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An international team of scientists have reset the agenda for future research in the highly diverse Amazon region by showing that the extraordinary diversity found there is much older than generally thought. The findings from this study, led by C. Hoorn from the University of Amsterdam, were published as a review article in this week's edition of 'Science'.

An international team of scientists have reset the agenda for future research in the highly diverse Amazon region by showing that the extraordinary diversity found there is much older than generally thought. The findings from this study, led by C. Hoorn from the University of Amsterdam, were published as a review article in this week's edition of Science, and show that the Amazonian diversity has evolved as by-product of the Andean mountain uplift over millions of years, despite previous focus on the more recent history.

The authors compare modern diversity patterns with geological and molecular datasets and show that the highest species diversity in Amazonia is found today on a surface of Andean origin spanning more than a million square kilometres, which has been formed in the past 23 million years (Ma). This tight link between the geological history of the Andes and the development of the Amazon basin means that studies aiming to understand how the mega-diverse Amazonian forests have evolved need to look further back in time, to the past c. 20 Ma.

A wide range of scientific theories on the origin and complexity of the present day biodiversity in the Amazonian region currently exist. Though scientists have long suspected that the Andes influenced rainforest composition, the timing and causes have remained uncertain. In their review article, Hoorn and her co-authors list the extraordinary flora and fauna that have evolved in the dynamic Amazonian landscape, which in turn has developed at a pace dictated by the reshuffling (Pacific) tectonic plates and subsequent uplift in the Andes. The paleogeographic evolution dictated by this geological reconfiguration included the formation of a vast wetland which, after the onset of the Amazon River around 10 Ma, dried up and was open to colonisation by flora and fauna.

In this article, fittingly published in the International Year of Biodiversity, the authors encourage scientists to refocus when seeking explanations for the evolution of modern biodiversity. In the case of Amazonia, the pre-Quaternary flora and fauna already showed a very high level of species richness which was, in the case of reptiles and plants, even higher than found today.

Publication details

C. Hoorn, F.P. Wesselingh, H. ter Steege, M.A. Bermudez, A. Mora, J. Sevink, I. Sanmartín, A. Sanchez-Meseguer, C. L. Anderson, J.P. Figueiredo, C. Jaramillo, D. Riff, F.R. Negri, H. Hooghiemstra, J. Lundberg, T. Stadler, T. Sarkinen, A. Antonelli: ‘Amazonia through time: Andean uplift, climate change, landscape evolution and biodiversity. Science (12November, 2010).

Note to Press:
For more information you can contact: Dr. Carina Hoorn email: M.C.Hoorn@uva.nl.

Link to 'Science' article