near neutrality
Ohta T & Kimura M 1971 On the constancy of the evolutionary rate of cistrons. J Mol Evol 1:18-25.
- remarkable constancy of the rate of amino acid substitution in each protein over a vast period of geologic time constitutes so far the strongest evidence for the theory (Kimura, 1968; King and Jukes, 1969) that the major cause of molecular evolution is random fixation of selectively neutral or nearly neutral mutations
- the term "nearly neutral mutants" has been used by Kimura (1968, 1969) to represent a class of mutants whose selection coefficients are so small that their behavior may not be very different from the strictly neutral mutants
- the deleterious and neutral mutations can not be distinctly separated but are connected by a cline determined by the amount of genetic load that they create
- a mutant with very small effect, with |Nes| < 1, can still create considerable load
- mutants with such small values of |Nes| may behave just like neutral mutations
