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A low rate of simultaneous double-nucleotide mutations in primates
Nick G C Smith1, Matthew T Webster, Hans Ellegren
1Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden. nick.smith@ebc.uu.se
Molecular Biology and Evolution
|January 10, 2003
Summary
Double-nucleotide (doublet) mutations are much rarer than previously assumed, occurring at only 0.3% of the rate of single-nucleotide mutations. This finding impacts our understanding of DNA sequence evolution in primates.
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- Point mutations typically affect single nucleotides, but double-nucleotide (doublet) mutations also occur.
- Previous estimates of doublet mutation rates may be confounded by regional variations in evolutionary rates.
Purpose of the Study:
- To develop a novel method for accurately estimating the doublet mutation rate.
- To investigate the influence of regional variation and sequence context on doublet mutation frequency.
Main Methods:
- Developed a new method to estimate doublet mutation rates, accounting for regional evolutionary rate variations.
- Applied the method to large-scale genomic DNA alignments (human-chimpanzee-baboon) and human single-nucleotide polymorphism data.
- Analyzed sequence context effects across various lineage lengths using comparative genomics.
Main Results:
- The doublet mutation rate was estimated to be 0.3% relative to the singleton mutation rate.
- Doublet mutations are significantly rarer than previously estimated.
- Regional variation and sequence context are crucial factors in primate DNA sequence evolution.
Conclusions:
- Doublet mutations are unlikely to explain the correlation between synonymous and nonsynonymous substitution rates in mammals.
- The developed method provides a more accurate assessment of doublet mutation rates.
- Understanding sequence context and regional variation is key to studying primate genome evolution.