BALL PYTHON GENETICS
Ball Pythons, like all animals that reproduce sexually (as opposed to asexually), receive half of their genetic makeup from each of their parents. Each gamete (female egg before fertilization) and each sperm carry half of that parent’s genetic material. When the gamete is fertilized by the sperm, a zygote (fertilized egg) is formed which now contains the chromosome halves from each parent. This recombining of genes results in predictable but distinctly different outcomes.
So, what does this mean in terms of the color and pattern variations in ball python morphs? In nature, most traits are dominant, allowing one gene within each allele (gene pairs found at the same place on a chromosome) to produce the typical phenotype (visual appearance) for that animal. There are many different dominant morphs. One example is the Pinstripe Ball Python, so called because it has thin black lines running down its back and sides against a tan background. If a Pinstripe is bred to a normal Ball Python, half of the resulting offspring, on average, will be Pinstripes, and half will be normals. If a Pinstripe is bred to another Pinstripe, all of the offspring will be Pinstripes, having received one gene for pin-striping from each parent.
When two dominant traits occur in the offspring, both traits will influence the appearance (phenotype) of the resulting snake. For example, if a Pinstripe was bred to a Spider Ball Python (a yellow tinted snake with white running up its sides and a random pattern of black lines running across its back and down its sides, resembling a spider’s web), instead of a normal, one quarter of the offspring, on average, will be what are known as Spinner Ball Pythons. Spinners exhibit patterns and colors influenced by both parents.
A recessive trait is one that is carried by one gene in the allele but is masked by the dominant gene. For the phenotype representing the recessive gene to occur, both halves of the allele must contain the gene representing the recessive trait. An example of this is the Albino (amelanistic) Ball Python. Amelanism is a recessive trait caused by a defective gene that cannot produce black pigment. Because amelanism a recessive trait, in a normal Ball Python the dominant half of the gene pair takes over producing the “normal” coloration. An Albino Ball Python occurs when both halves of the allele contain the recessive trait for amelanism. Without the dominant gene present, the resulting phenotype contains no black pigment, producing the yellow and white pattern of the Albino.
There also a type of genetic recombination known as co-dominance, which affects color and pattern in different forms. In one form, a dominant trait occurs in both halves of the allele, resulting in a phenotype known as a “super form” showing exaggerated pattern and coloring. An example of a co-dominant trait is found in the Pastel Ball Python. Pastels have lighter, brighter coloring than a normal and slight changes in pattern. When a Pastel is bred to another Pastel, one quarter of the offspring will have two Pastel genes occurring in the same allele, resulting in a “super form” with intensified coloring, a cleaner pattern and white on the top of the head. This phenotype is known as a Super Pastel Ball Python. The Super Pastel is valuable in breeding, because although each of the off-spring contain can only one half of the allele, that one half is guaranteed to be a Pastel gene. This means that all of the offspring will be Pastels, with no normals being produced. This type of recombining is true for all “super form” morphs.
In another co-dominant form, the genetic recombination creates a completely new phenotype. An example of this is found with the Mojave Ball Python, which is visually similar to a normal, but with softer browns and brighter whites. When a Mojave is bred to another Mojave, one quarter of the offspring will be what are known as Leucistics. A Leucistic Ball Python is a white snake with a grey head, blue eyes and light yellow tinting down it’s back. Beautiful!
What makes breeding Ball Pythons exciting is that all of these morphs can be bred together, with additive results (each morph can be added to an existing morph to produce yet another morph). To demonstrate this, let’s take our Pastel and breed her to our Spider. The resulting new morph is called a Bumblebee, a yellow snake with white sides and black transverse bands. Differing from, but resembling both parents. When the Bumblebee matures, it can be bred to our Pinstripe, producing a new morph called a Spinner Blast. The Spinner Blast is the combination of the Pastel, the Spider and the Pinstripe, and is known as a triple-morph. Fourth and fifth genes can be added by continuous breeding, creating quadruple and quintuple morphs. Amazing!
Many more basic morphs have come out of Africa than the ones I’ve mentioned here. With all of the possible combinations, there is literally no limit to the number of new morphs that can be created. There are currently over 7,500 named morphs, and the list is growing every day!