Abstract
Fixation or extinction of neutral genes by genetic drift is especially important for understanding the evolution of small populations. Assuming a monoecious diploid species, I derived expressions for the fixation probability of a neutral gene in age-structured populations with cyclic change in size. Stochastic simulation with a small population showed that the obtained formulae give a good prediction of the fixation probability. Extension to a dioecious diploid species was also presented.
