So scaleless, a true Co-Dom morph?

So most of us know, that what we call co-dom morphs technically fall under the definition of incomplete dominance. Incomplete Dominance is a blending of the two phenotypes (how the snake looks). When you have 2 normal genes or 2 lesser genes, the snake has a distinct phenotype (normal or BEL). have one normal and one lesser gene and you get blending of the phenotypes. not showing 1 or the other completely. Normal books give you the example of you mix a red a white flower together and you get pink.

Co-Dominance, will show both phenotypes in their entirety. Normal books give an example of you mix a red and white flower and you get a white flower with red spots. Normal and Scaleless and then the Scaleless Head, Which is Showing both Scaleless and Normal phenotypes.

So I think we have a true co-dom morph.

Isn't the full scaleless a recessive?

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Originally Posted by Kodieh

Isn't the full scaleless a recessive?

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no. the heterozygous form has a few scales missing on the top of its head.

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Originally Posted by TheSnakeGeek

no. the heterozygous form has a few scales missing on the top of its head.

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I guess I took the thread title as describing the full scales, not het scaleless.
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Originally Posted by Kodieh

I guess I took the thread title as describing the full scales, not het scaleless.
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one is heterozygous (scaleless head or het scaleless) one is homozygous (scaleless), same gene which is what I am referring to.

Very interesting point!!! I believe you hit the nail on the head.

why is the het scaleless not an incomplete dominant?

Just because it has some scales missing on top of the head means it's not a recessive trait?

i think this is true.

we have one gene, lets call it scaleless.

and in the heterozygous form it has a few scales missing on the head, lets call it "scaleless head" or "het scaleless". very visual, no guesswork.

and in the homozygous form we have the completely scaleless BP. we could call them "fully scaleless" or "super scaleless" or "OMFG what dark wizardry is that" ;)

seems to be a textbook example of incomplete dominant, or as we say codom.

especially if Brians assessment that scaleless head x scaleless head gives you 25% normals, 50% scaleless head, and 25% full scaleless holds true.

Ok so I accept the premise that scaleless is codom, but indulge my curiosity: what would an incomplete dominant look like in this case? A snake completely covered in half-scales? Very weak/miniscule scales?

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Originally Posted by snakesRkewl

why is the het scaleless not an incomplete dominant?

Just because it has some scales missing on top of the head means it's not a recessive trait?

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Recessive traits don't show up in the phenotype of the animal unless the gene is homozygous for that trait. Take brown eyes and blue eyes in people. Brown eyes are dominate.... if you have just one copy of the gene, you'll have brown eyes. Blues eyes are recessive because if you only have one copy of the gene, you will not have blue eyes. So the scaless head is incomplete dominant as the op suggested. Its more like the genes that control melanin production in people. Most of them are incomplete dominant genes.

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Ok so I accept the premise that scaleless is codom, but indulge my curiosity: what would an incomplete dominant look like in this case? A snake completely covered in half-scales? Very weak/miniscule scales?

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incomplete dominant is a scientific term, and codominant is an inaccurate term we commonly use when we mean "incomplete dominant", but somehow everyone just says codom.

so they are truly the same.

and incomplete dominant can range from close to recessive to close to dominant.

two hypothetical examples:

you have a gene where the super form is fully scaleless. the heterozygous form only has one single scale missing, on the head between the eyes.

or you have a gene where the super form is fully scaleless. the heterozygous form is 90% scaleless and only has some belly scales and head scales, the rest is completely scaleless.

BOTH examples would be perfectly fine examples of incomplete dominant (or, as we like to say, codominant).


recessive = normal form and heterozygous form look identical; only the homozygous form looks different.
dominant = heterozygous form and homozygous form look completely identical, or no homozygous form exists.
incomplete dominant / codom = everything else. anything that is somewhere in between goes here.

so it could theoretically look like anything, from 99% scaled to 99% scaleless. as long as the heterozygous form looks different from both the fully scaleless and the normal BP, its incomplete dominant. in this particular case, its the scaleless head.

flawed, but ok

Recessives are not hidden like most people theorize.
Every trait in it's het form has markers that show, if one has eyes open enough to learn those markers.

Dominant form versus incomplete dominant forms ~ no proof that the homozygous looks the same as the heterozygous, except in books.
When there is proof of a Dominant trait that throws all hets, I'll happily agree.

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Originally Posted by snakesRkewl

why is the het scaleless not an incomplete dominant?

Just because it has some scales missing on top of the head means it's not a recessive trait?

