Chaos in seasonally perturbed ratio-dependent prey-predator system

We investigate the effects of periodic forcing, in the intrinsic growth rate of the prey, on the Holling-Tanner ratio-dependent prey-predator system. Lyapunov exponents, Lyapunov dimension, and Poincare section are obtained for section of parametric space for the resulting forced system. The abundance of steady state chaotic solutions is detected when seasonality is super imposed on the system, which otherwise has a globally stable equilibrium state or globally stable limit cycle. The results support the conjecture that seasons can very easily give rise to complex population dynamics. (C) 2002 Elsevier Science Ltd. All rights reserved.