Parasitoids as drivers of symbiont diversity in an insect host

Immune systems have repeatedly diversified in response to parasite diversity. Many animals have outsourced part of their immune defence to defensive symbionts, which should be affected by similar evolutionary pressures as the host’s own immune system. Protective symbionts provide efficient and specific protection and respond to changing selection pressure by parasites. Here, we use the aphid Aphis fabae, its protective symbiont Hamiltonella defensa and its parasitoid Lysiphlebus fabarum to test whether parasite diversity can maintain diversity in protective symbionts. We exposed aphid populations with the same initial symbiont composition to parasitoid populations that differed in their diversity. As expected, single parasitoid genotypes mostly favoured a single symbiont that was most protective against that particular parasitoid, while multiple symbionts persisted in aphids exposed to more diverse parasitoid populations, which in turn affected aphid population density and rates of para..., For an exact description of the methods used to obtain the data herein, please refer to the associated article. basic.txt: Data collected during aphid transfer in every generation. See methods for exact procedured to obtain each meassurement. mol.txt: Information on the presence and absence of H. defensa and the identity of the H. defensa strain present. This data was obtained by diagnostic PCRs on aphids collected during transfer in generation 2, 6, and 10 and subsequent sequencing if H. defensa was present (see methods for more details). Data for generation 0 was known because of the strain each aphid belonged to during set up., See readme.txt for a description of column names used in the data sets.免疫系统会随寄生虫多样性的演化发生反复多样化。诸多动物会将部分免疫防御功能外包给防御性共生菌，此类共生菌理应承受与宿主自身免疫系统相近的演化压力。保护性共生菌可提供高效且特异性的防御，并能响应寄生虫施加的动态选择压力。本研究以甜菜蚜（Aphis fabae）、其保护性共生菌汉森菌（Hamiltonella defensa）以及其寄生蜂蚜茧蜂（Lysiphlebus fabarum）为实验体系，探究寄生虫多样性是否能够维持保护性共生菌的多样性。我们将初始共生菌组成一致的蚜群暴露于多样性水平各异的寄生蜂种群中。实验结果符合预期：单一寄生蜂基因型大多会偏向筛选出对该特定寄生蜂防御效果最优的单一共生菌；而当蚜群暴露于多样性更高的寄生蜂种群时，多种共生菌可在蚜体内持续存留，这进而会影响蚜虫种群密度以及寄生率等相关指标……。若需精准了解获取本研究数据所用的实验方法，请参阅相关发表论文。 basic.txt：每一代蚜虫转接过程中采集的数据。各项测量指标的具体获取流程详见实验方法。 mol.txt：包含H. defensa的存在情况以及所检测到的H. defensa菌株类型的相关信息。该数据通过对第2、6、10代转接时采集的蚜虫进行诊断PCR，并在检测到H. defensa存在时开展后续测序获得（详细信息参见实验方法）。第0代的数据为已知，因为实验搭建时每个蚜虫所属的菌株信息已明确。请参阅readme.txt以了解数据集所用的列名说明。