The role of model selection in describing stochastic ecological processes

Authors

  • Anna Kuparinen,

  • Tord Snäll,

  • Simopekka Vänskä,

  • Robert B. O'Hara


A. Kuparinen(anna.kuparinen@helsinki.fi), T. Snäll, S. Vänskä and R. B. O'Hara, Dept of Mathematics and Statistics, Univ, of Helsinki, P.O. Box 68, FI-00014 University of Helsinki, Helsinki, Finland. TS also at: Dept of Conservation Biology, Swedish Univ. of Agricultural Sciences (SLU), P.O. Box 7002, SE-75007 Uppsala, Sweden.

Abstract

A great deal of variation in ecological processes can be generated through variation in environmental conditions. Models describing the underlying processes should be able to account for this variation. However, models may not be flexible enough, so that different realizations of a process may be better described by different models. This may lead to uncertainty in model selection.

Here we examine the question of whether two empirical models can provide consistent fits to different realizations of a process affected by environmental variation. We further examine the sensitivity of the model predictions to the amount of data available and the selection of the model. To study this, we simulated pollen dispersal patterns under varying wind conditions and then investigated whether the datasets consistently supported the same model. The role of the model selection and the impact of the spatial range over which the dispersal distances were observed were assessed by comparing model predictions at long dispersal distances.

There was no consistent pattern of one model providing a better fit than the other across simulations. The model providing better fit varied depending on the range of distances over which the dispersal patterns were observed, and on the amount of long-distance dispersal. The model predictions were found to be very sensitive to the selection of the model.

The variation between datasets produced with the same underlying mechanisms cannot be easily described using one model, which also limits our ability to reliably predict the underlying process. Therefore, the amount of information about a model choice provided by an individual field study may be rather limited. If we are to understand processes that are affected by environmental variation then we have to observe the range of possible outcomes of the processes under varying spatio-temporal conditions.

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