codominant or dominant spiders

so the spider characteristic is considered dominant because there is no super form of the spider morph. in reality the spider gene is a codominant one because the theoretical clutch odds of a spiderXnormal pairing is 50% spiders and 50% normals.

when breeding a spiderXpastel the odds for a bumblebee to pop out are exactly the same odds as pairing a pastelXpastel and hoping for a super pastel to pop out. which are the same odds as breeding a pair of 100% het animals and having a 25% chance at hatching out the homozygous form of the bred hets.

so by breeding a pastel to spider i have a 25% chance at hatching out a bumblebee right?

Quote:

---

Originally Posted by bigballs

so the spider characteristic is considered dominant because there is no super form of the spider morph. in reality the spider gene is a codominant one because the theoretical clutch odds of a spiderXnormal pairing is 50% spiders and 50% normals.

when breeding a spiderXpastel the odds for a bumblebee to pop out are exactly the same odds as pairing a pastelXpastel and hoping for a super pastel to pop out. which are the same odds as breeding a pair of 100% het animals and having a 25% chance at hatching out the homozygous form of the bred hets.

so by breeding a pastel to spider i have a 25% chance at hatching out a bumblebee right?

---

Each egg has a 1/4 chance of being a bumblebee, and 1/4 chance of being a spider, a 1/4 chance of being a pastel, and a 1/4 chance of being a normal.

Quote:

---

Originally Posted by Wh00h0069

Each egg has a 1/4 chance of being a bumblebee, and 1/4 chance of being a spider, a 1/4 chance of being a pastel, and a 1/4 chance of being a normal.

---

so in a pastelXpastel pairing you get 25%normal, 50%pastel, and 25% super pastel. these odds are pretty much the same as a pastelXspider except that instead of the 50% pastel, you get 25% pastel and 25% spider because of the spider gene and 25% normal and 25% bumblebee.

Well we call spiders Dominate because there is no "super" form but that doesn't mean that their can be a Homozygous form which means its Co-dominate we just call it Dominate to keep the genetics simple. :D

It's dominant in the sense that it only takes one copy of the gene to pass along the full expression of the phenotype of the gene instead of the two genes like a pastel or a recessive trait.

Quote:

---

Originally Posted by littleindiangirl

It's dominant in the sense that it only takes one copy of the gene to pass along the full expression of the phenotype of the gene instead of the two genes like a pastel or a recessive trait.

---

so because the spider phenotype is fully expressed after only one breeding, the phenotype or spider characteristic is considered dominant. the genotype of the spider however, is codominant, so calling the spider characteristic dominant is only a way of saying there is no further expression of this phenotype.

so the genotype and phenotype of a pastel is codominant, then that of a super pastel is dominant?

Very very very close. You have it just about correct.

Quote:

---

Originally Posted by bigballs

so because the spider phenotype is fully expressed after only one breeding, the phenotype or spider characteristic is considered dominant.

---

I get what your saying in the whole, but the terminology is off. Since the spider gene is fully expressed when heterozygous (only one copy), then it is considered dominant.

Quote:

---

Originally Posted by bigballs

the genotype of the spider however, is codominant, so calling the spider characteristic dominant is only a way of saying there is no further expression of this phenotype.

---

I'm not sure if we could consider the gene co-dominant or incomplete, or just dominant in reference to terminology. I have never understood why people consider it just a dominant. Maybe someone wants to step up to the plate and explain that one. ;)

Generally speaking, if you were in a biology class, co-dominant and incomplete dominant means something different than what we think of in our everyday hobbyist lingo.

http://www.emc.maricopa.edu/faculty/...ninteract.html

Quote:

---

Codominant alleles

Codominant alleles occur when rather than expressing an intermediate phenotype, the heterozygotes express both homozygous phenotypes. An example is in human ABO blood types, the heterozygote AB type manufactures antibodies to both A and B types. Blood Type A people manufacture only anti-B antibodies, while type B people make only anti-A antibodies. Codominant alleles are both expressed. Heterozygotes for codominant alleles fully express both alleles. Blood type AB individuals produce both A and B antigens. Since neither A nor B is dominant over the other and they are both dominant over O they are said to be codominant.

(or a red and white flower when crossed will give a red and white spotted flower because both colors are dominant)

Incomplete dominance

Incomplete dominance is a condition when neither allele is dominant over the other. The condition is recognized by the heterozygotes expressing an intermediate phenotype relative to the parental phenotypes. If a red flowered plant is crossed with a white flowered one, the progeny will all be pink. When pink is crossed with pink, the progeny are 1 red, 2 pink, and 1 white.

