Distribution of changes in galactocentric radius, R_f − R_i , as a function of R_i for different time intervals during the 6 Gyr integration. The upper panel represents the simulation run DM_25_1000; the lower panel represents the simulation run MOND_25_1000 (corresponding parameters as listed in Tables 1 and 2). Vertical lines represent theoretical values of resonances: green lines represent resonances produced by the galactic bar, and grey lines represent resonances caused by the spiral arms. In both cases, the solid lines represent OLRs and the dashed line the m = p = 1 co-rotation resonance.