Genetics questions you were afraid to ask...

[Ssthisto]

Just another "ask any question, no matter how silly it may seem" thread. To start off with, I'll ask and answer the absolute basics - so that they're here at the top of this thread

What makes my animal look different to a normal?
Each animal has dozens or hundreds or thousands of pairs of genes - think of these as being like paired seats on a train. Each pair of seats (called a "gene locus") is reserved for a specific "family" of traits, which can affect everything from colour and pattern to size, shape, temperament and health. For example, you might have a pair of seats reserved for the "Amelanistic family". If there are mutant gene alleles at the Amelanistic locus, you might get an animal that is "not normal" at the Amelanistic locus - and that might give you an animal that doesn't look normal at all.

What does "Het" mean?
"Het" is short for "Heterozygous" - and it means that the two genes of a specific pair are different. In recessive genes, this usually means that the animal looks normal, but carries one copy of the code to produce the recessive gene morph. In dominant and codominant genes, however, an animal can also be "het" for the gene - they just don't look like a normal. They still only carry one copy, and can produce animals that do not carry their trait.

What does "recessive" mean?
Traits have varying amounts of dominance to each other - some genes override the physical appearance of others. For example, in most species, Amelanistic is recessive to "not amelanistic". This means that an animal with even one copy of "not amelanistic" looks normal; only an animal with two copies of Amelanistic will be visually amelanistic.

What does "Dominant" mean?
A dominant trait is a trait that you only need one copy of the gene to look like the morph (for example, "Not-Amelanistic" is dominant to "Amelanistic") - and an animal with two copies of the trait looks exactly the same as an animal with only one copy.

What does "Codominant/incomplete dominant" mean?
A codominant/incomplete dominant trait is a trait that has three distinct "looks". "Not Mack Snow" looks like a normal leopard gecko, and carries no copies of the Mack Snow gene. "Mack Snow" has a distinct look, reducing the yellow pigmentation to a minimal amount, and often introduces pattern changes; it carries one copy only of the Mack Snow gene. And "Super Snow" is another look again, a white gecko with black spots in a linear pattern and solid black eyes; they carry two copies of the Mack Snow gene. If a trait looks different depending on whether you have one or two copies of the gene, it is a codominant or incomplete dominant trait.

What does 50% het or 66% het mean?
These are just a way of saying "This animal MIGHT carry a hidden recessive gene." If an animal is 50% het, this means it had one parent who was het for a trait; there's a 50/50 chance that this animal inherited that trait. It could also be a normal with no trait at all. If an animal is a 66% het, this means both parents were het for a trait - there is a 2 in 3 chance that this animal inherited the trait, and a 1 in 3 chance it did not.
The only way to know whether you have a genuine het is to do breeding trials - even one visual trait animal turns your 50%/66% het into a 100% het.

Is it possible to get an "invisible het" for a dominant or codominant morph?
In a word, no. If you are buying morphs - particularly if you're spending a lot of money - be aware of what genes are dominant or codominant in your chosen species. A normal-looking animal probably doesn't carry a dominant or codominant trait. There are some exceptions - for example, adult Mack Snows, depending on the lines, can look a lot like normals. Some Pastel Royals do not look like anything unusual. In these cases use your judgement and ask to see the parents of the animal; get a written guarantee from the seller that you are purchasing the genetics you think you are.

[Corny-Dawny]

Hi,
Are there any dominant corn snakes genes?

Dawn

[HABU]

so how do you get a snake that glows in the dark?...... like those new glow fish?

[Tops]

Originally Posted by HABU

so how do you get a snake that glows in the dark?...... like those new glow fish?

In theory it would be possible. They have done it in labs with rats, pigs and chickens by altering the genetic makeup. Its been done in the UK and china that I know of. Its done through the introduction of a gene from a jellyfish though due to cost issues and practical implications im not sure we will be getting 'glowing' corns any time soon. (apparently its for disease research but i reckon they did it because they thought it would look cool)

[paulh]

A lot of good stuff here.

Some points:
1. In my opinion, it would be better to use dominant, codominant, or recessive mutant gene rather than dominant, codominant, or recessive trait.

2. For the last point, hidden hets for a dominant mutant, the actual answer is "sometimes, for some mutant genes". But then we are getting into variable expressivity and incomplete penetrance. The rest of the answer is good.

3. Needs explanation of wild type. What is the difference between non-albino and non-Mack snow? None; both are the same thing -- wild type or normal.

Will get back to this later.

[lukendaniel]

Same As You Do The Fish Lmao Inject Them With Glow In The Dark Crap And Them Fish Are Not New They Gave Been Out A Couple Of Years


Luke

[CBR1100XX]

Interesting info have made it a sticky.

