Basically, Genetics is the study of how traits are passed from generation to generation and how they manifest in the receiving generation.

Put another way, why the kids look and behave like Mom and Dad (or the next door neighbor if somebody has some explaining to do).

Definitions:

• Phenotype – This is the resulting outward appearance of an organism’s genetic code.

• Wild Type – The normal phenotype for an animal. (Your everyday Ball Python, Boa Constrictor, Bearded Dragon, etc.)

• Morph – On this website the term Morph will be used when referring to a reptile’s appearance that differs from what is considered normal or Wild Type.

• Gene – This is the basic unit in genetics and come in pairs. An offspring’s gene pairs are made up one gene each from the mother and the father.

• Locus – The location of a pair of genes.

• Allele – Versions of genes. For example: An albino has two albino alleles on the locus that determines whether or not and animal is an albino. An animal that has one or two wild type alleles on this same locus would not be an albino. The albino allele and the wild type allele are two different versions of the same gene.

• Heterozygous (Het) – Containing only one copy of an allele.

• Homozygous (Homo) – Containing two copies of the same allele.

There are several types of alleles in relation to how the traits determined by them show up:

Dominant – One copy (Heterozygous) of a dominant allele is enough to show the trait represented for that locus. On the albino locus, if one of the alleles is the wild type, it will show in the animal’s phenotype because it is a dominant allele. An animal with two copies (Homozygous) of the Dominant allele looks the same as that with one copy.

Recessive (aka Simple Recessive) – Two copies of the same recessive allele are required for the animal to show the trait represented by that locus. Albino alleles are recessive therefore, an animal with two albino alleles (see Homozygous) will be an albino. An animal that only has one albino allele and one wild type allele will not be an albino because the dominant wild type allele will override the recessive. This animal would be described as Heterozygous for albino and can pass the albino allele to it’s offspring.

Incomplete Dominant (aka Co-Dominant or CoDom) – One copy (heterozygous) of an incomplete dominant allele will change the appearance of the animal. However, two copies (homozygous) of that same allele further changes the appearance. This is commonly referred to as a “Super”.

Diminished (Hidden) – Okay, this is a weird one. The best way for me to describe it is to give an example:

A Platinum Ball Python has a Genotype of Heterozygous Lesser Platinum and Heterozygous Platinum (a gene that interacts with the Lesser Platinum allele). When this animal is bred to a Normal animal there are two possibilities: Lesser Platinums (this is an Incomplete Dominant allele the does change the Phenotype of the animal but does not look like a Platinum) and Heterozygous Platinums. Heterozygous Platinums look like normal, wild type ball pythons. Breeding two Lesser Platinums will never result in a Platinum and breeding two Heterozygous Platinums, also, will never result in a Platinum. The only way to get a Platinum Ball Python is to breed a Lesser Platinum and a Heterozygous Platinum and, hopefully the Lesser will pass it’s Lesser Platinum allele and the Heterozygous Platinum will pass the allele that interactis with the Lesser Platinum allele. These two alleles are versions of the same gene and must be combined in order to result in the Platinum Phenotype.

 

• Genotype – The description of the genes of an animal.

Be careful: Phenotype descriptions and Genotype descriptions are not the same thing. An albino ball python would have a Phenotype description of Albino but the Genotype description would be Homozygous for Albino (or Homozygous Albino). The descriptions for more more complex (multiple morphs) animals tends to be a mix of the two types of descriptions. An albino that is also carrying one piebald allele that is also recessive and doesn’t show in the animals Phenotype is still an Albino Phenotype but it’s Genotype is Homozygous for Albino, Heterozygous for Piebald. If this animal is listed in a classified add it would typically be described as Albino, Het for Piebald or Albino, 100% Het Piebald.