Population distribution models: species distributions are better modeled using biologically relevant data partitions

Despite high Area Under the ROC Curve (AUC) values for all models, the composite species distribution model of P. polionotus generated from individual subspecies models represented the known distribution of the species much better than did the models produced by partitioning data into geographic quadrants or modeling the whole species as a single unit.Because the AUC values failed to describe the differences in the predictability of the three modeling strategies, we suggest using omission curves in addition to AUC values to assess model performance. Dividing the data of a widespread species into biologically relevant partitions greatly increased the performance of our distribution model; therefore, this approach may prove to be quite practical and informative for a wide range of modeling applications.Species distribution modeling (SDM) has become a common tool for understanding spatial distribution patterns of biodiversity worldwide [1-4]. The goal of SDM is to build a model predicting the relative probability of occurrence of a species across geographic space commonly using environmental data (i.e. climate, vegetation, soil, etc.) and a dataset of known presence or presence/absence localities. The terms ecological niche model, environmental niche model, and species distribution model have all been used to describe this type of modeling in the literature; for the sake of simplicity we will use species distribution modeling. SDM techniques continue to evolve with an increasingly broad range of applications from conservation planning [5,6], to predicting species colonization and abundance [4,7,8], predicting disease outbreaks [1], and understanding phylogeographic patterns [9]. Methods of producing SDMs vary with the type of data available, purpose, and software used.There is a direct link between climate and the distribution of plant species [10]. Because climate is a causal factor in the distribution of plant species (and plant species assemblages), climatic pattern