Mutations are one of the fundamental forces of evolution because they fuel the variability in populations and thus enable evolutionary change. Since, mutations are random, caused by physical changes to the hereditary material there are many possible ways which can change DNA sequence as it is organized into physically unlinked chromosomes. Mutation rates are difficult to measure because the events are so rare that it is like measuring the frequency of needles in haystacks.The distribution of mutational effects on fitness specifies the probability distribution of selection coefficients for spontaneous mutations of a given genome.

Some deleterious mutations are lethal while others appear to be effectively neutral in populations. Not all mutations are harmful; Occasional fitness increasing mutations drive adaptive evolution. Some intriguing statements can be made about advantageous mutations beyond the fact that they are usually rare and difficult to observe. Theories on population genetics of mutations can be categorized as: those restricted to single sites, in which all mutations are treated as completely independent of each other; those invoking linkage, in which changes in the frequency of mutations are no longer independent, when their effects are independent; and those invoking epistasis in which the effects of mutations depend on which others are present. Many simple theories have been developed and a major challenge for future research is to integrate them with the aim of accurately predicting the behaviour of systems that lie near boundaries.

An insight into the population genetics of mutations can contribute to a deeper understanding of many practical and theoretical challenges. At the fundamental level, broad questions such as the origin of species and their extinctions are influenced by the accumulation of mutations and various models have accordingly been developed. Much work remains to be done in order to integrate existing theories more fully and to better understand their implications. Mutations, however, also provide the raw material for the improvement of plants and animals for food production.The population genetics of mutations is undoubtedly central to many theoretical and applied questions in biology.

1. Allen O. H., 2010, The population genetics of beneficial mutations. Phil. Trans. R. Soc. Biol. Sci.,365: 1195-1201.
2. Laurence Loewe and William G. H., 2010, The population genetics of mutations: good, bad and indifferent. Phil. Trans. R. Soc. Biol. Sci., 365: 1153-1167.
3. Laurence Loewe and Brian Charlesworth., 2006, Inferring the distribution of mutational effects on fitness in Drosophila. Biol. Lett., 2: 426-430.

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