There are around 20,000 described ant species on earth, and they exhibit vast ecological and behavioural diversity. Social organization in ant colonies is one of the fundamental social traits in ant colonies and there have been multiple transitions from single-queen social organization to multiple-queen social organization. These different social organizations are associated with demographic, ecological and behavioural differences among the ant species and affect intracolony conflicts and evolutionary trade-offs. There is a huge body of theoretical studies on how selection shapes the evolution of new social systems, but which genetic mechanisms underlie such changes are yet to be thoroughly investigated.
Our project was designed to investigate the genetic mechanisms of the convergent evolution of the multiple-queen social organization from the single-queen social organization in ants. We wanted to understand the mechanism involved in such independent transitions from single-queen to multiple-queen social organization as well as the long-term effects of such transitions. We used the protein-coding genes to differentiate between ant species belonging to the two types of social organizations. We specifically focused on genes associated with reproduction, communication and immunity. For investigating the long-term effects of such evolutionary transitions on the biology of the species, we looked into the prevalence of viruses in ant colonies belonging to these two types of social organizations.
We used multiple ant species, some obligately single-queen species and some obligately multiple-queen species to address these questions. Ant species exhibiting the multiple-queen social organization are generally invasive. Hence, understanding the genetic mechanisms of such evolutionary transitions to the multiple-queen social organization would enable us to gain a better understanding of the genetic changes that are responsible for a species becoming invasive in a particular habitat. Such investigations in turn would enable us to design future research for controlling invasive species. In addition to this, the investigation involving the viral prevalence in ant colonies would enable us to predict whether they have the potential of becoming pathogen reservoirs and in turn, would enable us to design research for preventing any kind of pathogen spillover to other species.
The conclusion of the project was that there are consistent differences between species belonging to obligately single- or multiple-queen social organizations. Genes underlying cellular communication and recognition, which help in key processes like chemical communication, neurotransmission and immune response appeared to be under similar selection pressures and might have played significant roles during the independent transitions from single queen to multiple queen colony lifestyles. In addition to this, the project also found that multiple-queen colonies harbour greater viral load and viral diversity compared to the single-queen colonies.
