g′−r′ colour as a function of stellar mass for Fornax main (blue) and Fornax group (orange). Galaxies with a nucleus are highlighted with a black circle. The upper and right panels show the distributions of stellar mass and g′−r′ colour, respectively, for galaxies with (bold) and without (dashed) a nucleus. Bins of 0.5 dex and 0.1 mag were used for the stellar mass and g′−r′ colour, respectively.