Determining the evolutionary forces shaping genotype-by-environment interactions

项目总结 了解进化力量如何塑造数量性状的遗传变异是至关重要的 用于确定人类群体中遗传病的流行率。尽管有许多 基因与环境的相互作用(GxE)对维持 生物和医学上重要性状的变异，我们缺乏对其作用的清楚了解 GxE在形成遗传变异和形成GxE的进化过程中发挥作用。 具体地说，有两个广泛的过程可以促进GxE：对塑料反应的局部适应 以及不同环境中选择性约束的差异。 这项拟议的工作评估了这两个进化过程在塑造中的重要性 GxE在自然种群中的分布。我们将利用大型基因组、转录和表型 系统中的数据集，其中相同的基因类型可以跨多个 生物上真实的环境。首先，我们将使用先前开发的测试的扩展 通过PI来寻找局部适应影响塑料反应的遗传变异的证据， 对GxE的贡献。接下来，我们将开发一种新的分析方法，寻找 等位基因频率和环境特定效应大小，与假设一致 选择性约束形状GxE的变化。最后，我们将测试放松的假设 对很少表达的塑料反应的选择性限制限制了适应性的进化 通过测试减少对只表达的基因的负选择的证据来实现可塑性 在特定环境中。 总体而言，这项工作将确定塑造GxE的进化过程，填补一个关键的空白 在我们对数量性状的变异维持和提供 这些方法将对各种系统中的研究人员有用。

PROJECT SUMMARY Understanding how evolutionary forces shape genetic variation for quantitative traits is crucial for determining the prevalence of genetic disease in human populations. Despite numerous examples that genotype-by-environment interactions (GxE) are important for the maintenance of variation for biologically and medically important traits, we lack a clear understanding of the role that GxE plays in shaping genetic variation and of the evolutionary processes that shape GxE. In particular two broad processes could contribute to GxE: local adaptation for plastic responses and variation in selective constraint across environments. The proposed work evaluates the importance of these two evolutionary processes in shaping GxE in natural populations. We will leverage large genomic, transcriptomic, and phenotypic datasets in systems where identical genotypes can be phenotyped across multiple biologically-realistic environments. First, we will use an extension of a test previously developed by the PI to look for evidence of local adaptation shaping genetic variation for plastic responses, contributing to GxE. Next, we will develop a new analysis looking for a covariance between allele frequency and environment-specific effect sizes, consistent with the hypothesis that variation in selective constraint shapes GxE. Finally, we will test the hypothesis that relaxed selective constraint on rarely-expressed plastic responses limits the evolution of adaptive plasticity by testing for evidence of reduced negative selection on genes that are only expressed in specific environments. Overall, this work will determine the evolutionary processes that shape GxE, filling a crucial gap in our understanding of the maintenance of variation for quantitative traits and providing methods that will be useful to researchers in a variety of systems.