  We have studied the properties of Las Campanas Loose Groups in the
neighbourhood of rich (Abell, APM and X-ray) clusters of galaxies. These loose
groups show strong evidence of segregation measured in terms of the group
richness and the group velocity dispersion: loose groups in the neighbourhood
of a rich cluster are typically 2.5 times more massive and 1.6 times more
luminous than groups on average, and these loose groups havevelocity
dispersions 1.3 times larger than groups on average. This is evidence that the
large-scale gravitational field causing the formation of rich clusters enhances
the evolution of neighbouring poor systems, a phenomenon recently established
in numerical simulations of group and cluster formation.
