Left: quartile D1 (low density environment). Right: quartile D4 (high density). Points refer to the observed quantities, lines to the GSMFs derived from the mock catalogues. Black points and solid lines: GSMFs relative to the considered density quartile, renormalised to the same integral at log ℳ/ℳ_⊙ > 10.5. Red triangles and dotted lines: galaxies with B−I > 1.15. Blue squares and dashed lines: galaxies with B − I ≤ 1.15.