Dust-to-stellar mass ratios for the DGS (crosses) and KINGFISH (downwards triangles) samples as a function of sSFR, colour coded by the gas-to-dust mass ratio (G/D), M_gas/M_dust, from Rémy-Ruyer et al. (2014). The distribution of M_dust/M_star is indicated on the side for both samples: solid line for DGS and dashed line for KINGFISH. Modelled evolutionary tracks from Asano et al. (2013) are shown, for different star formation timescales (τ_SF = 0.5, 5 and 50 Gyr), with the red, blue, and purple lines.