Polymorphism
A gene is said to be polymorphic if more than one allele (a variant of a given gene) occupies that gene’s locus (the fixed position of a gene) within a population. In addition, each allele must also occur in at least 1% of the population to be generally considered polymorphic. If the rate is lower, this variant is considered to be a mutation.A good example of human polymorphisms are our different blood types.