M_W1 versus spectroscopic redshift for galaxies in our sample. The red line represents the predicted evolution for a slowly evolving galaxy with W1 = 14.7 at z = 0. The violet and orange boxes define the two volume-limited samples we search for pairs in. We refer to the violet box (−21 < M_W1 < −24 and z < 0.03) as Box 1 and to the orange box (−24 < M_W1 < −27 and z < 0.10) as Box 2.