Section: New Results

Sex-specific impact of meiotic recombination on nucleotide composition

Meiotic recombination is an important evolutionary force shaping the nucleotide landscape of genomes. For most vertebrates, the frequency of recombination varies slightly to considerably between the sexes (heterochiasmy). We extended the examination of the evolutionary impact of heterochiasmy beyond primates to include four additional eutherian mammals (mouse, dog, pig, and sheep), a metatherian mammal (opossum), and a bird (chicken). We compared sex-specific recombination rates with nucleotide substitution patterns evaluated on transposable elements. Our results, based on a comparative approach, revealed a great diversity of the relationship between heterochiasmy and nucleotide composition. We found that the stronger male impact on this relationship is a conserved feature of human, mouse, dog, and sheep. In contrast, variation in genomic GC content in pig and opossum is more strongly correlated with female, rather than male, recombination rate. We also showed that the sex-differential impact of recombination is mainly driven by the chromosomal localisation of recombination events, not the overall average recombination rate. We proposed a new explanation for the evolutionary impact of heterochiasmy on nucleotide composition. This work has been submitted for publication. This work was done in collaboration with D. Mouchiroud.