We have defined Evolution as a change in gene frequency at one or more loci in a population, and have seen that this correspond to our intuitive notion of evolution as a change in the genetic composition of a population over time. Mutation as a cause of evolutionary change. A. Mutation is a very weak evolutionary force 1. Mutation can cause change in gene frequencies directly. For example, in a population that is fixed for allele A , and hence the frequency of that allele is 1.0, a mutation introductin allele a automatically reduces the frequency of A below 1.0.
Additional mutations reduce the gene frequency even further.
However, typical mutation rates are on the order of 1 mutation per gene per 10 -5 meiotic events. B. Nevertheless, mutation is crucial for the evolutionary process because it introduces genetic variation on which other processes can act to cause evolutionary change. A large majority of organisms in the world exhibit sexual reproduction, and thus carry on some sort of mating process. Intuitively, one might not expect the act of mating to affect gene frequencies. However, historical developments in evolutionary genetics have suggested that intuition may not be a good guide on this issue.