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Forces shaping the fastest evolving regions in the human genome
Katherine S Pollard1, Sofie R Salama, Bryan King
1Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America. kspollard@ucdavis.edu
Plos Genetics
|October 17, 2006
Summary
Researchers identified 202 human genomic elements conserved across vertebrates but rapidly evolving since human-chimp divergence. These accelerated regions, mainly non-coding DNA, reveal insights into human evolution and genome function.
Area of Science:
- Genomics
- Evolutionary Biology
- Comparative Genomics
Background:
- Comparative genomics aids in identifying functional genomic segments by comparing species.
- Human and chimpanzee genomes diverged approximately 5 million years ago, offering a timeframe for evolutionary changes.
Purpose of the Study:
- To identify human genomic elements that have undergone significant evolutionary changes since divergence from chimpanzees.
- To investigate the functional implications of these rapidly evolving genomic regions.
Main Methods:
- Comparative genomic analysis to detect conserved elements with accelerated substitution rates in humans.
- Resequencing of top accelerated elements to confirm evolutionary changes in primates.
- Analysis of nucleotide composition, recombination rates, and genomic location (e.g., near telomeres).
Main Results:
- Identified 202 genomic elements conserved in vertebrates but accelerated in humans.
- These elements are predominantly in non-coding DNA, often near transcription and DNA-binding genes.
- The five most accelerated elements showed substantial human-specific changes, with seven times more substitutions than in chimpanzees.
- Accelerated regions exhibit a bias towards AT to GC nucleotide changes and are located in high-GC, high-recombination environments near telomeres.
Conclusions:
- A combination of evolutionary forces, potentially including biased gene conversion or isochore selection and directional selection, drives the accelerated evolution of specific human genomic elements.
- These findings highlight unique evolutionary pressures on the human genome.
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