You asked for it. Or, well, one of you did, and now you all have to suffer my spergy ass. Good job @IvyLB . Enjoy the first of my (possibly) many posts about my favorite scale puppies, ball pythons! Fist Topic: Ball Python Genetics; A Simple Breakdown Ball pythons have amazing varitety. From the basic normal, or “wild type” python found in sub-saharan Africa has sprung over a hundred base “morphs”, or color mutations, and breeders have produced literally thousands of morph combinations. As of right now, the World of Ball Pythons website lists over 4,000 produced color and pattern combinations. But what is a morph? For ball pythons, a morph is a deviation in color or pattern from the standard wild type animal that has proven to be genetically inheritable by a snake’s offspring. This isn’t always as straight forward as it sounds, as the normal animals can come in a wide range of color and pattern already. Some animals might be hatched darker or lighter than others. They might have a very reduced pattern, or a very busy one. But until the animal has proved out- that is, demonstrated that its special quality can be passed down to its young- it can not be considered a morph. How does a ball python inherit a morph from it’s parent? To be as basic as possible for this explanation, the genes passed down generally come in three varieties: dominant, incomplete or co-dominant, and recessive. (Note, since very few ball python morphs are polygenic I won’t be covering that, but it’s basically what we do with dogs: line breeding to take a desired trait and multiply its intensity over several generations. These aren’t truly distinctive morphs in the same way that most ball python mutations are, and can be bred into or out of lines.) Genes are (usually, unless something goes wrong) passed down in pairs, but the pairs don’t always match. A word that get’s tossed around when speaking about ball python morphs is ‘het’. No, this isn’t the same as what tumblr refers to as “dirty cishets oppressors!" This is actually a shortened way of saying ‘heterozygous’. What heterozygous means is that the pair of genes the baby snake got from it’s parents are mis-matched. The opposite is homozygous, when both pairs are the same. What the baby snakes will look like largely depends on which pairs of genes they get from each parent, and if those genes are dom, co-dom, or recessive. One member of this pair by itself is called an allele. The location of where a gene/allele sits on a strands of DNA is called a locus. Later on I’ll explain why this is important to some morphs, but let’s move on to basic inheritance. If a snake inherits a dominant morph allele, no matter what other allele they get in the pair (with little exception, which I’ll explain later), that gene will be visually expressed. Examples of dominant morphs include spider, pinstripe, and leopard. If a snake inherits only one co-dominant allele (in other words, the allele pair is heterozygous), the color or pattern will be expressed, much like the simple dominant gene. However, co-dom genes do something special when you get two of a kind. They express a form that’s been dubbed “super”. An example of a co-dom gene and its super version is pastel and super pastel. Recessive is the trickiest type of gene to work with when you’re trying to get a snake that expresses this trait. If a snake inherits only one recessive allele (het), it WILL NOT visually show it. You will have to pair this animal up with another that carries at least one of the same allele, and hope that one or more of their babies get one from each parent. The odds increase significantly if you pair up homozygous snakes instead of heterozygous snakes. Examples of recessive morphs are piebald, albino, and clown. One thing I mentioned previously was that loci- where the allele is located on a strand of DNA- can be important to some morphs. In certain cases, alleles from different morphs will occupy the same locus, and crazy stuff can happen when they do. Instead of expressing like either of the two parent alleles, they combine to form something completely new. One of the most famous examples of a morph who’s alleles often occupy the same locus as other morphs’ genes is the mojave. The mojave is a co-dom morph. It’s super form makes a snake that has blue eyes and is mostly white except for some head pattern. But when combined with a lesser, the pattern disappears entirely, creating a pure white snake with blue eyes known as a BEL or blue eyed leucistic ball python. This is where that exception comes in about dominant genes always being visible; you can’t see a spider pattern on an all white snake! More striking, however, is what mojaves produce when combined with specials. The heterozygous alleles combine to create a completely different looking morph named a crystal. That’s it for basic inheritance. If I didn’t make your eyes glaze over with that info dump (or if I did, but you’re still interested, and want some sort of clarification) let me know, and I’ll keep going!