---

Quote:

---

Originally Posted by bigballs

so the genotype and phenotype of a pastel is codominant, then that of a super pastel is dominant?

---

Two different ideas here, but also, very close.

Since the super pastel has two copies of the pastel gene, each animal that it sires will receive one copy of the pastel gene from them, making them pastels.

The pastel gene is still incomplete dominant, whether the animal has one or two copies of the gene. That is just the way the gene works. The pastel, which only carries one copy of the gene, is only showing a partial expression of the pastel gene. The pastel has only one pastel gene to pass along, so some of the babies get the normal gene, and some get the pastel gene.

When that pastel has both copies, they show the full expression of the gene, the Super pastel. It is still an incomplete dominant, but the super has 2 pastel genes to pass along instead of just one.

I think your getting methods of inheritance crossed with the way the genes work by themselves.

Correct :gj: but its not dominate in the fact that it still produces the wild type offspring so in a since its not. A true Dominate gene would have no super and not produce any normal offspring.

Quote:

---

Originally Posted by Freakie_frog

Correct :gj: but its not dominate in the fact that it still produces the wild type offspring so in a since its not. A true Dominate gene would have no super and not produce any normal offspring.

---

Ed, that's not correct. Spider is a dominant gene. It truly is, however most spiders are hets, and they do not pass all spiders because of the way genes are inherited.

If each animal receives one copy of a gene from the parents, using the heterozygous spider as an example, what guarantees that this "dominant" gene is the one that gets passed along to the offspring and not the normal gene?

A gene can be dominant, but that in no way means that there will be no normal offspring unless the animal is homozygous for that gene.

New to BP's but not new to genetics.

The question that needs to be asked is the phenotype (the way it looks) different between the heterozygous Spider and the homozygous Spider. Since as far as I know there is no living homozygous Spider. I would have to say that there is a big difference. Het Spiders look awesome and homozygous spiders start to smell bad really quickly and don't move much.

So I would say that the Spider mutation is a codominent one with its super form being lethal. This is not unheard of in other species. If a living homozygous spider can be produced that looks the same as a heterozygous spider and all previous failures turn out not to be related to the genotype of the animal then its a dominant mutation.

Quote:

---

Originally Posted by littleindiangirl

If each animal receives one copy of a gene from the parents, using the heterozygous spider as an example, what guarantees that this "dominant" gene is the one that gets passed along to the offspring and not the normal gene?

---

Fair enough.I'm going to Play devils advocate here for a sec. So help me out here Pastel's are Hets also only needing one copy of the gene to be expressed. The homozygous form of the mutation is a super pastel correct or a visual difference between the two. Now you breed any two animals together say pastel for example you get a 1:4 shot at producing a homozygous pastel. Now lets look for a moment at spiders you breed two spiders together and does each parent still pass half of its genetic material on to the offspring? If so then 1:4 animals will be Homozygous. Now where is it written that the Homozygous form of a mutation must look different that the Het. If the mutation only effect the scales to a certain extent or the super is so subtle we can't tell the difference from the Het form how would you know.

Just fun to think that just because some body said so doesn't mean that other possibility's don't exist

Quote:

---

Originally Posted by Egapal

New to BP's but not new to genetics.

The question that needs to be asked is the phenotype (the way it looks) different between the heterozygous Spider and the homozygous Spider. Since as far as I know there is no living homozygous Spider. I would have to say that there is a big difference. Het Spiders look awesome and homozygous spiders start to smell bad really quickly and don't move much.

So I would say that the Spider mutation is a codominent one with its super form being lethal. This is not unheard of in other species. If a living homozygous spider can be produced that looks the same as a heterozygous spider and all previous failures turn out not to be related to the genotype of the animal then its a dominant mutation.

---

So far, the current theory is that the spider gene is dominant, in that it does not need to be homozygous for the full expression of the phenotype.

Meaning, there very well could be homozygous spiders out there, but no one has proven it.

BHB believes he has a homozygous Pinstripe, and it also does not look any different from any other pin. ;)

Quote:

---

Originally Posted by Freakie_frog

So help me out here Pastel's are Hets also only needing one copy of the gene to be expressed. The homozygous form of the mutation is a super pastel correct or a visual difference between the two.

---

A pastel is an incomplete dominant. When an animal carries one copy, it is only showing a partial expression of the gene.

