中国特有种无距耧斗菜的物种形成和适应性进化

The genus Aquilegia (Ranunculaceae) has been a model system for investigating a wide range of questions relating to the evolution and ecology, due to its phenotypic diversity, habitat range. In Aquilegia, two contrasting, recent radiations have occurred simultaneously in North America and Europe, after the colonization by an Asian ancestor, and both have given rise to about the same number of species (Bastida et al. 2010). In North America, the diversification of the Aquilegia groups has been associated with floral adaptation to different pollinators and recent speciation events may have occurred in sympatry. In Europe, the Aquilegia groups have diverged in response to adaptation to different habitats and recent speciation events may have occurred in allopatry. The elongated petals that form a nectar spur in Aquilegia is a key evolutionary innovation and leads to a recent and rapid radiation. The same number species of Aquilegia occurred in Asia. But we still unknow the evolutionary pattern in Asian lineage. There is an interesting Aquilegia species in Asian, which has no spur. This species is A. ecalcarata, only spurless species in Aquilegia, and it is endemic to China. Because of spurless condition of A. ecalcarata, its systematic position and speciation is confusing. In this research project, we will find out the evolutionary adaptation pattern of A. ecalcarata based on pollination, genetic diversity, and phylogeography. We will compare variation of floral characteristics and observe pollinator among populations of A. ecalcarata and among sympatric species of Aquilegia with A. ecalcarata in order to find out the relationship between floral characteristics and pollinators in different ecological habitat. We will estimate the genetic diversity and genetic structure in most populations of A. ecalcarata in China, using Simple Sequence Repeat (SSR) in order to find out how they response to adaptation to different habitats. To determine the speciation and divergence pattern of A. ecalcarate, we will use a phylogeographic analysis of most populations across its geographic ranges, using internal transcribed spacer (ITS) sequence, four low-copy nuclear genes, and some chloroplast (cp) DNA fragments. This project will illustrate the speciation and divergence of Asian Aquilegia, and will give a complement for theories of Aquilegia speciation and adaptation.

耧斗菜属因其形态特征多样化、生境适应性广，是研究适应辐射进化的理想材料。研究表明北美和欧洲分布的耧斗菜属植物表现出相对立的物种形成和分化模式。花距是该属进化历程中的关键革新性状，花距的变异产生了物种间的生殖隔离，导致了物种形成和快速辐射。亚洲分布的耧斗菜属种数与北美或欧洲的相当，但关于物种形成和分化尚不清楚。无距耧斗菜（A. ecalcarata Maxim.）为我国特有种，是属内唯一无花距的种类，其系统位置存在争议。本项目以无距耧斗菜为研究对象，在野外观察不同居群的花部特征与传粉昆虫的适应性；利用简单重复序列（SSR）分子标记揭示居群遗传多样性和遗传结构；利用核基因和叶绿体基因片段重建地理居群谱系树，综合探讨无距耧斗菜的物种分化及适应性进化机制。本项目的实施将为阐述国产耧斗菜属的物种形成和进化的自然遗传机制奠定基础，也为全面理解整个耧斗菜属植物的起源与演化提供资料。

毛茛科耧斗菜属（Aquilegia L.）植物约70种，分布于北半球温带。耧斗菜属植物表现了较高的形态性状的多样化及较广的生境适应性，是研究适应辐射的理想材料。耧斗菜属植物的花距在长度和形状上表现的多样性与专性传粉昆虫相适应。无距耧斗菜（Aquilegia ecalcarata Maxim.）为我国特有种，是该属内唯一无花距的种类。由于无距耧斗菜花瓣无距，其系统地位与物种形成都存在争议。本项目中，我们通过比较研究不同居群的花形态、繁殖生物学、遗传多样性和亲缘地理关系，探究了无距耧斗菜是适应性进化模式。. 我们比较无距耧斗菜的10个居群的花部特征和繁殖性状，并在野外观察不同居群的传粉昆虫的适应性，我们发现横断山地区分布的居群的花距长度在居群内和居群间的变化都很大（0-6 mm），这些居群倾向于异交，传粉昆虫为熊蜂；而大巴山分布的居群，都为无距的特征，这些居群则倾向于自交，未观察到传粉昆虫。雌雄异位也是一个重要的特征可保证无距耧斗菜的繁殖成功。.我们采用简单重复序列（SSR）分子标记进行了涵盖所有分布的17个居群的遗传多样性和遗传结构的分析。结果表明无距耧斗菜的居群间的遗传多样性和遗传分化水平都很高。同时，遗传结构分析、UPGMA树和主成分分析均表明无距耧斗菜的17个居群可以聚类成两个大的分支，其中一个分支是来自横断山区的10个居群，另一大分支是来自青藏高原-秦岭大巴山的7个居群。. 我们选择了3个叶绿体基因以及1个核基因ITS片段，重点研究了17个无距耧斗菜居群的分歧时间和历史动态。研究结果表明无距耧斗菜居群同样也揭示了无距耧斗菜存在两个进化谱系单元，包括横断山谱系和青藏高原东部谱系，这两支谱系大概在2.76百万年前，晚上新世时期分化出来的。.这些研究结果揭示了冰期后的地质历史和最近的种群动态历史影响了无距耧斗菜的居群遗传分化。这些研究也表明异质环境因子驱使了无距耧斗菜在环境适应性、繁殖适应性等方面的分化。无距耧斗菜的适应性进化方式可能代表了亚洲祖先类群的进化模式。. 本项目综合探讨我国特有种无距耧斗菜的物种分化及其适应性进化的机制，为全球耧斗菜属植物的物种形成和适应性模式进行了补充。项目资助已发表SCI期刊论文1篇，投稿论文1篇，待整理论文2-3篇。