A method for simulating patterns of habitat availability at static and dynamic range margins

The dynamics of populations inhabiting range margins are likely to be critically important in determining the response of species to climate change. Despite this, there is a lack of both empirical and theoretical work that examines the behaviour of these populations. Populations living on the edge of a species' range frequently inhabit a more patchily distributed habitat than those that live closer to the centre of the range. This difference is likely to play an important role in determining the dynamics of range margin populations, both when the range is static and when it is dynamic, for example shifting in response to climate change. Here, we present a simple method that simulates the distribution of suitable habitat sites at the edge of a range. Habitat availability is determined as a function of both latitudinal and local environmental variability, and the relative importance of the two can be adjusted. The method is readily extended to describe shifting habitat availability during a period of climate change. We suggest that there is a need for a greater effort to examine the ecology of range margin populations, and believe that the method presented here could be of considerable use in future theoretical studies.