Effect of plant chemical diversity on structuring herbivore populations across different spatial scales

在生态群落中，物种间的相互作用构成了当地种群，并影响着物种的共存。两种不同但互补的研究物种相互作用的方法是群落遗传学，它认识到物种内的遗传变异可以改变不同物种之间的相互作用;和，后居生态学，强调分散在构建当地社区中的作用。本文以艾菊-蚜虫系统为模型，研究了群落遗传相互作用对后居动态的影响.艾菊挥发性有机化合物（VOCs）的种内变异较大，影响蚜虫及其天敌的选择性。在这个项目的第一阶段，我们的特点是在一个单一的领域网站的艾菊的化学型多样性，并详细研究了如何小规模的变化，在宿主植物的化学成分决定艾菊植物上的昆虫群落的殖民模式。我们还研究了挥发性（萜类化合物）和代谢组学（主要是酚类化合物）的艾菊配置文件之间的关系，以及蚜虫定殖的代谢表型（“代谢型”）的作用。我们开发了蚜虫的微卫星，并发现，在我们的现场小空间尺度，植物的挥发性配置文件和蚜虫基因型之间的关联。使用实验室设置，我们的特点是不同的艾菊化学型攻击蚜虫和咀嚼草食动物，蚜虫和蚂蚁主机的选择。总的来说，第1阶段提供的证据，植物化学型的重要性，为结构的昆虫metacheidity艾菊植物。在这里，我们建议扩展我们的分析，1）一个更大的空间尺度和2）地下植物-昆虫相互作用的特征根化学型。在实验室环境中，我们将分析植物根的化学型组成，以了解植物地上部分的萜类化合物模式与根的萜类化合物模式之间是否存在代谢和基因型关系。然后，我们将使用根食蚜虫调查，如果有蚜虫种之间的相互作用，在地下和地上部分的植物喂养，以及什么角色根和芽化学型发挥蚜虫metaceritivity结构？使用来自整个德国和超越的样本，我们将研究的根和茎萜类化合物的化学型的艾菊的地理分布和分析的作用，为结构化的昆虫群落的艾菊的优势和次要化合物。通过开发和应用SNP遗传标记，我们还将把植物之间的化学型差异与优势蚜虫食草动物的群体遗传学联系起来。总的来说，该项目将阐明构建田间生态群落的基本机制。

In an ecological community, species interactions structure local populations and influence species coexistence. Two different, yet complementary, approaches to studying species interactions are community genetics, which recognises that within-species genetic variation can alter the interactions between different species; and, metacommunity ecology, which emphasizes the role dispersal plays in structuring local communities. We investigate how community genetic interactions influence metacommunity dynamics, using a model tansy (Tanacetum vulgare) plant – aphid system. Tansy exhibits high intraspecific variation in volatile organic chemicals (VOCs), which can influence the preference of aphids and their natural enemies. In Phase 1 of this project, we characterized the chemotypic diversity of tansy within a single field site and studied in detail how small-scale variation in the chemical composition of the host plant determines colonisation patterns of the insect community on tansy plants. We also studied the relationship between volatile (terpenoids) and metabolomic (mostly phenolic compounds) profiles of tansy, and the role of the metabolic phenotype (‘metabotype’) for aphid colonisation. We developed microsatellites for aphids and found, at the small spatial scale of our field site, an association between the volatile profile of plants and the aphid genotypes. Using laboratory set-ups, we characterized the response of different tansy chemotypes to attack by aphids and a chewing herbivore, and aphid and ant host choice. Overall, Phase 1 provided evidence for the importance of plant chemotypes for structuring the insect metacommunity on tansy plants. Here we propose to extend our analysis to 1) a larger spatial scale and 2) to belowground plant-insect interactions by characterizing the root chemotype. In a laboratory setting, we will analyze the chemotypical composition of the plant roots, to understand if there a metabolic and genotypic relationship between the terpenoid patterns in the aboveground part of the plant and those of the roots. We will then use root-feeding aphids to investigate if there is an interaction between aphid species feeding on the belowground and aboveground parts of the plant, and what roles root and shoot chemotypes play for aphid metacommunity structure? Using samples from across Germany and beyond, we will study the geographical distribution of root and shoot terpenoid chemotypes of tansy and analyze the role of dominant and minor compounds for structuring the insect communities on tansy. By developing and applying SNP genetic markers, we will also link the chemotypical differences between plants to the population genetics of the dominant aphid herbivore.Overall the project will shed light on fundamental mechanisms structuring ecological communities in the field.