Evolutionary Genomics of Plant Adaptation and Speciation

植物适应和物种形成的进化基因组学

• 批准号: RGPIN-2022-03002
• 负责人: Rieseberg, Loren
• 金额: $ 6.92万
• 依托单位: University of British Columbia
• 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=746341
• 关键词: Evolutionary; Genomics; Plant; Adaptation; Speciation

Recombination plays a central role in how new species arise. Three evolutionary forces (selection, mutation, and genetic drift) create differences between populations, while two other forces (gene flow and recombination) homogenize them. Evolutionary biologists have long recognized this antagonism, leading many to question the likelihood of speciation in the absence of geographic barriers to mating between diverging populations. However, in recent decades, speciation with gene flow has received both theoretical and empirical support. One emerging theme is the evolution of mechanisms that suppress recombination between genes underlying local adaptation and/or reproductive isolation. Here, I propose to leverage genomic and germplasm resources for sunflower to test fundamental hypotheses regarding the origin, establishment, and evolutionary role of recombination suppressors. First, I will investigate the genomic basis of polymorphic recombination cold spots. This will allow me to test theoretical predictions regarding how different recombination suppressors contribute to ecological divergence and speciation, as well as to explore parallels between the evolution of recombination cold spots on autosomes versus sex chromosomes. Second, I will determine the mechanisms by which such regions become established. Models of divergence with gene flow typically assume that recombination suppression evolves to reduce recombination between locally adapted alleles. However, recombination modifiers (e.g., chromosomal inversions) might spread for other reasons, including direct selection on inversion breakpoints or due to chance events in small populations (genetic drift). Third, I will search for associations between these regions and traits that cause individuals to preferentially mate with others in the same population (i.e., assortative mating). Such associations are predicted to facilitate speciation with gene flow. Overall, this work will help define the role of recombination suppressors in plant adaptation and speciation. Also, a better understanding of the recombination landscape in sunflower will facilitate breeding programs in this important oilseed crop. Additional benefits to Canada will accrue from the training of highly qualified personnel in ecological genetics, genomics, and bioinformatics.

进化在新物种的产生中起着核心作用。三种进化力量（选择、突变和遗传漂变）造成了种群之间的差异，而另外两种力量（基因流动和重组）则使它们同质化。进化生物学家长期以来一直认识到这种对抗，这导致许多人质疑在不同种群之间没有地理障碍进行交配的情况下物种形成的可能性。然而，近几十年来，物种形成与基因流得到了理论和经验的支持。一个新出现的主题是机制的演变，抑制基因之间的重组当地适应和/或生殖隔离。在这里，我建议利用向日葵的基因组和种质资源来测试有关重组抑制子的起源，建立和进化作用的基本假设。首先，我将研究多态性重组冷点的基因组基础。这将使我能够测试关于不同的重组抑制因子如何促进生态分歧和物种形成的理论预测，以及探索常染色体上重组冷点与性染色体进化之间的相似之处。第二，我将确定建立这些区域的机制。基因流趋异模型通常假设重组抑制的进化是为了减少局部适应等位基因之间的重组。然而，重组修饰剂（例如，染色体倒位）可能由于其他原因传播，包括在倒位断点上的直接选择或由于小群体中的偶然事件（遗传漂变）。第三，我将寻找这些区域与导致个体优先与同一群体中的其他人交配的特征之间的关联（即，交配）。这种关联预计将促进物种形成与基因流。总的来说，这项工作将有助于确定重组抑制因子在植物适应和物种形成中的作用。此外，更好地了解向日葵的重组景观将有助于这一重要油料作物的育种计划。加拿大还将从培养生态遗传学、基因组学和生物信息学方面的高素质人才中获得更多的利益。