REPRODUCTIVE CONFLICT IN BUMBLEBEES AND THE EVOLUTION OF WORKER POLICING

• Published in: Evolution Vol. 66; no. 12; pp. 3765 - 3777
• Main Authors: Zanette, Lorenzo R. S., Miller, Sophie D. L., Faria, Christiana M. A., Almond, Edd J., Huggins, Tim J., Jordan, William C., Bourke, Andrew F. G.
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.12.2012; Wiley Subscription Services, Inc; Oxford University Press
• Subjects: Animal behavior; Animal reproduction; Animals; Ants; Bees; Bees - genetics; Bees - physiology; Behavior, Animal; Bombus terrestris; Bumblebees; Colonies; Cues; Evolutionary biology; Female; inclusive fitness theory; Insect colonies; Insect eggs; kin selection; Larva; Male; Male animals; Microsatellite Repeats; Ova; Oviparity; Ovum - chemistry; Ovum - physiology; Police services; Queen insects; Reproduction; Sex Ratio; social insect; Worker insects; worker reproduction
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.1558-5646.2012.01709.x

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.