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Syst Biol. 2015 Sep;64(5):869-78. doi: 10.1093/sysbio/syv027. Epub 2015 May 4.

Heterogeneous Rates of Molecular Evolution and Diversification Could Explain the Triassic Age Estimate for Angiosperms.

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National Institute for Mathematical and Biological Synthesis (NIMBioS);
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996-1610, USA;
School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT 06511, USA; and.
Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT 10620, USA.


Dating analyses based on molecular data imply that crown angiosperms existed in the Triassic, long before their undisputed appearance in the fossil record in the Early Cretaceous. Following a re-analysis of the age of angiosperms using updated sequences and fossil calibrations, we use a series of simulations to explore the possibility that the older age estimates are a consequence of (i) major shifts in the rate of sequence evolution near the base of the angiosperms and/or (ii) the representative taxon sampling strategy employed in such studies. We show that both of these factors do tend to yield substantially older age estimates. These analyses do not prove that younger age estimates based on the fossil record are correct, but they do suggest caution in accepting the older age estimates obtained using current relaxed-clock methods. Although we have focused here on the angiosperms, we suspect that these results will shed light on dating discrepancies in other major clades.


Angiosperms; birth–death; divergence times; land plants; rates of molecular evolution

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