Slide 13: Niche-based modelling - assumptions
There are a number of assumptions implicit in any model:
Environmental factors drive species distribution (at least those factors used are integral in the process)
Species are in equilibrium with their environment - if the ecosystem is transitional, then current distributions may not correspond to optimum conditions for a species, but be driven primarily by interspecific interactions.
Limiting variables - are they really limiting?
Coincidence with climate or climate shift - the ability of a species to move in response to climatic change is assumed to be great.
Evidence for species dying/not reproducing due to climate - for climate change models the fact that a species is able to move and will not die out is essential.
Collinearity of variables - they may not vary together, and if this is the case, (for instance, rainfall goes down but temperature goes up), the species response may not be as expected.
Assumption of assembly rules - it is assumed that the current distribution of species is guided more by the suitability to the current niche than as a result of historical and evolutionary dispersal of the species.
Static vs dynamic approaches - is it more appropriate to model for a given period in the present or future and assume that there is a constant trend between these periods, or to model for a number of intermediary steps and assess the suitability of response to the changing conditions.