喜马拉雅-横断山地区红豆杉属同倍体杂交物种形成研究

杂交在植物的进化和物种形成中具有重要作用。在杂交介导的物种形成中，同倍体杂交物种形成较为罕见，目前植物中仅有少数案例。我们在红豆杉属的谱系地理学研究过程中发现分布于四川西南部的"Emei type"谱系是由喜马拉雅红豆杉和中国红豆杉杂交形成的同倍体种，但其杂交成种机制尚不清楚。本项目拟选取以上三个物种为研究对象，采用居群遗传学和谱系地理学的研究方法，通过对叶绿体和核基因两个基因组数据的分析，揭示其遗传多样性和遗传结构，追溯它们的居群进化历史。此外，利用生态位模拟和生态位分化的研究方法，检测这三个物种生态位的分化程度。基于以上结果，阐明其可能的同倍体杂交成种机制。研究结果不仅有助于理解红豆杉属植物的物种形成方式和喜马拉雅-横断山地区植物多样化机制，而且也可为该属自然资源的可持续利用和保护提供科学依据。

Hybridization plays an important role in plant evolution and speciation. Homoploid hybrid speciation (HHS) is considered to be rare, with only a few well-documented cases reported in plants to date. The Taxus "Emei type" lineage, which is mainly found in southwest Sichuan Province, probably arose via HHS involving hybridization between Taxus wallichiana and T. chinensis based on our previous phylogeographic studies. However, the speciation process is unclear. In the present project, by combining data from the chloroplast and nuclear genome, we aim to examine the genetic diversity and structure of the invovled species, to unravel the evolutionary history of these populations, with population genetics and phylogeographic analyses. In addition, we will use ecological niche modelling and ecological divergence analysis to test the level of their ecological niche differentiation. The results may reveal possible mechanisms underlying this case of homoploid hybrid speciation. The project not only helps to understand the speciation processes in Taxus and diversification mechanisms of plants in the Himalaya-Hengduan Mountains region, but also provides valuable baseline information for the sustainable use and conservation of the natural resources of Taxus.