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Originally Posted by Pythonfriend

i think this is true.

we have one gene, lets call it scaleless.

and in the heterozygous form it has a few scales missing on the head, lets call it "scaleless head" or "het scaleless". very visual, no guesswork.

and in the homozygous form we have the completely scaleless BP. we could call them "fully scaleless" or "super scaleless" or "OMFG what dark wizardry is that" ;)

seems to be a textbook example of incomplete dominant, or as we say codom.

especially if Brians assessment that scaleless head x scaleless head gives you 25% normals, 50% scaleless head, and 25% full scaleless holds true.

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Originally Posted by smalltimeballz

Recessive traits don't show up in the phenotype of the animal unless the gene is homozygous for that trait. Take brown eyes and blue eyes in people. Brown eyes are dominate.... if you have just one copy of the gene, you'll have brown eyes. Blues eyes are recessive because if you only have one copy of the gene, you will not have blue eyes. So the scaless head is incomplete dominant as the op suggested. Its more like the genes that control melanin production in people. Most of them are incomplete dominant genes.

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I think all of you missed the post, I am saying it is NOT incomplete dominant as it really doesn't fit the definition of it, it IS co-dominant. It is showing both phenotypes in their entirety.

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Originally Posted by MootWorm

Ok so I accept the premise that scaleless is codom, but indulge my curiosity: what would an incomplete dominant look like in this case? A snake completely covered in half-scales? Very weak/miniscule scales?

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I would say something that changes the scales, but doesn't make them disappear.

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Originally Posted by Pythonfriend

incomplete dominant is a scientific term, and codominant is an inaccurate term we commonly use when we mean "incomplete dominant", but somehow everyone just says codom.

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co-dominant is a scientific term explained in my original post.

Codominance
Definition
noun
A condition in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive.

Incomplete dominance
Definition
noun
A kind of dominance occurring in heterozygotes in which the dominant allele is only partially expressed, and usually resulting in an offspring with an intermediate phenotype.

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Originally Posted by snakesRkewl

flawed, but ok

Recessives are not hidden like most people theorize.
Every trait in it's het form has markers that show, if one has eyes open enough to learn those markers.

Dominant form versus incomplete dominant forms ~ no proof that the homozygous looks the same as the heterozygous, except in books.
When there is proof of a Dominant trait that throws all hets, I'll happily agree.

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Recessive are a whole nother subject, no reason to get into it now
Dominant has a definition, the book definition is the proof. If the trait does not fit the definition, then you are classifying it wrong.

I've looked through several genetics books. There may be as many as 4 intermediate categories of inheritance or as few as one. I'm defining an intermediate category of inheritance in which the heterozygous phenotype can be distinguished from both homozygous phenotypes.

Here's a source that has only one category:
ghr.nlm.nih.gov/handbook/inheritance/inheritancepatterns

"In codominant inheritance, two different versions (alleles) of a gene can be expressed, and each version makes a slightly different protein (illustration). Both alleles influence the genetic trait or determine the characteristics of the genetic condition."

How reliable is the missing scale on the head as a mark of the heterozygote? If more than 5% of the heterozygotes have full scalation, then I would call scaleless a recessive mutant gene. The missing scale character would simply be a het marker.

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Originally Posted by paulh

I've looked through several genetics books. There may be as many as 4 intermediate categories of inheritance or as few as one. I'm defining an intermediate category of inheritance in which the heterozygous phenotype can be distinguished from both homozygous phenotypes.

Here's a source that has only one category:
ghr.nlm.nih.gov/handbook/inheritance/inheritancepatterns

"In codominant inheritance, two different versions (alleles) of a gene can be expressed, and each version makes a slightly different protein (illustration). Both alleles influence the genetic trait or determine the characteristics of the genetic condition."

How reliable is the missing scale on the head as a mark of the heterozygote? If more than 5% of the heterozygotes have full scalation, then I would call scaleless a recessive mutant gene. The missing scale character would simply be a het marker.

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only a handful have been made, but so far no evidence of any full scaled hets, one of them was missing the top part of it's head. The ones I saw in person were missing 5 or more scales on the head.

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Originally Posted by snakesRkewl

Dominant form versus incomplete dominant forms ~ no proof that the homozygous looks the same as the heterozygous, except in books.
When there is proof of a Dominant trait that throws all hets, I'll happily agree.

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Dominant mutant genes are scarce in reptiles. They are more common in mammals and birds. For example, in pigeons, a bird with two spread genes is solid black. A bird with a spread gene paired with a normal gene is also solid black. A bird with two normal genes is shades of slate gray with two black bars on each wing.

I have bred a bird with two spread genes to a bird with two normal genes. All the babies had a spread gene paired with a normal gene and were hets. All were solid black.

By the way, how are you defining dominant and incomplete dominant? When a creature with two copies of a codominant (AKA incomplete dominant) mutant gene is mated to one with two copies of the normal gene, all the babies are hets, too.

