亚洲-西北太平洋典型马尾藻的时空演化动力学研究

The late Quaternary glacial oscillations and associated tectonic processes (e.g. topological and structural configurations of habitats) are increasingly believed to have greatly influenced the tempo-spatial adpative evolutionary dynamics and biodiversity gradients of terrestrial organisms in the Northern Hemisphere. In the marine ecosystems, however, accumulating evidence indicated that factors shaping population genetic variations and distribution patterns of marine taxa vary considerably with either distinct biological features (e.g. larval stage and drifting dispersal capability) or environmental forces including biogeographical latitude and complex hydrogeological dynamics (e.g. diverse oceanic current systems and no dispersal barrier among marine regimes). Deciphering how these factors contributed to range shifts of population genetic connectivity and molecular phylogeographic architecthures can largely promote our understanding on speciation, adaptation and diversification of marine organisms drove by selective forces, whether historically or contemporarily, from both ecological and evolutionary perspectives. In this project we will focus on four typical Sargassum species (S. thunbergii, S. fusiforme, S. pallidum and S. polycystum) in the Asia-Northwest Pacific with each harboring distinct biological characteristics, through approaching the combined analyses of coalescent population genetics and geographic information system (GIS)-based ecological niche modeling. Our main objectives are as follows: 1) comprehensively investigate the geographical patterns of genetic variation of Sargassum species in the Asia-Northwest Pacific from both evolutionary and ecological timescales, and then reveal the deep tempo-spatial profiles of genetic affinity and evolutionary processes based on the integration of molecular, ecological, geographical and paleoenvironmental data sets; 2) explore the potential influential mechanisms of ice age, oceanic circulation and biological features on geographic distribution of Sargassum species, extrapolate some cryptic glacial refugia in the Asia-Northwest Pacific coastlines, and probe the corresponding influence of climatic, environmental and biological factors respectively on the biodiversity of seaweed species, and the even mutural interactions between each factor. The implement of this project can provide significant theoretical and practical insights for discovery and conservation of genetically important marine biological resources, and even monitoring coastal environmental ecosystems.

第四纪冰期造成的海岸带栖息环境急剧变更对北半球生物区系的形成和演化产生了深远影响，该重大气候事件协同其它重要的地理和环境因素（海区间缺乏天然屏障、物种扩散能力、近岸多向的海流）使得海洋生物的时空演化模式与多样性分布复杂而多样。本项目以在亚洲-西北太平洋呈同域分布的四种马尾藻（羊栖采、鼠尾藻、海蒿子和匐枝马尾藻）为研究对象，运用进化遗传学、分子系统地理学和基于地理信息系统（GIS）生态位模拟的多学科整合方法，目的在于：1）全面解析亚洲-西北太平洋地区马尾藻遗传多样性的时空分布模式与规律，结合分子、生态、地质和古环境数据，揭示它们自第四纪冰期以来的地理演化历史和动力学过程；2）探讨冰期、海流、生物学特性对马尾藻属地理分布的影响机制，推断一些潜在的冰期避难所，评估气候、环境和生物因子对海藻遗传多样性影响的协作关系。本项目既能丰富海洋生物进化地理学理论，又能为重要海藻资源的管理与保护提供科学指导。

第四纪冰期造成的海岸带栖息环境急剧变迁对北半球生物区系的形成和演化产生了深远影响，该重大气候事件协同其它重要的地理和环境因素使得海洋生物的时空演化模式与多样性分布复杂而多样。本项目以在亚洲-西北太平洋呈同域分布的3种马尾藻（鼠尾藻、羊栖菜和匍枝马尾藻海蒿子）和Chondrus ocellatus及Palmaria palmata为研究对象，通过整合进化遗传学、分子系统地理学和地理信息系统生态位模拟的多学科研究方法，重要研究结果包括：1）澄清5种海藻种内的遗传多样性和时空变动模式、不同遗传世系的分隔历史和潜在的驱动因子，发掘了各自种内隐存的多样性，分析了不同繁殖方式（有性vs.营养）对于物种在分布区内隔离分化的影响；2）确定了羊栖菜的重要保护单元、种群和世系，初步鉴定了具有优先保护价值的地区，3）发现西北太平洋近岸的海流系统（特别是黑潮、中国沿岸流、对马暖流等）对鼠尾藻不同种群之间的遗传相通性起到了重要的驱动作用；4）剖析了冰期鼠尾藻祖先种群的存留对于现今物种地理分布和多样性变动的贡献，明确了历史隔离和当前海流驱动的种群间基因交流是导致中国近岸鼠尾藻种群遗传动力变动模式的关键过程；5）首次提出了第四纪末期冰期避难所假设来解答为何海南岛西南部的莺歌海地区具有较高的物种多样性和局地特有性——这一重要的进化生物学研究难题。这些成果是亚洲-西北太平洋地区海流和冰期如何协作进而影响近海海洋生物地理分布与多样性结构的重要范例，不仅对于揭示亚洲-西北太平洋地区其他海洋生物的特有多样性及进化历史亦具有重要的理论意义，而且在全球变化背景下可为该地区海洋生物类群的保护和管理提供重要科学指导。

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