Local gene duplication (aka tandem gene duplications) is the process by which a gene gets an additional genomic copy of itself that is located proximal. While the exact mechanism that creates the initial local duplicate is not known, once a double exists, it sets the stage for additional local duplicates to be created through nonhomologous recombination or unequal crossing-over.
Tandem gene duplication in human and chimp visualized by a GEvo
analysis. Pinks blocks indicated regions of sequence similarity identified between these two genome regions; wedges connect regions of sequence similarity. Note the set of three genes in each genome each with sequence similarity to all the genes in the other set. This is a tandem gene duplication consisting of three genes. Results can be regenerated at http://genomevolution.org/r/g5