Assessing the conservation status of species with limited available data and disjunct distribution

Abstract

Current techniques for estimating the extent of occurrence (EOO) of species, especially those with a naturally disjunct distribution and limited available data, lead to overestimations of their geographic distributions. Accurate EOO estimates are of great importance because they are used to assess conservation status. Topological methods, such as those proposed by the International Union for Conservation of Nature (IUCN), are not able to estimate the geographical distribution of these species accurately because they do not consider the abiotic characteristics suitable to maintain viable populations. In this study, we propose the use of ecological niche models (ENMs) to estimate the EOO. We use the Maximum Entropy (MaxEnt) algorithm and the topological method suggested by IUCN (α-hull method) to estimate the EOO for a species with disjunct distribution and limited available data. The estimate obtained using the ENM was considered the most accurate because only areas with suitable abiotic conditions were taken into account. Thus, analyses related to the conservation status of species become more accurate, especially when evaluating the effects of potential threats in the potential areas occupied by the taxon. The estimate obtained from ENM can also assist the design of conservation strategies for the species, by indicating areas for specific surveys and assessing changes in the EOO over time.