Human-specific Accelerated Evolution of Noncoding Sequences
Published Online: 15 APR 2013
Copyright © 2001 John Wiley & Sons, Ltd. All rights reserved.
How to Cite
Webster, M. T. 2013. Human-specific Accelerated Evolution of Noncoding Sequences. eLS.
- Published Online: 15 APR 2013
Mutations in functional noncoding elements are likely to be responsible for a large fraction of phenotypic evolution. There is considerable interest in identifying genes and genomic regions under positive selection on the human lineage, as they may govern the traits that make us unique. Several studies have attempted to identify functional noncoding elements under positive selection in the human lineage by identifying those with evidence of accelerated evolutionary rates since the common ancestor of humans and chimpanzees. These studies have identified a catalogue of human-accelerated regions (HARs). Two of the most extremely accelerated HARs are implicated in controlling human-specific morphology and cognition. However, detailed analyses of the forces governing the evolution of HARs suggest that a number of different processes distinct from positive selection may be involved in their accelerated rates. These include relaxation of constraint, variation in mutation rate and GC-biased gene conversion.
Noncoding genomic regions under evolutionary constraint are likely to be functional elements such as the transcription binding sites.
Evolutionarily constrained elements that have undergone accelerated evolution on the human lineage are candidates for governing human-specific traits.
Positive selection represents a bias towards fixation of alleles conferring an increased fitness.
GC-biased gene conversion (gBGC) is a recombination-associated process that increases the probabilty of fixation of G and C nucleotides independent of their fitness.
Multiple processes, including positive selection and gBGC are implicated in governing the evolution of human-accelerated regions.
- natural selection;
- gene conversion;