铁线莲属灌木铁线莲组的演化历史与谱系地理学研究

Geological and climate changes since late Tertiary and Quaternary was the main cause of aridification in northern China, and have greatly influenced the distribution of living organisms. Clematis sect. Fruticella containing five xerophilous species is a natural group with unique erect shrubby habit and distribution pattern in the genus. Among them, one species is distributed in the dry slopes of north-eastern Qinghai-Tibetan Plateau, and the other four are mainly distributed in arid areas of northern China. Based on our previous studies on the classification and molecular phylogeny on Clematis, this project will conduct comprehensive population investigation and sampling of sect. Fruticella. Analyses of molecular systematics, population genetics and phylogeography will be applied in this study. In addition, based on distribution data of the current species, the species distributions at the Last Glacial Maximum and at present were predicted using Ecological Niche Modeling. Based on all the analyses, we will elucidate evolution shrubby habit, relationship of species, temporal and spatial modes of evolution, population genetic and phylogeographic structure of this section to infer the diversification of species and distribution changes in response to the past climate changes. All these results will help us to further understand the changes of biodiversity under the global climate oscillation during the Quaternary and to direct the conservation of natural resources.

晚第三纪到第四纪的地质与环境气候变化是中国北方干旱荒漠化重要因素，同时也影响着现代植物的地理分布。灌木铁线莲组是毛茛科铁线莲属中具有独特旱生适应性与分布式样的自然类群。该组共有5种植物，均为直立灌木，其中1种分布于青藏高原东北部的干旱草坡，另外4种主要分布于我国北方干旱荒漠和半荒漠地区。本项目在申请人对铁线莲属前期的分类学与分子系统学研究基础上，对该组植物进行全面的居群取样，开展分子系统发育分析和居群遗传与谱系地理学分析等工作。然后，根据现存物种的地理分布数据，利用生态位模型模拟第四纪冰期时灌木铁线莲组物种的分布状况。通过上述研究，明确灌木铁线莲组的灌木习性起源、物种之间关系、演化的时间与空间过程，以及居群遗传与谱系地理结构，阐明灌木铁线莲组响应气候变化的物种形成和分化历史与分布区的形成过程。研究结果对理解气候变化对物种多样性形成与变化的影响和生态环境资源的保护具有重要意义。

灌木铁线莲组在铁线莲属中具有独特旱生适应性与分布式样，其起源、演化与扩散深受新近纪以来地质与环境气候变化的影响。本项目研究组基于多年研究积累，对灌木铁线莲组植物进行全面野外调查与取样工作，开展了包括形态学、细胞学、系统发育基因组学、分子钟及生物地理学分析、杂交分析等研究工作。同时，根据现存物种的地理分布数据，利用生态位模型模拟第四纪冰期时灌木铁线莲组物种的适生分布区状况。通过上述研究，明确了铁线莲属灌木习性的多次独立起源与趋同演化，揭示了灌木铁线莲组物种之间复杂的杂交关系，推断了灌木铁线莲组演化的时间与空间过程，确定了灌木铁线莲组物种的谱系地理结构，阐明了灌木铁线莲组植物通过古杂交来响应气候变化并进行快速分化以获得新的适应性的过程。本研究的结果对理解植物天然杂交与环境气候变化对生物多样性形成与演化的影响，以及我国北方旱区生物资源的保护、利用与荒漠化治理具有重要意义。