Sex differences in crossover interference in house mice

Meiotic recombination ensures the fidelity of chromosome segregation in most organisms with sexual reproduction. The distribution of crossovers along chromosomes is governed in part by interference, which prevents multiple crossovers from occurring in close proximity, though not all crossovers are subject to interference. Neither the factors that control strength of interference, nor the extent to which they vary within and between species, are well understood. Here we confirm that that crossover interference is stronger in male than in female meiosis in house mice ( Mus musculus ), provide the first estimate of the proportion of non-interfering crossovers in female mice, and show that this proportion is lower than in males. Interference is stronger on shorter chromosomes in both sexes, but the frequency of interference escape is similar across the range of chromosome size. Together with evidence that interference varies across strains and subspecies, our results provide a foundation for studying the evolution and sexual dimorphism in this important feature of meiosis in mice.