Data from: Reproductive conflict in bumblebees and the evolution of worker policing

Worker policing (mutual repression of reproduction) in the eusocial Hymenoptera represents a leading example of how coercion can facilitate cooperation. The occurrence of worker policing in “primitively” eusocial species with low mating frequencies, which lack relatedness differences conducive to policing, suggests that separate factors may underlie the origin and maintenance of worker policing. We tested this hypothesis by investigating conflict over male parentage in the primitively eusocial, monandrous bumblebee, Bombus terrestris. Using observations, experiments, and microsatellite genotyping, we found that: (a) worker- but not queen-laid male eggs are nearly all eaten (by queens, reproductive, and nonreproductive workers) soon after being laid, so accounting for low observed frequencies of larval and adult worker-produced males; (b) queen- and worker-laid male eggs have equal viabilities; (c) workers discriminate between queen- and worker-laid eggs using cues on eggs and egg cells that almost certainly originate from queens. The cooccurrence in B. terrestris of these three key elements of “classical” worker policing as found in the highly eusocial, polyandrous honeybees provides novel support for the hypothesis that worker policing can originate in the absence of relatedness differences maintaining it. Worker policing in B. terrestris almost certainly arose via reproductive competition among workers, that is, as "selfish" policing.真社会性膜翅目（eusocial Hymenoptera）中的工蜂监督（worker policing，即繁殖互斥行为）堪称胁迫促进合作的经典范例。在交配频率低、缺乏利于工蜂监督的亲缘关系差异的“原始真社会性”类群中出现工蜂监督，提示工蜂监督的起源与维持或许由独立因素驱动。我们以原始真社会性、单雄交配型的地熊蜂（Bombus terrestris）为研究对象，通过调查其雄性父权冲突验证了这一假说。本研究结合观察法、实验操作与微卫星基因分型（microsatellite genotyping）技术，得到以下结论：（a）工蜂所产的雄性卵（而非蜂王所产）在产下后几乎会被蜂王、具繁殖能力的工蜂以及无繁殖能力的工蜂快速取食，这解释了野外观测到的幼虫期及成虫期工蜂繁殖的雄性个体占比极低的现象；（b）蜂王与工蜂所产的雄性卵具有同等的孵化存活率；（c）工蜂可通过卵表面及卵室上的信号线索区分蜂王与工蜂所产的卵，而这些信号线索几乎必然源自蜂王。在高级真社会性、多雄交配型的蜜蜂中所观测到的“经典”工蜂监督的三大核心特征，在地熊蜂中同时出现，这为“工蜂监督可在缺乏维持其存在的亲缘关系差异的情况下起源”这一假说提供了全新的实证支持。地熊蜂的工蜂监督几乎可以肯定起源于工蜂间的繁殖竞争，即属于“自私型”监督行为。