CLUSTERS OF IDENTICAL NEW MUTATION IN THE EVOLUTIONARY LANDSCAPE

In contrast to the common assumption that each new mutant results from a unique, independent mutation event, clusters of identical premeioti c mutant alleles are common. Clusters can produce large numbers of rel ated individuals carrying identical copies of the same new genetic cha nge. By entering the gene pool in multiple copies at one time, cluster s can influence fundamental processes of population genetics. Here we report evidence that clusters can increase the arrival and fixation pr obabilities and can lengthen the average time to extinction of new mut ations. We also suggest it may be necessary to reconsider other fundam ental elements of population genetic theory.