Social wasps build an internal society or specialized workers. How do they do this on a genetic level? What makes a wasp do one task or another? The workers all support the queen of the colony. Scientists at the University of Bristol have sequenced the active parts of the genome — or transcriptome — of primitively eusocial wasps to identify which part makes a queen or a worker. The study, published in BioMed Central’s open access journal Genome Biology, shows that workers have a more active transcriptome than queens. This suggests that in these simple societies, workers may be the jack-of-all-trades in the colony, leaving the queen with a somewhat restricted set of work tasks.
Studying primitively eusocial species like these wasps can tell us about how sociability evolves. Dr Seirian Sumner from Bristol's School of Biological Sciences and colleagues sequenced transcriptomes from the eusocial tropical paper wasp Polistes canadensis. All social species ultimately evolved from a solitary ancestor — in this case a solitary wasp, who lays the eggs and feeds the brood. But how does this ancestral solitary phenotype split to produce specialized reproducers (queens) and brood carers (workers) when a species becomes social?
In wasps, as in other Hymenoptera, sexes are also significantly genetically different. Wasps store sperm inside their body and control its release for each individual egg as it is laid; if a female wishes to produce a male egg, she simply lays the egg without fertilizing it. Therefore, under most conditions in most species, wasps have complete voluntary control over the sex of their offspring.
Eusocial is defined as living in a cooperative group in which usually one female and several males are reproductively active and the nonbreeding individuals care for the young or protect and provide for the group.
This paper gives a first insight into the secret lives of social insects. It shows that workers retain a highly active transcriptome, possibly expressing many of the ancestral genes that are required for our solitary wasp to be successful on her own. Conversely, queens appear to shut down a lot of their genes, presumably in order to be really good reproducers.
Long-standing analyses based on the fossil record holds ants and wasps in a clade known as Vespoidea, with bees as a sister group. The researchers reassess the relationships between the subfamilies of bees, wasps and ants and suggest that wasps are part of a separate clade from ants and bees, though further genome sequences and comparative data will help to resolve this controversy.
Dr Sumner said: "This finding would have important general implications for our understanding of eusociality as it would suggest that bees and ants shared an aculeate wasp-like ancestor, that ants are wingless wasps, and that bees are wasps that lost predacious behaviors."
This study suggests that novel genes play a much more important role in social behavior than was previously thought. Is society a result of genes or a result of the members of the society working together?
For further information see Eusocial or Article.
Wasp image via Wikipedia.