In: Biology
Describe a scenario where selection occurs on a trait, but there is no evolutionary change.
Heritability, i.e., the fraction of phenotypic variation that arises due to genetic variation is an essential component of selection which is primarily responsible for the phenomenon of evolution. However, phenotypic differences alone (regardless if they are the result of the environment or genetically determined) affect reproductive success. If traits are not heritable, there will be what is called PHENOTYPIC SELECTION. Phenotypic selection occurs when individuals with certain characteristics produce more surviving offspring than individuals with other characteristics. Because natural selection occurs through the differential reproduction of phenotypes, it's possible to have natural selection without evolution.
That is, there will be differential reproduction but no evolutionary response to selection. Only if genetic variation for a trait occurs will there be an evolutionary response.