My PHD concerns the study of an unusual reproductive system, social hybridogenesis, among ants of the genus Messor. In this system, which is characterized, depending on the case, by the presence of two lineages or two species, caste is determined entirely by the genotype. If a gyne reproduces with a male of her own lineage or species, her female offsprings will also be gynes. If she reproduces with males of the other species or lineage, her offsprings will instead be sterile workers. My works consists on the study of 3 members of the genus Messor which practice social hybridogenesis. To do this, I will employ several population genomics tools. My resuts should allow us to better understand how this system evolved convergently among different Messor species.