Almost all approach for GIS-based distribution modeling depend in some way on species occurrence data. In range-shifting species, however, the correlative approach usually requires extrapolation to novel environments, which could lead to erroneous predictions. Kearney et. al. used an alternative approach with emphasis on the ecology of organisms based on ecophysiology and organism traits, which is independent from species current distribution. They used fine-resolution spatial dataset together with a set of biophysical and behavioral models to make the predictions of Cane Toads distribution under current and future climate in Austrilia, assessing the direct climatic constraints on their ability to move, survive, and reproduce. The results show that the current species range can be explained by thermal constrains for the adult stage and water availability for the larval stage. Their research provided a framework showing trait-based approaches can be used in investigates the range limits of any species by quantifying spatial variation in physiological constraints and therefore defining regions where survival is impossible. They claimed that mechanistic approaches have broad application to process-based ecological and evolutionary models of range-shift. In my opinion, an effective mechanistic model depends on sophisticated observational or empirical data to from the mechanism of the target organism, which maybe not that easy to obtain for all kinds of species. In addition, researchers could never capture all factors for the fundamental niche. The way Kearney et. al. addressed this problem is by identifying areas outside the niche and to locate impossible areas for the organisms. Therefore, their predicted areas are less restricted than the actual range.
Kearney, M., Phillips, B. L., Tracy, C. R., Christian, K. A., Betts, G., & Porter, W. P. (2008). Modelling species distributions without using species distributions: the cane toad in Australia under current and future climates.Ecography, 31(4), 423-434. DOI: 10.1111/j.0906-7590.2008.05457.x