Quote:

---

Now you breed any two animals together say pastel for example you get a 1:4 shot at producing a homozygous pastel. Now lets look for a moment at spiders you breed two spiders together and does each parent still pass half of its genetic material on to the offspring?

---

Yes, the inheritance is still the same. Each animal is going to give one of the copies of it's gene. It could be the normal gene it gives, or the pastel gene.

Quote:

---

If so then 1:4 animals will be Homozygous. Now where is it written that the Homozygous form of a mutation must look different that the Het. If the mutation only effect the scales to a certain extent or the super is so subtle we can't tell the difference from the Het form how would you know.

---

Exactly my point. So far as we know it, the spider gene is a dominant in that only one copy of the gene is needed for the FULL expression of the phenotype. ;) So a het spider would look exactly the same as a homozygous spider.

No one has come forward about their homozygous spider as of yet, so it is still very possible it is homozygous lethal.

Like I said, BHB believes he has a homozygous pin, because when bred to normals, he gets all pins. ;)

Quote:

---

Originally Posted by Freakie_frog

Fair enough.I'm going to Play devils advocate here for a sec. So help me out here Pastel's are Hets also only needing one copy of the gene to be expressed. The homozygous form of the mutation is a super pastel correct or a visual difference between the two. Now you breed any two animals together say pastel for example you get a 1:4 shot at producing a homozygous pastel. Now lets look for a moment at spiders you breed two spiders together and does each parent still pass half of its genetic material on to the offspring? If so then 1:4 animals will be Homozygous. Now where is it written that the Homozygous form of a mutation must look different that the Het.

---

A homozygous form of a mutation does not have to be different than the Het. Thats what we are talking about. If its a recessive mutation you need a pair of the genes, if its a codominant mutation then a single gene gets you something and a pair gets you the super form. If its Dominant then a single gene gets you the mutation and a pair of the genes gets you the same thing but when you breed an animal that's homozygous for a dominant trait you are guaranteed the offspring will show that trait. Whether they are homozygous or heterozygous then depends on the other parent and luck if the other parent is heterozygous for the same trait.

The question is whether the Spider mutation is codominant or dominant and that depends entirely on whether the phenotype of the homozygous is different than the heterozygous. I would still have to assert that since the homozygous spiders all die they are a super form.

The answer is unknown and can only be proven by a living homozygous spider (something that can only be proven by multiple breedings to normals throwing only spiders or a genetic test).

Or else it comes down to a strict definition of whether or not a lethal homozygous gene is considered a super form despite no visible difference. I am not sure on that one.

Quote:

---

Originally Posted by littleindiangirl

So a het spider would look exactly the same as a homozygous spider.

No one has come forward about their homozygous spider as of yet, so it is still very possible it is homozygous lethal.

---

So if the spider mutation is homozygous lethal would you then say that its codominant or would you say that the lethal/non lethal question is irrelevant.

Quote:

---

Originally Posted by littleindiangirl

Like I said, BHB believes he has a homozygous pin, because when bred to normals, he gets all pins. ;)

---

My understanding is that the pinstripe is a separate mutation from the spider. Pinstripe may be a true dominant mutation this would not prove anything regarding the spider mutation. The fact that a spinner has been produced and its is yet another phenotype would help validate that they are separate mutations.

so the pastel gene is codominant and does not become dominant in the super form. the super form is just two copies of the codominant gene, right? just like mojaves and lucys? one is codom and the other is two copies of the codom gene. so what morph is truely dominant? the normal wild type?

Quote:

---

Originally Posted by Egapal

So if the spider mutation is homozygous lethal would you then say that its codominant or would you say that the lethal/non lethal question is irrelevant.

---

I'm majorly sorry, but that is a very confusing question.

Quote:

---

My understanding is that the pinstripe is a separate mutation from the spider. Pinstripe may be a true dominant mutation this would not prove anything regarding the spider mutation. The fact that a spinner has been produced and its is yet another phenotype would help validate that they are separate mutations.

---

Yes, I know they are separate mutations. That was not my point, I'm sorry to have confused you.

The reason I used the pin as an example is because the spider and pinstripe are the two BP mutations that are unknown to whether or not it is possible there are homozygous animals out there. We DO know that if there are, they do not look any different from a heterozygous animal.

The question is and always has been, is it lethal, or are their homozygous animals out there. Since all the animals from a pin x pin or spider x spider pairing all look the same, meaning they have no "super".

so many people told about the lethal homozygot Spider´s.
or when breeding 2 Spiders there will be nearly 25% "death snakes"

Is there someone who can show us such an 25%-Snake(Superspider)?

