Figure 1.

Mean relative difference between observed and expected map distance against the expected map distance. The figure shows all data, i.e. all recombination measurements in all intervals of all lines (35 distinct recombination measurements in control lines, and 24 distinct recombination measurements in coevolved lines). Recombination frequencies were transformed into map distances. Map distances were averaged over interval and line. a, The relative difference does not deviate from a non-difference line and does not correlate with interval length (linear regression, n = 9, F_{1, 7} = 0.986, P = 0.354), suggesting that recombination in the control treatment did not deviate from expected recombination. b, In the coevolving lines a significant logarithmic relationship was observed (linear regression, n = 8, F_{1, 6} = 64.310, P < 0.001, R² = 0.915), which might indicate an overall increase in recombination. The grey areas represent the theoretical change in observed recombination rate, in terms of percentage, in the cases of a 50% (light grey), 100% (medium grey) and a 150% (dark grey) genome-wide increase in actual map distance. Kosambi's map function was used to convert map distances into recombination frequencies. The areas illustrate that for large intervals it might be hard to detect a change in recombination frequency, even in the case of a substantial increase in the actual map distance.