# New paper - Dynamics of a physiologically structured population in a time-varying environment

Friday 06 Jan 17
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We have studied a model of a size structured Daphnia population feeding on an algae resource that have a periodically varying growth rate. Depending on parameter values, the system exhibits irregular solutions or solutions where the population dynamics synchronize with the driving frequency.

Physiologically structured population models have become a valuable tool to model the dynamics of populations. In a stationary environment such models can exhibit equilibrium solutions as well as periodic solutions. However, for many organisms the environment is not stationary, but varies more or less regularly. In order to understand the interaction between an external environmental forcing and the internal dynamics in a population, we examine the response of a physiologically structured population model to a periodic variation in the food resource. We explore the addition of forcing in two cases: (A) where the population dynamics is in equilibrium in a stationary environment, and (B) where the population dynamics exhibits a periodic solution in a stationary environment. When forcing is applied in case A, the solutions are mainly periodic. In case B the forcing signal interacts with the oscillations of the unforced system, and both periodic and irregular (quasi-periodic or chaotic) solutions occur. In both cases the periodic solutions include one and multiple period cycles, and each cycle can have several reproduction pulses.

The paper can be found here.

Heilmann, I. L. T., Starke, J., Andersen, K. H., Thygesen, U. H., & Sørensen, M. P. (2016). Dynamics of a physiologically structured population in a time-varying environment. Ecological Complexity, 28, 54-61. DOI: 10.1016/j.ecocom.2016.10.004

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21 FEBRUARY 2020