Coarsening Model of Chromosomal Crossover Placement

Chromosomal crossovers play a crucial role in meiotic cell division, as they ensure proper chromosome segregation and increase genetic variability. Experiments have consistently revealed two key observations across species: (i) the number of crossovers per chromosome is typically small, but at least one, and (ii) crossovers on the same chromosome are subject to interference, i.e., they are more separated than expected by chance. These observations can be explained by a recently proposed coarsening model, where the dynamics of droplets associated with chromosomes designate crossovers. We here introduce an extended coarsening model, which includes material exchanges between droplets, the synaptonemal complex, and the nucleoplasm. Using a comprehensive analysis, including scaling laws for the crossover count, allows us to analyze data across species. Moreover, our model provides a coherent explanation of experimental data across mutants, including the wild type and mutant of . Consequently, the extended coarsening model provides a solid framework for investigating the underlying mechanisms of crossover placement.