Declining plant diversity alters ecological networks, such as plant–herbivore interactions. However, our knowledge of the potential mechanisms underlying effects of plant species loss on plant–herbivore network structure is still limited. We used DNA barcoding to identify herbivore–host plant associations along declining levels of tree diversity in a large‐scale, subtropical biodiversity experiment. We tested for effects of tree species richness, host functional and phylogenetic diversity, and host functional (leaf trait) and phylogenetic composition on species, phylogenetic and network composition of herbivore communities. We found that phylogenetic host composition and related palatability/defence traits but not tree species richness significantly affected herbivore communities and interaction network complexity at both the species and community levels. Our study indicates that evolutionary dependencies and functional traits of host plants determine the composition of higher trophic levels and corresponding interaction networks in species‐rich ecosystems. Our findings highlight that characteristics of the species lost have effects on ecosystem structure and functioning across trophic levels that cannot be predicted from mere reductions in species richness.

中文翻译：

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寄主的功能和系统发育组成，而不是寄主的多样性构成植物-草食动物的网络。

植物多样性的下降会改变生态网络，例如植物与草食动物的相互作用。但是，我们对植物物种流失对植物-草食动物网络结构潜在影响的潜在机制的认识仍然有限。在大规模的亚热带生物多样性实验中，我们利用DNA条形码识别了草食动物与寄主植物之间的树木多样性下降的关联。我们测试了树木物种丰富度，宿主功能和系统发育多样性以及宿主功能（叶片性状）和系统发育组成对草食动物群落的物种，系统发育和网络组成的影响。我们发现，系统发育寄主的组成和相关的适口性/防御性状，而不是树木的丰富度，在物种和群落水平上都显着影响草食动物群落和相互作用网络的复杂性。我们的研究表明，寄主植物的进化依赖性和功能性状决定了物种丰富的生态系统中较高营养水平的组成和相应的相互作用网络。我们的研究结果突出表明，失去的物种特征会影响整个营养层的生态系统结构和功能，而仅凭物种丰富度的下降是无法预测的。