What is it about?
Determining the timing of the evolution of modern birds has been difficult. We combined DNA sequences of clock-like genes for most avian families with 130 fossil birds to generate a new time-tree for modern birds and investigated their biogeographic and evolutionary dynamics. We found that the most recent common ancestor of modern birds inhabited South America around 91 million years ago but it was not until the Cretaceous-Paleogene transition, around 66 million years ago, that modern birds began to diversify rapidly and spread around the world. They used two main dispersion routes, reaching the Old World through North America, and Australia and Zealandia through Antarctica. Net-diversification rates increased during periods of global cooling, suggesting that fragmentation of biomes stimulated speciation.
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Why is it important?
Understanding how birds evolved has important implications for understanding current avian diversity and the potential long-term impacts of habitat fragmentation and global warming.
Perspectives
Previous hypothesis about the evolution of modern birds emphasized the role of the meteorite impact at the end of the Cretaceous. In contrast, we found that rather than being determined by fortuitous extraterrestrial events, avian evolution was influenced by plate tectonics and environmental change, two basic features of Earth’s dynamics.
Dr Santiago Claramunt
University of Toronto
Read the Original
This page is a summary of: A new time tree reveals Earth historys imprint on the evolution of modern birds, Science Advances, December 2015, American Association for the Advancement of Science,
DOI: 10.1126/sciadv.1501005.
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