Coexistence and Chaos in Complex Ecologies

J. C. Sprott, J. A. Vano, J. C. Wildenberg, M. B. Anderson, and J. K. Noel
Departments of Physics and Mathematics, University of Wisconsin- Madison, Madison, WI 53706, USA

(Received 28 September 2004; received in revised form 14 December 2004; accepted 15 December 2004)

ABSTRACT

Many complex dynamical systems in ecology, economics, neurology, and elsewhere, in which agents compete for limited resources, exhibit apparently chaotic fluctuations. This Letter proposes a purely deterministic mechanism for evolving robustly but weakly chaotic systems that exhibit adaptation, self-organization, sporadic volatility, and punctuated equilibria.

Ref: J. C. Sprott, J. A. Vano, J. C. Wildenberg, M. B. Anderson, and J. K. Noel, Phys. Lett. A 335, 207-212 (2005)

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Fig. 1. Evolution of the largest Lyapunov exponent (0.02 full scale), total biomass (0.05 full scale), and biodiversity (1 full scale) showing how a typical system with 100 species slowly evolves toward a weakly chaotic state with high diversity and then remains there with fluctuations in the biodiversity suggestive of sporadic volatility and punctuated equilibria.

Fig. 1


Fig. 2. Typical chaotic fluctuations in the total biomass and biodiversity for a system with 100 species after adaptation has been turned off.

Fig. 2


Fig. 3. A portion of the strange attractor for the same typical system as in Fig. 2 with 100 species after adaptation has been turned off.

Fig. 3