Mutation, Selection and Divergence of Plant Populations

植物种群的突变、选择和分化

• 批准号: RGPIN-2022-04288
• 负责人: Johnston, Mark
• 金额: $ 2.04万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745752
• 关键词: Mutation; Selection; Divergence; Plant; Populations

Evolutionary biology seeks to understand the processes underlying the diversity of life on earth. All current diversity-whether among species, populations or individuals-originated by mutation. Mutations accumulating in geographically separated populations can generate both phenotypic divergence and reproductive isolation, the first step in the formation of new species. The research proposed here will address how mutations cause population divergence and reproductive isolation within Lobelia cardinalis, a widespread diploid species ranging from southern Canada to Central America. Because of multiple paternity, the male and female functions of plants have different optimal levels of offspring provisioning. Female parents are related by half to each of their offspring. Male parents, in contrast, are related by half only to their own offspring and by less than half to offspring of other sires. This difference generates a sexual conflict: in theory, female parents benefit from equal provisioning of all offspring, while each male parent benefits by higher provisioning of its own offspring at the expense of other males. We have (1) discovered that crosses between geographically divergent L. cardinalis populations often result in abnormally small or large seeds and developed methods (2) to test for evidence of sexual conflict and (3) to distinguish sexual conflict from other causes of abnormal offspring provisioning. This set of projects will investigate both the genomics and developmental biology of reproductive isolation arising from sexual conflict evolving independently in geographically separated populations. We have recently discovered that experimental crosses among geographically separate populations of L. cardinalis always produce seeds but that, depending on the population pair and the crossing direction, the seeds are either all sexual, all asexual (apomictic) or a mixture. Sexual seed production in angiosperms involves a complex set of coordinated interactions between maternal and paternal genomes in both embryo and endosperm. Apomixis following pollination represents complete post-mating reproductive isolation. Using molecular and microscopy techniques developed in our lab, we will explore the genomic, genetic and developmental basis of apomixis in L. cardinalis, including the role of repetitive elements and genome size. This set of projects will thus address the evolutionary origin of both apomixis and post-mating reproductive isolation, a defining step in speciation. The proposed research aims to advance our understanding of the combined roles of mutation and selection in shaping plant evolution and the divergence of populations. 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 field biology.

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，无论是在物种、种群还是个体之间，都起源于突变。在地理上分离的种群中积累的突变可以产生表型分化和生殖隔离，这是新物种形成的第一步。这里提出的研究将解决突变如何导致种群分化和生殖隔离内半边莲，广泛分布的二倍体物种，从加拿大南部到中美洲。植物的雄性功能和雌性功能由于多重父系关系而具有不同的后代供应最优水平。雌性父母与其子女各有一半的血缘关系。相比之下，雄性父母只与自己的后代有一半的亲缘关系，与其他父系后代的亲缘关系不到一半。这种差异产生了性冲突：从理论上讲，雌性父母受益于所有后代的平等供应，而每个雄性父母都受益于牺牲其他雄性的代价来更高地供应自己的后代。我们发现（1）地理上不同的L.红雀种群经常导致异常小或大的种子，并开发了方法（2）测试性冲突的证据和（3）将性冲突与异常后代供应的其他原因区分开来。这一系列的项目将调查基因组学和发育生物学的生殖隔离所产生的性冲突，在地理上分开的人口独立演变。我们最近发现，在地理上分离的L。红雀总是产生种子，但根据种群对和杂交方向，种子要么是全有性的，要么是全无性的（无融合生殖），要么是混合的。被子植物有性种子的产生涉及到胚和胚乳中母本和父本基因组之间复杂的相互作用。授粉后的无融合生殖代表完全的交配后生殖隔离。利用本实验室开发的分子和显微技术，我们将探索L.红雀，包括重复元件和基因组大小的作用。因此，这套项目将解决无融合生殖和交配后生殖隔离的进化起源，物种形成的一个决定性步骤。拟议的研究旨在促进我们对突变和选择在塑造植物进化和种群分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上提供了包括生物信息学、计算机模拟、共聚焦显微镜、统计分析和野外生物学在内的几个领域的现代和高级培训机会。