Title: Mutation Rates Change Natural Selection for Genes
According to a recent University of Chicago study, the amount of mutations accepted by natural selection can differ depending on the ration of neutral (referred to as synonymous mutation [Ks]) and mutations which do effect protein structure, nonsynonymous (Ka).
By comparing the ration of Ka/Ks in any particular gene, a coefficient can be derived that defines the selection pressure on that gene. A low ration signifies high selection, and high ratio signifies weak selection.
Pseudogenes, for instance, have a ration of 1, meaning the mutations are accepted at the same rate of natural selection since the gene is functionless.
quote:
The new data show that if more mutations show up at a gene, that gene tends to accept a higher percentage of those mutations.
"A gene under strong mutational pressure succumbs to that pressure," Lahn said. "For genes that have a high mutation rate, somehow selection appears to become less stringent."
quote:
"Lahn and his associates have found a most striking result, one that is totally unexpected," said geneticist James Crow, professor emeritus of genetics and zoology at the University of Wisconsin-Madison. "If this result is indeed confirmed it would cast doubt on use of this ratio [Ka/Ks] as an indicator of selection."
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