A novel supergene regulates alternative dispersal morphs without variation in social organization in the ant Myrmecina nipponica

Abstract

Polymorphisms in complex traits with discrete phenotypes are often underpinned by non-recombining complexes of co-adaptive genes, known as supergenes. In disparate lineages of ants, it is increasingly evident that supergenes are important in regulating intra-specific variation in social organization (number of reproductive queens in a colony). Variation in social organization in ants is often associated with variation in dispersal, with multiple-queen (polygynous) colony types exhibiting more limited dispersal than single-queen (monogynous) colony types. It has been suggested that this association may give rise to antagonistic selection, which in turn may help explain the multiple independent evolutions of social supergenes in ants. In this study, we provide evidence of an exception to this pattern in the form of a novel supergene in the ant Myrmecina nipponica. This species exhibits a dispersal polymorphism with winged and wingless queens but without variation in social structure, as all colonies have a single, reproductive queen. We show that the dispersal polymorphism in this species is underpinned by an approximately 6.8 Mb supergene novel to ants. Interestingly, this supergene is structurally and functionally different from that recently reported in another member of this genus, illustrating how patterns of supergene evolution can show marked intrageneric variation.