Quote:

---

Originally Posted by bigballs

so what morph is truely dominant? the normal wild type?

---

Good question.

And it's very muddy waters. :oops:

When I think of dominant, I think in terms of this gene is dominant over another gene, or a recessive gene.

When I think of codominant, I think of the same thing, but in the sense that only one copy is needed for the full expression of the gene. (heterozygous)

(I could very well have codominant and dominant wrong)

When I think of incomplete dominant, I always think of the partial expression when heterozygous, and complete expression when homozygous.

I know, I'm terrible about explaining terminology, so usually when it gets ugly in these threads, I leave them alone from sheer exhaustion at trying to get people to understand simple inheritance VS. dominant/recessive expressions.

Quote:

---

Originally Posted by bigballs

so the pastel gene is codominant and does not become dominant in the super form. the super form is just two copies of the codominant gene, right? just like mojaves and lucys? one is codom and the other is two copies of the codom gene. so what morph is truely dominant? the normal wild type?

---

Pinstripe appears to be dominant other than that normal is basically the dominant expression of the various genes. Keep in mind that many morphs are not mutually exclusive. For instance a snake can be both axanthic and albino at the same time. What you see is not one Phenotype called Snow its two phenotypes albino and axanthic that are both visible at the same time.

It can get very complicated though. Look at the Labrador retriever for instance. Yellow is a recessive trait that covers up both Chocolate and Black when expressed. Black is dominant and Chocolate is recessive. This means that unless you know the underlying genetics you can get a lot of variety out of a single litter. Genetics can get very complicated and it sometimes takes years and years before the interactions of genes is understood if ever. Blood type is another interesting complicated genetic trait that turns out has many subtleties beyond just A/B, +/-.

Quote:

---

Originally Posted by littleindiangirl

I know, I'm terrible about explaining terminology, so usually when it gets ugly in these threads, I leave them alone from sheer exhaustion at trying to get people to understand simple inheritance VS. dominant/recessive expressions.

---

Connie, I think you are great at explaining everything. And everything you have said goes along with my years of education and the last 2 months of feverish reading on how the various morph genetics work and interact.

You didn't confuse me by throwing pinstripe into the mix. I often say qualify statements with "as far as I know" or "it's my understanding" when there is not a lot of evidence to be certain. I think that it will be interesting to see if the homozygous spider turns out to be lethal or not.

I just think that being dead should count as looking different and therefor constitute a super form making spider codominant.

Quote:

---

Originally Posted by Egapal

I just think that being dead should count as looking different and therefor constitute a super form making spider codominant.

---

But there's the problem right there, you can end up with dead hatchlings for any number of reasons. Theoretically, if you breed a spider to a spider, you'll either have 25% less eggs, or 25% dead hatchlings. It may be because noone really tries it very often, but I haven't heard of many clutches like that. I do know that lots of people also thought the pinstripe could be homozygous lethal, but as was mentioned BHB thinks he has a homozygous pinstripe right now. I do know that when we asked him about the idea of pinstripe being homozygous lethal last year, he said that he's had plenty of pinstripe x pinstripe clutches, and never noticed anything odd with the number of eggs or hatchlings that didn't make it. The guy to ask about spider x spider clutches would definitely be Kevin McCurley from NERD. He's the guy that imported the original, and I know he's the guy that probably tried the hardest to produce a super spider.

Quote:

---

Originally Posted by Egapal

Pinstripe appears to be dominant other than that normal is basically the dominant expression of the various genes. Keep in mind that many morphs are not mutually exclusive. For instance a snake can be both axanthic and albino at the same time. What you see is not one Phenotype called Snow its two phenotypes albino and axanthic that are both visible at the same time.

---

so if the pinstripe is said to have a homozygous form that has a phenotype very similar to it's heterozygous form would the pinstripe morph still considered dominant or is it now considered codominant because the full expression of the gene requires two copies?

i understand the concept of double homozygous recessive morphs such as the snow, i think i am confusing the difference between labelling dominant and codominant morphs with dominant and codominant genes.

for example one book i read says that the pastel is a codominant form where as super pastel is the dominant form. but after reading the posts in this thread i now think that pastel is a codom gene that requires two copies of itself to be fully expressed and that a super pastel is not a dominant gene, it is just a visual expression of two copies of the codominant pastel gene but we label it as the dominant or super form.

so i think that when we talk about dominant or codominant in ball python terms we are refferring to whether or not a certain morph has a known super form or not and we are not reffering to the actual genotype of the animal.

