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Abstract
The red imported fire ant (Solenopsis invicta) is a pesty yet successful global invader. Since its introduction to the US almost a century ago, S. invicta has become a model organism for the study of social evolution by virtue of its ease of collection and rearing. Particularly, the social form polymorphism in S. invicta presented a unique research opportunity to understand how colony social structure is regulated. The two forms of S. invicta differ not only in queen number but also in a variety of natural history traits. The genetic basis of the social form polymorphism is an inversion-based supergene. In the multiple-queen social form, supergene-carrying workers induce the whole colony to accept additional queens, but only the ones also carrying the supergene. However, mechanistic details regarding the chemical communication of supergene status and factors governing queen genotype preference are needed to fulfill the genotype-to-phenotype map underlying multiple-queen social form. In this dissertation, I reviewed the functional properties of queen pheromones in ants. Next, using high throughput behavioral assays, I identified unsaturated cuticular hydrocarbons as the pheromonal signal through which supergene-carrying queens communicate their genotype status to workers. I then designed novel experiments to reveal the critical factors through which supergene-carrying workers influence colony collective queen preference.