Population genomics supports multiple hybrid zone origins of socially hybridogenetic lineages of Pogonomyrmex harvester ants

Obligate chimerism in male yellow crazy ants

Multicellular organisms typically develop from a single fertilized egg and therefore consist of clonal cells. We report an extraordinary reproductive system in the yellow crazy ant. Males are chimeras of haploid cells from two divergent lineages: R and W. R cells are overrepresented in the males' somatic tissues, whereas W cells are overrepresented in their sperm. Chimerism occurs when parental nuclei bypass syngamy and divide separately within the same egg. When syngamy takes place, the diploid offspring either develops into a queen when the oocyte is fertilized by an R sperm or into a worker when fertilized by a W sperm. This study reveals a mode of reproduction that may be associated with a conflict between lineages to preferentially enter the germ line.

The unusual genetics of invasive ants

The males of an invasive ant species are chimeras of two distinct genetic lineages.

Digest: Recurrent evolution of worker production by interspecific hybridization in harvester ants: Parasitism or kludge?. Evolution 2022;76:2475-2476. [PMID: 36097357 DOI: 10.1111/evo.14611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Multiple ant lineages have evolved a bizarre system called social hybridogenesis, involving multiple co-occurring genetic lineages, in which mating between lineages produces workers but mating within a lineage produces daughter queens. A new study reveals that this system evolved multiple times within harvester ants, each time from interspecific hybridization. A third finding, that the system likely evolves in small or isolated populations, could be explained either by exploitation of heterospecific males for their sperm, or simply by failure to avoid interspecific mating.