Characterizing the establishment of the watershed divide between the Orinoco and Amazonas river basins and its influence on paleoenvironments and biotic diversification

Abstract

Despite the growing recognition that the fluvial dynamics plays an important role in the Amazonian landscape evolution and biota diversification, information about the timing and mechanisms of the Amazonian fluvial system through time is lacking. This knowledge gap results from the lack of robust ages for the Late Cenozoic geological records, and absence of proxies suitable for comparison between ancient and modern fluvial systems. This is the case of the northwestern Amazonia lowlands and sub-Andean areas, comprising the Caquetá and Guaviare rivers that drain the watershed-divide of the Amazon and Orinoco basins, respectively. This research project aims to use an integrated approach based on geological, geochronological and phylogeographic methods to reconstruct the paleogeographic history of the northwestern Amazonia and its effects in the biotic evolution during the Neogene and Quaternary. Bringing novel techniques, we will generate one of the most detailed records of landscape evolution ever produced in a fluvial system that drains Amazon-Orinoco interfluve. Such a record will provide insight into the fundamental questions about the (1) timing and mechanism of the separation of the Amazon and Orinoco basins, (2) response of the both fluvial systems to climate and tectonic changes, and (3) how changes in riverine landscape impact the evolution of birds and plants in different timescales. An important part of our proposal will be to further develop the existing collaborations between Brazilian and Colombian colleagues, which use geological and biogeographic data to test and tune their landscape evolution models. Our data will permit significant improvements in these models, ultimately contributing to more accurate prediction of future changes to Amazonian rivers and biodiversity, and to smart conservation and mitigation strategies by scientists and policymakers. (AU)