Polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species

It occurs regularly in social insects and is manifested by the presence of multiple morphologically different forms (morphs, castes).

Polymorphic organisms have evolved during phylogenesis from a single genotype, as an adaptation to different environments or different life functions. They usually serve to maintain different forms of a population living in a diverse environment, they represent diversity within a population. Currently, polymorphic organisms also arise through human intervention, through breeding with the aim of obtaining individuals with the desired appearance or properties (e.g. domestic dog, Brussels sprouts). Polymorphism is based on hereditary properties, therefore, rarely occurring mutations are not labeled. A rough guide to determining the boundary between mutation and polymorphism is the regular occurrence of different individuals in more than 1% of cases.