Measurement of genetic differentiation in plant populations

Abstract

It is argued that the studies of genetic differentiation within plant populations should explicitly take into account three major stages in the life cycle: adult plants, seed before dispersal, and seed after dispersal. The simultaneous consideration of these three stages is necessary in order to evaluate the effectiveness of the three main causes of differentiation, namely, non-random pollination and fertilization of the ovules, limited seed dispersal, and locally differential selection. In order to experimentally analyze genetic characteristics of adaptive strategies of plant populations, it is suggested that the association between genetic diversity and the combination of genetic differentiation at the three stages be considered.The shortcomings of Wright’s FST measure for population differentiation are pointed out, and a new measure is proposed which consistently combines the levels of differentiation for the individual subpopulations with the total level of population differentiation. The use of this measure is demonstrated with the help of two experimental data sets, one referring to differentiation in the mating system of pines (differentiation within populations), and the other concerned with differentiation among populations of wild barley in Israel (differentiation between populations). Appropriate data sets alowing simultaneous anlysis of the three major life cycle stages do not yet seem to have been obtained.KeywordsSeed ProductionSeed DispersalAdult PlantSeed OrchardPollen DispersalThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.