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.

Understanding simple population dynamics.

Ellner, Stephen^*,1, ¹ Cornell University, Ithaca, NY

ABSTRACT- Hundreds of populations exhibit cyclic dynamics; in perhaps half a dozen cases we think we know why. One promising approach to narrowing this gap is based on fitting and comparing models that represent each plausible candidate for the causal mechanism. Noise makes this difficult, in particular the combination of measurement and process noise on top of data that typically represent a low-dimensional projection of a high-dimensional nonlinear system. This formerly intractable problem now suffers from an overabundance of solutions. I will describe simulation-based methods that can be applied to a wide class of models and data, and applications to field and laboratory data. The field application is the pine looper moth Bupalus piniarius, a classic forest insect cycle whose cause remained unresolved despite many decades of intensive empirical study; for once it isn't trophic interactions. The laboratory application is a plankton microcosm where model-based conclusions about underlying mechanism were tested experimentally and confirmed. Many other methods work (in the hands of their proponents, on computer-generated data); objective, comparative evaluation of these is now a pressing need.

Key words: population cycles, Bupalus piniarius, model selection