Fluctuating Environments and the Role of Mutation in Maintaining Quantitative Genetic Variation

We study a class of genetic models in which a quantitative trait determined by several loci is subject to temporally fluctuating selection. Selection on the trait is assumed to be stabilizing, but with an optimum that varies periodically and may be perturbed stochastically. The population mates at random, is infinitely large, and has discrete generations. We pursue a statistical and numerical approach, covering a wide range of ecological and genetic parameters, to determine the potential of fluctuating environments in maintaining quantitative-genetic variation. Whereas, in contrast to some recent claims, this potential seems to be rather limited in the absence of recurrent mutation, in combination with it fluctuating environments may frequently generate high levels of additive genetic variation. It is investigated how the genetic variation maintained depends on the ecological parameters and on the underlying genetics