ner_tags: O O O O O O O O O O O O O O O O O B-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O B-CelestialObject O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: targets since the spectroscopic target selection was mostly done in a colour–colour space. The well-established morphology–density relation (Dressler 1980 ; Postman et al. 2005 ) can be translated to a morphology–clustercentric radius relation (e.g. Whitmore, Gilmore Jones 1993 ; Goto et al. 2003 ). That is, early-type galaxies are more frequent in the cluster core while late-type galaxies are more frequent in the outer regions of clusters. Moreover, the morphology of galaxies is related with other physical properties such as their stellar masses, colours and SF rates. In this sense, the morphology of galaxies can also be inferred from their colours, for example: early-type galaxies tend to be red, whereas late-type galaxies tend to be blue. In this context, the relation between the morphology of galaxies and the environment can be explained by a colour–environment relation (Blanton et al. 2005 ; Skibba et al. 2009 ; Grützbauch et al. 2011a ). In the case of MACS0416 and MACS1206, the spectroscopic colour fractions as a function of projected distance from the cluster centre obtained in Section 4.6.1 (see left-hand panel of Fig. 5 ) show that galaxies in clusters and substructures follow a colour–clustercentric radius relation. Galaxies within , independent of whether they are part of a cluster or substructure, tend to be redder than galaxies beyond . This suggests that this result is likely a consequence of the effect of the cluster environment over the properties of galaxies traced by their colours (e.g. Miller 1986 ; Byrd Valtonen 1990 ; Boselli et al. 2014 ). Moreover, studying the colour fraction of galaxies as a function of the distance from the cluster or substructure centre (see right-hand panel of Fig. 5 ), we note that the total colour–clustercentric radius relation in substructures follows similar trends observed in the main clusters. According to this, substructures may be considered as down-scaled versions of clusters in which galaxy properties, traced by their colours, have been sculpted by the gravitational potential and physical processes within the substructures (e.g. ram-pressure stripping and galaxy–galaxy interactions), which can stop SF and turn galaxiesred. Fig. 6 shows the spectroscopic colour fractions as a function of projected distance by separating galaxies in all environments according to their stellar masses in massive () and less massive (). We note that fraction of green galaxies is constant in all environments, independent of the stellar mass of the galaxies and that massive galaxies tend to be red independent of the environment in which they are located. Besides, the fraction of red galaxies ( f r ) in clusters and substructures at is higher than the f r in the field, independent of the stellar mass. This result is in agreement with the result presented in the left-hand panel of Fig. 5 , in which the cluster environment models galaxy properties traced by their colours at least within . Beyond f r in