Crossover during sexual recombination of parental genomes Evolution of eukaryotes is mediated by sexual recombination of parental genomes and since introns are longer than<unk> s most of the crossovers occur in noncoding regions. In these introns there are large numbers of transposable elements and repeated sequences which promote recombination of nonhomologous genes. In addition it has also been shown that mosaic proteins are composed of mobile domains which have spread to different genes during evolution and which are capable of folding themselves. There is a mechanism for the formation and<unk>  of said domains, this is the modularization hypothesis. This mechanism is divided into three stages. The first stage is the insertion of introns at positions that correspond to the boundaries of a protein domain. The second stage is when the "protomodule" undergoes tandem duplications by recombination within the inserted introns. The third stage is when one or more protomodules are transferred to a different nonhomologous gene by intronic recombination. All states of modularization have been observed in different domains such as those of hemostatic proteins.
Exon shuffling
Osseoincorporation
Exon skipping
Fusion transcript
Gene duplication
Fusion gene
Copy number variation
Insertion sequence