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）的物种形成通常源于对新型宿主植物的定殖，这是因为植物与昆虫演化支的辐射演化往往呈现异步性。近期的系统发育比较分析，已为昆虫植食类群与特化传粉者的这一分化模型提供了实证支持。榕属植物（Ficus species，桑科Moraceae）与其传粉榕小蜂（膜翅目Hymenoptera榕小蜂科Agaonidae）之间的专性互利共生，是一个有望出现植物-昆虫同步分化的特例。该互利共生在热带与亚热带生态系统中的普遍性及其生态重要性，长期以来一直令生物学家着迷，但750余对互作类群带来的分类学挑战，阻碍了学界对其演化历史的研究进程。具体而言，类群取样与分析工具的不足，制约了大规模协同系统发育（cophylogenetic）分析的开展。本研究在全球范围内采集了近200对榕属植物与传粉榕小蜂的互作类群，构建了两套超级矩阵（supermatrices）：平均而言，榕小蜂获得了6个基因（总长5.6 kb）中77%的序列数据，榕属植物则获得了5个基因（总长5.5 kb）中60%的序列数据，本研究共新增850条DNA序列。我们还开发了一款全新的分析工具Jane 2，用于针对超大型数据集开展基于事件的系统发育和解（phylogenetic reconciliation）分析。基于宽松分子钟（relaxed molecular clock）假设的榕属植物与传粉榕小蜂独立贝叶斯系统发育分析结果显示，二者冠群的分化发生于白垩纪，且近半数的榕属植物与传粉者演化支出现了同步分化。基于事件的协同系统发育分析进一步验证了协同分化（codiversification）假说。生物地理学分析表明，现今榕属植物与传粉者类群的分布格局符合欧亚起源后向外扩散的模式，而非冈瓦纳大陆隔离分化（Gondwanan vicariance）的结果。综上，本研究结果表明，榕属植物与其传粉榕小蜂的互利共生，是植物-昆虫互作体系中协同扩散与长期协同分化的极端案例。