P. Blacher, O. De Gasperin, G. Grasso, S. Sarton-Lohéac, R. Allemann and M. Chapuisat,
Molecular Ecology,
2022.
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, Formica selysi, a large and ancient social supergene with two haplotypes, M and P, controls colony social organization. Single-queen colonies only contain MM females, while multi-queen colonies contain MP and PP females. The derived P 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 PP queens. With a combination of field and laboratory experiments, we show that the P haplotype has deleterious effects on female fitness. The survival rate of PP queens and workers was around half the one of other genotypes. Moreover, P-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.
https://www.geneconvenevi.org/wp-content/uploads/2020/04/Molecular-Ecology-2.png300300David Obrochta/wp-content/uploads/2019/10/GC-color-logo-for-header-3277-x-827-1030x260.pngDavid Obrochta2022-12-11 11:15:442022-12-14 11:19:27Cryptic recessive lethality of a supergene controlling social organization in ants