Quaternary paleoclimatology, neotropical biodiversity, and potential effects of global warming

Abstract

The Quaternary paleoclimatic trends documented for the Northern Hemisphere also affected the neotropical region, and contributed to the shaping of its present-day biodiversity patterns. DNA molecular-clock studies on extant neotropical species have recorded a significant acceleration of speciation rates in the last 5 million years (my), coinciding with a marked Plio-Pleistocene global cooling. Furthermore, around half of the species studied originated during the last 2.6 my, in the frame of Pleistocene glaciations. The refuge hypothesis is considered inadequate for the Neotropics, and alternative diversification mechanisms linked to climate change are discussed herein. Among them, recurrent vertical migrations controlled by alternating glacial/interglacial climates, and the resulting connection and disconnection of lowland and highland biotas, have been considered important speciation factors. A significant number of endemic taxa from the neotropical highlands is potentially threatened of extinction by habitat loss/fragmentation, due to the global warming predicted by the end of the present century.