2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80705The concept of cross diffusion is applied to some biological systems. The conditions for persistence and Turing instability in the presence of cross diffusion are derived. Many examples including: predator-prey, epidemics (with and without delay), hawk-dove-retaliate and prisoner's dilemma games are given.15 pages, Accepted in Adv. Complex SystAdaptation and Self-Organizing SystemsPopulations and Evolutiontext