Data from: Cryptic recessive lethality of a supergene controlling social organization in ants

<p>Supergenes are clusters of linked loci that control complex phenotypes, such as alternate forms of social organization in ants. Explaining the long-term maintenance of supergenes is challenging, particularly when the derived haplotype lacks homozygous lethality and causes gene drive. In the Alpine silver ant, <em>Formica selysi</em>, a large and ancient social supergene with two haplotypes, <em>M</em> and <em>P</em>, controls colony social organization. Single-queen colonies only contain <em>MM </em>females, while multi-queen colonies contain <em>MP</em> and <em>PP</em> females. The derived <em>P</em> haplotype, found only in multi-queen colonies, selfishly enhances its transmission through maternal effect killing, which could have led to its fixation. A population genetic model showed that a stable social polymorphism can only be maintained under a narrow set of conditions, which includes partial assortative mating by social form (which is known to occur in the wild), and low fitness of <em>PP</em> queens. With a combination of field and laboratory experiments, we show that the <em>P</em> haplotype has deleterious effects on female fitness. The survival rate of <em>PP</em> queens and workers was around half the one of other genotypes. Moreover, <em>P</em>-carrying queens had lower fertility and fecundity compared to other queens. We discuss how cryptic lethal effects of the P haplotype help stabilize this ancient polymorphism.</p>