Resumo

PRIETO-TORRES, David A.  e  PINILLA-BUITRAGO, Gonzalo. Estimating the potential distribution and conservation priorities of Chironectes minimus (Zimmermann, 1780) (Didelphimorphia: Didelphidae). Therya [online]. 2017, vol.8, n.2, pp.131-144. ISSN 2007-3364.  https://doi.org/10.12933/therya-17-478.

The water opossum (Chironectes minimus) is an elusive and solitary Neotropical semi-aquatic species, whose population dynamics cannot be studied using traditional methods to capture small mammals. Therefore, some aspects of its distribution, habitat requirements, and abundance are mostly unknown; which makes a proper determination of its conservation status difficult. Considering that new techniques known as species distribution models (SDMs) allow us to estimate the suitable areas and the most important variables for the distribution of a species, we compiled water opossum occurrences and modeled its potential distribution on a continental scale. We performed a SDM for the water opossum using MaxEnt and assessed the extent of habitat loss (km2) and the importance of Protected Areas (PAs). We compared the suitability values within and outside PAs using a Kolmogorov-Smirnov (KS) test to evaluate the efficiency of PAs. The results obtained were compared with the IUCN historical water opossum’s map. Additionally, we identified gaps in the potential distribution where for future surveys should be focused. We obtained models that describe the distribution of this species based on 292 occurrences with new information for 16 countries. Deforestation reduced the area of suitable habitat by ~40 % and only ~18 % corresponds to natural forest within PAs. Areas inside PAs showed higher suitability values (0.351 ± 0.276; P < 0.001) than areas outside them. We identified gaps within the distribution that need attention during future surveys such as the frontier between Venezuela and Guyana, the Amazonian region, and central-eastern Brazil. Our results showed areas absent in the IUCN’s distribution map, indicating that it needs to be updated. Thus, we proposed a new tentative extent of the water opossum distribution information here obtained. We demonstrated that PAs included areas with high habitat suitability values for C. minimus, which could protect the water opossum in the medium and long-term. Modifications to the physicochemical characteristics of the habitat due to forest loss and fragmentation can considerably affect water opossum populations and reduce local diversity. Thus, the preservation of river ecosystems and surrounding areas represents a necessary step for the conservation of C. minimus.

Palavras-chave : conservation; ecological niche models; mammals; marsupials; species distribution models; water opossum.

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