neutrality

Nei M 2007 The new mutation theory of phenotypic evolution. PNAS 104:12235-12242.

• I want to emphasize that any mutation would never be strictly neutral
• because its function depends on other genes and environmental conditions
• in this sense, any mutation can only be nearly neutral as was conceived by early molecular evolutionists

• the evolutionary change of phenotypic characters can be generated by neutral or nearly neutral mutations that may be fixed in the population by chance
• once these mutations are incorporated into the genome, they may generate new developmental constraints that affect the future direction of phenotypic evolution

• the driving force of phenotypic evolution is mutation, and there is a significant component of neutral or nearly neutral changes