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 ...真社会性膜翅目（eusocial Hymenoptera）中的工蜂监督（worker policing）即个体间对生殖行为的相互抑制，是阐释强制协作如何促进合作演化的经典范例。在“原始”真社会性类群中，这类类群往往交配频率较低且缺乏利于监督的亲缘关系差异，而工蜂监督仍可稳定存在，这提示其起源与维持可能依赖独立的演化驱动因素。我们以原始真社会性、单雄交配的地熊蜂（Bombus terrestris）为研究对象，针对雄性父权冲突开展实验以验证该假说。通过观察法、操控实验与微卫星基因分型（microsatellite genotyping）技术，我们获得如下发现：(a) 工蜂产下的雄蜂卵（而非蜂王所产）会在产出后不久被蜂王、有生殖能力的工蜂以及无生殖能力的工蜂尽数取食，这解释了野外观测到的幼虫与成虫阶段工蜂来源雄蜂比例极低的现象；(b) 蜂王与工蜂产下的雄蜂卵具有同等存活能力；(c) 工蜂可通过卵表面及卵室的相关线索区分蜂王与工蜂产下的卵……