CONICET | Buscador de Institutos y Recursos Humanos

Through presence-only data, ecological niche modeling can use environmentalvariables to generate maps of areas that are potentially suitable for thepresence of a species, improving our knowledge of its niche requirements andextending our understanding of its geographic distribution. We used the ecologicalniche model MaxEnt to predict the potential distribution of black-and-goldhowlers (Alouatta caraya) and brown howlers (Alouatta guariba clamitans) inSouth America, as well as the potential sympatry area between both species. Wemodeled distributions of Alouatta caraya (196 presence localities, 8 bioclimaticvariables) and A. guariba clamitans (74 presence localities, 13 bioclimaticvariables) using bioclimatic variables from WorldClim with habitat suitabilitycategorized as low, moderate, or high. Alouatta caraya showed a broader potentialdistribution, occupying a wide variety of habitats in a broad range oftemperatures. Temperature annual range (Bio 7) was the bioclimatic variablewith most influence in modeling the potential distribution of this species.Alouatta guariba clamitans was more restricted to rainy areas of mature forestsat higher altitudes with low minimum temperatures. Mean temperature of coldestquarter (Bio 11) was the bioclimatic variable with the highest influence in thismodel. The predicted area of potential sympatry of both species was a relativelysmall area in the interior Atlantic Forest ecoregion, and a new syntopy localityoccurred within the predicted area of sympatry. This narrow zone of overlapcould be maintained, among other causes, by the role of the Paraná River as anatural barrier for dispersion, differences in niche requirements, potential interspecificcompetition, and hybridization

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