Pattern of scorpion diversity across a bioclimatic dry-wet gradient in Neotropical forests

Abstract

Understanding large-scale patterns of biological diversity is one of the most important issues in ecology. Parameters of scorpion assemblages may serve as a proxy to understand how arthropods respond to bioclimatic changes by adjusting their spatially structured distribution. We analysed how scorpion species richness, abundance, and composition respond to climatic variations found along a longitudinal gradient between wet (Atlantic Forest) and dry (Caatinga hypo and hyperxerophilic) forests in Brazil. A total of 20 sites were sampled four times along a 712 km longitudinal wet-dry bioclimatic gradient in north-eastern Brazil. We recorded 2653 scorpions from 12 species, belonging to five genera and two families. Environmental variables associated with precipitation and temperature had a strong effect on scorpion distribution, resulting in a distinct faunal composition at both extremes of the gradient. Species composition presented a turnover along the bioclimatic gradient, with beta diversity increasing towards the drier sites. The increase of dryness coincide with increases in temperature, moisture reduction, and a general environmental harshness. Our study, therefore, indicates that species sensitivity to climatic variation determines scorpion distribution in Neotropical forests.