To fit or not to fit? A poorly fitting procedure produces inconsistent results when the species-area relationship is used to locate hotspots

Ulrich and Buszko (2005, Biodivers Conserv 14:1977-1988) have recently applied the species-area relationship (SAR) to find butterfly hotspots in Europe using the linearized power function. They found that, with this method, despite the fact that the larger southern European countries and the Asian part of Turkey belong to the group of ecological hotspots defined by Myers et al. (2000, Nature 403:853-858), the SAR was unable to separate these countries from others. However, this result was a consequence of a poor fit. When different fitting models are compared, there is no obvious reason to prefer the linearized power function model, while a curvilinear fit to the power function should be selected as a best fit for this data set. Using this fit, two large southern European countries (Italy and Greece) and the Asian part of Turkey are identified as hotspots by the SAR. This simple exercise illustrates how an inappropriate choice of the fitting equation for the SAR may lead to inconsistent results.