Amazonian rainforests gave birth to the world´s most diverse tropical region
A new study finds that plants and animals have moved into novel habitats surprisingly often. It turns out that many species in the American tropics can trace their origins back to the Amazon basin.
An article published today in the Proceedings of the National Academy of Sciences of the USA, by an international team including researchers from Sweden, Brazil, France, Switzerland and USA, found that a dynamic process of colonisation and speciation led to the formation of the most species-rich region on the planet. This is a region that largely coincides with today’s Latin America.
Over tens of millions of years, thousands of species have naturally made their way to new regions, where some of them survived and adapted to new 
conditions. These adaptations added up, and when the offspring were sufficiently different from earlier generations, new species were formed. Over time, this dynamic process occurred so many times in the American tropics that the area became the exceptionally diverse region we see today.
"We were astonished to detect so much movement across such different environments and over such large distances. Up until now, these natural dispersal events were assumed to be quite rare. Our results show how crucial these events have been in the formation of tropical America’s unique and outstandingly rich biodiversity”, says Alexandre Antonelli, lead author of the study.
The team used information on the evolutionary relationships, distribution, and timing of the origin of thousands of tropical species to calculate how often species were able to colonise new regions and environments, dispersing for instance between mountains and lowlands, or rainforests and savannas. They found that all regions in the American tropics have exchanged species with one another, but Amazonia stood out as the main source. This pattern was basically the same for all of the groups they looked at, which included plants, birds, frogs, mammals, frogs, snakes and lizards – suggesting that biotic movements are important for generating diversity among all life forms.rainforest
"This is a dynamite study in bringing together a truly massive amount of data and distilling it down in a way that gives crucial insights into the history of biodiversity in the tropics. The previous paradigm in the tropics focused on local evolution when explaining high tropical diversity, but clearly there is a shift happening to acknowledge the importance of dispersal, and this study contributes decisively to this shift." says Kyle Dexter, Senior Lecturer in the School of GeoSciences at the University of Edinburgh and Research Associate at Royal Botanic Garden Edinburgh.
This study highlights the far-reaching importance of tropical regions – comprising rainforests, savannas and mountain ecosystems, among others – in sustaining the world’s biodiversity. Most tropical ecosystems are now threatened due to human activities, and many species are on the edge of extinction, further highlighting the need for immediate and widespread protection.
Details on the publication:
A. Antonelli, A. Zizka, F. Antunes Carvalho, R. Scharn, C. D. Bacon, D. Silvestro, F. L. Condamine. ‘Amazonia is the primary source of Neotropical biodiversity’. Proceedings of the National Academy of Sciences of the USA.
Note to Press:
Please see also accompanying package with photos of tropical ecosystems and the author(s) for free use: http://tiny.cc/Antonelli_PNAS
For more information please contact:
Professor Alexandre Antonelli. Director, Gothenburg Global Biodiversity Centre; Visiting Scholar, Harvard University.
E-mail: alexandre.antonelli@bioenv.gu.se
Phone: +1 617-642-6005