An individual organism has two sets of attributes – an endowment which it gets from the parents and an individuality which reflects a reaction of the hereditary potentiality with the surroundings
In order to clearly demarcate the two in genetic terms, Johansen (1909) a Danish scientist proposed the genotype – phenotype concept. Genotype of an individual has been defined as the sum total of all the hereditary potentialities that the organism inherits from the parents; while the phenotype is the morphological and physiological attributes of the organism – like size, shape, colour, metabolic reaction, rate etc.
Phenotype reflects the interaction between the genotype and the environment. Since the individuals of a species may grow in different environments there: interactions are different. In other words the same genotype may interact variously in different environment and produce various phenotypes. In the case of Potentilla glandulosa, the same genotype behaved differently in different environments.
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To sum up, we can say that as far as an individual is concerned its genotype is permanent (baring extreme circumstances) while its phenotype is transient. Individuals with different genotypes some time show similar phenotypes in a similar environment.
The diverse phenotypes possible for a given genotype under various environmental influences (without causing lethality to the individual) are called the norm or reaction range.
The norm or reaction range extends from one extreme to the other (with reference to all factors or parameters of the environment) in which a given genotype can interact and survive.
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The full reaction range of a genotype perhaps can never be understood in its entirety, because in order to assess this, one has to know all parameters of the environment. This is easier said than done.