Gene duplication

Gene duplication: An extra copy of a gene. Gene duplication is a key mechanism in evolution. Once a gene is duplicated, the identical genes can undergo changes and diverge to create two different genes.

A duplication is the opposite of a deletion.

Duplications typically arise from an event termed unequal crossing-over (recombination) that occurs between misaligned homologous chromosomes during meiosis (germ cell formation). The chance of this event happening is a function of the degree of sharing of repetitive elements between two chromosomes. The recombination products of such an event are a duplication at the site of the exchange and a reciprocal deletion.

A remarkable class of duplications in which the duplicated region has popped up far away from home base has also been discovered.