The notorious promiscuity of queen bees makes for a genetically diverse colony. Sounds good, but until now, researchers hadn't actually found any clear benefit. However, new research suggests that one payoff may be in regulating the temperature of the hive.
It can get hot in a beehive; the baby bees must stay between 32o and 36oC for normal development. Bees cool their nests using different methods, including evacuating the nest and fanning at its entrance. If some bees like it hot, and some like it colder, they will begin fanning to cool off at different times, and the colony response as a whole will be more gradual. In a less diverse colony, the temperature can swing wildly as many bees start and stop fanning simultaneously.
In the 24 June Sciencexpress, researchers at the University of Sydney report that the differences between the bees' liking for heat can be accounted for by genetics. Julia Jones and colleagues developed four genetically uniform colonies by artificially inseminating the queen. They then compared these colonies to ones with queens who mated freely and were therefore much more genetically diverse. Measurements of the two groups after a week in late winter showed that the diverse groups were able to keep their temperature more stable than the homogenous colonies. The team then raised the mercury to 40oC. Again, the uniform colonies fluctuated in temperature more than the diverse colonies. The key to the diverse colonies' stable temperatures was the diversity in the bees' internal thermostats. Using genetic markers, the scientists showed that within the same colony, bees from one lineage started fanning at a slightly different temperature than did bees from a different lineage.
There have been a number of hypotheses suggested to explain queen bee's multiple mates, but there has been no convincing evidence for an adaptive value, says Robert Page, an entomologist at Arizona State University. "What had been missing was good studies showing these kinds of effects," he said. "To my knowledge, this is the first evidence" of the adaptive value of genetic diversity.