Résumé
Sexual reproduction generally requires no more than two partners. Here, we
show convergent evolution of social hybridogenesis, a reproductive system
requiring three reproductive partners in harvester ants. In this
unorthodox reproductive system, two distinct genetic lineages live in
sympatry and queens have to mate with males of their own lineage to
produce queens along with males of the alternative lineage to produce
workers. Using a large transcriptomic data set of nine species, we show
that social hybridogenesis evolved at least three times independently in
the genus Messor. Moreover, a study of 13 populations of Messor barbarus
revealed that this mode of reproduction is fixed in the whole range of
this ecologically dominant species. Finally, we show that workers can
produce males carrying genes of the two genetic lineages, raising the
possibility of rare gene flow between lineages contributing to the
long-term maintenance of pairs of interdependent lineages. These results
emphasize the evolutionary importance of social hybridogenesis, a major
transition possibly linked to the peculiar ecology of harvester ants.