In gene transposition an entire gene functions as a transposon and transposes itself to the beginning of the chromosome. In contrast to the other forms of transposition, in gene transposition the transposon (the gene) is deleted in the place of origin. This way, the length of the chromosome is maintained.

The chromosome to undergo gene transposition is randomly chosen, and one of its genes (except the first, obviously) is randomly chosen to transpose. Consider the following chromosome composed of 3 genes:

012345678012345678012345678
*a-*abbab-QQ/aaabbQ+abababb

Suppose gene 2 was chosen to undergo gene transposition. Then the following chromosome is obtained:

012345678012345678012345678
-QQ/aaabb*a-*abbabQ+abababb

Note that for numerical applications where the function chosen to link the genes is addition, the expression evaluated by the chromosome is not modified. But the situation differs in other applications where the linking function is not commutative, for instance, the IF function chosen to link the sub-ETs in the 11-multiplexer problem in section 6.5.2. However, the transforming power of gene transposition reveals itself when this operator is conjugated with crossover. For example, if two functionally identical chromosomes or two chromosomes with an identical gene in different positions recombine, a new individual with a duplicated gene might appear. It is known that the duplication of genes plays an important role in biology and evolution (e.g., [11]). Interestingly, in GEP, individuals with duplicated genes are commonly found in the process of problem solving.