Abstract
Genetic fixation in finite populations under different degrees of restriction of pollen flow in an animal-pollinated allogamous plant species was investigated through computer simulation. A single locus with two alleles in a population of self-incompatible, diploid plants was considered. A gene-pool model, a random pollen flow model and a neighborhood model were also included for comparison. Under restricted pollen flow models, the fixation probability was depressed considerably in comparison with the gene-pool model. To distinguish the effect of patch formation, plants were relocated randomly just after mating at each generation. The extent of probability of an increase in fixation was manifested for restricted pollen flow models and a random pollen flow model. The random pollen flow model with relocation exhibited an even lower fixation probability than the gene-pool model. This departure can be ascribed to zygote formation, which is not accounted for in the gene-pool model. In conclusion, the depression of fixation observed for restricted pollen flow models is due not only to patch formation caused by pollen flow restriction, but also to zygote formation. Any theoretical model based on the gene-pool model is misleading when attempting to understand the genetic properties of a natural plant population, since neither of these two factors is taken into account.
