Tropical paper wasps aren’t typecast like honeybees. From early development, honeybees are locked into specific roles—drone, worker, or queen—by the genes they express. In contrast, if a queen tropical paper wasp is injured or killed, a worker wasp can take over her role as monarch. Despite the paper wasp’s interesting social mobility, until now researchers have focused instead on the honey bee.
“Wasps represent one of the earliest stages of social behavior, at the other end of the spectrum from the honeybee. [The tropical paper wasp] is the most primitive type of social wasp,” said study author Seirian Sumner, a senior lecturer in behavioral biology at the University of Bristol.
In the study, the team used an assembly of pooled wasp individuals to identify genes expressed by adult females and then sequenced their RNA to quantify the expression levels of those genes in worker and queen wasps. As a result, the team found that 2442 genes were differentially expressed between queens and workers, and 75% of those had no known homology with honeybees.
“That was really surprising. They’re either taxonomically important to wasps or important to the early stages of sociality—we just don’t know at the moment,” said Sumner.
Of those differentially expressed genes, the researchers found that about 90% were upregulated in workers. “We didn’t expect to see this marked asymmetry. The workers are jacks-of-all-trades, expressing a lot of genes at high levels, whereas queens upregulate only a small subset of genes,” said Sumner.
With this in mind, Sumner and colleagues suggest that if researchers focus only on honeybee genetics to study insect sociality, they are not seeing the complete story.
The study could also have implications for other areas of research. Insect societies are just one form of sociality. Another is the transition from single-celled organisms to cooperative, multicellular organisms. “Asymmetry of gene expression between two phenotypes could shed light on other levels of biological organization and address how complexity evolves at a lot of different levels,” said Sumner.
She hopes that other researchers will follow her team’s lead and conduct similar studies of a range of different organisms with different levels of social organization. For her part, she is currently doing a full genome sequence of the tropical paper wasp and plans to investigate how epigenetics regulates the genetic differences between workers and queens. “It’s the next natural step in the study,” said Sumner.
1. Ferreira, P., S. Patalano, R. Chauhan, R. F. Constant, T. Gabaldon, R. Guigo, and S. Sumner. 2013. Transcriptome analyses of primitively eusocial wasps reveal novel insights into the evolution of sociality and the origin of alternative phenotypes. Genome Biology 14(2):R20+.