Data from: Genetic structure and hybridization in the species group of Ficus auriculata: can closely related sympatric Ficus species retain their genetic identity while sharing pollinators?

Obligate mutualistic nursery pollination systems between insects and plants have led to substantial co-diversification involving at least some parallel cladogenesis, as documented in Yucca, Ficus and Phyllanthaceae. In such systems pollinators are generally species specific thus limiting hybridization and introgression among interfertile host species. Nevertheless, in the three systems, cases of one insect pollinating several plant species are reported. In most cases host plants sharing pollinators are allopatric. However in the case of the species group of Ficus auriculata, forms may co-occur over large parts of their range. We show here that the species group of F. auriculata is constituted by four well-defined genetic entities that share pollinators. We detected hybrids in nature mainly when both parental forms were growing nearby. Controlled crosses showed that F1 offspring could be successfully backcrossed. Hence, despite sharing pollinators and despite hybrid viability, the different forms have preserved their genetic and morphological identity. We propose that ecological differentiation among forms, coupled with limited overlap of reproductive season has facilitated the maintenance of these inter-fertile forms. As such, establishment of pollinator host specificity may not be a prerequisite for sympatric diversification in Ficus.昆虫与植物间的专性互利共生传粉育苗系统（obligate mutualistic nursery pollination systems），已促成显著的协同分化（co-diversification），其中至少包含部分平行分支成种（parallel cladogenesis）事件，这一点在丝兰属（Yucca）、榕属（Ficus）以及叶下珠科（Phyllanthaceae）类群中已有文献记载。此类系统中的传粉者通常具有物种专一性，因此限制了可杂交寄主物种间的杂交与基因渐渗（introgression）。不过，在上述三个类群的研究系统中，仍有单种昆虫为多种植物传粉的案例被报道。多数情况下，共享传粉者的寄主植物呈异域分布。但在歪叶榕（Ficus auriculata）物种群中，其不同形态类群可在分布区的大片区域内同域共存。本研究表明，歪叶榕物种群由四个共享传粉者的、界定清晰的遗传类群所构成。我们在自然环境中检测到的杂交个体，主要出现在亲本类群相邻生长的场景中。控制性杂交实验显示，F1代子代可成功回交。因此，尽管这些类群共享传粉者且杂交子代具备生存能力，各形态类群仍维持了各自的遗传与形态特征同一性。我们推测，类群间的生态分化，加之繁殖季的有限重叠，共同促成了这些可杂交类群的稳定维持。由此可见，传粉者寄主专一性的确立，或许并非榕属植物同域分化的必要前提条件。