Does hybridisation promote tree species diversification in the Amazon?

杂交是否促进了亚马逊的树种多样化？

• 批准号: NE/V012258/1
• 负责人: R. Toby Pennington
• 金额: $ 82.64万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV012258%2F1
• 关键词: Does; hybridisation; promote; tree; species

The Amazon rain forest holds the highest diversity of plant species on Earth, but the mechanisms which gave rise to this superlative diversity remain enigmatic. A long-held view, first proposed by Alfred Russell Wallace, was that this diversity reflected gradual accumulation of species over long geological periods due to minimal extinction. However, more recent studies point to a large contribution of rapid and recent formation of new species of some groups of trees. Inga, the focus of this proposal, is an exemplar for these recent evolutionary radiations, having evolved at least 300 species in the last 6 million years in the Amazon and other Latin American rain forests. Moreover, in Amazonia hundreds of tree species can coexist in a single hectare (up to 300), and this extremely high local diversity is largely accounted for by a few species-rich genera such as Inga. The high overall and local diversity of Amazonian forests suggests parallels with other species-rich systems where evolutionary radiation - the rapid rise of many species from one ancestor population - produced many new lineages. Here, we aim to develop Inga as a model for plant species radiation in Amazonia, building global examples beyond animals (e.g. Darwin's finches, rift lake cichlid fishes) and a few plant groups that are geographically restricted (e.g. Hawaiian silverswords), or non-tropical (e.g. Andean lupins).In particular, we will investigate the role of hybridization, the interbreeding between groups of species, as recent work shows it is a major cause of evolutionary radiations. Hybridization's effect on evolutionary radiation has not yet been studied within tropical trees, despite being widely acknowledged as a powerful creative force in plant evolution. Hybridization generates morphological and genetic novelty, impacting the rate of speciation in many groups and is evident in all major adaptive radiation events for which multiple sequenced genomes exist. In plants, one mechanism of speciation, polyploidy or the doubling of genome size, which is often linked with hybridisation, is known to be particularly important. While the prevailing view has been that hybridization between tropical tree species is exceptionally rare, this view is challenged by recent DNA sequence data. In Inga, hybridization has been recently demonstrated to occur, despite prior reports of species intersterility, and a few chromosome counts have demonstrated that unrelated species are polyploid. Here, using new genomic techniques for the first time in Amazonian trees, we aim to test the significance of hybridization and polyploidy in Inga diversification. We will use DNA sequences for 810 genes generated by the target capture technique to find signatures of hybridisation and polyploidy across all 300 Inga species. Because insect herbivore pressure demonstrably structures local Inga communities at fine spatial scales, we suspect that a powerful selective factor driving divergence among Inga species may be chemical defences. We will therefore search for signatures of selection among 113 chemical defence gene regions in our target capture gene set. We will then generate whole-genome data for multiple populations of a select number of widespread Inga species to determine whether groups of chemical defence genes are transferred together during hybridization in 'linkage blocks', thereby facilitating the movement of adaptive variation between species. Finally, we will use our target capture data to identify possible polyploid Inga species and use genome sequencing to discover if they are the result of hybridisation and genome doubling (allopolyploidy) or genome doubling without hybridisation (autopolyploidy).This project will improve our understanding of the evolution of a large portion of Amazonian tree diversity, because Inga is an exemplar for other species-rich tree genera that have high local species diversity and underwent similar recent evolution.

亚马逊雨林是地球上植物物种多样性最多的，但是导致这种最高级多样性的机制仍然神秘。阿尔弗雷德·罗素·华莱士（Alfred Russell Wallace）最初提出的长期观点是，这种多样性反映了由于最小的灭绝而导致的长期地质时期逐渐积累。然而，最近的研究表明，一些树木的新物种的快速和近期形成了很大的贡献。 INGA是该提案的重点，是这些最近进化辐射的典范，在过去600万年中，在亚马逊和其他拉丁美洲雨林中，至少有300种进化。此外，在亚马逊中，数百种树种可以在一公顷（最高300公顷）中共存，而这种极高的局部多样性在很大程度上由INGA等少数物种的属来解释。亚马逊森林的总体和局部多样性表明，与其他富含物种的系统相似，在这些系统中，进化辐射（许多物种从一个祖先种群中的迅速上升）产生了许多新的谱系。在这里，我们旨在开发INGA作为亚马逊植物物种辐射的模型，在动物（例如Darwin's Finches，Rift Lake Cichlid Fishes）和几个受到限制的植物群（例如，夏威夷银牌）或非恋爱中（例如Andean lupins）中的角色，尤其是shy Brbrbrive conterbrive coolbrive，建立了全球范围。工作表明这是进化辐射的主要原因。杂交对进化辐射的影响尚未在热带树中研究，尽管人们被广泛认为是植物进化中的强大创造力。杂交产生形态学和遗传新颖性，影响许多组的物种速率，并且在所有主要的测序基因组都存在的所有主要自适应辐射事件中都很明显。在植物中，众所周知，一种通常与杂交相关的物种形成，多倍体或基因组大小的加倍，这一点尤其重要。尽管主要的观点是热带树种之间的杂交异常罕见，但这种观点受到最近的DNA序列数据的挑战。在INGA中，尽管事先报道了物种互性性，但最近已证明杂交发生了，并且一些染色体计数已证明无关的物种是多倍体。在这里，我们首次在亚马逊树木中使用新的基因组技术，旨在测试杂交和多倍体在INGA多样化中的重要性。我们将使用目标捕获技术生成的810个基因的DNA序列，以在所有300种INGA物种中找到杂交和多倍体的特征。由于昆虫的草食动物压力明显地结构了当地INGA社区的精细空间尺度，因此我们怀疑驱动INGA物种差异的强大选择性因素可能是化学防御剂。因此，我们将在目标捕获基因集中的113个化学防御基因区域之间寻找选择的签名。然后，我们将为选择数量的广泛INGA物种的多个种群生成全基因组数据，以确定在“链接块”中杂交期间是否将化学防御基因组一起转移，从而促进物种之间适应性变化的运动。最后，我们将使用目标捕获数据来识别可能的多倍体INGA物种，并使用基因组测序来发现它们是否是杂交和基因组的结果，并且基因组加倍（杂质素）或基因组不加倍而没有杂交（自动卵布）（自动卵性）。这将改善我们对Amazon Ingrian Insplian Ingrian Ingraar is exem Ingra的了解，因为Exem at exem Ingraar是Inga的多部分，因为Inga的发展是Inga的，因为Ingraar是Inga的多部分，因此物种多样性并经历了类似的最近进化。

项目成果

Hybridization: a 'double-edged sword' for Neotropical plant diversity

杂交：新热带植物多样性的“双刃剑”

• DOI: 10.1093/botlinnean/boab070
• 发表时间: 2022
• 期刊: Botanical Journal of the Linnean Society
• 影响因子: 2.4
• 作者: Schley R