RUI: Quantifying and Interpreting Costs of Phenotypic Plasticity Using Recombinant Inbred Lines of Arabidopsis

物种内的变异反映了遗传和环境因素，表型可塑性指的是由环境变量可预测地触发的一个或多个性状的变异。以温带一年生植物拟南芥（Arabidopsis thaliana）为研究对象，研究越冬温度对开花时间的影响，强调开花时间及其可塑性对适合度的影响。这些现象在拟南芥中得到了广泛的研究，但生态实验尚未评估可塑性是适应性的、中性的，还是可能是不适应的。我们将在模拟暖冬和严冬的环境中使用平行实验室和现场实验来解决两个问题。第一，开花时间及其可塑性是否存在自然选择？我们将量化不同环境的可塑性，并将环境中的适应性和开花时间联系起来。然后，我们可以评估观察到的可塑性是否倾向于在一个或两个环境中增加适应性。第二，健康是否与拥有可塑性有额外的关联？如果这种相关性为负，则被称为可塑性成本，可能表明参与检测或响应环境的基因间接降低了适应性。理论模型表明，可塑性成本可以解释为什么适应性表型可塑性既不是最优的，也不是普遍的。利用拟南芥，将是劳动密集型的，但可以进行大规模的、重复良好的实验室和田间试验，在这些试验中对开花时间和适合度进行评分。开花时间有广泛的自然变异，一些品系具有极强的可塑性，而另一些品系则很少或没有。调控开花时间可塑性的主要基因在许多菌株中都有特征，对比菌株的杂交已经产生了几个实验群体，现在可供拟南芥研究人员使用。我们选择了其中的几个来做实验。这些种群的可变性将增强我们检测自然选择和可塑性成本的能力，并将可塑性及其成本与潜在的遗传机制联系起来。这项拟议中的研究将在巴纳德学院（Barnard College）进行。巴纳德学院是纽约市哥伦比亚大学（Columbia University）下属的一所女子文理学院，在那里，终身教职的评定标准是，教员既能在课堂上表现出色，又能开展涉及本科生的高水平研究。建议的项目符合这些标准。此外，通过在女教师的实验室工作，暑期实习生和学生雇员将获得重要的技能，指导和鼓励，这是在自然科学领域取得成功所必需的。在科学领域未被充分代表的群体在巴纳德的学生群体中得到了充分的代表，并且之前在PI的实验室接受过培训。

Variation within species reflects both genetic and environmental factors, and the term phenotypic plasticity refers to variation in one or more traits predictably triggered by an environmental variable. The temperate annual plant species Arabidopsis thaliana will be used to investigate variation in flowering time triggered by exposure to over-wintering temperatures, emphasizing the impact of flowering time and its plasticity on fitness. These phenomena are widely studied in Arabidopsis, but ecological experiments have not yet assessed whether plasticity is adaptive, neutral, or perhaps even maladaptive. We will address two questions using parallel lab and field experiments in environments mimicking mild and severe winters. First, is there natural selection on flowering time and its plasticity? We will quantify plasticity across environments and correlate fitness and flowering time within environments. We can then assess whether the observed plasticity tends to increase fitness within one or both environments. Second, is fitness additionally correlated with possessing the ability to be plastic? Such a correlation, if negative, is referred to as a plasticity cost and may indicate that the genes involved in detecting or responding to the environment indirectly reduce fitness. Theoretical models indicate that plasticity costs can explain why adaptive phenotypic plasticity is neither optimal nor universal. Using Arabidopsis, it will be labor-intensive but feasible to conduct large, well-replicated lab and field experiments in which flowering time and fitness are scored. There is extensive natural variation for flowering time, with some strains possessing extreme plasticity, and others little or none. Major genes involved in regulating flowering time plasticity have characterized in many strains, and hybridization of contrasting strains has yielded several experimental populations now readily available to Arabidopsis researchers. We have selected several of these for our experiments. The variability harbored by these populations will enhance our ability to detect natural selection and plasticity costs, and to relate plasticity and its costs to underlying genetic mechanisms. The proposed research will be conducted at Barnard College, a liberal arts college for women affiliated with Columbia University in New York City, where the tenure process evaluates faculty as teacher-scholars who can excel in the classroom while also conducting high caliber research that involves undergraduates. The projects proposed are consistent with these criteria. Moreover, by working in a female faculty member's lab, summer student interns and student employees will gain important skills, mentoring, and encouragement necessary for successful careers in the natural sciences. Groups underrepresented in the sciences are well represented in Barnard's student body and have previously received training in the PI's lab.