Vicariance and regionalization patterns in snakes of the South American Atlantic Forest megadiverse hotspot

ABSTRACT

Aim Vicariance has often been invoked to explain bioregionalization patterns in the Neotropics. Using a revised point locality data for endemic species, we aimed to test for the first time the predictions of the vicariance model in shaping biogeographical regions for endemic snakes in the Atlantic Forest (AF) megadiverse hotspot. Location South American Atlantic Forest. Taxon Snakes (Reptilia, Serpentes). Methods To identify the non‐random groups of co‐distributed species, we mapped 21,101 point locality records in a grid cell of 0.5° × 0.5° across the AF, and constructed a presence–absence matrix of endemic species. The two major predictions of vicariance model were tested by Biotic Elements (BE) analysis, searching for groups of significantly co‐distributed species (Biotic Elements) by comparing distances between observed and artificial random ranges, produced under null models from Monte Carlo simulations. We also tested for the occurrence of sister species in different Biotic Elements, and compared our results with previous bioregionalization schemes revealed by other organisms in the AF. Results We recorded 252 species of snakes in the Atlantic Forest, of which 79 (31%) are endemic to this domain. Biotic Elements analysis with endemic species revealed seven clusters of co‐distributed species (BEs) corresponding to biogeographical regions. The significant non‐random clusters of geographical ranges revealed in BE analysis, and the distribution of sister species in different BEs, validated both central predictions of the vicariance model. Main conclusions Snakes defined non‐random biogeographical regions in the Atlantic Forest, and these were congruent with previously identified areas based on other groups of organisms, indicating that general processes influenced geographical ranges across the region. Both central predictions of the vicariance model were valid, indicating that vicariant events must have been important in shaping non‐random clusters of co‐distributed snakes in this biodiversity hotspot, harbouring some of the richest snake faunas on the planet.