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Originally Posted by paulh

Dominant mutant genes are scarce in reptiles. They are more common in mammals and birds. For example, in pigeons, a bird with two spread genes is solid black. A bird with a spread gene paired with a normal gene is also solid black. A bird with two normal genes is shades of slate gray with two black bars on each wing.

I have bred a bird with two spread genes to a bird with two normal genes. All the babies had a spread gene paired with a normal gene and were hets. All were solid black.

By the way, how are you defining dominant and incomplete dominant? When a creature with two copies of a codominant (AKA incomplete dominant) mutant gene is mated to one with two copies of the normal gene, all the babies are hets, too.

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Okay, so I've seen some confusion from a few other posters on the difference between dominance and incomplete dominance. I'll add my two cents and see if it clarifies things for anyone.

A dominant gene overrides the other gene on the same locus. Just to review, a locus is the specific spot on the chromosome where a particular gene resides. A good example of dominance in ball pythons is the spider gene. There is, as far as we know, no super form of the spider gene. This means that it overrides the normal colour and pattern gene the snake carries. This also means you can't visually tell if a ball has two spider genes; since the gene is dominant a second copy of that gene won't affect what the snake looks like. The only way to know if you had a homozygous spider is if you bred that spider to a normal ball python and all of its babies were spiders.

An incomplete dominant gene means that it is expressed equally with the other gene on its loci. Any of the genes in the BEL complex are a good example of this. For example, one copy of the lesser or butter gene shows a snake that is visually different from a normal, and you can tell visually that it only has one copy of this gene. Two copies of the butter or lesser gene produces a white snake, which means that both genes on the same locus are being expressed equally, neither one is overriding the other. If the lesser or butter gene was only a dominant gene, two copies of that gene would not produce a white snake.

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Originally Posted by paulh

I've looked through several genetics books. There may be as many as 4 intermediate categories of inheritance or as few as one. I'm defining an intermediate category of inheritance in which the heterozygous phenotype can be distinguished from both homozygous phenotypes.

Here's a source that has only one category:
ghr.nlm.nih.gov/handbook/inheritance/inheritancepatterns

"In codominant inheritance, two different versions (alleles) of a gene can be expressed, and each version makes a slightly different protein (illustration). Both alleles influence the genetic trait or determine the characteristics of the genetic condition."

How reliable is the missing scale on the head as a mark of the heterozygote? If more than 5% of the heterozygotes have full scalation, then I would call scaleless a recessive mutant gene. The missing scale character would simply be a het marker.

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A het scaleless bhb line or scaleless head ball python should have a few obviously missing scales, period. Until we see more het scaleless ball pythons produced from this line, we won't know if its merely confined to the head or if it has a variable range, producing anything from a snake that has only a few missing scales on its head or a 50% scaleless ball python.

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Originally Posted by smalltimeballz

Recessive traits don't show up in the phenotype of the animal unless the gene is homozygous for that trait.

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Says who?
Hard to see maybe, not super visual maybe, but the het forms are not hidden.
Het clowns I can speak for, made many of them and they are ALL visual in that they show in het form no different than a yellowbelly shows.

i will attempt to avoid the confusion and stick to the most basic that we all agree on, hoping to clear things up.

we look at one gene. that leads to 3 different possibilities.

Number one: the animal does not have the gene. instead it has two copies of "normal" where the gene would be. it looks normal, its the wild type. a normal.

Number two: the animal carries one copy of the fancy gene we are interested in. the second possibility where the gene could be is inhabited by just the wild type gene.

Number three: the animal carries two copies of the fancy gene, the maximum number allowed. nowhere for a normal / wild type gene to hide on that location, its gone.

Recessive is when number two looks like number one, and only number 3 is visually different. like albino for example. number two carries one copy the gene, but it doesnt do anything visual.

Dominant is when number two looks like number 3. One copy is enough, you get the full visual, you cannot tell from looking at the appearance of the animal if it has one or two copies in it. One copy is enough to make it really REALLY different-looking from number one, the normal.

When all 3 look different, when all 3 can clearly be differentiated, you have an incomplete dominant / codominant.

i know things get fuzzy at the boundaries between those clear distinctions. (examples: is a dominant still dominant if the super-form is lethal and we dont know how it looks like out of the egg? or, desert, is it dominant while the super-form would probarbly look different, but we are barred from producing it? or, is a recessive still recessive when the hets have markers?). Apart from these difficulties, can we agree on the basics?


if yes, then i would say: scaleless is codominant / incomplete dominant because we have 3 visually distinct phenotypes: Normal, scaleless head (some scales missing on top of the head), and fully scaleless. and these appear to correspond to zero, one, or two copies of the scaleless gene being present.

