where, b > c > 0 . We denote by x and y the frequency of individuals adopting strategy C and D, respectively. We have x + y = 1 . In case of uniform interaction rate between any two individuals. We assume that interaction rate is independent of their strategies. The selection dynamics can be described by replicator equation [7] ˙ x = x (1 − x )( f C − f D ) (2) f C = ( b − c ) x − cy , f D = bx. (3) The fitness of C and D players are linear functions of x and y , given by The entire population will eventually consist of Defectors ,since b > b − c and 0 > − c .The only stable equilibrium is x = 0 . D is a strict Nash equilibrium,and therefore an evolutionarily stable strategy (ESS). Suppose that an interaction between two players depends on their strategies. Let r$_{1}$, r$_{2}$, r$_{3}$ be reaction rates between each two players and r$_{1}$, r$_{2}$, r$_{3}$ > 0 . where, r$_{1}$ is an interaction rate of Cooperator with another Cooperator, r$_{2}$ is an interaction rate of Cooperator with Defector, and r$_{3}$ is an interaction rate of Defector with another Defector. For uniform interaction rates r$_{1}$ = r$_{2}$ = r$_{3}$ the strategy D dominates the strategy C. Hence, eventually the entire population will consist of defectors. However, if players only interact with opponents of the same strategy, then cooperators cannot be exploited by defectors. In this case, where r$_{2}$ = 0 and r$_{1}$, r$_{3}$ > 0 ,cooperation is the dominant strategy, because b − c > 0 . Assume r$_{2}$ = 0 which means that cooperators and defectors do interact. Without loss 3 2 Stability in dynamical PD game with non- uniform interaction rates