a1 National Institute of Genetics, Mishima, Japan
The age of an allele segregating in a finite population may be defined in two ways. They are (1) the age of a mutant gene that has never reached fixation in the population, and (2) the age including any fixation period in the past. Theoretical expressions for these are derived on the assumption that every mutant is unique.
(Received April 24 1973)
* Contribution No. 960 from the National Institute of Genetics, Mishima, Shizuoka-ken, 411 Japan.