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寄主。因此，寄主植物群落的系统发育组成，在决定昆虫取食特化程度、食物网结构与物种多样性方面发挥着关键作用。已有研究显示，草食性昆虫对同属乃至同科寄主具有显著的取食偏好，这表明不同层级的寄主植物亲缘关系对昆虫的影响程度存在差异。
2. 本研究旨在量化寄主系统发育对定量植物-草食昆虫食物网结构的影响。此外，我们还针对3个具有不同生活史特征的昆虫功能群，明确其取食模式的特异性，并探讨寄主植物系统发育在维持其物种多样性中的作用。
3. 我们选取日本与捷克共和国的3处温带森林开展草食昆虫群落研究。通过冠层起重机、高空作业车及伐倒木三种采样方式，对3块0.1公顷样地内的食叶幼虫、潜叶昆虫与虫瘿昆虫的植物-草食昆虫互作关系进行了全面普查。本研究通过将实测食物网与寄主选择的随机模型进行对比，分析了寄主系统发育的影响效应。
4. 在三个研究样地中，食叶幼虫均表现出较高的取食广度，而虫瘿昆虫与潜叶昆虫几乎均为单食性类群。当将距今5~80百万年的较古老寄主谱系合并为单一谱系时，食叶幼虫的取食广度会快速下降；但仅合并亲缘关系最近的同属寄主时，其取食广度仅出现小幅降低。这表明，食叶幼虫的取食广度主要通过取食同科寄主得以维持，而亲缘关系较远的植物谱系间仅存在极少数共享的草食昆虫；令人意外的是，部分同属寄主间也不存在共享的草食昆虫。与之形成鲜明对比的是，潜叶昆虫与虫瘿昆虫的取食广度主要由寄主系统发育的末端分支所维持，仅合并同属寄主为单一谱系后，其取食广度便会立刻下降。
5. 本研究证实，寄主植物系统发育的不同层级对植物-草食昆虫食物网结构的调控效应并不均等。对于泛食性昆虫功能群而言，驱动食物网结构的是较深层级的植物系统发育关系，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取食特化程度与种群丰度，主要受植物系统发育的末端分支影响，通常无法反映较深层级的寄主亲缘关系。