a) IR luminosity, b) stellar mass, and c) absolute r-band magnitude vs. redshift. Red dots indicate IRGs (only 30% of IRGs are shown), and black dots denote galaxies without IR detection in the spectroscopic sample (only 1% of galaxies in the total sample are shown). Solid and dashed lines in c) define the volume limited samples, L1 and L2, respectively. The bottom curve corresponds to the apparent magnitude limit (m_r = 17.77) for the main galaxy sample in SDSS.