Sex-Specific Evolution of the Genome-wide Recombination Rate

Although meiotic recombination is required for successful gametogenesis in most species that reproduce sexually, the rate of crossing over varies among individuals. Differences in recombination rate between females and males are perhaps the most striking form of this variation. To determine how sex shapes the evolution of recombination, we directly compared the genome-wide recombination rate in females and males across a common set of genetic backgrounds in house mouse. Our results reveal highly discordant evolutionary trajectories in the two sexes. Whereas male recombination rates show rapid evolution over short timescales, female recombination rates measured in the same strains are mostly static. Strains with high recombination in males have more double-strand breaks and stronger crossover interference than strains with low recombination in males, suggesting that these factors contribute to the sex-specific evolution we document. Our findings provide the strongest evidence yet that sex is a primary driver of recombination rate evolution.