During meiosis, DNA double-strand breaks initiates homologous recombination at specific loci called hotspots. In many mammals, their localization corresponds to specific DNA sequences bound by the zinc finger (ZnF) array of PRDM9. A remarkable property of PRDM9 is the high diversity and fast evolution of its ZnF domain. The consequence is the fast evolution of recombination map for species having a PRDM9 for hotspot localisation, and thus higher adaptive potential. PRDM9 appears in the last common ancestor of metazoans but its partial or complete loss have been surprisingly reported in many taxa. Species lacking a full-length PRDM9 have evolutionary stable hotspots that are located near promoter-like regions, that are evicted by PRDM9. The involvement of PRDM9 in meiotic recombination has not been yet explored outside vertebrate species, one reason being that invertebrate model species have no PRDM9. Here, we propose to fill these gaps by investigating PRDM9 function in meiotic recombination in four closely-related species of freshwater snails for which we recently identified full-length PRDM9 conservation by exploring their recently published genome assemblies. The MeioSnail project will address the following questions: Where are meiotic hotspots located along the genome? Is PRDM9 essential for meiotic progress and fertility? Can we find evidence of PRDM9 function in the localisation of hotspots? We will use complementary approaches such as population genomics, genotyping of PRDM9 zinc finger array, molecular mapping, histology and genetic manipulation of snail. We will take advantage of the unique collection of biological material, as well as the molecular methods and tools developed and mastered for one snail species in the laboratory hosting the project. Providing the first exploration of PRDM9 role outside vertebrates will help to understand if this mechanism controlling the distribution of meiotic recombination is conserved across the tree of life.