Reptile & Amphibian Forums

ok I give up... I have read all the breeders pages and searched book stores all over and cannot find any info that explains the whole genetics thing in a ball python. The info I do find I just cant grasp. Is there someone or a site/book that explains the mapping thing a little better?

This is the part that is really getting me:

Symbols
Some of the names that are used to describe various color and pattern mutations are rather long. For example, the name “Lavender albino” contains 14 letters. Using the entire word when filling in a Punnett Square would make for an enormous Punnett Square. Abbreviations of the names are used instead of the entire name describing the mutation. Mendel originated some of the rules used for symbolizing today.
1. The symbol is a unique one to four letter abbreviation of the mutant name. For example, a could be used for albino. As a is already taken, ax could be used for axanthic.
2. All characters in a recessive mutant’s symbol are lower case. Again, a is for albino, a recessive mutation.
3. All characters in a dominant or codominant mutant’s symbol are lower case, except for the first letter, which is upper case. For example, Ti could stand for tiger, a codominant mutant in the reticulated python.
4. The symbol of the locus is the same as the symbol for the first mutant gene found at that locus. For example, a stands for both the albino mutant gene and the albino’s locus. Ti stands for both the tiger mutant gene and the tiger’s locus.
5. The symbol of the wild type or normal allele at each locus is the locus symbol followed by a plus sign as a superscript. For example, the wild type allele at the a locus would be a . The wild type allele at the Ti locus would be Ti . If usage is clear, the wild type allele can be symbolized by a plus sign alone.
6. As genes come in pairs, there are two alleles in a genotype. The two symbols may be separated by two slash marks (//), particularly in complicated genotypes. While useful, the slash marks are optional. For example, an albino individual could be symbolized either a//a or aa. A heterozygous tiger could be either Ti//Ti or TiTi .
7. The more dominant allele goes on the left side of the genotype and the more recessive allele goes on the right side of the genotype.
Always remember to clearly label all the symbols used in your Punnett Squares.

I just cant grasp it and it seems like I should be with no prob...in turn its making me feel a little...not smart.

Ah, that's mine.

It comes down to saving bandwidth. On these forums there are emoticons like and abbreviations like ROTFL (roll on the floor laughing). They minimize typing and save bandwidth. That page you put in is just a list of accepted guidelines for making abbreviations for gene names.

Alphabet books start with a is for apple to help make a easier to memorize. In the same way, using a is for albino or p is for pied makes it easier to remember what the a and p abbreviations stand for.

This forum will not accept the plus character, which is the accepted international symbol for the wild type or normal gene. And I haven't figured out how to do superscripts, either.

An creature only shows the effect of a recessive gene when there are two copies of the gene. A creature shows the effect of the dominant gene is there is either one or two copies of the gene in the gene pair. A ball python is pied only if it has two copies of the pied mutant gene. A ball python looks normal if it has a normal gene paired with a pied gene or two normal genes. In other words, Mendel would say that pied is the recessive gene and the normal gene is the dominant gene. We've gone a bit beyond that classification, but you see it in textbooks still.

The letter P is big and commanding while the letter p is smaller and less impressive. So Mendel would use p for the recessive gene (pied) and P for the dominant gene (normal). Now we would still use p for pied. But p with the plus character for a superscript (p^plus) stands for the normal gene.

The symbol has to be unique. If p is for pied and p^plus is the normal gene, then P is reserved in case another version of the gene appears.

p = pied, a recessive mutant gene
p^plus = the normal version of the pied mutant gene
P = unused but reserved

As both p and P are claimed, then neither can stand for pastel. Pastel is a codominant mutant gene, and both dominant and codominant mutants start with an upper case letter.

Pa = pastel, a codominant mutant gene
Pa^plus = the normal version of the pastel mutant gene
pa = unused but reserved.

The plus superscript really works much better with paper and pencil than in these forums.

By Mendel's convention, the more dominant gene goes on the left of a gene pair, and the more recessive goes on the right of a gene pair. So PaPa^plus stands for a gene pair containing a pastel and a normal gene. And p^plusp stands for a gene pair containing a normal gene and a pied gene.

Those are the basics right there. In the guidelines sheet I went a bit further, but the bells and whistles can be skipped at this time.

Does that help? Post your questions.

Paul Hollander

There isn't any web site that does a really first rate job of explaining the whole ball python genetics thing. Markus Jayne's page (http://www.ballpythons.ca/genetics.html) is good as far as it goes, but it is on the brief side. And I've seen a few genetics sites that ought to be marked "Abandon hope, all ye who enter here."

About the best you can do is learn the jargon and the principles and then apply them to the ball python as a specific case. Genetics for Herpers (see link) does a good job presenting the principles.

Paul Hollander
Genetics for Herpers