【作者】 徐磊；

【导师】 杨大荣； 李捷；

【作者基本信息】 中国科学院研究生院（西双版纳热带植物园） ， 生态学， 2009， 博士

【摘要】 榕树及其传粉榕小蜂形成的互惠共生体系长期以来都是进化生物学家研究协同进化和协同物种形成的模式体系,并被认为它们之间具有严格的种类“一对一”对应关系。随着对该系统研究的不断深入,发现了许多打破一对一种类对应关系的实例,它们之间复杂的系统发育关系受到越来越多的关注。中国的榕树分布区位于印度—大洋洲榕树分布中心的北缘地带,有榕属全部六个亚属的榕树种类,这在除榕树分布中心以外的分布区是非常少见的,且拥有一些中国—喜马拉雅地区的特有种。为了研究榕树及其传粉榕小蜂的系统发育关系及其生物地理演化过程,本研究选取榕树ITS、ETS、G3pdh序列和传粉榕小蜂线粒体COI、Cytb序列,利用最大简约法(MP)和Bayesian方法研究榕树和传粉榕小蜂的分子系统发育,并利用BEAST软件计算它们的生物地理演化时间。本研究获取了中国分布的35种榕树的38条ITS序列、30条ETS序列和33条G3pdh序列,以及39种传粉榕小蜂的50条COl序列片段和48条Cyt b序列,此外从GenBank中直接下载获得181条ITS、151条ETS和124条G3pdh序列(包括2条外类群序列),以及143条COI序列(包括4条外类群种类序列)、Ceratosolen属小蜂的35条Cyt b序列,共计219条ITS序列、181条ETS序列、157条G3pdh序列和193条COI序列,以及Ceratosolen属小蜂的55条Cyt b序列。对榕树ITS-ETS-G3pdh联合矩阵和传粉榕小蜂COl序列的分析结果显示,白肉榕亚属(subg. Pharmacosycea) Pharmacosycea组的榕树和其Tetrapus属传粉榕小蜂为最原始的类群。在榕树系统发育树中,榕亚属(除Urostigma组)、聚果榕亚属、糙叶榕亚属(subg. Sycidium)和攀援榕亚属(subg. Synoecia)榕树均为单系类群,并且其中大部分组的种类也形成单系分支,并得到了很好的支持。传粉榕小蜂的系统发育分析结果很好的反应了传粉榕小蜂各属间的系统发育关系,每个亚属榕树所对应的传粉榕小蜂基本上都形成一个单系类群。虽然Urostigma组榕树没有与其他榕亚属种类聚在一起,但其传粉榕小蜂却与其他榕亚属榕树的小蜂聚在一个进化枝内。无花果亚属和攀援榕亚属榕树的传粉榕小蜂聚在一起,表现为复系类群,为除Tetrapus属种类外最早分化的类群。所有榕树和传粉榕小蜂种类以及榕亚属、聚果榕亚属榕树和传粉榕小蜂的系统发育分析结果显示,虽然每种榕树对应了一种传粉榕小蜂,但它们之间的系统发育关系却错综复杂,在榕树组内种间可能发生了许多寄主转移事件,即使是在榕树组和传粉榕小蜂属这样的分类水平,它们之间的协同进化关系也并不完全一致。对榕亚属(subg. Urostigma)和聚果榕亚属(subg. Sycomorus)榕树及其传粉榕小蜂的系统发育研究结果显示,榕亚属的各个组或亚组均为单系类群,其对应的传粉榕小蜂也各自形成单系分支,且都有较高的分支支持率；而聚果榕亚属榕树大部分组、亚组也形成单系类群,但有部分种类的系统发育位置在MP和Bayesian两种分析结果中有所不同,且没有足够的分支支持率,其传粉榕小蜂的系统发育关系也存在同样的问题,这可能是由于该亚属类群分布范围很广,从非洲、印度、亚洲到马来群岛、澳大利亚均有不同程度的分布,经历了复杂的生物地理变迁,在复杂的进化过程中发生了快速分化,因而目前所用的分子标记无法很好的反映其进化历程。对榕树和传粉榕小蜂的生物地理演化时间的计算结果显示,它们约在90百万年前从南美大陆起源,之后扩散到印度大陆,在印度大陆发生了适应性辐射进化,并在印度大陆与亚洲大陆、非洲大陆与亚洲大陆发生碰撞之后在各大板块之间发生了迅速的适应辐射。其系统分化时间与几个大的地质事件比较吻合,其起源发生在白垩纪后期Cenomanian-Turonian生物大灭绝之后(约90百万年前),并且几个主要分支也是在Cretaceous-Tertiary (K/T)生物大灭绝(65百万年前)发生之后发生了爆炸性辐射进化。由于缺少更多的化石证据,这些结果还需要通过更系统全面的系统发育和生物地理演化研究的进一步证实。平枝榕(Ficus prostrata Miq)和鸡嗉果榕(Ficus semicordata J.E. Smith)的分类地位在我们的系统发育分析中得到了很好的解决,它们与聚果榕亚属种类的关系最近,且由于其传粉榕小蜂种类为Ceratosolen属的小蜂,因此根据Berg最新的分类系统,可以确切的将这两种榕树划分到聚果榕亚属Hemicardia组内。综合分子序列数据和生态学数据对木瓜榕(Ficus auriculata Lour.)、苹果榕(Ficus oligodon Miq.)、勐醒河的Ficus sp榕树及其传粉榕小蜂的分析结果显示,木瓜榕和苹果榕是同一种榕树的不同地理型,而勐醒河的Ficus sp.则是不同的种,但这几种榕树的传粉榕小蜂在同一分布区是同一种,在不同分布区之间由于长期的生物地理隔离而形成了不同的种类。更多还原

