The genome of the evolutionary ancestor of humans and present-day apes underwent a burst of activity in duplicating segments of DNA, according to a study to be published in Nature Feb 12, the 200th anniversary of Charles Darwin's birthday.
"The new study shows big differences in the genomes of humans and great apes within duplicated sequences containing rapidly evolving genes. Most of these differences occurred at a time just prior to the speciation of chimpanzees, gorillas, and humans,"said University of Washington (UW) researchers Tomas Marques-Bonet and Jeffrey M. Kidd who headed the study. Both are fellows in the lab of Evan Eichler, UW professor of genome sciences, a Howard Hughes Medical Institute investigator and senior author of the paper.
"It is unclear why, but the common ancestor of humans, chimps and gorillas had an unusual activity of duplication," Kidd added. "Moreover, we don't yet know the functions of most of the genes that were affected by these duplications."
The great ape ancestors, from whom humans, gorillas and chimps descended, lived in Africa between 8 million and 12 million years ago. Most scientists think that the lineage that eventually led to chimps and humans diverged from the African great ape ancestors about 5 million to 7 million years ago.
"What's exciting for us to learn," Eichler added, "was that sequence duplication acceleration occurred in an era when other types of mutations had slowed within the hominid (human-like) lineage."
"There was significant increase in genome activity in both the number of duplication events and the number of base pairs of DNA that were affected," Marques-Bonet noted.
The results suggest that evolutionary properties of copy-number mutations, such as repeated segments, differ from other forms of mutations.
To understand the pattern and rate of genomic duplication during evolution, the researchers constructed a map of segmenta
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University of Washington