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DY: Fachverband Dynamik und Statistische Physik
DY 9: Poster I: Statistical Physics in Biological Systems (joint with BP)
DY 9.7: Poster
Montag, 11. März 2013, 17:30–19:30, Poster B2
Effects of a stage structure in a population dynamics model to explain cyclic dominance of pacific sockey salmon — •Fabian Fertig1, Christoph Schmitt1, Christian Guill2, and Barbara Drossel1 — 1Institut für Festkörperphysik, TU Darmstadt — 2Institut für Zoologie and Anthropologie, Georg-August-Universität Göttingen
The number of sockeye salmon that return from the ocean to their lakes of birth in the Fraser River basin in Canada shows a remarkably strong and regular four-year oscillation. This so-called cyclic dominance phenomenon is reproduced as a stable attractor by a recently introduced predator-prey model for salmon fry and their main predator in the rearing lakes, rainbow trout. However, rainbow trout is known to prey also strongly on kokanee salmon, which spend all their life in the lakes. Including kokanee in the model typically leads to a breakdown of cyclic dominance and often also to the extinction of one of the salmon species. This means either that the observed coexistence of the two species together with the occurence of cyclic dominance in the sockeye population is a transient phenomenon, or that the model is not detailed enough. In order to explore the conditions under which cyclic dominance could persist in the presence of both salmon species, we investigate various models that take the stage structure of trout and the different preference of adult and juvenile trout for kokanee and sockeye salmon into account. We show that the parameter range for cyclic dominance can be increased in stage structured models.