武汉东湖及周边水系中优势原生动物类群营养功能及群落演替机制研究

As the core components of structure and function within aquatic microbial food web, protozoa are important for the energy flow and material circulation in aquatic ecosystem. Yet, functional trait and succession mechanism of these micro eukaryote remain largely unknown because of various reasons. In China, Lake Donghu and its surrounding water, which locate in the middle and lower reaches of Yangtze River, are typical and representative in the temperate regions. In the proposed project, protozoa samples that collected from Donghu water system will be investigated by using the combination of traditional taxonomic methods and high-throughput sequencing technologies. Data will be analyzed through several platforms (e.g. QIIME). For the dominant groups, we will first deeply analysis the community composition. We will then analysis the nutritional function group, spatiotemporal pattern and the functional mechanism between environmental factor and phylogeny. We aim to (1) get a clear picture of dominant groups of protozoa in Donghu water system; (2) reveal the succession process of dominant groups of protozoa based on net relatedness index (NRI) or nearest taxon index (NTI), and further emphasize influence of environmental selection and dispersal limitation on the succession process; (3) find out the environmental factors that play a determinant or dominant role during succession of dominant groups of protozoa. Not only will this project provide a preliminary insight for community stability and the associated mechanisms in aquatic microbial food web, but also important theoretical reference and the first-hand data for ecological conservation and water restoration.

原生动物作为水体微食物网中核心的结构和功能组分，对水生态系统中物质循环及能量流动具有重要意义。但由于多种原因，该类动物在水体生态系中的功能特征和演化机制并未得到完整的解读。源于长江中下游的武汉东湖及相邻水体在我国温带地区具有典型性和代表性，本工作拟以此水系为核心采样地，结合经典与现代高通量测序技术，利用QIIME等分析手段，在综合解析优势原生动物物种组成的基础上，探索功能营养类群和群落时空分布模式、分析群落结构演化与环境因子间的相互关系。目标：1) 完整刻画该水系中优势原生动物结构组成及功能营养类群；2) 基于净亲缘指数等信息，解析优势类群的时空演替过程，着重阐述环境选择和扩散限制对该演替过程的影响；3) 寻找优势群落演替过程中具有决定性和优势作用的环境因子。本工作将初步解答水体微食物网中的结构稳定及其维持机制，也为生态保护、水环境修复等提供重要的理论依据和第一手的参考资料。

原生动物在水体微食物网中扮演核心角色，在执行本项目的3年中，根据项目要求，研究团队开展了武汉东湖中该类群的生态学研究，利用经典形态分类和现代高通量测序相结合技术，我们深度解析了武汉东湖中原生动物及相关类群（如：细菌）的生物多样性、群落构建和演替的生态学过程及它们之间的相互关系，主要揭示单细胞原生动物细胞大小对其群落构建的影响，研究发现：即使微米/纳米级(0.22-20 μm)尺寸的微型真核生物与micro级别(20-200 μm)的微型真核生物在淡水生态系统中的多样性相差无几，但是它们在群落结构和定殖的生态学过程方面具有显著差异，表现为micro级别的微型真核生物在局域尺度上主要受环境选择影响，在区域尺度上主要受扩散限制影响。另一个有意思的结果是：微米/纳米尺寸的微型真核生物与原核生物表现出更加相似的群落构建过程和分布格局。然而，上述结果仍只是全面揭开淡水微型真核生物群落构建机制的一个开始，相比于大地里尺度研究，未来应当着重开展微型真核生物与原核生物在长时间序列尺度上相互作用的研究。