Synergistic effects of climate and human-induced landscape changes on the spatial distribution of an endangered dung beetle

Abstract

Introduction: the Brazilian Atlantic Forest (BAF) is undergoing alarming deforestation, land overexploitation, and unregulated occupation. The Coastal Sandy Vegetation of BAF, known as Restinga, is under the most pressure of the BAF ecosystems. Understanding the effects of Restinga deforestation on biodiversity is a conservation priority. Aims/Methods: we predicted the effect of landscape modifications on the large-scale spatial distribution of an endangered dung beetle (Dichotomius schiffleri) endemic to the BAF Restinga ecosystem. We tested the hypothesis that almost all the potential distribution area of this species has suffered from landscape modification, and reduced its spatial distribution. We used niche-based modeling approaches to predict the potential species distribution (climate-based models) and the species distribution under the current land-use scenario (landscape-based models). We then combined these models to predict the effects of landscape modification. Results: the spatial distribution of D. schiffleri has decreased drastically as a consequence of landscape modification. The decreasing patch size, canopy cover percentage, and functional connectivity, and the increasing edge distance explain the decrease in the potential species distribution as predicted by climate variables. Discussion: suitable sites for this species are isolated in a vast matrix of pasture, tree plantations, and urban areas. D. schiffleri is sensitive to anthropogenic changes such as disturbances of preserved Restinga areas. Therefore, human coastal-plain land uses over the past five centuries pose multiple synergistic threats to the persistence of this species. Implications for insect conservation: our findings suggest an alarming trend toward species extinction in the near future, highlighting the need for specific conservation actions to protect Restinga biodiversity.