Résumé
While the meiotic recombination is a widely conserved process accross all sexually reproducing species, there is also a considerable diversity in the patterns of where it takes place along the genome. Where recombination occurs has important and direct consequences on species evolution and adaptation. Understanding the dynamics and diversity of recombination landscapes is therefore a pressing but challenging issue, as is elucidating the molecular determinants of this evolution.Prdm9 determines the position of meiotic double-strand break (DSB) hotspots in most mammals and, as recently shown, in some other vertebrates. Its zinc finger (ZnF) domain, which binds specific DNA targets, is rapidly evolving and highly diversified within and between populations. This leads to hypervariable DSB hotspots and thus to amazingly dynamic recombination maps for species carrying functional Prdm9. As a metazoan-specific mechanism, with multiple independant losses in different taxa, Prdm9 is also an intriguing gene. Why did it appear ? Why has it been lost so many times ? What is its role for species that have conserved this gene ? Addressing these evolutionary questions requires studying its function in a broad panel of species that diverged earlier in the metazoan tree. Here, we focus on non-vertebrate species as new models to study the function of Prdm9. We are studying the molecular evolution of Prdm9 (presence, expression and diversity of its ZnF domain) and applying molecular approaches to map DSB hotspots in two non-vertebrate model species.