METAPOPULATION DYNAMICS - EFFECTS OF HABITAT QUALITY AND LANDSCAPE STRUCTURE

Metapopulation dynamics have received much attention in conservation a nd population biology, but the standard approach has also been critici zed for being too restrictive, as it is based on the effects of habita t patch area and isolation only. Here we demonstrate how the effects o f habitat quality (extra environmental factors) and detailed landscape structure (described with GIS [Geographical Information System]) can be included in a spatially realistic metapopulation model, the inciden ce function model. Expanded models are tested with a large data set on the Glanville fritillary butterfly (Melitaea cinxia). The incidence f unction model supplemented with additional environmental factors revea led some new and confirmed some previously known interactions between M. cinxia and its environment. However, the ability of the additional environmental factors to explain the error in the fit of the basic mod el was generally low (less than or equal to 15%). In the second varian t of the basic model, landscape structure was used to modify effective patch isolations. This approach, though biologically appealing, faile d to improve significantly the fit of the incidence function model. Th ere are several possible reasons for this failure, including inaccurat e satellite data, problems with habitat classification, and most impor tantly, generic problems in the modeling of migration. Our results dem onstrate that additional complexity beyond the effects of habitat patc h area and isolation does not necessarily improve the predictive power of a metapopulation model.