English: Mathematical modelled oscillating ON/OFF selection. The video illustrates the temporal shifts in allelic distribution when a mathematical modelled population is subjected to oscillating ON and OFF selection (non-oscillating ON and OFF selection shown in Figure S4, case 2 and 3). The population does not reach steady-state equilibrium as long as it is under oscillating penalizing selection pressure, a time average of the oscillating allelic distributions is shown in Figure S5. In the modelled population, K = 100, μ = 5, ds = 1 and dl = 5, where ds and dl oscillates for tract lengths that are multiple of three (6, 9, 12) and not multiple of three (5, 7, 8, 10, 11, 13).