PARENT SESSION
Oral Session # 16: Ecological Modeling I.
Presiding: C Ray
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 102.
Dynamical effects of demographic stochasticity in stage-structured population models.
Wearing, Helen*,1, Rohani, Pejman1, Cameron, Tom2, Sait, Steven2, 1 University of Georgia, Athens, Georgia2 University of Leeds, Leeds, U.K.
ABSTRACT- Stage-structured population models have often ignored the role of demographic stochasticity when investigating both single and multi-species dynamics. In this talk, we describe a framework that can be used to simulate stochastic birth, death and maturation processes. This approach also permits a systematic analysis of the dynamical significance of the variance in the duration of each stage, assuming a gamma delay distribution. Applying this to the well-studied Plodia and Plodia-Venturia systems, we demonstrate that certain dynamical patterns predicted by deterministic delay-differential equation models are sensitive both to demographic stochasticity and to the assumed variance of the distributed delays. We discuss how our findings may explain why specific phenomena (e.g. half-generation cycles) predicted by the deterministic models, despite occurring for a wide range of parameter values, are seldom observed in real systems.
Key words: demographic stochasticity, distributed delays, stage-structured models, host-parasitoid systems