Capturing the diversity of population recombination landscapes in fish and insects

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Raynaud, Marie | Gagnaire, Pierre-Alexandre | Galtier, Nicolas

Edité par CCSD -

International audience. In most mammals and snakes, recombination hotspots are regulated by the PRDM9 protein and evolve rapidly. Loss of a functional Prdm9 gene in other taxa, such as birds, some teleost fish or invertebrates, is associated with a different map of hotspot localisation and more stable recombination landscape dynamics. However, recombination landscapes are well described in only a handful of species, and the determinants of recombination rate variation in non-mammalian species are still poorly understood. We reconstructed fine-scale linkage disequilibrium recombination maps in wild populations of several teleost and insect species, including salmonids, thysanopterans, stick insects and termites, which have a full-length PRDM9. In contrast to European sea bass, salmonids show that hotspots are localised independently of transcription start sites and CpG islands, and evolve rapidly between populations, suggesting that PRDM9 is the main driver of hotspot regulation in this group. Insects show a high diversity of recombination landscapes, with some groups totally lacking hotspots. Recombination is strongly correlated with methylation landscapes, as previously described in some social insects. Since methylation inhibits recombination, recombination rates are higher outside gene regions, explaining the differences observed with vertebrates, where methylation is elevated along the entire genome. Preliminary evidence suggests that the function of PRDM9 in regulating recombination was also ancestral to insects. Taken together, these results provide a more comprehensive view of the diversity of recombination landscapes in animals and their main drivers.

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