PARENT SESSION
Symposium 16: Death of Determininism? Noise in a Non-Linear World
Organized by: M Pascual and P Rohani
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Oglethorpe Auditorium.

Introduction: From fuzzy trajectories to new patterns.

Pascual, Mercedes ^*,1, ¹ University of Michigan, Ann Arbor, MI

ABSTRACT- There have been many earlier debates in ecology on the role of stochasticity: Andrewartha and Birch vs. Nicholson and Smith, Gleason vs. Clements, Chaos vs. Noise, etc. In these debates, however, random fluctuations were seen as an alternative to determinism. Today, ecological modelling is beyond this simple dichotomy and it is generally agreed that noise and determinism interact. There is, however, no consensus on the consequences of this interaction. At one extreme, noise has been assumed merely to blur equilibria or deterministic attractors, while more interesting examples have shown how noise provides the fluctuations responsible for the transient transitions between attractors. Recent work highlights a much more interesting outcome in which noise, via its interaction with nonlinearities, gives rise to 'surprising' dynamics. I introduce the session by briefly presenting these different classes of interaction and the questions they raise on the usefulness of deterministic skeletons. Examples are drawn from recent results on quasicycles in predator-prey systems and on the irregular interannual variability of historical cholera patterns.

Key words: nonlinearity, disease dynamics, noise, quasicycles