Model Thresholds are More Important than Presence Location Type: Understanding the Distribution of Lowland tapir (Tapirus Terrestris) in a Continuous Atlantic Forest of Southeast Brazil

Abstract

Modeling the distribution of rare and endangered species is challenging, and there is substantial debate regarding what species distribution models (SDMs) actually represent. Here I investigated whether locations of different lowland tapir signs (feces, trails and tracks) generated different distributions of suitable habitat using a presence-only species distribution modeling technique.Comparison of the equivalence and overlap of the predicted distributions showed no significant differences between the different signs. The contribution of the 11 variables used to build the distribution models was also similar between signs. Although predictions from different signs were similar, the use of different threshold selection methods generated substantially different suitable areas and omission errors. These results highlight the importance of a fundamental understanding of species natural history to determine not only appropriate model parameters, but also the biological relevance of SDMs. My findings also support the need for healthy skepticism regarding what is represented by presence-only species distributions. To help address this skepticism I conclude by providing guidelines for generating reliable local-scale distribution models.Key words: Atlantic Forest, habitat suitability, MaxEnt, species distribution modeling, Tapirus terrestris Resumo A modelagem da distribuição de espécies raras é um desafio e há um debate substancial sobre o que os modelos de distribuição de espécies (MDEs) realmente representam. Aqui, através de nichos ecológicos modelados utilizando apenas dados de presença eu investiguei se sinais indiretos diferentes (fezes, pegadas/carreiros) de anta (Tapirus terrestris) resultaram em diferentes distribuições de habitat. Comparações das equivalências e sobreposições das distribuições não apresentaram diferenças significativas entre os diferentes sinais. A contribuição de 11 variáveis utilizadas para construir os modelos de distribuição também foi semelhante entre os tipos de sinais. Embora as distribuições fossem semelhantes, a utilização de diferentes métodos de seleção de limiares gerou diferenças expressivas nas áreas adequadas e erros de omissão. Estes resultados destacam a importância de uma compreensão de história natural da espécie para determinar não só os parâmetros adequados do modelo, mas também a relevância biológica do MDEs. Os resultados também apoiam a necessidade de ceticismo cauteloso em relação ao que é representado pela distribuição das espécies com apenas pontos de presença; e que esse ceticismo deve ser tratado antes de informar as políticas e programas da conservação.

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