A supergene for queen number

In the fire ant Solenopsis invicta, a polymorphism in queen number is regulated by a 12Mb supergene. The molecular mechanism through which the supergene drives this shift from single queen (monogyne) to multiple queen (polygyne) colonies remains unknown. I proved that rather than a single gene of large-effect, the fire ant supergene confers the polygyny phenotype via numerous parallel changes to gene expression across the supergene. This effect is consistent across workers and queens, conferred directly by the supergene rather than indirectly via social influences, and produces transcriptional patterns mirroring sex chromosome systems. In this work, I showed that the supergene drives the polygyne polymorphism via multiple parallel changes to gene regulation rather than a single change of large effect.