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Calibration age and quartet divergence date estimation
Journal article   Open access

Calibration age and quartet divergence date estimation

Christopher A Brochu
Evolution, Vol.58(6), pp.1375-1382
06/2004
DOI: 10.1111/j.0014-3820.2004.tb01715.x
PMID: 15266985
url
https://doi.org/10.1111/j.0014-3820.2004.tb01715.xView
Published (Version of record) Open Access

Abstract

The date of a single divergence point--between living alligators and crocodiles--was estimated with quartet dating using calibrations of widely divergent ages. For five mitochondrial sequence datasets, there is a clear relationship between calibration age and quartet estimate--quartets based on two relatively recent calibrations support younger divergence estimates than do quartets based on two older calibrations. Some of the estimates supported by young quartets are impossibly young and exclude the first appearance of the group in the fossil record as too old. The older estimates--those based on two relatively old calibrations--may be overestimates, and those based on one old and one recent calibration support divergence estimates very close to fossil data. This suggests that quartet dating methods may be most effective when calibrations are applied from different parts of a clade's history.
Alligators and Crocodiles - genetics Animals Biological Clocks - genetics DNA, Mitochondrial - genetics Evolution, Molecular Fossils Likelihood Functions Models, Genetic

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