Neogene origins and implied warmth tolerance of Amazon tree species
Article first published online: 26 FEB 2013
© 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.
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Ecology and Evolution
Volume 3, Issue 1, pages 162–169, January 2013
How to Cite
Ecology and Evolution 2013; 3(1): 162–169
- Issue published online: 26 FEB 2013
- Article first published online: 26 FEB 2013
- Manuscript Accepted: 1 NOV 2012
- Manuscript Revised: 27 OCT 2012
- Manuscript Received: 20 JUL 2012
- The National Science Foundation. Grant Number: DEB 0640379
- The Smithsonian Tropical Research Institute
- The Royal Society
- Amazon forests;
- comparative phylogeography;
- ecological niche models;
- global change;
- molecular clock;
- thermal tolerance;
- tropical trees
Tropical rain forest has been a persistent feature in South America for at least 55 million years. The future of the contemporary Amazon forest is uncertain, however, as the region is entering conditions with no past analogue, combining rapidly increasing air temperatures, high atmospheric carbon dioxide concentrations, possible extreme droughts, and extensive removal and modification by humans. Given the long-term Cenozoic cooling trend, it is unknown whether Amazon forests can tolerate air temperature increases, with suggestions that lowland forests lack warm-adapted taxa, leading to inevitable species losses. In response to this uncertainty, we posit a simple hypothesis: the older the age of a species prior to the Pleistocene, the warmer the climate it has previously survived, with Pliocene (2.6–5 Ma) and late-Miocene (8–10 Ma) air temperature across Amazonia being similar to 2100 temperature projections under low and high carbon emission scenarios, respectively. Using comparative phylogeographic analyses, we show that 9 of 12 widespread Amazon tree species have Pliocene or earlier lineages (>2.6 Ma), with seven dating from the Miocene (>5.6 Ma) and three >8 Ma. The remarkably old age of these species suggest that Amazon forests passed through warmth similar to 2100 levels and that, in the absence of other major environmental changes, near-term high temperature-induced mass species extinction is unlikely.