subfunctionalization

This term is a highly specialized technical descriptor used almost exclusively within evolutionary biology and genetics. It describes a specific outcome of gene duplication where the ancestral gene's roles are split between two copies, preventing either from being lost to mutation because both now perform essential, albeit limited, tasks.

In a scientific context, it is often contrasted with neofunctionalization, where one duplicate gene evolves an entirely new function while the other maintains the original. Because it refers to a specific biological mechanism, it is used in formal academic papers and textbooks rather than general conversation.