Mutations and New Variation: Overview


A mutation is a heritable change in the genetic material that is not due to genetic recombination. Mutation alters the structure or number of genes or entire chromosomes.

Keywords: evolution; selection; variation; human disorders; sex; recombination; self‐fertilization; polyploidy; aneuploidy

Figure 1.

Gene mutations. (a) A GC→AT mutation caused by guanine shifting from its common (keto) form to a rare enol form at the time of DNA replication. This enol form pairs with thymine instead of cytosine. During the subsequent replication, the newly incorporated thymine pairs normally with adenine. It is also possible for guanine to convert to its rare enol form during its incorporation opposite a template strand, rather than at the time of replication (not shown). In this case, guanine will be located opposite a thymine and replication will result in an AT→GC mutation. (b) Addition and deletion mutations caused by strand slippage. On the left, addition mutations are caused by slippage of the newly synthesized strand. On the right, deletion mutations are caused by slippage of the template strand. Repetitive bases (A on the left, CT on the right) stabilize the looped out portion of the DNA. (Adapted from Gardner and Snustad (1984) Principles of Genetics, New York: Wiley; Griffiths et al. (1996). An Introduction to Genetic Analysis, New York: WH Freeman.)

Figure 2.

Chromosome mutations. (a) Structural mutations. Wavy arrows in the diagrams for terminal and interstitual deletions indicate an agent such as ionizing radiation. (b) Numerical mutations during meiosis. Aneuploid gametes are firmed by nondisjunction; that is, homologues (far left) do not separate and move to opposite poles. Nondisjunction can occur during the first (upper diagrams) or second (lower diagrams) meiotic division. Circles within chromosomes indicate centromeres. Nondisjunction may also occur during mitosis, in which case the sister chromatids do not properly move to opposite poles. (Partly adapted from Griffiths et al. (1996). An Introduction to Genetic Analysis, New York: WH Freeman.)


Further Reading

Crow JF (1986) Basic Concepts in Population, Quantitative, and Evolutionary Genetics. New York: WH Freeman.

Crow JF (1997) The high spontaneous mutation rate: Is it a health risk?. Proceedings of the National Academy of Sciences of the USA 94: 8380–8386.

Freeman S and Herron JC (2004) Evolutionary Analysis, 3rd edn. Upper Saddle River, NJ: Prentice Hall.

Futuyma DJ (1998) Evolutionary Biology, 3rd edn. Sunderland, MA: Sinauer.

Genetics (1998) 148. [April; a special issue of this journal concerning mutations].

Gillespie JH (1994) The Causes of Molecular Evolution. Oxford: Oxford University Press.

Griffiths AJF, Wessler SR, Lewontin RC et al. (2005) An Introduction to Genetic Analysis, 8th edn. New York: WH Freeman.

Kimura M (1983) The Neutral Theory of Molecular Evolution. Cambridge: Cambridge University Press.

King M (1993) Species Evolution: The Role of Chromosome Change. Cambridge: Cambridge University Press.

Kondrashov AS (1997) Evolutionary genetics of life cycles. Annual Review of Ecology and Systematics 28: 391–435.

Li W‐H (1997) Molecular Evolution. Sunderland, MA: Sinauer Associates.

Page RDM and Holmes EC (1998) Molecular Evolution: A Phylogenetic Approach. Oxford: Blackwell Science.

Ridley M (2004) Evolution, 3rd edn. Malden, MA: Blackwell Science.

Russell PJ (1992) Genetics, 3rd edn. New York: Harper Collins.

Science (1998) 281(5385) [25 September issue with several articles concerning the evolution of sex, mate choice, etc.].

Whittle C‐A and Johnston MO (2003) Male‐biased transmission of deleterious mutations to the progeny in Arabidopsis thaliana. Proceedings of the National Academy of Sciences of the USA 100: 4055–4059.

Woodruff RC and Thompson JN Jr (eds) (1998) Genetica. 102/103. [A special issue of this journal, Mutation and Evolution].

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Johnston, Mark O(Jan 2006) Mutations and New Variation: Overview. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0004165]