Quote:

---

Originally Posted by bigballs

so if the pinstripe is said to have a homozygous form that has a phenotype very similar to it's heterozygous form would the pinstripe morph still considered dominant or is it now considered codominant because the full expression of the gene requires two copies?

---

Not very similar. Its the same. The homozygous pinstripe we are talking about looks the same as the heterozegous pinstripe.

Quote:

---

i understand the concept of double homozygous recessive morphs such as the snow, i think i am confusing the difference between labelling dominant and codominant morphs with dominant and codominant genes

---

When someone says dominant or codominant morph they are saying that the gene that causes the morph is dominant or codominant.

Quote:

---

for example one book i read says that the pastel is a codominant form where as super pastel is the dominant form.

---

The super pastel is the homozygous phenotype (form).

Quote:

---

but after reading the posts in this thread i now think that pastel is a codom gene that requires two copies of itself to be fully expressed and that a super pastel is not a dominant gene, it is just a visual expression of two copies of the codominant pastel gene but we label it as the dominant or super form.

---

We label it the Super form and say that its homozygous for the trait. The key is that a super pastel when bred to a normal ball python will produce all pastels. And when you breed two pastels together you get 1/4 normal, 1/2 pastels, and 1/4 super pastels.

Quote:

---

so i think that when we talk about dominant or codominant in ball python terms we are refferring to whether or not a certain morph has a known super form or not and we are not reffering to the actual genotype of the animal.

---

Kinda, The important thing is to learn how recessive and dominant traits work. Once you got that you are left knowing that there is no way short of a genetic test or breeding the animal to tell if an animal is het for a recessive or homozygous for a dominant. Once you understand that we go a head and complicated things by saying "Oh yeah there is another way a gene can work and that's called codominant" and that's really the most intuitive. The problem is that we spend so much time understanding dominant and recessive that its hard to understand something as simple as codominant. With codom, if you have no gene you have no signs of the trait, if you have one you have some signs, if you have two you have the actual trait.

I didnt read through all of it, but I was going to suggest super spiders being a potentially lethal genotype...but Connie beat me to it a long time ago....I just searched for this thread looking for a list of codom morphs. Sorry to drag out the dead.

Where is Randy Remmington! He is usually all over the genetics questions....
But yes there is some good information in here from LittleIndianGirl and Egapal

I think Egapal and Littleindiangirl covered it.

I would vote that if spider is somehow proven homozygous lethal (very hard to prove something by its absence) that would seem to me to qualify as co-dominant due to the homozygous being different.

Also, a book that talks about the co-dominant and dominant form of the same mutation would be very unfortunate. I see enough of that terminology thrown around that I don't doubt that it's written down somewhere. As already stated, the mutation type (recessive, co-dominant, dominant) is defined by the relationship of the phenotypes (appearance) between the different genotypes (heterozygous and homozygous mutant) so it doesn't change. The pastel mutation is still a co-dominant mutation type regardless of if you are looking at a pastel or a super pastel, the difference is that the pastel is the heterozygous genotype and the super pastel is homozygous for the pastel mutation.

Cool that we finally have a ball python dominant mutation type example in pinstripe where the heterozygous pins and the homozygous pinstripe are reported to look the same (same phenotype) to fit the dominant definition. And you can see that it's the genotype that's important to know what the babies will be like with only the homozygous pinstripe producing 100% pinstripes.

Quote:

---

Originally Posted by RandyRemington

I think Egapal and Littleindiangirl covered it.

---

Yep....Agreed. Just was surprised not to see ya on this one yet.
You always have a great way of wording your post so that most people can understand the information being presented. I enjoy reading them at least.

I heard a while back that someone actually produced the super form of a spider, but it looked the same in appearence. The only difference was that when breed to a normal, all the eggs would be spiders, but i think a lot of people just forgot about the idea, because it wasn't worth raising all of them up and proving them out as super spiders and then selling them, it wouldn't be worth it... Hmmm, you should look into it. Ill go back through my posts and try to find where i heard it and get back to you.

Heres the link to another post on some other forum about super spiders.http://www.reptileforums.co.uk/1169209-post3.html
Now looking back on it, it's not as informative as i thought it was, and is really the same type of answer you might get on here. So my thoughts are that there is a 1% chance there is REALLY a super spider, and a 99% chance this person didn't know what they were talking about...