SFR−M_∗ diagram where we have corrected the SFRs to z = 0 using the redshift evolution from Eq. (1). The dashed line shows this relation for z = 0, above which we selected galaxies in our sample, as described in Sect. 2.6. The points are coloured by the logarithm of the dust-corrected O32 ratio. The symbols show galaxies in the final selection (circles), galaxies below the selection threshold (triangles), and galaxies with a lower limit on the O32 ratio (squares).