"We've discovered a striking phenomenon that challenges a paradigm of molecular evolution that has been around for several decades," said lead author Bruce Lahn, Ph.D., assistant professor of genetics at the University of Chicago and Howard Hughes Medical Institute investigator. "As such, it may cause a significant shift in the field."
The researchers report their findings in the July 2005, issue of the journal Trends in Genetics, available early online June 7. Other authors are Gerald Wyckoff, Ph.D., previously a postdoctoral fellow in Lahn's lab and now an assistant professor at the University of Missouri-Kansas City, and Christine Malcom and Eric Vallender, both graduate students in Lahn's lab.
For more than three decades, molecular evolutionists have thought that no matter how many genetic mutations show up on a specific gene, whether or not those mutations become fixed in the species is determined primarily by natural selection. The new study shows that the speed at which these new mutations arrive also affects whether the mutations become fixed.
Lahn's team looked at nearly 6,000 genes in their study. For each gene, they compared sequences between two mammalian species. This enabled them to measure the mutation rate of the gene specifically, the rate of those mutations that do not affect the protein's structure, called synonymous mutation (Ks). These mutations are functionally neutral, which means natural selection is not a factor in whether they are accepted during evolution.
Lahn's team also looked at the
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Contact: Catherine Gianaro
catherine.gianaro@uchospitals.edu
773-702-6241
University of Chicago Medical Center
7-Jun-2005