polymorphism

In genetics, the coexistence of several distinctly different types in a population (groups of animals of one species). Examples include the different blood groups in humans, different colour forms in some butterflies, and snail shell size, length, shape, colour, and stripiness.

Analysis of the human genome has revealed different kinds of polymorphisms. The simplest type are those locations, where only one base is different, known as single nucleotide polymorphisms or SNPs.