It refers to the presence in the same population of two or more alternative forms of a distinct phenotype such as flower color. These can occur in any morphological, behavioral, or physiological trait, and in any coding or noncoding segment of DNA (nucleus, mitochondria, or chloroplast).

How does a polymorphism occur?

Polymorphism, in biology, a discontinuous genetic variation resulting in the occurrence of several different forms or types of individuals among the members of a single species. A discontinuous genetic variation divides the individuals of a population into two or more sharply distinct forms.

What are polymorphic sites?

A gene is said to be polymorphic if more than one allele occupies that gene's locus within a population. ... Gene polymorphisms can occur in any region of the genome. The majority of polymorphisms are silent, meaning they do not alter the function or expression of a gene.