Data from: Multi-year genetic sampling indicates maternal gene flow via colony emigrations in the army ant Eciton burchellii parvispinum

Sex-biased dispersal occurs when one sex disperses more frequently or farther than the opposite sex. In ants, dispersal is often male-biased and males typically contribute more strongly to gene flow within and among ant populations. However, army ants may offer an exceptional case of female-biased dispersal because army ant colonies (particularly species in the Neotropical genus Eciton) routinely emigrate among nest sites. We hypothesized that maternal mobility via successive colony emigrations would reduce the relative male bias in dispersal, and that emigrations would contribute to gene flow within an Eciton population. We genotyped workers (highly variable DNA microsatellite loci) from Eciton burchellii parvispinum colonies collected over a 10X10 km area in Monteverde, Costa Rica. Samples were spaced approximately three years apart (in 2006 and 2009), the typical time between colony reproductive bouts. We used worker genotypes to reconstruct the genotypes of their mother queens and of a subset of the males that sired the workers. We then analyzed the population genetic structure of the queen and male genotypes by comparing individual-based relatedness estimates for each sex across geographic distance and over time. There was no significant difference in spatial genetic structure between the sexes, either within or between the 2006 and 2009 samples. There was some evidence against genetic philopatry: 2009 queens were significantly unrelated to 2006 queens collected nearby (within 0.5 km). The patterns suggest maternal dispersal via emigrations contributes to gene flow, reducing or eliminating male biases in dispersal. From two populations we estimated average queen dispersal distance to be 0.63-1.04 km, a greater distance than many winged ant queens disperse. Because emigrations over the lifetime of army ant queens queen may contribute to gene flow across the landscape, habitat connectivity should be maintained to permit colony emigrations and support genetic diversity in populations of this keystone species.性偏扩散是指某一性别相较于另一性别，扩散频率更高或扩散距离更远的现象。在蚂蚁类群中，扩散通常呈现雄性偏向，雄性往往对种群内部及种群间的基因流贡献更为突出。然而，行军蚁则可能属于雌性偏向扩散的特例：行军蚁蚁群（尤其是新热带区（Neotropical）游蚁属（Eciton）的物种）会频繁在巢址间进行迁移活动。本研究提出假设：通过蚁群连续迁移实现的母系移动，可缓解扩散行为中的雄性偏向性，且迁移活动能够促进游蚁属种群内部的基因流。我们采集了哥斯达黎加蒙特维德地区10×10公里范围内的布氏游蚁小刺亚种（Eciton burchellii parvispinum）蚁群的工蚁样本，并对其进行基因分型，检测位点为高多态性DNA微卫星位点（microsatellite loci）。两次采样间隔约为三年（2006年与2009年），这恰好是蚁群繁殖周期的典型间隔时长。我们借助工蚁的基因型，重构了其母蚁后的基因型，以及部分与这些工蚁存在父子关系的雄蚁的基因型。随后，我们通过比较不同地理距离与时间跨度下，各性别个体间的亲缘关系估计值，分析了蚁后与雄蚁基因型的种群遗传结构。无论是2006年与2009年的样本内部，还是样本之间，两性的空间遗传结构均未呈现显著差异。研究结果存在证据反对遗传留居现象：2009年采集的蚁后，与2006年采集的0.5公里范围内的蚁后之间无显著亲缘关系。上述结果表明，通过迁移实现的母系扩散可促进基因流，缓解甚至消除扩散行为中的雄性偏向性。我们基于两个种群估算得到，蚁后的平均扩散距离为0.63至1.04公里，这一距离远大于多数具翅蚁后的扩散距离。由于行军蚁蚁后一生的迁移行为可促进整个景观尺度的基因流，因此应当维持栖息地连通性，以保障蚁群迁移活动顺利进行，进而维持这一关键物种种群的遗传多样性。