled laboratory conditions rather than under the evolutionarily relevant conditions of the field. Of particular interest is the conditionality of new mutations - i.e., is a new mutation harmful regardless of the environment in which it is found? In other words, what is the extent of genotype-environment interaction for spontaneous mutations? We studied the fitness effects of 25 generations of accumulated spontaneous mutations in Arabidopsis thaliana in two geographically widely separated field environments, in Michigan and Virginia. At both sites, mean total fitness of MA lines exceeded that of the ancestors, contrary to the expected decrease in the mean due to new mutations but in accord with prior work on these MA lines. We observed genotype-environment interactions in the fitness effects of new mutations, such that the effects of mutations in Michigan were a poor predictor of their effects in Virginia and vice versa. In particular, mutational variance for fitness was much larger in Virginia compared to Michigan. This strong genotype-environment interaction would increase the amount of genetic variation maintained by mutation-selection balance.自发突变（spontaneous mutation）作为遗传多样性的终极来源，对进化过程至关重要。目前针对自发突变适合度效应（fitness effects）的研究，几乎均在受控实验室条件（controlled laboratory conditions）下开展，而非野外中契合进化相关要求的真实环境中进行。尤为值得关注的是新发突变的条件依赖性（conditionality）——即新发突变的有害性是否与其所处环境无关？换言之，自发突变的基因型-环境互作（genotype-environment interaction）程度究竟如何？本研究以拟南芥（Arabidopsis thaliana）为实验材料，在地理上相距甚远的两处野外试验环境——美国密歇根州与弗吉尼亚州——中，探究了25代自发突变积累的MA（Mutation Accumulation）品系的适合度效应。在两处试验位点，MA品系的平均总适合度均高于祖先品系，这与新发突变预期会导致适合度均值下降的结论相悖，但与此前针对这些MA品系的研究结果一致。我们在新发突变的适合度效应中观测到了基因型-环境互作现象：即在密歇根州观测到的突变效应，无法有效预测其在弗吉尼亚州的表现，反之亦然。尤为值得注意的是，弗吉尼亚州的适合度突变方差（mutational variance）远高于密歇根州。这种强烈的基因型-环境互作，会提升突变-选择平衡（mutation-selection balance）所维持的遗传变异水平。