Persistence, attractivity, and delay in facultative mutualism

Relations between persistence and ultimate boundedness of the solutions of the Lotka-Volterra system dx(t)/dt = x(t)[r(1) - a(11)x(t - tau) + a(22)y(t - tau)] dy(t)/dt = y(t)[r(2) + a(21)x(t - tau) - a(22)y(t - tau)] modelling ''facultative mutualism'' with delayed responses are established and sufficient conditions are obtained for the global attractivity of the positive equilibrium of the delay system. (C) 1997 Academic Press.