Rates of mitochondrial DNA evolution in sharks are slow compared with mammals

THE rate of mitochondrial DNA (mtDNA) evolution has been carefully calibrated only in primates 1 . Similarity between the primate calibration and rates estimated for other vertebrates 2–4 has led to widespread assumption of a constant molecular clock in vertebrates even though this has never been ri...

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Bibliographic Details
Published in:Nature (London) 1992-05, Vol.357 (6374), p.153-155
Main Authors: Martin, Andrew P., Naylor, Gavin J. P., Palumbi, Stephen R.
Format: Article
Language:English
Subjects:
Animals
Biochemistry
Biological and medical sciences
Biological Evolution
Calibration
Chondrichthyes
Codon - genetics
Cytochrome
Deoxyribonucleic acid
DNA
DNA, Mitochondrial - genetics
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
Humanities and Social Sciences
letter
Mammalia
Mammals
Mammals - genetics
Marine
Mitochondrial DNA
multidisciplinary
Polymerase Chain Reaction - methods
Regression Analysis
Science
Science (multidisciplinary)
Sharks
Sharks - genetics
Sphyrna tiburo
Taxa
Ungulates
Vertebrates
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Summary:THE rate of mitochondrial DNA (mtDNA) evolution has been carefully calibrated only in primates 1 . Similarity between the primate calibration and rates estimated for other vertebrates 2–4 has led to widespread assumption of a constant molecular clock in vertebrates even though this has never been rigorously tested 5 . We report here the examination of mtDNA sequence variation for 13 species of sharks from two orders that are well represented in the fossil record to test the constancy hypothesis. Nucleotide substitution rates in the cytochrome b and cytochrome oxidase I genes in sharks are seven- to eightfold slower than in primates or ungulates. This difference in substitution rate cannot be explained by nucleotide composition bias, codon-usage bias, selection, or choice of genes sequenced, and was confirmed by comparing species recently separated by the rise of the Isthmus of Panama. Such differences in mtDNA substitution rates among taxa indicate that it is inappropriate to use a calibration for one group to estimate divergence times or demographic parameters for another group. High-resolution studies of molecular evolutionary rates require taxon-specific calibrations.
ISSN:0028-0836
1476-4687
DOI:10.1038/357153a0