Test of Time

Several Amazon tree species survived warm periods millions of years ago, suggesting they may have a better chance than scientists thought against upcoming climate change.

Amazon forests will face higher temperatures and more intense droughts, but researchers haven’t been sure whether the trees can tough out these conditions. The past may hold clues, since the Amazon has been through warmer times before. About 3.6 to 5.3 million years ago and 8 to 10 million years ago, temperatures were similar to those predicted for 2100.

A research team studied DNA samples from 12 tree species in Panama, Ecuador, Brazil, Peru, Bolivia, and French Guiana. Genetic analyses suggested that nine species were more than 2.6 million years old, and seven were more than 5.6 million years old. “The remarkably old age of these species suggest that Amazon forests passed through warmth similar to 2100 levels,” the authors write in Ecology and Evolution.

The trees aren’t necessarily home-free. They may have lost their ability to withstand higher temperatures, and logging may be draining populations of the genetic diversity needed to adapt. Even if the forests can tolerate a warmer world, they will also have to survive drought, deforestation, fires, and other threats.Roberta Kwok | 14 December 2012

Source: Dick, C.W. et al. 2012. Neogene origins and implied warmth tolerance of Amazon tree species. Ecology and Evolution doi: 10.1002/ece3.441.

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