The Diversification of Extant Angiosperms in the South America Dry Diagonal

Abstract

The evolutionary processes leading to lineage diversification in Neotrop- ical plants are still poorly understood. Here, we provide a synthesis of phylogeographic patterns and unravel whether the Neogene geological events or the Quaternary climatic changes drove lineage diversification of Angiosperms in the South America dry diagonal. Despite the high number of plant species in the dry diagonal (~19,000) only few species (30) were studied. Major lineage divergences occurred in the Pliocene but most lineage diversifications occurred at the Early and Middle Pleistocene. The Last Glacial Maximum (LGM) may have had a more local and regional effect in differentiation among populations and patterns of genetic diversity distribution. Species responded differently to the Quaternary climate changes leading to high variation in spatial patterns in genetic diversity and phylogeographic patterns. Finally, our findings challenge the hypothesis of glacial refugia and the importance of the last glacial maximum (LGM) in the diversification of Angiosperms in the South America dry diagonal.