Supergene underlying sexual antagonism promotes genetic diversity in an invasive ant

The tawny crazy ant, Nylanderia fulva, is native to South America and has been introduced to many parts of the Caribbean and the southern U.S. In its invasive range, this species exhibits strong sexually antagonistic selection (SAS), in which alleles beneficial to one sex are harmful to the other sex. Previous research has shown a number of SAS markers present in this species, but the relative genomic position of these markers was unknown. In this study, we mapped the positions of 1.5 M SNPs to a chromosome level genome assembly. We identified SAS regions in which females are completely or nearly completely heterozygous on two of the 15 chromosomes. The SAS regions, comprising 68% and 78% of the two chromosomes, respectively, show strong linkage disequilibrium indicating suppressed recombination. Each of these chromosomes has two SAS regions with a large non-SAS (recombining) region in the middle. The SAS regions are inherited as a single genetic element and therefore act as a supergene.