Figure 5. The total recombination rate per chromosome, in males and females, as predicted by an obligate chiasma per bivalent (i.e, an intercept at 0.5 crossovers per gamete) and the physical length of the chromosome.

In red are the observed values for females and in blue the ones for males; circles denote metacentric chromosomes and diamonds acrocentric ones. The regression line is shown for each sex separately. In both cases, there is an excellent fit of this simple model to the data (R² = 0.94 for females; R² = 0.95 for males).