Selection, mutation and evolution in plant populations

进化生物学试图了解地球上生命多样性的潜在过程。目前所有的多样性，无论是在门、种或个体之间，都起源于种群内的突变。新突变的适应性效应和它们的出现率是进化中最重要的两个量，因为它们影响进化速率、常设遗传变异和其他特征的优势，如近亲繁殖的速率。这里提出的研究将解决有关植物进化中突变的原因和后果的基本问题。 大多数种子植物同时具有雄性和雌性性器官，因此在自花受精率上经历选择。交配系统反过来影响常设的遗传变异和长期的人口持久性。虽然这个主题已经产生了丰富的理论，实验测试远远落后。特别是，我们仍然不明白为什么这么多人口是部分自我实现的。我们以前曾提出，自花受精后代的数量可能往往与通过异交产生的既是母亲又是父亲的后代的数量相关，并且这些相关性将维持混合交配。使用最近开发的分子工具，我们将测试模型预测的自然种群的部分自我繁殖的植物。利用遗传模型和高性能计算，我们将研究多效性突变所产生的适应性成分之间的相关性如何影响自交率的长期进化。 拟议研究的第二个主要领域是调查基因突变传递给后代的性别偏见。几十年来，人们已经知道动物物种经常表现出雄性偏向的突变。本实验室的早期工作发现，雄性偏向的突变传递在裸子植物和被子植物中都存在。然而，植物中这种偏见的原因仍然是一个谜。我们将通过研究裸子植物的分子进化速率来检验这样一个假设，即与雌配子体相比，花粉产生中细胞分裂的数量更高，这导致了雄性偏向。我们将使用共聚焦显微镜来测试是否实验诱导的突变更强烈地选择对女性比男性配子体在开花植物。我们将测试诱变是否会引起表观遗传变化，这种变化通过精子传递比通过卵子传递对存活后代更有害。 这里提出的研究旨在促进我们对选择和突变在塑造植物进化中的综合作用的理解。这些项目在研究生和本科生两个层次提供现代和先进的培训机会，包括生物信息学，计算机模拟，共聚焦显微镜，统计分析和野外生物学技术。

Evolutionary biology seeks to understand the processes underlying the diversity of life on earth. All current diversitywhether among phyla, species or individualsoriginated as mutations within populations. The fitness effects of new mutations and their rate of appearance are two of the most important quantities in evolution because they affect evolutionary rates, standing genetic variation and the advantage of other features such as the rate of inbreeding. The research proposed here will address fundamental questions concerning the causes and consequences of mutation in plant evolution. Most species of seed plant possess both male and female sexual organs and therefore experience selection on the rate of self-fertilization. The mating system in turn influences standing genetic variation and long-term population persistence. Although this topic has generated a rich body of theory, experimental tests lag far behind. In particular, we still do not understand why so many populations are partially self-fertilizing. We have previously proposed that the number of self-fertilized offspring may often be correlated with the number of offspring produced as both mother and father by outcrossing, and that these correlations will maintain mixed mating. Using recently developed molecular tools, we will test model predictions in natural populations of a partially self-fertilizing plant. Using genetic models and high-performance computing, we will investigate how correlations among fitness components, generated by pleiotropic mutation, affect the long-term evolution of selfing rates. The second major area of proposed research investigates sex biases in mutation transmission to offspring. It has been known for several decades that animal species often exhibit male-biased mutation. Earlier work in our lab discovered that male-biased mutation transmission also exists in both gymnosperms and angiosperms. The cause of the bias in plants, however, remains a mystery. We will test the hypothesis that the higher number of cell divisions in the production of pollen compared to female gametophytes causes the male bias by studying rates of molecular evolution in gymnosperms. We will use confocal microscopy to test whether experimentally induced mutations are more strongly selected against in female than in male gametophytes in a flowering plant. We will test whether mutagenesis causes epigenetic changes that are more deleterious to surviving offspring when transmitted through sperm than through egg. The research proposed here aims to advance our understanding of the combined roles of selection and mutation in shaping plant evolution. The projects provide modern and advanced training opportunities at both the graduate and undergraduate levels in several areas including bioinformatics, computer-based simulation, confocal microscopy, statistical analysis and techniques in field biology.