Evolution of the Illustris galaxies on the I_e-R_e plane (left panel) and the 3DKS (right panel) from z = 4 to z = 0. There are four values of the redshift with the following color code: blue (z = 4.0), magenta (z = 2), green (z = 1), and red (z = 0). In the left panel, we also display the GLO and GAL lines of the reference case. The right panel is split in three parts showing the correlations k₃ vs. k₁ (top), k₂ vs. k₁ (middle), and k₃ vs. k₂ (bottom). In the k₃ vs. k₁ plane, which shows the fundamental plane, we also plot the relation derived by Burstein et al. (1997) for ETGs in the Virgo and Coma clusters (k₃ = 0.15k₁ + 0.36, dashed line) and the same for the Illustris objects falling in the region of ETGs of the MR plane (k₃ = 0.20k₁ − 0.075, solid line). The agreement is fairly good. In the middle diagram we also plot the ZOE line given by Burstein et al. (1997) with the equation: k₂ + k₁ = 8.