The alternative fates of duplicated genes

The alternative fates of duplicated genes. (a) The duplication of a gene. The orange, yellow, and pink boxes denote cis-regulatory elements; the beige box denotes the coding region. After duplication, several alternative fates of the duplicates are possible: (b) any inactivating mutation in a coding region will render that duplicate into a pseudogene, and purifying selection will then operate on the remaining paralog; (c) mutations may arise that alter the function of a protein and may be favored by positive selection (neofunctionalization); (d) mutations may affect a subfunction of either duplicate, and so long as the two paralogs together provide the ancestral functions, different subfunctions may be retained, resulting in the evolution of two complementary loci (subfunctionalization).