Flying rocks and flying clocks: disparity in fossil and molecular dates for birds
Daniel T. Ksepka1,†⇑, Jessica L. Ware2,3 and Kristin S. Lamm4
- Author Affiliations
1National Evolutionary Synthesis Center, Durham, NC 27705, USA
2Department of Biology, Rutgers University, Newark, NJ 07102, USA
3American Museum of Natural History, Division of Invertebrate Zoology, 79th and Central Park West, New York, NY 10024, USA
4Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA
- Author Notes
↵† Present address: Bruce Museum, Greenwich, CT 06830, USA.
e-mail: ksepka@nescent.org
Abstract
Major disparities are recognized between molecular divergence dates and fossil ages for critical nodes in the Tree of Life, but broad patterns and underlying drivers remain elusive. We harvested 458 molecular age estimates for the stem and crown divergences of 67 avian clades to explore empirical patterns between these alternate sources of temporal information. These divergence estimates were, on average, over twice the age of the oldest fossil in these clades. Mitochondrial studies yielded older ages than nuclear studies for the vast majority of clades. Unexpectedly, disparity between molecular estimates and the fossil record was higher for divergences within major clades (crown divergences) than divergences between major clades (stem divergences). Comparisons of dates from studies classed by analytical methods revealed few significant differences. Because true divergence ages can never be known with certainty, our study does not answer the question of whether fossil gaps or molecular dating error account for a greater proportion of observed disparity. However, empirical patterns observed here suggest systemic overestimates for shallow nodes in existing molecular divergence dates for birds. We discuss underlying biases that may drive these patterns.
divergence dating palaeontology K–Pg extinction
Received March 20, 2014.
Accepted May 27, 2014.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
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