Reptile & Amphibian Forums

What do the parents of a pastel have to be?

We are doing genetics in AP biology now, so I wanna be able to provide an example of codominace...

THanks!
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0.0.1 Chrysemys picta picta (Eastern Painted Turtle)
0.0.1 Teliqua gigas (Indonesian Blue Tongue Skink)
0.2.0 Eublepharis macularius (Leopard Geckos)
0.0.1 Nerodia sipedon (Northern Water Snake)
0.0.2 Rhacodactylus ciliatus (Crested Geckos)
0.0.1 Python regius (Ball Python)
?.?.? Assorted goldfish, minnows and guppies
1.0.0 Ferret
1.1.0 Cats
1.0.0 Aussie Cattle Dog/ Border Collie Mix

at least one parent has to be at least pastel or super pastel. pastel to pastel will produce all pastels. pastel to normal will produce - give or take - 50% pastels, 50% normals.

So its basically like a normal trait, except there are no hets?
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0.0.1 Chrysemys picta picta (Eastern Painted Turtle)
0.0.1 Teliqua gigas (Indonesian Blue Tongue Skink)
0.2.0 Eublepharis macularius (Leopard Geckos)
0.0.1 Nerodia sipedon (Northern Water Snake)
0.0.2 Rhacodactylus ciliatus (Crested Geckos)
0.0.1 Python regius (Ball Python)
?.?.? Assorted goldfish, minnows and guppies
1.0.0 Ferret
1.1.0 Cats
1.0.0 Aussie Cattle Dog/ Border Collie Mix

right, pastels are dom/co-dom. no such things as hets for these beautiful snakes.

Pastel to pastel = 25% super pastels 50% pastels and 25% normals.....

Since your using this as an example for AP biology, it should be noted that pastel is actually an example of incomplete dominance, not codominance.

An example of codominance would be blood types A and B which are codominant to each other (both are expressed in a heterozygous individual, AB blood type). Also, both A and B are dominant over type O.

Hope that helps, Dave

So then: a bumblebee is a co-dominant condition in which both Pastel (A) and Spider (B) are dominant over 'normal'.

or AB 'Bumblebee' is dominant over normal.

Nice example.
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As for AP Bio and hets: Pastels are certainly the hets for an incomplete dominant condition we all like to call Super Pastel.

Get good grades in AP Bio. It is a solid start for College Bio and then onto med school. Just don't go to Haiti for med school. Those guys don't have the right training. Get a USA education. Pick a lucrative specialty and go to work making the bux. You'll be able to afford all those cool pythons.

Dr Quim.

hmm... confused now

My bp, gorbetrev, was a sibling to a pastel. He said pastel was codominant...
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0.0.1 Chrysemys picta picta (Eastern Painted Turtle)
0.0.1 Teliqua gigas (Indonesian Blue Tongue Skink)
0.2.0 Eublepharis macularius (Leopard Geckos)
0.0.1 Nerodia sipedon (Northern Water Snake)
0.0.2 Rhacodactylus ciliatus (Crested Geckos)
0.0.1 Python regius (Ball Python)
?.?.? Assorted goldfish, minnows and guppies
1.0.0 Ferret
1.1.0 Cats
1.0.0 Aussie Cattle Dog/ Border Collie Mix

incomplete domiance is the correct term. Pastel to normal = 50% pastel 50% normal

pastel to pastel = 25% superpastel 50% pastel 25% normal

superpastel to normal = 100% pastels

superpastel to superpastel = 100% superpastels in theory, I do not yet know if this has been done yet, sure it has, I've just never seen the outcome.......

hmmmm. I don't think they are codominant to each other unless both mutations exist on the same allele. The fact that you can get a super pastel spider suggests that the spider and pastel mutations are on different alleles.

So my thought is that a bumblebee is simply an example of an incomplete dominant (pastel) and a dominant (spider) trait occuring in the same snake. That's my take on it anyway.

What about the Pewters then.
Would they not be considered a co-dominate morph ?
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Charles Glaspie

I'm not real familar with that morph, cinnamon pastel X pastel??

It's likely that they are simply two incomplete dominant traits combined in one animal. The alleles that control each trait would have to be homologous, or code for variations of the same thing for them to be considered codominant.

The fact that super pastels and I think super cinnamons have been produced independently makes it seem more unlikely. But then traits can have more than 2 diiferent types of alleles. Again, human blood type has 3 different possible alleles (A, B, O).

