Generic terms and Abbreviations

This page is intended to aid readers in understanding the basic Generic terms and Abbreviations used in herpetology. If you have any questions or concerns about the information provided here, please contact me.

Albino – having absent or deficient melanin. Widely used term for “amelanistic”. See tyrosinase-negative and tyrosinase-positive.

Allele – either of the two paired genes which affect an inheritable trait.

Amelanistic – having no melanin.

Anerythristic – having no red color.

Axanthic – having no yellow color.

Codominant – a gene that causes the homozygous form to look different than the wild-type and the heterozygous form to have traits of both.

Dihybrid Cross – shows the possible genotype of offspring as the result of the pairing of two different genes.

DNA (Deoxyribonucleic Acid) – molecules bearing genetic information of all living cells. Gene. Also referred to as “unit of inheritance”.

Dominant – a gene that causes an animal to look different than the wild-type and where the homozygous form and the heterozygous form look the same as each other.

Double Heterozygous – being heterozygous for two different traits.

Gene – unit of heredity that determines the characteristics of the offspring.

Genetics – the study of heredity.

Genotype – an organism’s genetic composition. Heredity – the transmission of genetic characters from parents to offspring.

Het – an abbreviation for heterozygous.

Heterozygous – possessing two different genes for a given trait. An animal with one mutated, recessive gene still appears normal; its mutated gene can be inherited by future offspring. A co-dominant animal is heterozygous for the dominant form of its mutated gene, yet is different in appearance than both the wild-type and homozygous forms.

Homozygous – A state in which both genes for a specific trait are the same. When a recessive gene is it its homozygous form, it makes the animal look different from the wild-type. When a dominant gene is in its homozygous state, it causes the animal to look different from both the wild-type and the heterozygous (co-dominant) forms.

Hypomelanistic – an animal having less black and/or brown color than a wild-type.

Leucistic – a pure white animal with dark eyes.

Locus – a gene’s position on a chromosome (plural: loci).

Melanin – black or brown skin pigments.

Melanistic – abnormally dark, especially due to an increase of melanin.

Mutation – an abnormal gene that under certain circumstances can cause an animal to be born with an appearance other than wild-type.

Normal – an animal with no mutated genes – “wild type” in appearance. (See wild type).

Phenotype – an animal’s external appearance, as caused by its genotype.

Possible Het – an animal from a known breeding that has either a 50% or 66% possibility of being “heterozygous” for a mutant gene.

  • A 66% possible het comes from breeding 2 heterozygous animals together: 50% of the offspring are heterozygous, 25% will be homozygous, and 25% will be wild-type. Of the normal appearing animals, 66% (or roughly 2 out of 3) will actually be heterozygous for the mutated gene.
  • A 50% possible het comes from breeding a heterozygous animal to a wild-type animal. All of the resulting offspring will be wild-type in appearance, but 50% of them will actually be heterozygous for the mutated gene and must be bred out to determine which animals are really hets.

Recessive – a gene that affects an animal’s appearance if it’s present in the homozygous state. A heterozygous animal carrying a mutated, recessive gene looks normal.

Super – commonly used herpeto-cultural term for the dominant form of a co-dominant mutation. i.e. Super Motley.

Tyrosinase – an enzyme required for synthesizing melanin.

Tyrosinase-negative – an albino whose cells lack tyrosinase, producing a white and yellow/orange animal with pink eyes. A separate albino mutation from tyrosinase-positive. Also called T-.

Tyrosinase-positive – an albino not able to synthesize melanin, but capable of synthesizing tyrosinase. Also referred to as T+.

Wild-type – the way the animal usually looks in nature (i.e. the normal color and pattern).

Xanthic – having more yellow color than wild-type.


Blumen Boas (2016)

Generic terms and Abbreviations
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