[intravenous]

Originally Posted by Tops

In theory it would be possible. They have done it in labs with rats, pigs and chickens by altering the genetic makeup. Its been done in the UK and china that I know of. Its done through the introduction of a gene from a jellyfish though due to cost issues and practical implications im not sure we will be getting 'glowing' corns any time soon. (apparently its for disease research but i reckon they did it because they thought it would look cool)

The gene is for Green Fluorescent Protein (original huh ?).

Same As You Do The Fish Lmao Inject Them With Glow In The Dark Crap And Them Fish Are Not New They Gave Been Out A Couple Of Years

Unfortunately yes, a lot of funny coloured fish are made by injecting dye under their skin...not nice .

[Ssthisto]

Originally Posted by Corny-Dawny

Hi,
Are there any dominant corn snakes genes?

Dawn

Well, other than the "not-mutant" gene at every gene locus (which are generally dominant) I don't know of any PROVEN dominant genes.

There is a chance that the "Buff/Orange/Hyperxanthic/Xanthic" gene that's been discovered in Germany is a dominant gene - this gene enhances the yellow colours in the animals and thus far, crosses of a Buff (Normal + Xanthic) have produced Buffs and Normals, crosses from a Buff to an Orange (Amel + Xanthic) have produced Buffs, Normals, Oranges and Amels. This would imply that the animals are not rootbeers or creamsicles, because you'd expect the Amels from that cross to be yellow too.

PaulH - You've got good points on all but the last one... but the reason I phrased it the way I did is because it's possible to be normal for one trait at the same time as the animal is "not-normal" for another. A "not-mack snow" who is "albino" is not wildtype/normal visually I use "Not(mutant)" to describe this so that I can make it clear that each mutant gene has its own corresponding not-mutant gene.

[paulh]

Originally Posted by Ssthisto

PaulH - You've got good points on all but the last one... but the reason I phrased it the way I did is because it's possible to be normal for one trait at the same time as the animal is "not-normal" for another. A "not-mack snow" who is "albino" is not wildtype/normal visually I use "Not(mutant)" to describe this so that I can make it clear that each mutant gene has its own corresponding not-mutant gene.

I come at it from the other side -- there is a normal or wild type gene for every locus. Mutant genes may occur at one or more loci. We ignore all the normal genes at their loci to focus on the mutants, but we have to keep the existence of all the normal genes in the back of our minds. A "not Mack Snow" doesn't just look like a normal leopard gecko. It IS a normal leopard gecko. Because the genes at the Mack snow locus are specified to be normal, and no mutant gene was specified. As all unspecified genes are assumed to be normal, this non-Mack snow gecko must be a normal.

Part of the completed file should be an explicit declaration that all genes are normal except those that are specified to be mutant. Otherwise you'd wind up having to do a complete genotype specification, like Tremper albino not-Mack snow not-patternless not-Bell albino ... normal, where ... includes thousands of loci with normal genes.

What makes my animal a normal?
When geneticists use the word "normal", they use it as a synonym for "wild type" or "standard type". Wild type is defined as
1. the most common phenotype (the observable physical characteristics) in the wild population
2. the most common allele (version of a gene) at a given locus in the wild population. Every locus has its unique wild type allele. In contrast, there may not be a mutant allele known for a given locus.

When an animal has every locus populated with wild type or normal genes, the animal's phenotype is the wild type phenotype.

In other words, each creature has dozens or hundreds or thousands of pairs of genes -- think of these as being like paired machines on an assembly line. Each pair of machines can do only one or a few things before passing the product on to the next station in the line. If each pair of machines works normally, as it is expected to work, what rolls of the end of the assembly line is the normal product of the line.

What makes my animal look different to a normal?
Going back to the assembly line analogy, if at least one pair of machines malfunctions, the product that comes off the end of the line is not what was expected. The product has an abnormal or mutant phenotype even though most of the machines in the assembly line are working normally.

Your animal has one or more mutant genes that do not function the way a normal gene does. The mutant gene blocks or diverts a biochemical assembly line, which produces a mutant phenotype.

How many genes are needed to make a normal leopard gecko and a Mack snow leopard gecko?
Leopard geckos undoubtedly have many thousands of genes, even though we don't know exactly how many. The simplest answer is that all of the normal leopard gecko's genes are required to make it. And all of the Mack snow leopard gecko's genes are required to make it. The minimum difference between the genes of a normal and a Mack snow leopard gecko is one -- a Mack snow gecko has a Mack snow mutant gene where the normal gecko has a normal gene. All the other genes in the Mack snow gecko either are or are assumed to be the same as the corresponding genes in the normal gecko. Because there are so many normal genes, we ignore them to focus on the mutant genes.