Data from: Plant–insect interactions: double-dating associated insect and plant lineages reveals asynchronous radiations

AbstractAn increasing number of plant-insect studies using phylogenetic analysis suggest that cospeciation events are rare in plant–insect systems. Instead, nonrandom patterns of phylogenetic congruence are produced by phylogenetically conserved host switching (to related plants) or tracking of particular resources or traits (e.g., chemical). The dominance of host switching in many phytophagous insect groups may make the detection of genuine cospeciation events difficult. One important test of putative cospeciation events is to verify whether reciprocal speciation is temporally plausible. We explored techniques for double-dating of both plant and insect phylogenies. We use dated molecular phylogenies of a psyllid (Hemiptera)–Genisteae (Fabaceae) system, a predominantly monophagous insect–plant association widespread on the Atlantic Macaronesian islands. Phylogenetic reconciliation analysis suggests high levels of parallel cladogenesis between legumes and psyllids. However, dating using molecular clocks calibrated on known geological ages of the Macaronesian islands revealed that the legume and psyllid radiations were not contemporaneous but sequential. Whereas the main plant radiation occurred some 8 million years ago, the insect radiation occurred about 3 million years ago. We estimated that >60% of the psyllid speciation has resulted from host switching between related hosts. The only evidence for true cospeciation is in the much more recent and localized radiation of genistoid legumes in the Canary Islands, where the psyllid and legume radiations have been partially contemporaneous. The identification of specific cospeciation events over this time period, however, is hindered by the phylogenetic uncertainty in both legume and psyllid phylogenies due to the apparent rapidity of the species radiations.摘要：越来越多采用系统发育分析（phylogenetic analysis）的植物-昆虫研究表明，协同成种（cospeciation）事件在植物-昆虫体系中较为罕见。与之相对，系统发育一致性（phylogenetic congruence）的非随机模式，往往由具备系统发育保守性的宿主转换（host switching，即转向近缘植物）或是对特定资源、性状（如化学物质）的追踪所形成。在多数植食性昆虫（phytophagous insect）类群中，宿主转换占据主导地位，这可能使得真正的协同成种事件难以被检测到。 验证推测的协同成种事件的一项重要标准，是确认互作成种（reciprocal speciation）在时间上是否具备合理性。我们探索了针对植物与昆虫系统发育树的双重定年（double-dating）技术。本研究使用了木虱（psyllid，半翅目Hemiptera）-金雀儿族（Genisteae，豆科Fabaceae）体系的定年分子系统发育数据：该体系以单食性（monophagous）的昆虫-植物关联为主，广泛分布于大西洋马卡罗尼西亚群岛（Atlantic Macaronesian islands）。 系统发育调和分析（phylogenetic reconciliation analysis）结果显示，豆科植物与木虱之间存在高度的平行分支发生（parallel cladogenesis）现象。然而，基于马卡罗尼西亚群岛已知地质年代校准的分子钟（molecular clock）定年结果表明，豆科与木虱的辐射演化（radiation）并非同时发生，而是存在先后顺序：植物的主要辐射演化发生在约800万年前，而昆虫的辐射演化则始于约300万年前。我们估算，超过60%的木虱成种事件源于近缘宿主间的宿主转换。 唯一能够证实真正协同成种的证据，来自加那利群岛（Canary Islands）中金雀儿类豆科植物（genistoid legumes）近期且局限的辐射演化事件——在该区域内，木虱与豆科植物的辐射演化曾部分同步。但由于物种辐射演化速度极快，导致豆科与木虱的系统发育均存在不确定性，这阻碍了该时间段内特定协同成种事件的识别。