If a super pastel that is also cinnamon or a super cinnamon that is also pastel is produced, that would rule out the two traits being codominant to each other since there would be the two alleles for the super and the other allele would have to reside at another locus on the chromosome.

The Co-dominant term is widely used incorrectly in the ball python world. It's not a huge deal when talking about just one trait like pastel, but will become more important I think when trying to figure out some of the newer, non simple recessive morphs. Time will tell I guess. What do you think?

Ok,either i am way off,or the fog has cleared.

Say the Mojave turns out to be Dom and not Co-dom (bear with me a moment). Would then a Ball that is both Mojave and Spider be considered Co-dominate?
In other words is Co-dominate actually a dual dominate ?
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Charles Glaspie

No, not unless the Mojave trait and the Spider trait were both alleles of the same gene. It's more likely that an individual that was displaying both traits is just displaying two dominant type characteristics in the same individual. (not a real good example, but it would be kind of like a human displaying both Brown eyes and Brown hair which are dominant to blue eyes and blonde hair respectivly)

>>Ok,either i am way off,or the fog has cleared.
>>
>> Say the Mojave turns out to be Dom and not Co-dom (bear with me a moment). Would then a Ball that is both Mojave and Spider be considered Co-dominate?
>> In other words is Co-dominate actually a dual dominate ?
>>-----
>>Charles Glaspie

Nope, it would still be just two dominant morphs that happen to exist in the same animal.

Unless, (as MarkS said) they happen to be different alleles of the same gene.

Codominance happens when two different alleles for the same gene (code for the same thing) and both are fully expressed, not one,the other, or a blended intermediate (pastel).

The M and N blood types are good examples, but since people are most familar with A, B, O. Forget about O for now, a person with type AB blood does not have a mixture...he has both types (of carbohydrates on the blood cell surface).

Thank for taking the time to explain it properly.
Yep,my head hurts,but i get it now.
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Charles Glaspie

Wow.. thanks for all the replies!

And to Dr. Quin, I plan on being a zoologist, no medical school for me I don't acre about the money, I would rather live in a tent in the woods than in a nice victorian house

And my school weights AP courses, by .7

So if I get a 70, that becomes a 91 on my GPA (I don't get 70's, more mid eighties, but that was biochem. Now that real bio is here, I plan to excell There are 4 kinds of kids in our school: AP Bio freaks, AP Chem people, Ap Physics weidos, and the non honours bunch lol)
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0.0.1 Chrysemys picta picta (Eastern Painted Turtle)
0.0.1 Teliqua gigas (Indonesian Blue Tongue Skink)
0.2.0 Eublepharis macularius (Leopard Geckos)
0.0.1 Nerodia sipedon (Northern Water Snake)
0.0.2 Rhacodactylus ciliatus (Crested Geckos)
0.0.1 Python regius (Ball Python)
?.?.? Assorted goldfish, minnows and guppies
1.0.0 Ferret
1.1.0 Cats
1.0.0 Aussie Cattle Dog/ Border Collie Mix

It's my understanding that pastel is a "visual het" for the homogonous form which is superpastel.

Pretty much. A pastel is heterozygous, having one allele for pastel and the other for "wild type". Since the two alleles are incomplete dominant to each other, neither is fully expressed and the phenotype is generally midway between the wild type and super pastel (homozygous pastel).

it's 5:11 am...i just read all of that dominant/co-dominant stuff there...and my head is going to explode.

so i have a normal snake. if i get a pastel, and breed it to the normal, i get 50/50 split.

then i can breed two pastels and get super pastels.

ball python genes are sooooo much cooler than corn snakes.
don't get me wrong, i love my corns, but co-doms are my new best friend.

Yes, pastel X normal will produce 50% pastels. Of course results in a single clutch can vary widely.

Pastel X Pastel will produce 25% supers pastel, 50% pastel, and 25% normals.

As you are doing this for a course, you should check the textbook and see whether it makes a distinction between codominance and any other term other than "dominant" and "recessive". If so, then I would advise against using pastel as an example of codominance. Over the years, there has been movement to synonymize "codominant", "incomplete dominant", "partial dominant", "semidominant", "transdominant", and half a dozen other terms. But many textbooks still provide separate definitions.

"Codominant" comes out of blood typing and molecular genetics. "Incomplete dominant" comes out of plant breeding. A dozen other more or less synonymous terms have come from other subject areas.

