Initial radius (r_in) of stars (i.e. where it is first identified as a star) as a function of their radius (r_{(z = 0)}) at z ~ 0 for a galaxy with strong (upper panel) and weak (lower panel) signal of migration. Both galaxies have similar stellar metallicity gradients (− 0.02 dex kpc^-1 and − 0.03 dex kpc^-1, respectively) and similar stellar masses (1.1 × 10¹⁰M_⊙ and 4.7 × 10¹⁰M_⊙, respectively).