Study investigates climate change impact on tree of life
Could 21st century climate change alter the shape of the tree of life? New EU-funded research shows that this may not be the case. An analysis of high-resolution evolutionary trees reveals that although the tree may become thinner as a result of climate change, it is unlikely to lose entire branches, so its overall structure will remain the same. Presented in the journal Nature, the study was funded in part by the ECOCHANGE ('Challenges in assessing and forecasting biodiversity and ecosystem changes in Europe ') project, which clinched EUR 7 million under the 'Sustainable development, global change and ecosystems' Thematic area of the Sixth Framework Programme (FP6). The Intergovernmental Panel on Climate Change (IPCC) estimates that about 20% to 30% of the world's species could be at risk of extinction if global warming tops the 2.5°C mark. If this increases to 3.5°C the IPCC believes between 40% to 70% of species could become extinct. Researchers are concerned that climate change could trigger an unbalanced loss of diversity if extinctions are not randomly distributed across the tree of life. Using 6 species distribution models, 4 emission scenarios and 3 high-resolution global climate models, the team modelled the potential impacts of climate change over the coming decades on 1,280 European plants, 140 mammals and 340 birds. 'To distinguish extinctions by climate change from those that would occur normally we created normal random extinction scenarios as controls,' explains Wilfried Thuiller from the French National Centre for Scientific Research (CNRS) in, France, the lead author of the study. Contrary to past theories, the study demonstrated that even if the tree thins out somewhat, the structure will likely remain intact and no major losses of biodiversity will result. Major losses would emerge only if localised 'branches' were totally eliminated. 'This is because vulnerable species have neither fewer nor closer relatives than the remaining clades,' the authors write. 'Reductions in phylogenetic diversity will be greater in southern Europe, and gains are expected in regions of high latitude or altitude. However, losses will not be offset by gains and the tree of life faces a trend towards homogenisation across the continent.' The study shows that the disappearance of species throughout our planet's history is nothing new; change is normal in evolution. Just 3% of species that have ever lived on Earth are still alive. The main problem, however, is that human activity is speeding up this process. Now experts are starting to believe that there is a chance that a new mass extinction, like the one that triggered the demise of the dinosaurs 65 million years ago, is underway. While predictions about the number of species disappearing due to the present course of climate change did not materialise in the study, the data sound an alarm that we need to quash this threat and ensure species' sustainability. Says Miguel Araújo of the University of Évora and the National Museum of Natural Sciences in Madrid, Spain: 'Whether random extinctions throughout the tree of life are less dangerous or not than extinctions in very specific parts of the tree only depends on the levels of climate change - if extinction is moderated, the loss of specific parts of the tree can be more dangerous than dispersed extinctions, if only because it affects the potential for evolution on earth. But if extinctions reach the level seen in episodes of mass extinctions then a more widespread pattern of extinctions can be catastrophic because it compromises the future of too many biological groups.' Where this study differs from the rest is that this team investigated the effects of climate change in phylogenetic groups rather than taxonomic groups. While the latter provide key information about evolutionary relations, they are based on form and function and so are less accurate when predicting future evolutions. Phylogenetic groups in contrast are based entirely on species' evolutionary relatedness to one another.For more information, please visit: Nature:http://www.nature.com/ECOCHANGE:http://www.ecochange-project.eu/Intergovernmental Panel on Climate Change (IPCC):http://www.ipcc.ch/
Countries
Spain, France, Portugal