榕树-传粉榕小蜂-非传粉榕小蜂的协同系统发育研究

Coevolution was considered to be a combination of two processes, coadaptation and cospeciation, thereby encompassing both microevolutionary and macroevolutionary processes. Coadaptation is a complex process and it can be difficult to test. However, cospeciation can be identified relatively easy by comparing the phylogenies of hosts and their parasites. Cophylogeny is the reconstruction of ancient relationships among ecologically linked groups of organisms based on their phylogenetic information, and can provide insight into the evolutionary history of intimate biological associations. Plant-insect coevolution has been widely investigated across a range of ecological conditions including herbivory, mutualism and parasitism which involve two trophic levels only. Few examples of cophylogeny are known across three trophic levels, including plants, herbivores, and their parasitoids..Fig-fig wasp symbiosis is composed by fig trees (Moraceae: Ficus), pollinators (Chalcidoidea: Agaonidae) and non-pollinationg fig wasps (Chalcidoidea: Eulophidae, Eurytomidae, Ormyridae, Pteromalidae, Torymidae), and provides a desired model to investigate the plant-insect coevolution across three trophic levels. The fig trees, in addition to being a keystone plant resource in many tropical ecosystems, are well-known for the extremely obligate mutualistic interactions with their host-specific pollinating wasps. However, in addition to pollinating wasps, figs also host various non-pollinating fig wasps (NPFWs) which are exclusively dependent on the fig-pollinating fig wasp mutualism to nourish themselves. According to the different ecological strategies, the NPFWs were divided into three functional groups, galler wasps, competitor wasps and parasitoid wasps, which hold two tropical levels in fig-fig wasp symbiosis. Considering the long symbiotic history with fig-pollinating fig wasp mutualism, the NPFWs of different functional groups should be included in the coevolution research of fig-fig wasp symbiosis. .To reveal the coevolutionary history of fig-fig wasp symbiosis, 34 fig species and the associated pollinating and non-pollinating fig wasps will be collected in present project. Chloroplast genome of the selected 34 Ficus species will be sequenced using a high throughput sequencing approach and three molecular markers (18S, 28S, COI) of fig wasps were sequenced by standard sanger method to conduct phylogenetic analyses. Then cophylogenetic analysis among fig trees, pollinating and non-pollinating fig wasps were carried out based on their phylogenetic information. The knowledge derived from this project will help us to understand better about the coevolutionary process of fig-fig wasp symbiosis.

协同系统发育通过对密切相关类群间系统发育关系的对比分析，进行宏进化层面的协同进化研究。植物-昆虫共生体系是协同系统发育研究的理想对象，但目前的研究集中在植物和植食昆虫两者间。榕树-传粉榕小蜂-非传粉榕小蜂共生体系包含了植物、传粉者/植食昆虫和寄生者三个营养级，为从宏进化角度研究多营养级植物-昆虫共生体系的协同进化提供了理想模型。本项目选择西双版纳34种榕树，及与其共生的36种传粉榕小蜂和约160种非传粉榕小蜂为研究对象。通过高通量测序获得榕树叶绿体基因组数据，和常规测序获得榕小蜂三基因序列（18S、28S、COI）数据，分别构建榕树、传粉和非传粉榕小蜂的系统发育树。而后借助协同系统发育分析，探究榕树、传粉榕小蜂、非传粉榕小蜂之间的协同进化关系。在此基础上，揭示非传粉榕小蜂不同功能群的宿主专一性是否一致，及不同性系统榕树的协同进化模式是否相同，完善对多营养级植物-昆虫共生体系协同进化的认识。

不同的种间相互关系会导致双方不对等的收益与代价，使得相对应的物种枝系形成不同的协同多样化模式。榕树-榕小蜂体系包括了榕树与传粉榕小蜂的互利关系，榕树与造瘿榕小蜂的敌对植食关系，造瘿和传粉榕小蜂的竞争关系，及拟寄生榕小蜂与传粉和造瘿榕小蜂的敌对寄生关系，为研究跨营养级的不同类型种间关系的协同多样化格局提供了理想模型。.本项目在西双版纳地区采集了26种榕树，及与其共生的26种传粉榕小蜂，2种欺骗性榕小蜂，33种造瘿榕小蜂和81种拟寄生榕小蜂样本，利用榕树的ITS、ETS、G3pdh和trnL-F，及榕小蜂的18S、28S和COI分子标记，重建各类群的系统发育树，利用基于距离矩阵的PACo方法和基于拓扑结构的Jane软件对不同类群间进行协同谱系分析，并比较了不同性系统榕树上榕小蜂种类及谱系关系的差异。结果显示，互利的榕树与传粉榕小蜂之间谱系关系显著一致，具有更多的协同成种事件；敌对植食关系的榕树与造瘿榕小蜂之间谱系关系不一致，具有更多的宿主转移事件；竞争关系的传粉与造瘿榕小蜂之间谱系关系显著一致，具有较多的协同成种和丢失事件；拟寄生榕小蜂与宿主榕小蜂间的敌对寄生关系及与榕树间接的敌对寄生关系间均有显著一致的谱系关系，其具有较多的协同成种和宿主转移事件。表明互利促进双方结合，互害促进双方分离，竞争高度一致的资源促进双方协同成种；一对多的敌对关系推动敌对者的宿主转移，发生宿主转移的强弱由敌对者间竞争的强弱决定，但当敌对者高度依赖对方时，会促进协同成种。雌雄同株榕树上的非传粉榕小蜂物种多样性更高，造瘿和拟寄生榕小蜂种类均较多；同时，共生于雌雄同株榕树上的传粉榕小蜂具有更少的协同成种和更多的宿主转移事件，支持雌雄同株榕树传粉榕小蜂的宿主专一性更高。欺骗性榕小蜂与共生同一宿主的传粉榕小蜂物种形成姐妹种关系。.发表标注本项目资助的文章5篇（Q1两篇，Q2一篇，Q4一篇，CSCD一篇），培养研究生两名。

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