Permanence for a two-species Gause-type ratio-dependent predator–prey system with time delay in a two-patch environment

This paper is devoted to a two-species periodic Gause-type ratio-dependent predator–prey system with time delay in a two-patch environment. By using the comparison theorem of differential equations, we establish sufficient conditions for the permanence of the system. As corollaries, some applications are listed. In particular, our results generalize and improve some known ones.