Data from: An extreme case of plant-insect codiversification: figs and fig-pollinating wasps

It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant–insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by >750 interacting species pairs has hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale cophylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two supermatrices were assembled: on an average, wasps had sequences from 77% of 6 genes (5.6 kb), figs had sequences from 60% of 5 genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based cophylogenetic analyses further support the codiversification hypothesis. Biogeographic analyses indicate that the present-day distribution of fig and pollinator lineages is consistent with a Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant–insect interactions of coordinated dispersal and long-term codiversification.学界普遍认为，植食性昆虫（phytophagous insects）的物种形成（speciation）通常源于对新宿主植物的定殖，这是因为植物与昆虫支系的辐射演化往往呈异步特征。近期的系统发育比较分析（phylogenetic comparisons）已针对植食性昆虫与特化传粉类群验证了这一分化模型。 榕树（榕属Ficus物种，桑科Moraceae）与其传粉榕小蜂（榕小蜂科Agaonidae，膜翅目Hymenoptera）之间的专性互利共生（obligate mutualism），则是一个有望出现植物-昆虫协同分化的特例。这类互利共生在热带与亚热带生态系统中兼具普遍性与极高生态重要性，长期以来令生物学家们深感好奇，但超过750个互作物种对带来的分类学难题，阻碍了学界对其演化历史的解析。具体而言，类群采样与分析工具的不足，使得大规模协同系统发育（cophylogenetic）分析难以开展。 本研究对全球范围内近200个榕-蜂互作物种对进行了采样。我们构建了两套超级矩阵（supermatrices）：平均而言，榕小蜂获取了6个基因（总长5.6 kb）中77%的序列数据，榕树获取了5个基因（总长5.5 kb）中60%的序列数据，本研究共计生成850条全新的DNA序列。此外，我们还开发了一款全新的分析工具Jane 2，用于面向超大规模数据集的基于演化事件的系统发育共祖分析。 基于宽松分子钟（relaxed molecular clock）假设的贝叶斯系统发育分析（Bayesian phylogenetic analyses）结果显示，榕与榕小蜂的冠群（crown groups）均起源于白垩纪，且近半数的榕与传粉者支系呈现同时期分化的特征。基于演化事件的协同系统发育分析进一步支持了协同分化（codiversification）假说。生物地理分析（biogeographic analyses）表明，当前榕与传粉者支系的分布格局符合欧亚起源后逐步扩散的模式，而非冈瓦纳分替（Gondwanan vicariance）假说所预测的格局。 综上，本研究结果表明，榕-传粉者互利共生是植物-昆虫互作系统中协同扩散与长期协同分化的极端典型案例。