No silver bullets in correlative ecological niche modelling: insights from testing among many potential algorithms for niche estimation

The field of ecological niche modelling or species distribution modelling has seen enormous activity and attention in recent years, in the light of exciting biological inferences that can be drawn from correlational modelsof species' environmental requirements (i.e. ecological niches) and inferences of potential geographic distributions. Among the many methods used in the field, one or two are in practice assumed to be best' and are used commonly, often without explicit testing. We explore herein implications of the no free lunch' theorem, which suggests that no single optimization approach will prove to be best under all circumstances: we developed diverse virtual species with known niche and dispersal properties to test a suite of niche modelling algorithms designed to estimate potential areas of distribution. The result was that (i) indeed, no single best' algorithm was found and (ii) different algorithms performing very different manners depending on the particularities of the virtual species. The conclusion is that niche or distribution modelling studies should begin by testing a suite of algorithms for predictive ability under the particular circumstances of the study and choose an algorithm for a particular challenge based on the results of those tests. Studies that do not take this step may use algorithms that are not optimal for that particular challenge.