Giovanna De Blasis

McGill University
The soldier inhibitory pheromone is a cuticular hydrocarbon that regulates size and allometry of the soldier subcaste in the hyperdiverse ant genus Pheidole

De Blasis Giovanna, Lillico-Ouachour Angelica, Liebig Juergen, Abouheif Ehab

Considering the central role of gene-environment interactions during organismal development, our research uses ants to investigate the effects of the ecological environment on organismal plasticity and diversity. Colonies of the ant genus Pheidole have evolved two types of workers – small headed minor workers and big headed soldiers, which exist in a 95:5 ratio respectively. This innovation led to their ecological success as a dominant and hyperdiverse genus. Multiple factors affect caste ratios, but adult soldiers play a primary role by producing an inhibitory pheromone that inhibits the soldier developmental pathway when there are too many soldiers. Previous work in the lab has shown that adult soldiers are also able to affect the size and allometry of soldiers, thus their caste identity, and give rise to intermediate individuals that do not naturally occur. Preliminary data shows that exposure to soldiers cuticular hydrocarbons causes similar effect, suggesting that the inhibitory pheromone is composed of cuticular hydrocarbons that are transmitted by passive and selective interactions. Future studies aim to investigate naturally occurring intermediates in other ant genera to understand how dimorphic caste systems might have evolved. Overall, our work aims to understand how environmental cues can influence organisms at various scales by regulating major evolutionary transitions such as the worker caste polyphenism in Pheidole ants that shift colony structures and influence their ecological success. By looking at multiple functional scales our work elucidates the role of the social environment in shaping the development and evolution of complex systems such as ant colonies.
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