Friday, August 5, 2011
The phenotype is the physical characteristics of an organism; the product of interactions between the genotype (the genetic information carried by the organism) and the environment. It is the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental. 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.