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The genomic rate of adaptive evolution.
1National Evolutionary Synthesis Center, Durham, NC 27705, USA. a.c.eyre-walker@sussex.ac.uk
Trends in Ecology & Evolution
|July 6, 2006
Summary
Adaptive evolution drives approximately 50% of genetic changes in fruit flies and even more in microbes. However, evidence for widespread adaptive evolution is minimal in humans.
Area of Science:
- Evolutionary biology
- Molecular evolution
- Genomics
Background:
- The extent to which positive Darwinian selection drives molecular evolution has been a long-standing debate.
- Limited DNA sequence data and analytical methods previously hindered definitive conclusions.
Purpose of the Study:
- To review the current understanding of adaptive evolution's role at the molecular level.
- To synthesize recent findings from increased DNA sequence data and advanced analytical techniques.
Main Methods:
- Review of existing literature and data on DNA sequence evolution.
- Analysis of estimates for the proportion of adaptive substitutions in various species.
Main Results:
- Approximately 50% of amino acid substitutions in Drosophila are attributed to adaptive evolution.
- A significant fraction of non-coding DNA substitutions in Drosophila also result from adaptive evolution.
- Estimates of adaptive evolution are even higher in microorganisms.
- Limited evidence suggests widespread adaptive evolution in humans.
Conclusions:
- Recent advances in genomics and analytical methods have made the study of adaptive evolution tractable.
- Positive Darwinian selection plays a substantial role in molecular evolution across many species, particularly in non-human organisms.
- Humans appear to exhibit less evidence of widespread adaptive molecular evolution compared to other species reviewed.