Selection, mutation and evolution in plant populations

植物种群的选择、突变和进化

• 批准号: RGPIN-2016-06778
• 负责人: Johnston, Mark
• 金额: $ 2.33万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684430
• 关键词: Selection; mutation; evolution; plant; populations

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.

进化生物学试图了解地球上生命多样性背后的过程。目前所有的多样性，无论是门、物种还是个体之间，都起源于种群内的突变。新突变的适应度效应及其出现率是进化中两个最重要的量，因为它们影响进化率、持续遗传变异以及其他特征的优势，例如近交率。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。 ******大多数种子植物物种都具有雄性和雌性性器官，因此会经历自体受精率的选择。交配系统反过来影响长期的遗传变异和长期的种群持续性。尽管这个主题已经产生了丰富的理论体系，但实验测试却远远落后。特别是，我们仍然不明白为什么如此多的种群是部分自体受精的。我们之前提出，自体受精后代的数量通常可能与通过异交产生的母亲和父亲后代的数量相关，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，我们将在部分自花受精植物的自然种群中测试模型预测。使用遗传模型和高性能计算，我们将研究由多效性突变产生的适应度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突变传播给后代的性别偏见。几十年来，人们已经知道动物物种经常表现出偏雄性的突变。我们实验室的早期工作发现，裸子植物和被子植物中也存在雄性偏向的突变传播。然而，植物产生这种偏差的原因仍然是个谜。我们将通过研究裸子植物的分子进化速率来检验以下假设：与雌配子体相比，花粉产生过程中细胞分裂次数较多，导致雄性偏见。我们将使用共聚焦显微镜来测试实验诱导的突变在开花植物中的雌性配子体中是否比雄性配子体受到更强的选择。我们将测试诱变是否会导致表观遗传变化，当通过精子传播时，这种变化对幸存的后代比通过卵子传播时更有害。 ******这里提出的研究旨在加深我们对选择和突变在塑造植物进化中的综合作用的理解。这些项目为研究生和本科生提供生物信息学、计算机模拟、共焦显微镜、统计分析和野外生物学技术等多个领域的现代和高级培训机会。