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Random genetic variation followed by natural selection is the workaday mechanism of evolution. But the occasional big genetic accident can jumpstart the process. University of Wisconsin evolutionary biologist Sean Carroll has a report in the current issue of Nature that looks at gene duplication—which he calls a “source of newness”—in the model organism yeast. Says Carroll, “When you have two copies of a gene, useful mutations can arise that allow one or both genes to explore new functions while preserving the old function. This phenomenon is going on all the time in every living thing.”
In the Nature study, Carroll tracked a piece of the last 100 million years of yeast evolution—what happened following the duplication of a gene involved in the digestion of the sugar galactose. The original gene had two functions related to metabolizing the sugar. Says Carroll, “Natural selection has taken one gene with two functions and sculpted an assembly line with two specialized genes.” And, in this case, two genes are better than one.
