“…In [3,4,12] the problem is modelled as a Cauchy problem for a parabolic system of semilinear partial differential equations describing the dynamics of the densities of different species. In the evolutive case, in particular see [12], it is proved that some populations can vanish under the competition of other species; moreover, in [3,4] the authors are able to estimate the number of the long-term surviving populations and other interesting qualitative properties of the spatial distributions of interacting populations. Note that also the study of the territoriality, that is how different groups of the same species divide an area, avoiding to effectively fight for resources, can be viewed as a habitat segregation produced by competition (see, for example, [5,16,20]); moreover, this kind of competition is a struggle between competitors having the same features, that is between perfect competitors.…”