Genetics 101:
I mentioned previously that the genes that affect colouration (and sometime also patterning) are caused by slight mutations of the Normal gene, and that these mutations do occur naturally in the wild - albeit rarely. In terms of the genetic composition of Royal Pythons, genes are kept in pairs, with one gene being randomly inherited from each parent. The term heterozygous refers to these two genes in the pair being different to each other, hetero being Latin for "mixed". When a snake has two of the same gene in a pair, one being received from each parent, this is a homozygous pairing - again, homo meaning "same". Ifrit is heterozygous for the Fire gene - he received one Fire gene from (for arguments sake) his father, and one Normal gene from his mother - or vice versa.
Of the many different types of individual / single mutated genes which determine the colouration (morph), these come in three different types - recessive, dominant, and co-dominant, in terms of their relationship to the other in the pair.
Remember earlier I said Ifrit is a heterozygous Fire? Well, this is because the mutation that causes the Fire gene is co-dominant in its relationship with the Normal gene, so when paired to a Normal, the visual traits of both of his parents are displayed in him, even in the heterozygous form. The Fire gene is a mutated normal gene, as with all "base morphs". This particular mutation causes lower levels of pigmentation in the skin cells, resulting in visually paler snakes. As this mutated gene is co-dominant, this visual trait can be passed from parent to offspring with only one parent carrying the Fire gene.
We'll assume that one of Ifrits parents was a Fire morph, carrying one Fire gene and one Normal gene, and the other was a Normal (carrying no mutated genes) - Ifrit being the result of inheriting one Fire gene from one parent, and one Normal gene from the other. If Ifrits parents had both been Fires, there would have been a 25% chance that he would have received one Fire gene from each parent, making him Homozygous - in which case he would have looked much different...
This is a perfect example of a Super-Fire, otherwise known as a Black Eyed Leucistic - a homozygous recipient of two Fire genes. As a single Fire gene results in visually lighter snake due to affected pigmentation levels, two snakes which both have this Fire gene can be selectively bred together in order to both pass one gene each to an offspring. As these genes are co-dominant in their relationship with one another, the recipient of two copies of this mutated gene would be visually different to the recipients of only one gene (and one Normal) - resulting, in this case, with a snake that has much lower levels of pigmentation that his parents - or none at all, as with the Super Fire above.
Now go make yourself a nice cup of tea, you've earned it - although if you really want to read more, this topic explains things a little more in depth.
Of the many different types of individual / single mutated genes which determine the colouration (morph), these come in three different types - recessive, dominant, and co-dominant, in terms of their relationship to the other in the pair.
- Recessive: The Albino gene, for example, is recessive in its relationship with the Normal gene, meaning in order for a snake to be visually albino, both parents must have at least been carrying (or heterozygous for) the Albino gene. In this scenario, there is a 25% chance that the offspring would receive two Albino genes (one from each parent) meaning it would be homozygous, and would visually have the characteristics of an Albino - lack of melanin in the skin, and pink eyes. Any of the offspring which inherit one Albino gene from one parent, and one Normal gene from the other, would visually be identical to a Normal (wild type) snake, as they would only carry one copy of the Albino gene - but not display it visually.
- Dominant: As int the above example, when a dominant gene is paired in the heterozygous form with a recessive gene such as Albino, the characteristics of the dominant gene will be always be visually evident. None of the characteristics of the recessive gene would be visually evident. In the homozygous form (two of the same gene) the offspring would be visually identical to the heterozygous offspring who only carry one dominant gene. It is therefore impossible to tell visually which offspring have received two dominant genes, from the offspring that have received one dominant and one recessive gene.
- Co-Dominant: Co-dominant genes act the same way dominant genes act when paired to a recessive gene. The co-doms traits would be visual in the any offspring that receive that particular gene, BUT the homozygous form of that morph ( offspring with two of the same genes) is visually different to the heterozygous offspring. When paired to a different co-dominant mutated gene, any offspring which receive one of each gene (heterozygous) display the visual characteristics of both parents. This is how combo-morphs are produced.
Remember earlier I said Ifrit is a heterozygous Fire? Well, this is because the mutation that causes the Fire gene is co-dominant in its relationship with the Normal gene, so when paired to a Normal, the visual traits of both of his parents are displayed in him, even in the heterozygous form. The Fire gene is a mutated normal gene, as with all "base morphs". This particular mutation causes lower levels of pigmentation in the skin cells, resulting in visually paler snakes. As this mutated gene is co-dominant, this visual trait can be passed from parent to offspring with only one parent carrying the Fire gene.
We'll assume that one of Ifrits parents was a Fire morph, carrying one Fire gene and one Normal gene, and the other was a Normal (carrying no mutated genes) - Ifrit being the result of inheriting one Fire gene from one parent, and one Normal gene from the other. If Ifrits parents had both been Fires, there would have been a 25% chance that he would have received one Fire gene from each parent, making him Homozygous - in which case he would have looked much different...
This is a perfect example of a Super-Fire, otherwise known as a Black Eyed Leucistic - a homozygous recipient of two Fire genes. As a single Fire gene results in visually lighter snake due to affected pigmentation levels, two snakes which both have this Fire gene can be selectively bred together in order to both pass one gene each to an offspring. As these genes are co-dominant in their relationship with one another, the recipient of two copies of this mutated gene would be visually different to the recipients of only one gene (and one Normal) - resulting, in this case, with a snake that has much lower levels of pigmentation that his parents - or none at all, as with the Super Fire above.
Now go make yourself a nice cup of tea, you've earned it - although if you really want to read more, this topic explains things a little more in depth.