Genomic response to selection for flowering time in Arabidopsis thaliana

进化遗传学的一个主要目标是了解遗传变化如何促进适应性进化。为了达到这样的理解，有必要将选择下性状的遗传基础的知识与自然选择如何作用于现有遗传变异的知识结合起来。实现这一目标一直是一个重大挑战，因为大多数感兴趣的性状是复杂的，这意味着有许多遗传和环境因素影响表型表达。上位性相互作用、基因型-环境相互作用和多效性的存在进一步增加了复杂性。尽管数量性状基因座（QTL）分析的出现提高了我们剖析复杂性状遗传基础的能力，但在相对简单的遗传背景下估计的等位基因效应是否能准确预测复杂遗传背景或多种环境中选择的进化结果仍不清楚。在这里，我建议调查的基因组反应选择早开花时间在远交人口的拟南芥，结合了19个加入的遗传多样性。这个项目将允许我们目前的知识与经验数据的方式选择在基因组水平上运作的开花时间的分子基础的整合。在这项研究中确定的遗传因素将代表在进化过程中很重要的因素，他们的身份将与已知的候选基因的开花时间进行比较。除了测试现有开花时间遗传基础模型对预测未来进化变化的适用性外，该项目还将为发现在调节开花时间中起重要作用的新遗传因子提供有价值的手段。选择实验将在两种环境条件下进行，模拟春季或秋季种子发芽所遇到的光周期和冷暴露。通过比较这两种环境条件下的结果，我们将能够研究基因与环境的相互作用对选择反应的影响。此外，将在两种环境条件下对大量生活史性状进行表型选择分析，以研究对选择的相关反应和可能影响实验结果的权衡。

A major goal of evolutionary genetics is to understand how genetic changes contribute to adaptive evolution. To achieve such an understanding it is necessary to combine knowledge of the genetic basis of traits under selection with knowledge of how natural selection acts on the genetic variation available. It has been a major challenge to achieve this goal because most traits of interest are complex, meaning that there are many genetic and environmental factors affecting phenotypic expression. Further complexity arises from the presence of epistatic interactions, genotype-environment interactions and pleiotropy. Although the emergence of quantitative trait locus (QTL) analysis has improved our ability to dissect the genetic basis of complex traits, it remains unclear whether allelic effects estimated in a relatively simple genetic background will accurately predict the evolutionary outcome of selection in a complex genetic background, or in multiple environments. Here, I propose to investigate the genomic response to selection for earlier flowering time in an outbred population of Arabidopsis thaliana that combines the genetic diversity of 19 accessions. This project will allow for the integration of our current knowledge of the molecular basis of flowering time with empirical data on the way selection operates at the genome level. Genetic factors identified in this study will represent factors that are important in the evolutionary process, and their identity will be compared with known candidate genes for flowering time. In addition to testing the applicability of current models of the genetic basis of flowering time to predicting future evolutionary change, this project will also provide a valuable means for the discovery of new genetic factor that play an important role in mediating flowering time. Selection experiments will be performed under two environmental conditions, simulating the photoperiod and cold exposure encountered by seeds germinating in the spring or the fall. By comparing the results under these two environmental conditions we will be able to investigate the influence of gene-by-environment interaction effects on response to selection. In addition, phenotypic selection analysis will be performed for a large number of life-history traits under both environmental conditions to investigate correlated responses to selection and trade-offs that could affect the outcome of the experiment.