BACKGROUND AND AIMS Highly controlled experiments document that plant genetic diversity and relatedness can shape herbivore communities and patterns of herbivory. Evidence from the field is however scarce and inconsistent. We assessed whether a genetic signal underlying herbivory can be detected in oak woodlands when accounting for variation at smaller (within-tree) and larger (among-stand) scales. METHODS We tested relationships between tree genetic relatedness, leaf chemical defences and insect herbivory for different canopy layers in 240 trees from 15 Pedunculate oak (Quercusrobur) forest stands. We partitioned sources of variability in herbivory and defences among stands, individuals, and branches. KEY RESULTS Leaf defences, insect herbivory and their relationship differed systematically between the upper and the lower tree canopy. When accounting for this canopy effect, the variation explained by tree genetic relatedness rose from 2.8 to 34.1 % for herbivory and from 7.1 to 13.8 % for leaf defences. The effect was driven by markedly stronger relationships in the upper canopy. CONCLUSIONS Our findings illustrate that considerable effects of the host plant genotype on levels of leaf chemical defences and associated insect herbivory can be detected in natural tree populations when within-individual variation is properly accounted for.

中文翻译：

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橡树的叶子化学防御和昆虫食草：对冠层位置的解释揭示了显着的遗传相关性影响

背景和目标 高度受控的实验证明植物遗传多样性和相关性可以塑造食草动物群落和食草动物模式。然而，来自该领域的证据很少且不一致。我们评估了在考虑较小（树内）和较大（林间）尺度的变异时，是否可以在橡树林地中检测到草食性的遗传信号。方法我们测试了来自 15 个有花序栎 (Quercusrobur) 林分的 240 棵树的不同冠层的树木遗传相关性、叶子化学防御和昆虫食草之间的关系。我们在林分、个体和分支之间划分了食草和防御变异的来源。主要结果 上部和下部树冠之间的叶防御、昆虫食草及其关系存在系统差异。当考虑到这种冠层效应时，由树木遗传相关性解释的食草性变异从 2.8% 上升到 34.1%，叶防御从 7.1% 上升到 13.8%。这种效果是由上层树冠中明显更强的关系驱动的。结论 我们的研究结果表明，当个体内部变异得到适当考虑时，可以在天然树种群中检测到宿主植物基因型对叶片化学防御水平和相关昆虫食草性水平的显着影响。