Study Reveals Hidden Negative Selection in Human Noncoding Genome
Researchers developed a statistical method to detect "cryptic selection"—negative selection on mutations in noncoding DNA regions that have biological function in some lineages but not others. Applying this method to 1000 Genomes Project data, they found evidence of selection affecting at least 7% of the human genome, exceeding previous estimates from conservation-based approaches. This finding suggests that current methods for identifying neutral variants may be missing substantial portions of functionally constrained DNA.
A new study published on bioRxiv challenges the conventional understanding of how much of the human genome is under evolutionary constraint. Researchers developed a statistical test to detect "cryptic selection"—negative selection acting on sites that have biological function in certain evolutionary lineages but not others, making them invisible to standard comparative genomic methods. Using polymorphism data from the 1000 Genomes Project, they compared variants in putatively functional noncoding regions against neutral regions and detected widespread signals of cryptic selection even after filtering out highly conserved sites. Through simulations calibrating different levels of cryptic selection, the team estimated that mutations in at least 7% of the human genome experience negative selection—substantially higher than the ~5% previously estimated by conservation-based methods. The findings underscore the evolutionary dynamic nature of noncoding DNA and suggest that functional turnover across lineages is a significant but previously underappreciated constraint on genetic variation.
Limitations & open questions
The study's own limitations and open questions are not detailed in the provided abstract. Specifically, the extent to which the 7% estimate may vary with different sample sizes, population compositions, or functional annotation methods is unclear. Additionally, the biological significance and phenotypic consequences of cryptic selection in these noncoding regions remain to be determined.
What different sources said
- bioRxivCenter
Pervasive cryptic selection in the human noncoding genome
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