IR LFs in galaxy groups estimated within 2 × r₂₀₀ in different redshift bins: 0 <z< 0.4 (black points), 0.4 <z< 0.8 (green points), 0.8 <z< 1.2 (red points), and at z ~ 1.6 (magenta points; this is the IR LF of the structure of Kurk et al. 2008). Error bars are 1σ. The IR LF in groups in the lowest redshift bin at z< 0.1 (blue points) is obtained by averaging the IR LF in groups obtained in three different group halo mass bins by Guo et al. (2014). The solid (resp. dashed) lines, colour–coded as the points of the IR LF, indicate the best fit Schechter (resp. modified Schechter, see Saunders et al. 1990) functions.