Genes' eye view of honeybee society

In a honeybee colony the queen is the only fertile females to mate and breed, leaving the roles of sibling care, foraging and defence to the sterile workers. Such behaviour in honeybees has been largely explained by results produced by an international research team from Canada and Saudi Arabia who looked at the signatures of positive selection, beneficial mutations in protein-coding genes that shape behavioural traits of honeybees.

The team scanned the genomes of 40 individual bees (Apis mellifera) from Africa, Asia and Europe using the McDonald–Kreitman (MK) test, a method for identifying selection on protein-coding sequences, reporting their results in Proceedings of the National Academy of Sciences.

Using the test, the researchers detected positive selection acting on the genes associated with G protein-coupled receptors (GPCRs) that fine-tune an organism's physiology and behavior in response to its environment.

The selection also controlled the evolution of the foraging gene and Major Royal Jelly Protein (Mrjp) genes in worker bees. Foraging gene selection benefits bee colonies by balancing the number of brood produced with the amount of food resources available. The sterile workers secrete the royal jelly proteins to feed their siblings.

"The fact that mrjp genes are under strong positive selection demonstrates that genes in sterile workers can adaptively evolve by benefiting fertile queens," says Amro Zayed, of York University in Toronto, a lead author of the study. In addition, influence of positive selection was found on genes associated with adult behaviour, cognition, nervous system development, metabolism and steroid hormones in honeybees, he adds.

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