Distribution of properties of the semi-analytic galaxy groups: 3D virial radius (top left panel), 3D velocity dispersion (middle left panel), virial mass (bottom left panel), ratio between stellar mass in bulge and total stellar mass of the first-ranked galaxy (top right panel), difference between the r-band absolute magnitude of the first- and second-ranked galaxies within half a virial radius (middle right panel), and difference between the r-band absolute magnitude of the first- and fourth-ranked galaxies within half a virial radius (middle right panel). Empty histograms correspond to FoF groups with 10 or more galaxy members, while grey histograms correspond to the 102 FoF groups that have virial masses higher than 10^13.5h^-1ℳ_⊙ and whose brightest galaxy is an elliptical galaxy (ℳ^∗_1,bulge/ ℳ^∗_1,total> 0.7).