Andean uplift drives diversification of the bothriurid scorpion genus Brachistosternus

Abstract

Aim. One of the planet?s most imposing geomorphological features, the Andes, played an important role in the evolution of South America?s flora and fauna. The bothriurid scorpion genus Brachistosternus Pocock, 1893 comprises more than 40 species with high diversity and endemism in the Andes. The present contribution investigates the biogeographical history of this genus using molecular phylogenetics and dating, to determine the role of Andean uplift on the distribution and diversification of its species.Location. South America.Methods. A dated phylogeny and species tree were obtained for 54 putative species based on two nuclear and three mitochondrial gene loci. Ancestral ranges and biogeographical events were estimated on the species tree, diversification rates and rate shifts were calculated, and areas with high phylogenetic diversity and evolutionary distinctiveness identified.Results. Brachistosternus diversified at a steady rate during the main Andean uplift. The central Andean and western slope/Pacific coastal biogeographical provinces played an important role as ancestral areas. Coastal areas of central Chile and southern Peru exhibit high levels of phylogenetic diversity in Brachistosternus, suggesting they experienced a relatively long period of ecological stability, while the Andes continued to rise.Main conclusions. Andean uplift created new habitats and climate regimes, favouring speciation in genera such as Brachistosternus. Coastal areas to the west of the Andes continued to harbour older lineages while accommodating more recently diverged lineages from the nearby Andes.