Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Population Dynamics and Evolution

BP 21.2: Talk

Thursday, February 28, 2008, 12:30–12:45, C 243

Stability of food webs with structured populations — •Christian Guill and Barbara Drossel — TU Darmstadt, Institute of Condensed Matter Physics, Hochschulstraße 6, D-64289 Darmstadt

Most existing models of population dynamics in food webs treat species as homogeneous aggregations of identical individuals. They neglect the fact that not all individuals of a species are reproducing, but are juveniles that invest their energy intake into growth in body size. Here, we investigate model food webs with populations that are structured in terms of physiological state (juvenile/adult). Each stage of a species has its own feeding relationships and population dynamics, but the stages are coupled through maturation and reproduction. This leads to time-dependent traits of the species as a whole, such as its mean body size. Since body size is a key factor in determining predation behaviour and also influences metabolic rates, structuring of populations changes the population dynamics and stability of the entire network. Simulation results obtained from networks with structured populations are compared to networks with unstructured populations.

The population dynamics in ecosystems with structured populations are studied in more detail in the example of a real aquatic system consisting of a homogeneous resource (zooplankton), two consumers (salmon species), and a top predator (trout) with structured populations. Simulation results are tested against empirical data of the system.