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，即繁殖行为的相互抑制）是阐释胁迫如何推动合作演化的经典例证。在“原始真社会性”且交配频率较低的类群中，工蜂监督现象依然存在——这类类群缺乏利于监督发生的亲缘差异，这提示工蜂监督的起源与维持或许由其他独立因素驱动。我们以原始真社会性、单雄交配的地熊蜂（Bombus terrestris）为研究对象，通过探究雄性父本冲突验证了这一假说。借助观察法、控制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（而非蜂王产下的雄蜂卵）几乎会在产下后即刻被蜂王、生殖型工蜂与非生殖型工蜂取食殆尽，这解释了野外观测到的幼虫与成虫阶段工蜂来源雄蜂频率极低的现象；(b) 蜂王与工蜂产下的雄蜂卵具有同等存活能力；(c) 工蜂可借助卵及卵室表面的、几乎必然源自蜂王的识别线索，区分蜂王与工蜂产下的卵。在高度真社会性、多雄交配的蜜蜂类群中存在“经典”工蜂监督的三大核心特征，而地熊蜂中这三大特征的同时出现，为“工蜂监督可在缺乏维持其存在的亲缘差异的情况下起源”这一假说提供了全新佐证。地熊蜂的工蜂监督几乎必然源于工蜂间的繁殖竞争，即属于“自私型”监督。