种间杂交对专性传粉榕属植物物种多样性形成的影响研究

The mechanism of species diversification is one of the fundamental questions in evolutionary biology. Obligate pollinated plants often have high species diversity, interspecies hybridization mediated with pollinator mistaking visitation may be one important factor generating species diversity, while empirical studies supporting this hypothesis are still lacking. In this project, we take Ficus plants, which have very high species diversity and been pollinated by highly obligate pollinating fig wasp, and their pollinating fig wasp as researching system, to investigate the ancient hybridization in different taxonomic level based on phylogenetic network analysis and Cyto-nuclear phylogenetic conflict analysis with genomic level data. Furthermore, the pollinator isolation degree of hybrid population with sympatric parents species, and the plasticity of pollinator host preference after artifical host shifting, will be evaluated to test potential quick pollinator isolation mechanism of hybrid groups. This project will not only supply a systematic empirical research case on testing the role of hybridization on improving diversification of obligate pollination plants, but also will supply a new view on the mechanism of general species diversification.

物种多样性形成机制是进化生物学最核心科学问题之一。专性传粉植物通常具有较高的物种多样性，传粉者错误拜访导致的种间杂交可能是促进专性传粉植物物种多样性的重要动力，然而该假说缺少实证研究。本项目拟以物种多样性极高且专性传粉程度最高的榕树－传粉榕小蜂系统为研究材料，通过组学水平的系统发育关系网络分析和核-质系统树冲突等方法，检测榕属不同分类层级上古老杂交事件及其规模，以检验种间杂交在榕属进化历史中的普遍性；并通过对杂交群体与双亲物种之间的传粉者隔离程度评估和人工辅助宿主转移前后榕小蜂宿主偏好性变化的比较，检验传粉者隔离促进榕属杂交类群快速生殖隔离建成的能力。研究结果不仅可为验证杂交促进专性传粉植物的物种多样性机制提供一个系统的实证案例，也将对探讨物种多样性形成机制提供新的思路。

物种多样化和性状进化是进化生物学的最核心问题之一。杂交渐渗和动植物协同进化对植物进化均具有重要影响，然而综合这两个因素的研究还很缺乏。基于基因组数据分析和操控实验手段，本项目揭示了以杂交渐渗和传粉者宿主转移为特点的发散式协同进化是榕树-榕小峰协同物种多样化的主导模式，且传粉者宿主转移可以快速重塑新的专性传粉关系，加速榕树和榕小蜂双方类群的生殖隔离建成。同时，还揭示了榕树-榕小蜂化学通讯和形态适应等相关基因区间的变化对双方协同适应和协同分化的关键作用。另外，本项目还揭示了土沉香果实通过释放虫食叶片类似气味来吸引胡蜂对其短命种子进行快速散布的新型种子散布机制和生态适应性。相关结果有力推动了当前对动植物协同进化影响模式和机制的前沿认识，并在Cell， Nature Communications，Current Biology等期刊上发表文章4篇。