Left panel: stellar mass–gas phase metallicity relation for low-mass galaxies. The filled coloured circles represent Bashful (red) and Doc (blue) in our simulation, at z = 0. The empty circles with coloured edges correspond to Bashful (red), Doc (blue), Dopey (purple) and Grumpy (green) simulated in Shen et al. (2014), with the blastwave feedback model. Other symbols show the observed stellar mass–gas phase metallicity relation for nearby dwarf irregulars (empty squares Lee et al. 2006), Local Group dwarfs (empty triangles down Woo et al. 2008), host galaxies of z < 1 long gamma-ray bursts (empty triangles up, Mannucci et al. 2011), low–luminosity galaxies in the local volume (empty diamonds Berg et al. 2012), and Leo P (black filled star Skillman et al. 2013). Right panel: stellar metallicity vs. V-band luminosity for the simulated dwarf galaxies at z = 0. Our simulated dwarf galaxies and those simulated in Shen et al. (2014) are represented with the same colours and symbols as in right panel. The empty symbols represent satellite galaxies of the Milky Way (diamonds) and Andromeda (squares), from the original sample of Local Group galaxies published by McConnachie (2012).