We’ve all been there – there’s one piece of cake left in the fridge and your roommates are out. Do you eat the cake by yourself? Or do you find a way to share? Biologists at the Kunming Institute of Zoology and Harvard University have come up with a plan to study how and when cooperation comes about.

Most of us are familiar with the honey bee – one of the most highly cooperative animals known to man. No individual within a honey bee colony is capable of surviving and reproducing on its own. But in fact, honey bees are only one type of bee among thousands. The vast majority of these bee species are solitary – they do not work together to help collect and share resources. Instead, each female collects food and raises offspring on her own.

Scientists at the Kunming Institute of Zoology and Harvard University are trying to figure out why females in some species stay together to work collectively while females in other species leave to forge their own paths. It turns out that some bee species are capable of both strategies: they can either work together in a group or work alone as individuals. These bees are particularly useful for finding the genetic differences that lead some individuals to cooperate while others do not.

The researchers have teamed up with BGI to focus on one of these bees, Lasioglossum albipes. This species can be found from Europe all the way to Asia, but depending on where it is, the behavioral strategy it uses is completely different. In the UK and parts of France, L. albipes is social, and daughters remain in the colony to help their mothers produce more of their siblings. But in Switzerland and Germany, the daughters leave to reproduce on their own. How and why some individuals stay to cooperate while others do not remains an evolutionary puzzle. To begin to answer this question, our biologists have sequenced the genome of this fascinating bee.

Kocher and colleagues first had to find and capture the bees in the field. Because no one had worked on this species for the past two decades, it took a great deal of exploration to find it. Kocher spent months in the field trying to find the right bee. “They were very difficult to track down”, she said. “I had to search through thousands of fields to find a few where these bees lived.”After several years of searching, she now has located a number of stable populations of this species and is now beginning more detailed studies on their behavior and physiology to better understand the differences between what makes these individuals solitary or social.

The genome sequencing was also no small feat. “We compared the Lasioglossum genome to those of other insect species, and used that to find some very interesting differences between the solitary and social populations,” said Dr. Douglas Yu, the senior scientist in this study. “We found six genes that appear to be rapidly diverging between these two social forms. Most interestingly, one of these genes encodes a putative odorant receptor, suggesting that differences in chemical signaling may be associated with differences between a cooperative and non-cooperative bee.” This is the first genome sequenced for an insect species capable of both social and solitary behavior.

 “The L. albipes genome has given us a lot of tantalizing places to start looking”, Yu said, “and now the really difficult work begins”. They are now sequencing the genomes of not one, but one hundred and twenty five individuals of this species, from both types of social forms. Using these data, they expect to find many critical genes that differ between solitary and social populations. Then, Kocher plans to conduct a series of behavioral and physiological studies to understand exactly how these genetic differences lead to the behavioral differences she observes in the field.

The research was funded by Yunnan Province, the Chinese Academy of Sciences, the National Natural Science Foundation of China, the University of East Anglia, and the State Key Laboratory of Genetic Resources and Evolution at the Kunming Institute of Zoology. It was also funded by Harvard University, the John Templeton Foundation, and the United States National Science Foundation.

“The draft genome of a socially polymorphic halictid bee, Lasioglossum albipes” is published in the journal Genome Biology on Dec. 20, 2013.

Journal reference:

Kocher, SD*, Li, C*, Yang, W, Tan, H, Yi, SV, Yang, X, Hoekstra, HE, Zhang, G, Pierce, NE, Yu, DW. (2013). The genome of a socially polymorphic halictid bee, Lasioglossum albipes. Genome Biology, 14(12):R142.