DISSERTATION RESEARCH: Shedding Light on the Complex Relationship Between Circadian Clock Variation and the Trade-off Between Flowering Time and Flower Size

进化生物学的一个关键问题是如何在种群内保持变异。一种可能的机制是特质之间的权衡。这项研究将证明这种权衡是否发生在猴花（Mimulus guttatus）的自然种群中，以及发育模式是否影响这种权衡。对许多植物来说，在开花时间和种子的数量或质量之间存在权衡。例如，开花早的植物通常花较小，对传粉者的吸引力较小，产生的种子也较小。然而，一个单一的种群可以保持早开花和大花的遗传变异，因为任何一种策略都可能成功。该项目还将为本科生和初高中学生提供实践经验。麻瓜是一种短命的一年生植物。在温室和田间，开花时间和花的大小之间存在着重要的权衡关系。昼夜周期长度可以作为鉴定开花时间变异遗传基础的一个信息丰富的中间性状。生物钟基因网络的特征很好，已知会影响开花时间，并且在种群中有所不同。该项目将识别和表征与花期长度变化相关的基因座，并确定花期长度、差异基因表达和不同开花参数之间的关系。第一个目标将通过确定由单个种群产生的200个已完全测序的自交系的所有成员的周期长度来实现。通过进行全基因组关联图谱，研究人员将确定与周期长度、开花时间和花大小变化相关的位点。第二个目标将使用基于RNA测序的方法来表征先前鉴定位点上的替代等位基因对差异基因表达的贡献。

A key question in evolutionary biology is how variation is maintained within populations. One possible mechanism is trade-offs between traits. This research will demonstrate whether such trade-offs occur in natural populations of the monkeyflower, Mimulus guttatus, and if developmental patterns influence such trade-offs. For many plants there is a trade-off between flowering time and number or quality of seeds. For example, plants that flower early typically have smaller flowers that are less attractive to pollinators and produce smaller seeds. However, a single population could maintain genetic variation for both early flowering and large flowers because either strategy might be successful. The project also will provide hands-on experience to undergraduates and outreach to middle and high school students.Mimulus guttatus is a short-lived annual. In both the greenhouse and field there exists a centrally important trade-off between flowering time and flower size. Circadian period length can serve as a highly informative intermediate trait for identifying the genetic underpinnings of flowering time variation. The circadian clock gene network is well characterized, is known to affect flowering time, and varies among populations. The project will identify and characterize loci associated with changes in period length, and determine relationships between period length, differential gene expression, and different flowering parameters. The first aim will be accomplished by determining period length of all members of a pre-existing set of 200 fully sequenced inbred lines generated from a single population. By conducting genome-wide association mapping the researchers will identify loci associated with variation in period length, flowering time, and flower size. The second aim will be accomplished using an RNA sequencing based approach to characterize the contribution of alternate alleles at previously identified loci to differential gene expression.