Human blood types M, N, and MN are a good example of traditional codominance. Individuals with M or N are homozygous for their respective types, while MN people are heterozygous.

If you can use pastel as an example, you should avoid herper slang such as "super". Your teacher is using the textbook terms that are standard to all areas of genetics, not a slang dialect developed by ill-educated herper pseudogeneticists for the even worse educated.

Paul Hollander

I wonder if some of the variation between "standard" terminology and notation between different species groups has to do with different groups developing there own textbooks to best suite their species. Sure herp keepers are particularly messed up on genetics right now and terms like "super" should probably not become part of our genetic nomenclature if it ever does develop into a textbook level of formality. I would just argue that with the variety of standards in "textbook" genetics that our mess isn't totally unprecedented. Other species might have started out this messed up before becoming "educated". Of course I think textbook education is sometimes overrated except where it can be applied to something practical like a goal of understanding actual breeding results.

I looked at some recent collegiate text books and codominant and incomplete dominant are distinct terms. As I feel they should be, they may not make it easy for the Ball python world but apply to some genetic situations.

We are just lucky that balls (and reptiles) have so many traits that are determined by one gene and not polygenic.

So how did the use(misuse) of the term "codominant" become so prevelant?

Another good example of people misusing genetics is the myth that when buying possible hets, you should buy siblings or the whole clutch. Of course not true (marketing ploy in my opinion). Dave

I'm not sure when "co-dominant" was first used in snakes. Maybe Tiger retic or Hypo boa. Seems to me that it's pretty hard to tell by looking if the het is a blend or not.

I think the idea of buying whole clutches of possible hets has two possible sources. Part is likely a misapplication of the Punnett's square to ideal clutches rather than understanding it as a visualization of the independent odds for each egg. For example the mistaken belief that the Punnett's square says there are two hets in a 4 egg clutch of 50% hets leads to the thinking that you better get the whole clutch to avoid missing the two hets. Of course statistics shows that the chance is the same with any random picked group of 4 possible hets.

The other angle on selling whole clutches is when possible hets can be picked in a non random way. When the sporadic pied marker wasn't publicly known selling whole clutches of possible het pieds together was a way around having to decide which customer gets the markered possible hets and which gets the unmarkered ones. Of course, there is still the issue of who got the clutches with more/less markers and so it still wasn't a perfect system.

So do you think there is much validity in the pied marker theory? I only have a male 100% het and he is not a "marker", reliable source though so I'm sure he is het.

Your right though, if there is even some tendency for the marker being prevalent in het then selling possible hets is full of questions. Good info, thanks

Dave

I have a lot of confidence in the marker when seen in possible hets. I don't have a genetic explanation for why it isn't seen in all hets but I think it is usefull when seen. As I haven't proven any hets yet my opinion doesn't carry much weight but it seems to me that it's seen too often in even very outbred pied lines not to be very closely associated with the actual pied gene. It also looks like the beginning of pied creeping up from the belly and the lines on the belly edge like the black lines in the normal areas of a pieds back. Maybe just wishful thinking and rationalization.

Textbooks are not renowned for being on the cutting edge.

>So how did the use(misuse) of the term "codominant" become so prevelant?

Partly from me through Rich Ihle. Rich grew up 20 miles or so from me. On a visit back here, we talked genetics, and I tried to explain dominant, codominant and recessive as three alternatives. I got it from the professor who taught the genetics course I took. And as I recall, he wanted to simplify things for his students. Mendel used the phenotypes to define dominant vs. recessive genes, so it made sense to just use phenotypes to define genes that were not dominant or recessive. Both incomplete dominant and codominant alleles have three genotypes producing three phenotypes, so they got lumped them together, as has already been done with "semidominant" and "partial dominant".

The difference between codominant and incomplete dominant gets pretty tiny when one moves from the macroscopic to the biochemical level. The most recent definition I've seen has two codominant alleles both producing functional versions of an enzyme in order to produce three phenotypes from three genotypes. OTOH one member of two incomplete dominant alleles produces a functional enzyme while the other produces a nonfunctional version of the enzyme in order to produce three phenotypes from three genotypes. We assume that the normal allele at the pastel locus produces a functional enzyme. Does the pastel mutant gene produce a functional or nonfunctional enzyme? As far as I know, nobody knows the answer to that question. Without that answer, we can't determine whether pastel is a codominant or incomplete dominant mutant gene.

