|Forager bee- Patrick Coin|
Two of the subcastes are the nurse bees and the foragers. The nurse bees are essential to maintaining the otherwise helpless queen and her larvae. Foragers bring back nectar to feed the hive. While their DNA was the same, there were differences in their DNA methylation. This suppresses the gene activation or its effect on the organism. Essentially it turns down the volume of its signal.
As explained in Naturalhistorymag.com article, they then removed all the nurse bees from the hive. When the foragers discovered the deserted queen and her larvae, some reverted to nurse bees and assumed their duties. The researchers found that those newly converted nurse bees showed DNA methylation changes from their forager status to those typical of nurse bees.
To quote the www.nature.com abstract:
"In honeybee societies, distinct caste phenotypes are created from the same genotype, suggesting a role for epigenetics in deriving these behaviorally different phenotypes. We found no differences in DNA methylation between irreversible worker and queen castes, but substantial differences between nurses and forager subcastes. Reverting foragers back to nurses reestablished methylation levels for a majority of genes and provides, to the best of our knowledge, the first evidence in any organism of reversible epigenetic changes associated with behavior."The whole field of epigenetics is a hot area of research, increasing our understanding of how DNA actually effects organisms. While seemingly impossible to understand at first glance, there is a very lucid discussion which you can find at Naturalhistorymag.com.
Picture with the kind permission of Patrick Coin.