Worker bees have become a highly skilled and specialized work force because the genes that determine their behaviour are shuffled frequently, helping natural selection to build a better bee, research from York University suggests.
The study, to be published October 15 at 3pm EST in PNAS (Proceedings of the National Academy of Sciences), sheds light on how worker bees -- who are sterile -- evolved charismatic and cooperative behaviours such as nursing young bees, collecting food for the colony, defending it against intruders, and dancing to communicate the location of profitable flowers to nestmates.
When York University researchers examined the honey bee genome, they discovered that the genes associated with worker behaviour were found in areas of the genome that have the highest rate of recombination. Recombination represents a shuffling of the genetic deck: recombination in the ovaries of a queen shuffles the chromosomes she inherited from her parents. As a result, the queen's female offspring are likely to inherit mosaic chromosomes with different combinations of mutations, says Biology Professor Amro Zayed, whose lab conducted the research.
Recombination allows natural selection to act on specific mutations without regard to neighbouring mutations.
"If I'm a good rower in a dragon boat with 49 poor rowers, I am going to lose all of my races. But if teams were shuffled after every race, I'll likely have a better chance of winning. I may even get to be in a boat with 49 good rowers just like myself," says Zayed. "The same thing happens with mutations on a chromosome. Recombination makes the evolutionary fate of mutations independent of their surrounding neighbours, which enhances the process of natural selection.."
The team believes that they have solved one of the mysteries of the honey bee's genome, says postdoctoral research associate Clement Kent, lead author on the study.
"The honey bee has the highest rates of recombination in animals -- ten times higher than humans. Our study shows that this high degree of genetic shuffling has turned on the evolutionary faucet in parts of the bee genome responsible for orchestrating worker behaviour," says Kent. "This can allow natural selection to increase the fitness of honey bee colonies, which live or die based on how well their workers 'behave'."
The study, "Recombination is associated with the evolution of genome structure and worker behavior in honey bees" was coauthored by Kent, Zayed, and graduate students Shermineh Minaei and Brock Harpur. The research was funded by the Natural Sciences and Engineering Research Council of Canada and the Province of Ontario.
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