The concept that chance determines the initial appearance of mutations, and that most of these mutations have no effect (i.e., the mutation is neutral) on the fitness of the organisms.

The theory that much of evolution has been primarily due to random drift of neutral mutations.

A view of molecular evolution that postulates that most mutations do not affect the amino acid being coded for, and that such mutations accumulate in a population at rates driven by genetic drift and mutation rates. Neutron (new´ tron) [E.: neutral] • One of the three most fundamental particles of matter, with mass approximately 1 amu and no electrical charge.

Link to a lecture on neutral theory of evolutionary change. niche the full range of biological and physical conditions under which an organism can live and reproduce. The realized niche is largely determined by interactions with other species