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Originally Posted by snakesRkewl

Says who?
Hard to see maybe, not super visual maybe, but the het forms are not hidden.
Het clowns I can speak for, made many of them and they are ALL visual in that they show in het form no different than a yellowbelly shows.

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says the definition.

now go out and convince everyone that all recessives where you see markers are in fact codominants :) . if you succeed, the morph will change from being a recessive to being a codominant, as has happened before with red axanthic and russo leucistic. het red axanthic, het russo. You just need to get people to ACCEPT the visually different optics of your het clowns like they would accept het red axanthic. For that you need to properly document the het clown markers and show that they are always present, in all het clowns, and when you have that documentation you can start convincing people until you convinced the majority and you reach a tipping-point and clown gets accepted as incomplete dominant or codominant. good luck :) . I think people will destroy your attempts with pictures of 100% het clowns that dont show the markers, but you can try, have at it :)

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Originally Posted by Pythonfriend

I think people will destroy your attempts with pictures of 100% het clowns that dont show the markers, but you can try, have at it :)

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Not a chance.

I think the issue lies in the fact that most people only grasp basic Mendelian genetics... And some (most) times, inheritance doesn't fit neatly into simple categories. Just my .02

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Originally Posted by MootWorm

I think the issue lies in the fact that most people only grasp basic Mendelian genetics... And some (most) times, inheritance doesn't fit neatly into simple categories. Just my .02

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It fits neater than you may think, I mean the definitions don't leave much gray area. Just once we assign a label to something the group doesn't like to change it. I'm 100% with jerry saying het clown can be picked out. But back when clowns first came around the "markers" I guess you could call them, weren't noticed and got labeled recessive. I would be comfortable saying I could pick out het clowns out of pos het clutch. But putting into words what I am looking for is difficult I guess i'd say it's the color and the sharpness of the pattern, Jerry might know some other visual cues and for someone else to take those words and apply them is also difficult. So we just leave it at why rock the boat and just say it's a recessive with markers, which is kinda like admitting it's inc-dom anyways lol. but it really isn't classified correctly.

Jerry I just also want to clarify since we do get into this occasionally, when I say dominant or recessive, I mean the actual standard biology definition most of the time. Whether or not this hobby actually classified these gene correctly or even in a way that makes sense is completely up for debate and I think you know you and me will agree they are not a lot of the time.

I just made this thread thinking it was kinda interesting how we had an actual co-dom gene and not inc-dom.

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Originally Posted by Pythonfriend

i will attempt to avoid the confusion and stick to the most basic that we all agree on, hoping to clear things up.

we look at one gene. that leads to 3 different possibilities.

Number one: the animal does not have the gene. instead it has two copies of "normal" where the gene would be. it looks normal, its the wild type. a normal.

Number two: the animal carries one copy of the fancy gene we are interested in. the second possibility where the gene could be is inhabited by just the wild type gene.

Number three: the animal carries two copies of the fancy gene, the maximum number allowed. nowhere for a normal / wild type gene to hide on that location, its gone.

Recessive is when number two looks like number one, and only number 3 is visually different. like albino for example. number two carries one copy the gene, but it doesnt do anything visual.

Dominant is when number two looks like number 3. One copy is enough, you get the full visual, you cannot tell from looking at the appearance of the animal if it has one or two copies in it. One copy is enough to make it really REALLY different-looking from number one, the normal.

When all 3 look different, when all 3 can clearly be differentiated, you have an incomplete dominant / codominant.

i know things get fuzzy at the boundaries between those clear distinctions. (examples: is a dominant still dominant if the super-form is lethal and we dont know how it looks like out of the egg? or, desert, is it dominant while the super-form would probarbly look different, but we are barred from producing it? or, is a recessive still recessive when the hets have markers?). Apart from these difficulties, can we agree on the basics?


if yes, then i would say: scaleless is codominant / incomplete dominant because we have 3 visually distinct phenotypes: Normal, scaleless head (some scales missing on top of the head), and fully scaleless. and these appear to correspond to zero, one, or two copies of the scaleless gene being present.

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I will sign on to those definitions.

As for the fuzzy areas, if the super form is lethal, then the mutant gene is codominant to the normal gene. The spider gene is a possible candidate for this classification, but we don't know for sure. The crested mutant gene in zebra finches definitely fits this classification.

A gene is recessive even when there are markers if the markers often do not appear. It's a gray area, and then we go with the best fit to the definitions, not the exact fit.

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Originally Posted by OhhWatALoser

only a handful have been made, but so far no evidence of any full scaled hets, one of them was missing the top part of it's head. The ones I saw in person were missing 5 or more scales on the head.

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Then I would prefer to wait until there are a few dozen babies from scaleless x normal matings before reaching a conclusion.