Mutation

Mutation is the ultimate, original source of all genetic variation — without it, none of the other evolutionary forces would have any raw material to act on. However, the mutation rate in most organisms is naturally low, so the direct change in allele frequency contributed by new mutations in any single generation is usually small. Mutation's real evolutionary importance lies less in its immediate, generation-to-generation effect on allele frequencies and more in its role as the continuous, long-term supplier of new variation that natural selection, ge …