Dissertation Research: Determining the Mechanisms of Recurrent Cline Evolution in White Clover (Trifolium repens)

研究适应的空间和时间尺度被证明是困难的，因为生态上重要特征的分子基础通常是复杂的。这个项目研究了白三叶草的适应过程，使用了五个独立的地理梯度，这个特征被称为氰化物生成(组织损伤后氰化物的释放)。具体地说，这项工作比较了三叶草基因组中的遗传变异和氰化物发生的两个基因的变异，目的是了解自然选择、基因流和其他过程在多大程度上是跨梯度保守的。还将调查每个梯度中自适应变化的来源。此外，生态实验将被用来确定维持种群内氰化物生成变异的生态权衡。了解创造和维持生态上重要变异的过程，对于预测物种对环境变化的反应和制定未来的政策是至关重要的。这项提议是在一个易于处理的自然系统中研究这些过程的。这项工作将回答有关适应的广泛问题，同时为预测物种反应提供一个有用的案例研究。这项建议为本科生和高中生提供了一个很大的教育推广部分，将三叶草氰化物发生作为理解遗传学和生态学之间联系的基本教学工具。该项目还将在实验室和实地环境中为青年科学家和高中教师提供培训。

Investigating the spatial and temporal scales of adaptation has proven difficult because the molecular basis of ecologically important traits is often complex. This project examines in white clover the process of adaptation using five independent geographical gradients in a well-characterized trait called cyanogenesis (cyanide release after tissue damage). Specifically, this work compares genetic variation throughout the clover genome to variation in the two genes underlying cyanogenesis, with the goal of understanding the degree to which natural selection, gene flow, and other processes are conserved across gradients. The origins of the adaptive variation in each gradient will also be investigated. Further, ecological experiments will be used to identify the ecological trade-offs that maintain cyanogenesis variation within populations. Understanding the processes that create and maintain ecologically important variation is fundamental in making predictions regarding species responses to changing environments and establishing future policy. This proposal investigates these processes in a tractable natural system. This work will answer broad questions about adaptation while providing a useful case study for predicting species responses. This proposal carries a large educational outreach component for undergraduates and high school students, using clover cyanogenesis as a basic teaching tool for understanding the connection between genetics and ecology. The project will also provide training to young scientists and high school teachers in laboratory and field settings.