The genotype x environment-to-phenotype relationship.

Proceeding from the formal genotype x environment-to-phenotype functional relationship, a few common concepts essentially based upon this relationship have been reviewed and redefined. Particular attention was given to forming unambiguous representations. In summary, these concepts were: the reaction norm and phenotypic range of a genotype, the genetic control of traits, the general representation of genotypic and environmental contributions to a phenotype and the related problem of genotype x environment interaction, the fitness function, selective neutrality and superiority. The role of joint frequency distributions of genotypes and environmental situations for detecting and describing certain properties of the underlying genotype x environment-to-phenotype functional relationship has been demonstrated by means of models for genotype x environment interaction and the fitness function.