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Gene Structure: Evolution

  1. Tomoko Ohta

Published Online: 15 APR 2013

DOI: 10.1002/9780470015902.a0005301.pub3



How to Cite

Ohta, T. 2013. Gene Structure: Evolution. eLS. .

Author Information

  1. National Institute of Genetics, Mishima, Japan

Publication History

  1. Published Online: 15 APR 2013


Two classes of genes are protein-coding genes and ribonucleic acid (RNA) specifying genes. Their expression is controlled by regulatory elements: promoters and enhancers. Two fundamental processes in the evolution of gene structure in populations are the production of variations by mutations and the natural selection that filters these variations. Mutations occur randomly in genomes of germ cell lineages and are rejected or selected for, so that genes perform needed functions. Protein functions and genetic regulatory systems have been attained during the long course of evolution, and many mutations are deleterious. However, genetic systems are robust and many mutations have minute effects. As a result of minute effects of many mutations, both genetic drift and natural selection influence their fate in a population.

Key Concepts:

  • New genes may be acquired through genome or segmental duplication, unequal crossing-over, gene conversion and duplicative transposition.

  • Because proteins, RNAs and genetic regulatory systems perform necessary functions for the organisms, most new mutations are deleterious.

  • Selective constraint is defined by the fraction of mutations that are removed by natural selection.

  • Genetic systems are robust and effects of mutations are often very small.

  • For mutations with very small effects, the interplay of drift and selection becomes important, that is, the near-neutrality concept is applicable.

  • Under the nearly neutral process, modification and shifting of various interacting systems may occur, accompanying changes in gene structure.


  • nucleotide substitution;
  • gene duplication;
  • natural selection;
  • random genetic drift;
  • near-neutrality