【Abstract】 Figs (Ficus spp., Moraceae) and fig pollinating wasps (Agaoninae, Agaonidae, Chalcidoidae, Hymenoptera) form the most specialized obligate mutualism during the long evolution history, which has been treated as the model system to study co-evolution, co-speciation and co-divergence. Previous molecular phylogenetic studies have provided some support for cocladogenesis and coadaptation between pollinating wasps’genera and their respective fig sections. However, existing studies on the fit of pollinator and host phylogenies show that the relationship between fig and their pollinators is not always so prescribed. Chinese Ficus distributional area is at the ndrthern edge of the India-Australian distributional center. There are all the six subgenera species and some endemic species in China. Here, we reconstructed the phylogenetic relationships of figs and fig pollinating wasps including Chinese species by using maximum parsimony and Bayesian methods, and estimated their divergent times in BEAST for the first time. We obtained 38 ITS,30 ETS and 33 G3pdh sequences of 35 Chinese figs species, and 50 COI and 48 Cyt b sequences of 39 pollinating wasp species. In addition,181 ITS,151 ETS,124 G3pdh (2 outgroup species), and 143 COI sequences (4 outgroup species) were directly downloaded from GenBank. As a result, a total number of 219 ITS,181 ETS,157 G3pdh, and 193 COI sequences were used in the final analyses.The results of combined ITS-ETS-G3pdh dataset and COI dataset showed that section Pharmacosycea and their related Tetrapus pollinating wasps are the most ancient species. Subgenus Urostigma (excluding section Urostigma), subgenus Sycomorus, subgenus Sycidium and subgenus Synoecia are monophyly, and each section is clustered into one group with great support. On the whole, the pollinating wasp species of each genera group together in the analyses. The passively pollinating genus Tetrapus is the most ancient species, and the Blastophaga and Wiebesia pollinators of dioecious Ficus are more primitive than others. Both Blastophaga and Wiebesia are not monophyletic. Although the section Urostigma figs did not group with the other species of subgenus Urostigma, its pollinators fall in one clade with other Urostigma pollinators. We analyzed the fig and pollinating wasp relationship among sections Conosycea and Urostigma of subgenus Urostigma, and among subgenus Sycomorus respectively. Our results showed that there is no strict coevolution and cospeciation between figs and fig pollinating wasps, even at the scale of wasp genera and associated fig subgenera and sections, and pollinator host-switching is a more common phenomenon in this mutualism.The biogeographic divergent times estimations results showed that the origin and divergence of Ficus and fig pollinating wasps are corresponding to two mass extinctive events (the Late Cretaceous Cenomanian-Turonian biotic crisis and Cretaceous-Tertiary (K/T) extinction). Moreover, our reconstruction shows the Afrotropical and Neotropical species originated from India-China continent ancestors with subsequent dispersal back from Africa to Old World.Ficus prostrata Miq. and Ficus semicordata J.E. Smith should be classified into section Hemicardia, subgenus Sycomorus, based on the phylogenetic results and the classification of Berg’s. The molecular data analyzed results of Ficus auriculata Lour., Ficus oligodon Miq., and Ficus sp. suggest that Ficus auriculata and Ficus oligodon are same species, but Ficus sp. is one different species. Their related pollinator species are closely related and originated from same ancestor. However, the pollinators of these figs are the same species in same location, while the pollinator species are different among locations. It suggested that the ancient wasp have evolved into different species in different habitats due to biogeographic isolation.更多还原