Genomic evidence of prevalent hybridization throughout the evolutionary history of the fig-wasp pollination mutualism

Ficus (figs) and their agaonid wasp pollinators present an ecologically important mutualism that also provides a rich comparative system for studying functional co-diversification throughout its coevolutionary history (~75 million years). We obtained entire nuclear, mitochondrial, and chloroplast genomes for 15 species representing all major clades of Ficus. Multiple analyses of these genomic data suggest that hybridization events have occurred throughout Ficus evolutionary history. Furthermore, cophylogenetic reconciliation analyses detect significant incongruence among all nuclear, chloroplast, and mitochondrial-based phylogenies, none of which correspond with any published phylogenies of the associated pollinator wasps. These findings are most consistent with frequent host-switching by the pollinators, leading to fig hybridization, even between distantly related clades. Here, we suggest that these pollinator host-switches and fig hybridization events are a dominant feature of fig/was...

榕属（Ficus，俗称无花果）与其传粉的榕小蜂科（Agaonidae）昆虫构成了具有重要生态意义的互利共生关系，同时也是一套优质的比较研究系统，可用于解析二者长达约7500万年的协同进化历程中所蕴含的功能协同多样化机制。我们从代表榕属所有主要演化支的15个物种中获取了完整的核基因组、线粒体基因组及叶绿体基因组序列。针对这些基因组数据的多维度分析表明，杂交事件贯穿了榕属的整个演化历史。此外，协同系统发育重组分析（cophylogenetic reconciliation analyses）检测到，基于核基因组、叶绿体基因组与线粒体基因组构建的系统发育树之间均存在显著的拓扑不一致性，且所有这些系统发育树均与已发表的对应传粉蜂的系统发育树不相符。上述发现与传粉蜂频繁发生宿主转换的假说最为契合——这类宿主转换甚至可发生在亲缘关系较远的演化支之间，进而引发无花果的杂交事件。在此我们提出，传粉蜂的宿主转换与无花果的杂交事件，是榕-蜂共生体系中一项核心的演化特征……