Morph Terminology

Co-dominant, sometimes used interchangeably with the term incomplete dominant, genes are displayed when a single copy of the gene is present. When two copies of a co-dominant gene is present, then an animal appears with the gene’s super form.

Dominant genes are displayed whenever the gene is present. An animal with a copy of a dominant gene will display that trait. Animals with two copies of a dominant gene look identical to those who have only one.

Describes animals that have a single copy of an gene. Animals that are heterozygous, or het, for a recessive trait will carry the gene but not show that trait visually.

Describes animals with two copies of the same gene. For co-dominant traits, homozygous animals will exhibit a super form of those genes. For recessive traits, this means the animal will display the trait visually.

Polygenic traits are controlled by several different genes.

Recessive genes are only expressed when they occur in pairs. Animals must inherit a copy of the gene from both parents to display the trait visually. Animals with one or no copies of a recessive gene will not show that trait.

When two copies of a co-dominant gene are present, an animals exhibits that gene’s super form, which is generally a more extreme version of the heterozygous form.