Title |
A new time tree reveals Earth history’s imprint on the evolution of modern birds
|
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Published in |
Science Advances, December 2015
|
DOI | 10.1126/sciadv.1501005 |
Pubmed ID | |
Authors |
Santiago Claramunt, Joel Cracraft |
Abstract |
Determining the timing of diversification 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 Neornithes and investigated their biogeographic and diversification dynamics. We found that the most recent common ancestor of modern birds inhabited South America around 95 million years ago, but it was not until the Cretaceous-Paleogene transition (66 million years ago) that Neornithes began to diversify rapidly around the world. Birds used two main dispersion routes: reaching the Old World through North America, and reaching Australia and Zealandia through Antarctica. Net diversification rates increased during periods of global cooling, suggesting that fragmentation of tropical biomes stimulated speciation. Thus, we found pervasive evidence that avian evolution has been influenced by plate tectonics and environmental change, two basic features of Earth's dynamics. |
X Demographics
Geographical breakdown
Country | Count | As % |
---|---|---|
Japan | 98 | 19% |
United States | 30 | 6% |
Spain | 10 | 2% |
United Kingdom | 8 | 2% |
Ecuador | 6 | 1% |
Colombia | 5 | <1% |
Canada | 4 | <1% |
Germany | 4 | <1% |
Mexico | 3 | <1% |
Other | 36 | 7% |
Unknown | 309 | 60% |
Demographic breakdown
Type | Count | As % |
---|---|---|
Members of the public | 455 | 89% |
Scientists | 49 | 10% |
Science communicators (journalists, bloggers, editors) | 8 | 2% |
Practitioners (doctors, other healthcare professionals) | 1 | <1% |
Mendeley readers
Geographical breakdown
Country | Count | As % |
---|---|---|
United States | 5 | 1% |
Brazil | 3 | <1% |
Germany | 2 | <1% |
Canada | 2 | <1% |
Czechia | 2 | <1% |
Portugal | 1 | <1% |
United Kingdom | 1 | <1% |
Norway | 1 | <1% |
Argentina | 1 | <1% |
Other | 3 | <1% |
Unknown | 419 | 95% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Researcher | 76 | 17% |
Student > Ph. D. Student | 74 | 17% |
Student > Bachelor | 59 | 13% |
Student > Master | 57 | 13% |
Student > Doctoral Student | 22 | 5% |
Other | 77 | 18% |
Unknown | 75 | 17% |
Readers by discipline | Count | As % |
---|---|---|
Agricultural and Biological Sciences | 218 | 50% |
Biochemistry, Genetics and Molecular Biology | 38 | 9% |
Environmental Science | 30 | 7% |
Earth and Planetary Sciences | 30 | 7% |
Nursing and Health Professions | 4 | <1% |
Other | 37 | 8% |
Unknown | 83 | 19% |