Large-effect flowering time mutations reveal conditionally adaptive paths through fitness landscapes in Arabidopsis thaliana
Large-effect flowering time mutations reveal conditionally adaptive paths through fitness landscapes in Arabidopsis thaliana
复制标题
大效应开花时间突变揭示了拟南芥适应性景观的条件适应性路径
DOI：
10.1073/pnas.1902731116
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Schmitt, Johanna
中科院分区：
文献类型：
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作者：
Taylor, Mark A.;Wilczek, Amity M.;Roe, Judith L.;Welch, Stephen M.;Runcie, Daniel E.;Cooper, Martha D.;Schmitt, Johanna
与之前大多数突变都是有害的假设相反，越来越多的证据表明自然群体中持续存在大效应突变。对这些观察结果的一个可能的解释是，突变体表型和适应性可能取决于突变体所暴露的特定环境条件。在这里，我们通过在多个田间地点和季节种植拟南芥的大效开花时间突变体来测试这一假设，以量化它们在现实自然条件下的适应性效应。通过根据开花时间和分支结构构建特定环境的适应度景观，我们观察到一部分突变增加了适应度，但仅限于特定环境。这些突变通过不同的途径提高了适应性：通过改变开花时间、分枝或两者兼而有之。分枝受到更强的选择，但开花时间的遗传变异更大，这表明通过突变对多种表型的多效性影响来间接选择的重要性。最后，在其调控网络中具有更大连通性的中心基因的突变对表型和适应性有更大的影响。总之，这些发现表明，大效应突变可能会在人群中持续存在，因为它们影响仅在特定环境条件下适应性的特征。因此，了解它们的进化动态需要测量它们在多种自然环境中的影响。
Contrary to previous assumptions that most mutations are deleterious, there is increasing evidence for persistence of large-effect mutations in natural populations. A possible explanation for these observations is that mutant phenotypes and fitness may depend upon the specific environmental conditions to which a mutant is exposed. Here, we tested this hypothesis by growing large-effect flowering time mutants ofArabidopsis thalianain multiple field sites and seasons to quantify their fitness effects in realistic natural conditions. By constructing environment-specific fitness landscapes based on flowering time and branching architecture, we observed that a subset of mutations increased fitness, but only in specific environments. These mutations increased fitness via different paths: through shifting flowering time, branching, or both. Branching was under stronger selection, but flowering time was more genetically variable, pointing to the importance of indirect selection on mutations through their pleiotropic effects on multiple phenotypes. Finally, mutations in hub genes with greater connectedness in their regulatory networks had greater effects on both phenotypes and fitness. Together, these findings indicate that large-effect mutations may persist in populations because they influence traits that are adaptive only under specific environmental conditions. Understanding their evolutionary dynamics therefore requires measuring their effects in multiple natural environments.