The rate of mutant substitution in populations with overlapping generations

Abstract

We consider an age-structured population that is observed at times t = 0, 1, 2,…. It is assumed that for each t there is the same number of individuals of a particular sex and age group. Another assumption we make is that an offspring of a specified sex has at all times the same probability of having a parent of a particular age and sex. It is shown that the rate of substitution of neutral mutants is [formula omitted]/L, where [formula omitted] and L are respectively equal to the mean fraction of mutants among gametes succeeding in forming newborn individuals and the mean age of reproduction. This result also applies to monoecious populations. The substitution rate is also derived for advantageous mutants in a monoecious population. Once again, the mutation rate in the usual expression is replaced by [formula omitted]/L. Implications of these results are discussed. © 1982, Cambridge University Press. All rights reserved.