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Ready for the Heat

The flower of Symphonia globulifera:  in the Amazon region for the last 15 million years

in the Amazon region for the last 15 million yearsROLANDO PEREZ/SMITHSONIAN TROPICAL RESEARCH INSTITUTE

Some species of trees in the Amazon region are expected to survive the rise in atmospheric temperature predicted to occur by the end of this century. This is because many of them have already faced even warmer climates in the past. Together with researchers from Panama and England, biologist Christopher Dick, of the University of Michigan, analyzed the genetic material of twelve tree species widely distributed throughout the Amazon region to estimate when they occupied this ecosystem. They found that nine of the twelve species have populated the region for at least 2.6 million years. Of the nine, three appeared more than 8 million years ago. The oldest of them, the African giant Symphonia globulifera, with a height of up to 60 meters, arrived in the Amazon region about 15 million years ago. Between 11.5 million and 3.6 million years ago, these species survived very hot periods, with temperatures similar to those predicted by climate models for the year 2100 (Ecology and Evolution, December 14, 2012). “Our results indicate that common neotropical tree species lived in climates warmer than the present, suggesting that they could tolerate the warming associated with climate change,” says Dick. He and his colleagues believe that it is unlikely that an increase in temperature, per se, would result in a mass extinction of Amazonian species. However, they do believe the future of the forest is uncertain. This is because the region is undergoing a level of transformation never before seen, with increasing temperatures and concentrations of carbon dioxide, plus widespread clearing of vegetation.