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，对于我们全面理解维持有性生殖的代价与收益具有重要意义。周期性孤雌生殖的蚜虫（Cyclically parthenogenetic aphids）在有性生殖频率上存在高度变异，现有研究大多聚焦于地表自由生活的蚜虫，而扩散限制以及对蚂蚁抚育的依赖，可能会对地下蚜虫有性生殖的代价与收益产生差异化影响。本研究针对一类与黄毛蚁（Lasius flavus）专性共生的根蚜群落，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：膨管蚜（Geoica utricularia）、榆绵蚜（Tetraneura ulmi）、缘边瘿绵蚜（Forda marginata）以及F. formicaria，开展了遗传种群结构分析，结果显示所有物种即便并非完全排他，也主要以无性生殖为主，种群内存在多个克隆谱系。研究发现种群粘性较高且有翅蚜极为罕见，这与蚁巢宿主间罕见的水平传播现象相符。三个研究物种缺乏有性生殖的原因，或许是其缺少原生寄主黄连木（Pistacia），而第四个物种（T. ulmi）的原生寄主榆树（Ulmus），却分布在研究种群周边数公里范围内。我们讨论了专性蚂蚁抚育与原生寄主缺失，在多大程度上影响了永久性孤雌生殖的选择压力，并强调需要在南欧开展进一步研究——在该区域原生寄主可能紧邻黄毛蚁种群分布，使得四种根蚜物种均具备完成有性生殖生命周期的现实条件。