Fig. 1: Number and location of crossovers affect the recombination frequency.

A An example of a chromosome with always two crossovers in the bivalent so that one occurs in the yellow and the other one in the blue area. The locations of the crossovers within their distinct regions are independent. B The table shows the probability for 0, 1, or 2 crossovers between the markers (p₀, p₁, and p₂, respectively) and the expected number of crossovers in the bivalent, the resulting recombination frequency of the marker pair (in the gamete) and the estimated map distance for every marker pair using different mapping functions. C Graph showing the relationship between the recombination frequency and map distance with different mapping functions; the linear function was capped at 0.5, shown with the dashed line. Notably, intervals A–C, A–D, and A–E have the same recombination frequencies but different map distances, whereas marker pairs A–C and B–D have the same map distances but different recombination frequencies.