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.具备偶发性有性生殖能力的克隆生物，对于我们全面理解维持有性生殖的成本与收益机制，具有核心学术价值。周期性孤雌生殖蚜虫（cyclically parthenogenetic aphids）的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类群；而扩散限制以及依赖蚁护共生的特性，可能会对地下蚜虫类群有性生殖的成本与收益产生差异化调控作用。本研究针对与黄毛蚁（Lasius flavus）形成专性共生关系的根蚜群落，探究其生殖模式与扩散特征。我们对荷兰种群内4个根蚜物种（Geoica utricularia、Tetraneura ulmi、Forda marginata 及 F. formicaria）的遗传种群结构开展了评估，结果显示：所有物种即便并非完全进行无性生殖，也均以无性繁殖为绝对主导方式，种群由多个克隆谱系构成。研究表明，该类群的种群粘性极高，有翅蚜个体极为罕见，这与蚂蚁宿主群落间罕有水平传播的现象相一致。黄连木（Pistacia）作为前3个研究物种的原生寄主的缺失，或可解释其无有性生殖的特性；而第4个物种（Tetraneura ulmi）的原生寄主榆树（Ulmus），在研究种群周边数公里范围内均有分布。本研究进一步探讨了专性蚁护行为与原生寄主缺失对永久性孤雌生殖选择压力的影响程度，并强调需在南欧地区开展后续研究：该区域内原生寄主可能与黄毛蚁种群毗邻分布，从而使4种根蚜均具备完成有性生殖生命周期的现实条件。