Gene flow within a population of the outbreeding Sinapis arvensis: Isozyme analysis of half-sib families

Progeny of several Sinapis arvensis L. plants sampled in a field were analysed for isozyme patterns at two highly polymorphic loci: esterase and acid phosphatase. Allele frequencies of pollen subpopulations that effectively fertilized each separate sampled plant were compared. In spite of self-incompatibility, large variations in allele frequencies were shown among pollen sub-populations. Non-random mating owing to gametic selection and plant density effects were evidenced and could reduce gene flow within a population.