Figure 1: Experimental design. Monogyne and polygyneSolenopsis invicta colonies differ in the number of reproductive queens. This difference is affiliated with an inversion-based supergene haplotype on the social chromosome (chromosome 16) denoted as Sb ; the homologous region is designated SB . Monogyne colonies produce only SB/SB gynes (unmated winged queens), which are relatively high in weight upon sexual maturity. Polygyne colonies produce 1)SB/SB gynes, which are slightly lighter than monogyneSB/SB gynes at maturity, 2) SB/Sb gynes, which are of intermediate weight, and 3) Sb/Sb gynes, which are low in weight. Monogyne-derived SB/SB gynes fly to a high altitude to mate and independently (claustrally) found a new colony upon landing. The relatively rare polygyne-derived SB/SB gynes evidently do the same, although empirical evidence for this is lacking (denoted by a question mark). Polygyne SB/Sb gynes fly lower to the ground and attempt to enter and join an existing colony after flying. PolygyneSb/Sb gynes depart on mating flights but rarely survive them. Gynes of each type were collected as they left their nests on mating flights; their brains and ovaries subsequently were dissected for RNA-sequencing.