Data from: Phylogenetic composition of host plant communities drives plant-herbivore food web structure

1. Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others. 2. We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity. 3. We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0.1 ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection. 4. Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80 myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages. 5. We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper plant lineages that drives the food web structure whereas the terminal relationships play minor roles. In contrast, the specialization and abundance of monophagous guilds is affected mainly by the terminal parts of the plant phylogeny and does not generally reflect deeper host phylogeny.1. 昆虫通常取食亲缘关系相近的宿主植物。因此，宿主植物群落的系统发育（phylogenetic）组成在决定昆虫特化模式、食物网结构与物种多样性方面发挥着关键作用。已有研究表明，植食性昆虫对同属（congeneric）与同科（confamilial）宿主具有显著的取食偏好，这提示宿主植物的不同亲缘关系层级可能发挥着差异化的重要作用。2. 本研究旨在量化宿主系统发育对定量型植食性昆虫-宿主植物食物网结构的影响。此外，我们针对三种具有不同生活史的昆虫功能群（guild），解析其特有的取食模式，并探讨宿主植物系统发育在维持其物种多样性中的作用。3. 我们在日本与捷克共和国的三处温带森林中开展了植食性昆虫类群调查。通过树冠起重机、高空作业车以及伐倒木采样，我们对三处面积为0.1公顷的样地内的植食性昆虫与宿主植物的互作关系进行了全面普查，涵盖食叶幼虫、潜叶昆虫与造瘿昆虫三类类群。本研究通过将观测得到的食物网与宿主选择的随机化模型进行对比，分析了宿主系统发育的影响效应。4. 食叶幼虫在三处样地均表现出较高的泛化度（generality），而造瘿昆虫与潜叶昆虫则几乎完全为单食性（monophagous）类群。当将起源时间为5-80百万年（myr）的较古老宿主谱系合并为单一类群时，食叶幼虫的泛化度会快速下降；但仅将亲缘关系最近的同属宿主合并时，其泛化度仅出现小幅降低。这表明，食叶幼虫的泛化度得益于其取食同科宿主的习性，而仅有极少数植食性昆虫会取食亲缘关系较远的植物谱系，且令人意外的是，部分同属宿主之间也几乎没有共享的植食性昆虫。与之相反，潜叶昆虫与造瘿昆虫的泛化度主要由宿主系统发育的末端节点所维持，仅需将同属宿主合并为单一类群，其泛化度便会立刻下降。5. 本研究表明，宿主植物系统发育的不同层级对植食性昆虫-宿主植物食物网的构建效应并不均等。对于泛食性昆虫功能群而言，驱动食物网结构的是起源较深的植物谱系的系统发育关系，而末端亲缘关系仅发挥次要作用。与之相反，单食性昆虫功能群的特化程度与种群丰度主要受宿主系统发育的末端部分影响，通常无法反映宿主的深层系统发育关系。