Neofunctionalization, one of the possible outcomes of functional divergence, occurs when one gene copy, or paralog, takes on a totally new function after a gene duplication event. Neofunctionalization is an adaptive mutation process; meaning one of the gene copies must mutate to develop a function that was not present in the ancestral gene.[1][2][3] In other words, one of the duplicates retains its original function, while the other accumulates molecular changes such that, in time, it can perform a different task.[4]
^Conrad B, Antonarakis SE (2007). "Gene duplication: a drive for phenotypic diversity and cause of human disease". Annual Review of Genomics and Human Genetics. 8: 17–35. doi:10.1146/annurev.genom.8.021307.110233. PMID17386002.
^Ohno (1970). Evolution by Gene Duplication. New York, Heidelberg, Berlin: Springer-Verlag. pp. 59–87. ISBN978-3-540-05225-8.