The evolution of adaptive genetic variation in relation to speciation divergence and introgression in conifers

与针叶树物种分化和基因渗入相关的适应性遗传变异的进化

• 批准号: RGPIN-2016-05415
• 负责人: Bousquet, Jean
• 金额: $ 6.41万
• 依托单位: Université Laval
• 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=765390
• 关键词: evolution; adaptive; genetic; variation; relation

Boreal conifers are among the living organisms with largest natural distributions. They are usually characterized by high genetic diversity and gene flow. We have shown that history has been an important factor in shaping this diversity given the existence of distinct geneticlineages at the intraspecific level, that have emerged as a result of vicariance during ice ages. This isolation may also have resulted in differential adaptation given thedifferent climates characterizing glacial refugia, in addition to more recent natural selection during Holocene, following the retreat of glaciers andrecolonization. We have also shown that this post-glacial colonization has also resulted in the existence of contact zones between hybridizing species andbetween intraspecific lineages, respectively called hybrid or suture zones. Therefore, genetic diversity can be highly structured in these zones, with different patterns observed for different genomes and even among genomic regions within the nuclear genome.The long-term goal of our research program is to decipher the genomic architecture of genetic adaptation in long-lived undomesticated organisms with wide distributionsuch as boreal conifers, and how it is related to speciation. One major aim is to identify how neutral and adaptive genetic variation are shaped in contact zones andhow species and lineages conserve their integrity in spite of ongoing gene flow. Another aim is to identify genes, gene families andnetworks responsible for adaptation to abiotic factors such as climate, and how these are conserved among conifers.Using association studies with environmental factors and adaptive traits, we will pursue the comparative analysis of adaptive molecular variation at the interspectificlevel among conifers. We will do so for boreal spruces but also by comparing subtropical mountain and boreal firs. We will further study hybrid zones and intraspecific zones of suture to evaluate genomicpermeability and identify which genomic regions and nuclear loci are responsible for genetic divergence potentially leading to speciation. We will further evaluate how permeable regionsare affected by introgression and possible directionality. We will further conduct these studies in a comparative context by relating the results obtained at theintraspecific level between glacial lineages and between hybridizing conifer congeneric species. The results will allow to better monitor adaptive genetic variation and the factors affecting its short- and long-term evolution, to better understand how species are maintaining their genetic integrity and the evolution of adaptive divergence in the presence of genetic contact. The results will be useful for the management of natural genetic resources and for tree breeding purposes, both in the context of increasing climate instability and change.

北方针叶树是自然分布最广的生物体之一。它们通常具有高度的遗传多样性和基因流动的特点。我们已经证明，历史是形成这种多样性的一个重要因素，因为在种内水平上存在着不同的基因谱系，这些基因谱系是冰河时代更替的结果。这种隔离也可能导致不同的适应，因为不同的气候具有冰川避难所的特点，此外，在冰川消退和重新殖民之后，全新世期间较新的自然选择也可能导致不同的适应。我们还表明，这种冰期后的殖民也导致了杂交物种之间和种内谱系之间存在接触区，分别称为杂交区或缝合区。因此，遗传多样性可以在这些区域高度结构化，不同的基因组甚至核基因组内的基因组区域之间可以观察到不同的模式。我们研究计划的长期目标是破译长期生存的非驯化生物的遗传适应的基因组结构，以及它与物种形成的关系。一个主要目标是确定接触区中性和适应性遗传变异是如何形成的，以及物种和谱系如何在持续的基因流动中保持其完整性。另一个目的是确定与气候等非生物因子相适应的基因、基因家族和网络，以及这些基因、基因家族和网络在针叶树中是如何保守的。利用与环境因素和适应性状的关联研究，我们将在种间水平上进行针叶树种间适应分子变异的比较分析。我们将对北方云杉这样做，但也会比较亚热带山区和北方冷杉。我们将进一步研究杂交区和种内缝合区，以评估基因组的渗透性，并确定哪些基因组区域和核基因座负责可能导致物种形成的遗传差异。我们将进一步评估渗透区域如何受到入渗和可能的方向性的影响。我们将进一步在比较的情况下进行这些研究，将在种内水平上冰川谱系之间和杂交针叶树同属物种之间的结果联系起来。这些结果将有助于更好地监测适应性遗传变异及其短期和长期进化的影响因素，更好地了解物种如何在遗传接触存在的情况下保持其遗传完整性和适应性分化的进化。在气候不稳定和气候变化日益加剧的背景下，研究结果将有助于自然遗传资源的管理和树木育种。