期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：34
DOI：10.1073/pnas.2201040119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Some of the most striking polymorphisms in nature are regulated by “supergenes,” which are clusters of tightly linked genes that coordinately control complex phenotypes. Here, we study the evolutionary history of a supergene regulating colony social organization in fire ants. We show that the three inversions constituting the social supergene emerged sequentially during the separation of the ancestral lineages of
Solenopsis invicta and
Solenopsis richteri. Once completely assembled in
S. richteri, the supergene introgressed into multiple closely related species despite recent hybridization being uncommon between several of the species. These findings provide a rare and striking example of how introgression can lead to the rapid spread of a novel variant controlling complex traits.
Supergenes are clusters of tightly linked genes that jointly produce complex phenotypes. Although widespread in nature, how such genomic elements are formed and how they spread are in most cases unclear. In the fire ant
Solenopsis invicta and closely related species, a “social supergene controls whether a colony maintains one or multiple queens. Here, we show that the three inversions constituting the
Social b (
Sb) supergene emerged sequentially during the separation of the ancestral lineages of
S. invicta and
Solenopsis richteri. The two first inversions arose in the ancestral population of both species, while the third one arose in the
S. richteri lineage. Once completely assembled in the
S. richteri lineage, the supergene first introgressed into
S. invicta, and from there into the other species of the socially polymorphic group of South American fire ant species. Surprisingly, the introgression of this large and important genomic element occurred despite recent hybridization being uncommon between several of the species. These results highlight how supergenes can readily move across species boundaries, possibly because of fitness benefits they provide and/or expression of selfish properties favoring their transmission.
