neofunktionalisaatioon

Neofunktionalisaatioon, or neofunctionalization in English, refers to the evolutionary process by which a duplicate gene acquires a new function that was not present in the ancestral gene. The concept emerged from studies of gene duplication in the early 1980s, most notably through the work of Susumu Ohno and later refined by scientists such as Michael Lynch. It is one of three primary mechanisms that explain the functional diversification of duplicated genes, the others being subfunctionalization and regulatory neofunctionalization.

In neofunctionalization, one copy of the duplicate retains the original function while the other copy is free to accumulate mutations that may confer a new advantageous activity. This new function can arise through various mechanisms, including changes in enzyme active sites, altered regulatory elements, or new protein–protein interactions. The process is typically slow, with many duplicated genes initially becoming nonfunctional or pseudogenes before a beneficial mutation is fixed. However, when a novel function confers selective advantage, natural selection can favor its retention and refinement.

Examples of neofunctionalization are found across all domains of life. In mammals, the gene copies HoxC6 and HoxC7 arose from duplication events and subsequently evolved distinct roles in skeletal patterning. In plants, the MADS-box transcription factor gene FLC is a well–studied example where a duplicated copy acquired a role in vernalization response. In bacteria, duplicated ribosomal proteins are sometimes repurposed to serve as stress‑responsive regulators.

Neofunctionalization plays a crucial role in increasing biological complexity and innovation. By providing a genetic substrate for the evolution of novel traits, it underpins the diversity of life observed in nature. Its study remains central to evolutionary genetics, comparative genomics, and the understanding of organismal adaptation.