Domestication (Exaptation) of Transposable Elements

There are two major ways by which Transposable Elements (TEs) can affect an organism's phenotype. A TE can be disruptive: it can insert into the coding sequence of a gene, thereby inactivating it, or it can be constructive: a TE can provide the raw material for a genome feature, such as a gene, noncoding RNA, or promoter element, that can then be co-opted by the host genome for a new purpose. This co-option process is also known as exaptation or molecular domestication. This chapter covers three major aspects of transposon domestication: host genes that are derived entirely from TEs or from TE-gene fusions (i.e. exonization); the ability of transposons to rewire gene regulatory networks; and the role of transposons in the formation of structural components of the genome.