Unlocking the genomics of species formation in Amazonian and high-latitude birds

解锁亚马逊和高纬度鸟类物种形成的基因组学

• 批准号: RGPIN-2022-04817
• 负责人: Weir, Jason
• 金额: $ 2.91万
• 依托单位: University of Toronto
• 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=744910
• 关键词: Unlocking; genomics; species; formation; Amazonian

My research investigates why the tropics harbor an extraordinary number of species in comparison with high latitudes. A key theory links high tropical richness to accelerated speciation-the formation of new species-yet our understanding of the biogeographic drivers of speciation and the length of time to complete speciation in biodiverse tropical regions remains rudimentary. The goal of this proposal is to harness the power of genomic data to determine the biogeographic processes that drive avian speciation in the most species-rich region of the planet-the Amazon basin-and to test whether the length of time required to complete speciation is shorter there compared to species-poor communities of Canada. Wide rivers are known to be effective barriers for understory birds over much of Amazonia and represent the most probable biogeographic barriers promoting Amazonian speciation. Yet our recent work demonstrated rivers cease to be effective dispersal barriers in headwater regions of the Amazon periphery, where species readily cross narrow river channels and hybridize. However, during glacial periods forests retracted out of headwater regions and large rivers may have been effective barriers driving speciation. To test this theory, our first set of projects will look for the expected genomic signatures of changes in population size and recent range expansion into headwater regions across a series of avian species. Following their isolation by geographic barriers, populations begin to accumulate genetic differences, culminating in reproductive isolation: the inability to produce successful offspring with each other. Reproductive isolation marks the endpoint of speciation. The second set of projects will sequence whole genomes and study hybridization to test the evolutionary speed at which reproductive isolation evolves in tropical versus high-latitude regions. My lab will quantify how species' genomes resist becoming homogenized between species through interbreeding at hybrid zones-geographic regions where diverging species come into contact and interbreed. Each hybrid zone provides a snapshot in time of the speciation process, with cessation of genomic homogenization between species occurring once reproductive isolation is complete. By analysing avian hybrid zones between 22 species pairs, varying from a few hundred thousand to over four million years in evolutionary age, we will determine whether the timeline to reproductive isolation is faster in Amazonia, as expected if rapid speciation drove high species richness. We will also sequence high-quality reference genomes for 15 pairs of sister species in Canada and 15 in the Amazon and compare rates at which genomes acquire chromosomal rearrangements. These rearrangements have been implicated as important in generating reproductive isolation. Together, these large-scale comparative projects will enable my lab to test the role of speciation in contributing to the Amazon's high species richness.

我的研究调查了为什么热带地区比高纬度地区拥有数量惊人的物种。一个关键的理论将热带物种的高度丰富与加速的物种形成联系起来新物种的形成然而，我们对物种形成的地理驱动力以及在生物多样性丰富的热带地区完成物种形成的时间长度的理解仍然是初步的。该提案的目标是利用基因组数据的力量来确定推动地球上物种最丰富的地区-亚马逊盆地-鸟类物种形成的地理过程，并测试完成物种形成所需的时间长度是否比加拿大物种贫乏的社区更短。宽的河流被认为是亚马逊河流域林下鸟类的有效屏障，也是促进亚马逊河物种形成的最可能的地理屏障。然而，我们最近的工作表明，在亚马逊周边的源头地区，河流不再是有效的扩散障碍，在那里，物种很容易穿过狭窄的河道并杂交。然而，在冰川时期，森林从源头地区和大河中退缩出来，可能是推动物种形成的有效障碍。为了验证这一理论，我们的第一组项目将寻找一系列鸟类种群规模变化的预期基因组特征，以及最近向源头地区的范围扩张。由于地理上的阻隔，种群开始积累遗传差异，最终导致生殖隔离：彼此之间无法产生成功的后代。生殖隔离标志着物种形成的终点。第二组项目将对整个基因组进行测序，并研究杂交，以测试热带和高纬度地区生殖隔离的进化速度。我的实验室将量化物种的基因组如何通过杂交区（不同物种接触和杂交的地理区域）的杂交抵抗物种之间的同质化。每个杂交区都提供了物种形成过程的快照，一旦生殖隔离完成，物种之间的基因组同质化就会停止。通过分析22个物种对之间的鸟类杂交区，从几十万年到超过400万年的进化年龄，我们将确定是否时间轴生殖隔离更快的亚马逊河流域，如预期的那样，如果快速的物种形成驱动高物种丰富度。我们还将对加拿大15对姐妹物种和亚马逊15对姐妹物种的高质量参考基因组进行测序，并比较基因组获得染色体重排的速率。这些重排在产生生殖隔离方面具有重要意义。总之，这些大规模的比较项目将使我的实验室能够测试物种形成在亚马逊高物种丰富度中的作用。