Period ratios for planet pairs in the reference population (R) for which both planets have K ≥ 10 m s^-1. The black, solid line corresponds to the initial distribution for all planet pairs, the dashed, red line to the distribution after 100 Myr for all planet pairs. The blue dot-dashed line and the magenta dotted lines denote the initial and final distributions, respectively, for planet pairs where both planets have K ≥ 10 m s^-1.