gwIMF, as defined in Eq. (12), of each 10 Myr star formation epoch (thin lines) and the time-integrated gwIMF for all formation epochs (TIgwIMF) for a galaxy with a final mass of M_dyn = 10^11.9 M_⊙. This TIgwIMF corresponds to the red model in Fig. 10. The corresponding approximating simple-population IGIMF model is shown in Fig. 9 as a red line. The gwIMF for the first and the last star formation epochs are highlighted by slightly thicker lines. The canonical IMF as given by Kroupa (2001) and the power-law IMF given by Salpeter (1955) are shown via the red dotted and blue dashed lines, respectively.