粗叶榕传粉蜂隐种形成，及同一地区（或榕树）内相似物种能否长期共存

Figs (Ficus, Moraceae) and their pollinating fig wasps (Agaonidae) constitute a classic example of an obligate plant-pollinator mutualism, and have become an ideal system to address questions on coevolution, speciation, and maintenance of mutualisms.Traditionally, it was thought that each fig species had its own species-specific fig wasp, and the fig-fig wasp mutualism was a classic example of the strict-sense cospeciation based on coevolution. However, more and more findings of cryptic fig wasp challenged species cospeciation and imply that fig wasp speciation maybe have the other ways, such as geographic isolation, host-shift or Wolbachia affection. At the same time, niche theory based on competitive exclusion has been challenged seriously because cryptic fig wasps are found in same site or even same tree with the common species. So we question:" Can different fig wasps with the similarities in morphology, ecology and behavior really co-exist in the same site or same tree? In this project, we will focus on the pollinator of a dioecious fig (Blastophaga javana Hill) to identify cryptic fig wasp using COI and ITS2 genes. We will analyze phylogenetic relationship among different fig wasps and among haplotypes for each species as well as Wolbachia, to study each fig species's spatiotemporal patterns, refuges or migration route during the Quaternary and then try to explore the speciation mechanism. On the other hand, we will study genetic stucture of each fig wasp among populations using microsatellite, to define their genetic differentiation, effective population size, migration rate and gene flow, then combine the other analyses such as cryptic fig wasps' occurrence frequency and distribution to test if different fig wasps can really co-exist in same site or same tree. It's helpful to understand species speciation and evolutionary mechanism better and to perfect species coexistence theory. The proposal tries to find the answers to the following questions: 1. How about the occurrence of cryptic fig wasps, commonly or occasionally? 2. How cryptic fig wasps generate,through geographical isolation, host shift or Wolbachia affection? If three ways are working, which one plays the major function? 3. Are co-pollinators in same site or same tree really co-exist

榕与榕小蜂组成目前所知道的联系最密切的互利共生系统，是研究协同物种形成的最典型模式之一。分子方法的应用使大量的榕小蜂隐种被发现，冲击着以协同进化为基础的物种共形成理论，暗示榕小蜂可能还有地理隔离、宿主转移或共生细菌侵染等其他物种形成方式；同时，对以竞争排除法则为基础的物种共存理论提出严峻挑战，为此，我们提出: 同一地区（或榕树）内的相似物种，能否长期共存?！因此，本项目以粗叶榕较广地理范围内的榕小蜂为研究对象，利用线粒体（COI）和核基因（ITS2）片段确定隐种，结合共生细菌、系统发育分析和亲缘地理研究，明确种间亲缘关系及其特定的时空分布格局，探究榕小蜂隐种的形成机理；同时分析其发生和分布特征、起源时间及迁移路线等，结合核基因SSR分子标记，明确榕小蜂种群间迁移率、有效种群大小等，探讨同一地区（或榕树）内相似物种能否长期共存。从而更好地丰富和完善物种形成理论及共存机制。

研究背景：. 榕与榕小蜂组成目前所知道的联系最密切的互利共生系统，是研究协同物种形成的典型模式之一。分子方法的应用使大量的榕小蜂隐种被发现，冲击着以协同进化为基础的物种共形成理论，暗示榕小蜂可能还有地理隔离、宿主转移或共生细菌侵染等其他物种形成方式；同时，对以竞争排除法则为基础的物种共存理论提出严峻挑战，为此，我们提出: 同一地区（或榕树）内的相似物种，能否长期共存?！. .主要研究内容：.利用榕小蜂线粒体（COI）和核基因（ITS2）片段对榕小蜂物种进行鉴定；利用共生细菌的专性引物对榕小蜂总DNA进行扩增以检测共生细菌的侵染情况；利用Beast软件对榕小蜂扩增出的所有线粒体基因单倍型和genebank上下载的传粉榕小蜂相同序列进行系统发育分析，检测榕小蜂物种形成方式及机理。.利用SSR分子标记研究各种榕小蜂的迁移和基因流特征，结合线粒体基因的亲缘地理分析和各种榕小蜂的分布特征，我们得出不同种榕小蜂在一个居群中不能长期共存，同域分布的榕小蜂物种间应存在竞争机制，长期以往，适应不同的环境占据不同的生态位。.取得重要结果和关键数据如下：.a. 对雌雄异株榕树在广泛的地理尺度上进行物种形成机制的研究，得出地理隔离是榕小蜂物种形成的主要机制；.b. 共生细菌虽然侵染粗叶榕的传粉榕小蜂，但对其物种形成影响不大；.c. 传粉榕小蜂具备远距离扩散能力，在同域共存的榕小蜂物种极少，说明榕小蜂不同物种间不能长期共存，不同物种在利用同一宿主方面存在竞争，各自适应不同的生态环境，最终异域分布，并促进新物种形成。.d. genebank 上长传166个粗叶榕榕小蜂COI单倍型序列和30个ITS2单倍型序列。.项目的科学意义：有助于更好地丰富和完善物种形成理论及共存机制；在国际著名刊物上发表SCI论文7篇，培养1个博士生和3个硕士生。