Persistence in a Periodic Competitor-Competitor-Mutualist Diffusion System1

In this paper we investigate the existence and the asymptotic behavior of periodic solutions for a periodic reaction-diffusion system of a competitorcompetitor- mutualist model under Dirichlet boundary conditions. We shall prove that under certain conditions this system is persistent and under some other conditions it exhibits extinction or, more exactly, the species of mutualist extincts.