Data from: Extreme polyandry aids the establishment of invasive populations of a social insect

While monandry is believed to have facilitated the evolution of eusociality, many highly eusocial insects have since evolved extreme polyandry. The transition to extreme polyandry was likely driven by the benefits of within-colony genetic variance to task specialization and/or disease resistance, but the extent to which it confers secondary benefits, once evolved, is unclear. Here we investigate the consequences of extreme polyandry on the invasive potential of the Asian honey bee, Apis cerana. In honey bees and other Hymenoptera, small newly-founded invasive populations must overcome the genetic constraint of their sex determination system, which requires heterozygosity at a sex-determining locus to produce viable females. We find A. cerana queens in an invasive population mate with an average of 27 males (range: 16-42), which would result in the founding queen/s carrying 75% of their source population’s sex alleles in stored sperm. This mating frequency is similar to native-range Chinese A. cerana (mean: 29 males, range: 19-46). Simulations reveal that extreme polyandry reduces the risk, relative to monandry or moderate polyandry, that colonies produce a high incidence of inviable brood in populations that have experienced a founder event, i.e. when sex allele diversity is low and/or allele frequencies are unequal. Thus, extreme polyandry aids the invasiveness of A. cerana in two ways: (i) by increasing the sex locus allelic richness carried to new populations with each founder, thereby increasing sex locus heterozygosity, and (ii) by reducing the population variance in colony fitness following a founder event.尽管单配制（monandry）曾被认为推动了真社会性（eusociality）的演化，但诸多高度真社会性昆虫后续却演化出了极端多配制（extreme polyandry）。向极端多配制的转变，其驱动因素大概率源于社群内遗传变异对任务特化及/或病害抗性的益处，但该策略演化后所能带来的次生收益究竟几何，目前仍不明确。本研究旨在探究极端多配制对东方蜜蜂（Apis cerana）入侵潜力的影响。在蜜蜂及其他膜翅目（Hymenoptera）昆虫中，新建立的小型入侵种群必须克服其性别决定系统的遗传限制：该系统要求性别决定位点（sex-determining locus）处于杂合状态，方可产生可存活的雌性个体。我们发现，入侵种群中的东方蜜蜂建群蜂后平均与27只雄蜂交配（交配范围：16至42只），这意味着建群蜂后可将其源种群75%的性别等位基因存储于精子内。该交配频率与中国本土分布的东方蜜蜂相近（平均交配频次：29只雄蜂，范围：19至46只）。模拟实验结果显示，相较于单配制或中度多配制，极端多配制可降低种群经历建群事件后（即性别等位基因多样性较低且/或等位基因频率不均等时），蜂群产生高比例无生活力子代的风险。综上，极端多配制通过两种途径助力东方蜜蜂的入侵性：其一，提升每个建群个体携带至新种群的性别位点等位基因丰富度，从而提高性别位点的杂合度；其二，降低建群事件后蜂群适合度的种群方差。