Interacting population models with pack behavior
  Models of coordinated behavior of populations living in the same environment are introduced for the cases when they either compete with each other, or they both gain by mutual interactions, or finally when one hunts the other one. The equilibria of the systems are analysed, showing that in some cases the populations may both disappear. Coexistence leads to global asymptotic stability for symbiotic populations, or to Hopf bifurcations for predator-prey systems. Finally, a new very interesting phenomenon is discovered in one of these rather simple models. Indeed tristability may be achieved in the competition case, for which competitive exclusion is allowed to occur together with populations coexistence. 
D. Melchionda, E. Pastacaldi, C. Perri, E. Venturino
math.DS q-bio.PE