Data from: Population genetic structure and secondary symbionts in host-associated populations of the pea aphid complex

Polyphagous insect herbivores experience different selection pressures on their various host plant species. How this affects population divergence and speciation may be influenced by the bacterial endosymbionts that many harbor. Here, we study the population structure and symbiont community of the pea aphid (Acyrthosiphon pisum), which feeds on a range of legume species and is known to form genetically differentiated host-adapted populations. Aphids were collected from eight legume genera in England and Germany. Extensive host plant-associated differentiation was observed with this collection of pea aphids comprising nine genetic clusters, each of which could be associated with a specific food plant. Compared to host plant, geography contributed little to genetic differentiation. The genetic clusters were differentiated to varying degrees, but this did not correlate with their degree of divergence in host use. We surveyed the pea aphid clones for the presence of six facultative (secondary) bacterial endosymbionts and found they were non-randomly distributed across the aphid genetic clusters and this distribution was similar in the two countries. Aphid clones on average carried 1.4 species of secondary symbiont with those associated with Lathyrus having significantly fewer. The results are interpreted in the light of the evolution of specialization and ecological speciation.多食性植食昆虫在不同寄主植物物种上会遭遇各异的选择压力。该过程对种群分化与物种形成的影响，或许会受到多数此类昆虫所携带的细菌内共生体的调控。本研究旨在探究豌豆蚜（Acyrthosiphon pisum）的种群结构与共生体群落，该物种取食多种豆科植物，且已知可形成具有遗传分化的寄主适应性种群。研究人员于英国与德国采集了来自8个豆科属的豌豆蚜样本。对该批包含9个遗传簇的豌豆蚜样本的分析显示，其存在广泛的寄主植物关联分化，每个遗传簇均可对应特定的寄主植物。相较于寄主植物种类，地理因素对遗传分化的贡献极小。各遗传簇间的分化程度存在差异，但这一差异与其寄主利用策略的分化程度并无关联。我们针对6种兼性（次级）细菌内共生体的存在情况，对豌豆蚜克隆株进行了检测，发现这些共生体在蚜虫遗传簇间呈非随机分布，且两国间的共生体分布模式相似。平均每个蚜虫克隆株携带1.4种次级共生体，其中与山黧豆属（Lathyrus）寄主相关的克隆株所携带的共生体种类显著更少。本研究结果可从特化演化与生态物种形成的视角进行解读。