Data from: Reproduction and dispersal in an ant-associated root aphid community

Clonal organisms with occasional sex are important for our general understanding of the costs and benefits that maintain sexual reproduction. Cyclically parthenogenetic aphids are highly variable in their frequency of sexual reproduction and studies have mostly focused on free-living aphids above ground, whereas dispersal constraints and dependence on ant-tending may differentially affect the costs and benefits of sex in subterranean aphids. Here, we studied reproductive mode and dispersal in a community of root aphids that are obligatorily associated with the ant Lasius flavus. We assessed the genetic population structure of four species (Geoica utricularia, Tetraneura ulmi, Forda marginata and F. formicaria) in a Dutch population and found that all species reproduce predominantly if not exclusively asexually, so that populations consist of multiple clonal lineages. We show that population viscosity is high and winged aphids rare, consistent with infrequent horizontal transmission between ant host colonies. The absence of the primary host shrub (Pistacia) may explain the absence of sex in three of the studied species, but elm trees (Ulmus) that are primary hosts of the fourth species (T. ulmi), occured within a few km of the study population. We discuss the extent to which obligate ant-tending and absence of primary hosts may have affected selection for permanent parthenogenesis and we highlight the need for further study of these aphids in Southern Europe where primary hosts may occur close to Lasius flavus populations, so that all four root aphid species would have realistic opportunities for completing their sexual life-cycle.偶有有性生殖的克隆生物（clonal organisms），对于我们全面理解维持有性生殖的演化成本与收益具有重要价值。周期性孤雌生殖（cyclically parthenogenetic）的蚜虫类群，其有性生殖频率存在显著变异；现有研究多聚焦于地表自由生活的蚜虫，而扩散限制与依赖蚂蚁抚育的特性，可能会差异化影响地下蚜虫有性生殖的成本与收益。本研究针对专性与黄毛蚁（Lasius flavus）共生的根蚜群落，探究其生殖模式与扩散能力。我们对荷兰种群中的4个物种——囊状根蚜（Geoica utricularia）、榆四脉绵蚜（Tetraneura ulmi）、缘福氏蚜（Forda marginata）以及福氏蚜（F. formicaria）——的遗传种群结构进行了评估，发现所有物种即便并非完全排他性地进行无性生殖，也主要以无性生殖为主，种群内包含多个克隆谱系。研究结果表明，该类群种群粘性较高、有翅蚜虫极为罕见，这与蚁寄主群落间罕见的水平传播现象相符。3个研究物种缺失有性生殖的现象，或可归因于其初级寄主灌木黄连木属（Pistacia）的缺失；而第四种研究物种榆四脉绵蚜的初级寄主榆属（Ulmus）植物，却分布于研究种群周边数公里范围内。我们讨论了专性蚁护与初级寄主缺失，在多大程度上影响了永久孤雌生殖的选择压力，并强调需在南欧开展进一步研究：该区域内初级寄主可能与黄毛蚁（Lasius flavus）种群近距离共存，使得全部4种根蚜均具备完成有性生殖生命周期的现实条件。