Phenotypic variation (due to underlying heritable genetic variation) is a fundamental prerequisite for evolution by natural selection. It is the living organism as a whole that contributes (or not) to the next generation, so natural selection affects the genetic structure of a population indirectly via the contribution of phenotypes. Without phenotypic variation, there would be no evolution by natural selection.
The interaction between genotype and phenotype has often been conceptualized by the following relationship:
genotype + environment → phenotype
A slightly more nuanced version of the relationships is:
genotype + environment + random-variation → phenotype
An example of random variation in Drosophila flies is the number of ommatidia, which may vary (randomly) between left and right eyes in a single individual as much as they do between different genotypes overall, or between clones raised in different environments.
A phenotype is any detectable characteristic of an organism (i.e., structural, biochemical, physiological, and behavioral) determined by an interaction between its genotype and environment (of this distinction).
The interaction between genotype and phenotype has often been conceptualized by the following relationship:
genotype + environment → phenotype
A slightly more nuanced version of the relationships is:
genotype + environment + random-variation → phenotype
An example of random variation in Drosophila flies is the number of ommatidia, which may vary (randomly) between left and right eyes in a single individual as much as they do between different genotypes overall, or between clones raised in different environments.
A phenotype is any detectable characteristic of an organism (i.e., structural, biochemical, physiological, and behavioral) determined by an interaction between its genotype and environment (of this distinction).
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