As the global interest in biodiversity loss has increased over the past few decades, Red List evaluations of threatened species have become increasingly important in assigning priorities for biodiversity conservation programs.  The standard procedures for Red List category assessment are delineated by the World Conservation Union (IUCN), and include several quantitative parameters that reflect various aspects of geographic distribution.  Among the most important of these spatial criteria in terms of assigning threat status is the Extent of Occurrence (EOO).  However, the most commonly-used methods for calculating EOO contain many sources for error; of greatest concern is the overestimation of geographic range.  To address this issue, species distribution modeling (SDM), specifically the program Maxent, which models ecological niche, was used to refine estimates of EOO for a number of endemic plant species in the Atlantic coastal forest of Northeastern Brazil. 

Results/Conclusions

The advantages and implications of applying SDM for Red List assessment will be illustrated using the case study, and the SDM method will be compared to standard measures for calculating EOO.  Further applications of SDM in determining threat status also will be presented, including the ability to calculate the relative contribution of different environmental variables to species distribution, and the combination of SDM output with evaluation of habitat decline and fragmentation.  The results of this study demonstrate that by utilizing ecological niche modeling and incorporating remotely-sensed habitat data, a more accurate assessment of a species’ EOO, and subsequently, its threat status may be achieved.