Might galaxies in filaments http://pil.phys.uniroma1.it/twiki/bin/view/Pil/GalaxyStructures and deep in voids have a different evolution from that of galaxies in clusters? One has a tapestry of superclusters (clusters of clusters) and of larger voids; with filaments leading(?) into rich clusters. How might one distinguish any differential evolving history of galaxies in filaments or voids vs in clusters? If there were late formation of most of mass of galaxies in filaments/voids, might they have more gas, and thus more star formation i.e. star burst and more emission lines? Would there be less dark matter (DM) http://en.wikipedia.org/wiki/Dark_matter in galaxies in filaments/voids? How would one ascertain this? By extent/lack of flattened rotation curves http://en.wikipedia.org/wiki/Rotation_curves for spirals? An extented flattened curve means more DM further out; the original discovery route of DM.