Genetic Strategies in Plantago

Abstract

The presence of genetic variation is a prerequisite for evolution. Particular genes or sets of genes are involved in adaptation to specific environmental stresses. Phenotypic variation, partly based on genetic variation, can be found on the molecular, biochemical, physiological and morphological levels as well as for fitness and life history traits. Contrary to the situation in most animal species, plant phenotypes are often not as rigidly canalized; in plants it is often hard to analyze the genotypic basis (if any) for the phenotypic variation observed in natural populations. This implies the separation of phenotypic and genotypic effects and the arduous task of quantification of the genetic contribution. The ability of a particular genotype to be plastic, that is to express different phenotypic states, can be of adaptive value itself; and it may be under genetic control. For studies on populations in an evolutionary context, it is of paramount importance to elucidate the contributions of both genetic and non-genetic variation to adaptation. It should be clear, however, that the ability of a species to colonize a particular habitat and to maintain itself in that habitat (in comparison with other species which are unable to do so) must be entirely ascribed to genetic reasons (Bradshaw 1984). It is the purpose of this chapter to discuss the data on genetic variation in the Plantago species which occur in the Netherlands against this background.