Paul Hollander

I suppose you may be right, textbooks can lag years behind by the time they go to print. Any current research you can point me towards would be appreciated. I have acces to most of the biological journals so that would be fine also.

I think the difference between codominant and incomplete dominant is even more pronounced at the biochemical level. For me, the key is that codominant traits are both fully expressed, no intermediate form.

Somebody needs to apply for a big fat grant to buy ball python morphs and study this. lol.

Thank for the good info, Dave

"Somebody needs to apply for a big fat grant to buy ball python morphs and study this. lol."

Seriously I think there is potential for private industry to actually turn a profit applying genetic technology to snakes.

I think a commercial paternity test (already available in more studied animals like most domestic animals and even several fish) would be in demand. Of course it would help if all the new morphs weren’t some sort of dominant as the main market would be for certifying recessive hets against sperm retention. However I think there could also be a security application as a theft deterrent. If you had genetic profiles on file for all your rare high dollar animals so that a thief knew he could be tracked down if he ever even sold an offspring it might be a good deterrent.

Brenner, Sidney et all. Encyclopedia of genetics. San Diego, Academic Press, c2002, 3 vol. Look for "incomplete dominance".

Miller, Wilmer J. Dominance, Codominance and Epistasis. This is on the ringneckdove.com web site. Go to the Contents page. It is the fourth entry in the "Science & ..." section. The fifth entry, Advances in Classical Genetics, may also be useful to you. Can you do the exercize problem in AiCG without looking at the answer?

Paul Hollander

http://www.ringneckdove.com

Thanks, I'll look it up......n/p

First you make the statement...

"If you can use pastel as an example, you should avoid herper slang such as "super". Your teacher is using the textbook terms that are standard to all areas of genetics, not a slang dialect developed by ill-educated herper pseudogeneticists for the even worse educated."

And later you say...

"Without that answer, we can't determine whether pastel is a codominant or incomplete dominant mutant gene."

If I understand this correctly, in the first statement you are expressing your disregard for the education (or lack thereof) of those interested in herps...

And yet, in the second statement, you blindly follow the "ill-educated herper preudogeneticists'" assumption that Pastel is a 2-allele trait...

Have you ever considered the possibility - no matter how remote it may seem to someone as well-educated as yourself - that Pastel is, in fact, a combination of multiple polygenic traits...???

Let me - an "ill-educated herper pseudogeneticist" - ask you a question...

Assume that I have a bucket filled with Pastels and "Super" Pastels...
I take this bucket and hand it to all of the big breeders in the ball python world...
I ask these breeders to separate the Pastels from the "Super" Pastels...
Certain animals will be classified as Pastels by all of the breeders...
Certain animals will be classified as "Super" Pastels by all of the breeders...
There are certain animals, however, that will be classified as high-grade Pastels by some breeders, and as low-grade "Super" Pastels by other breeders...
It seems to me that if the Pastel trait is indeed based upon 2 alleles, the Pastels and "Super" Pastels should be as distinguishable as night and day...
Why, then, do we have the animals that are so inconsistently classified...???

I have yet to see any direct evidence that Pastel is a 2-allele trait...
I understand that "ill-educated herper pseudogeneticists" have implicitly characterized it as such...
I am puzzled, however, why you - with your disregard for the educational competence of these very same herpers - would blindly follow their assumptions...
Especially considering your views regarding their knowledge of genetics...

Who is more the fool...
The blind sheep who stumble accidentally over the precipice...
Or the sighted sheep who blindly follows them...???

>Have you ever considered the possibility - no matter how remote it may seem to someone as well-educated as yourself - that Pastel is, in fact, a combination of multiple polygenic traits...???

I considered it until the Sutherlands told me that pastel mated to several normals produced only pastels and normals. A combination would come apart in that sort of mating. I have a high opinion of the Sutherlands as breeders and observers.

It is possible that homozygous (super) pastels are most easily distinguished from heterozygous pastels at hatching time. However, if many homozygous pastels cannot be distinguished from heterozygous pastels at all ages, then we will have to change the classification of the pastel mutant gene from "codominant" to "dominant and showing variable expressivity". The variable expressivity is most likely caused by modifier genes and environmental factors. Salmon in the boa constrictor has had to be reclassified that way.

>I have yet to see any direct evidence that Pastel is a 2-allele trait...

And I've never seen a pastel in the flesh, much less bred them. I'm going on the reports of the breeders like the Sutherlands and NERD. Anything I write about pastel should be qualified by something like "if the data is accurate ...".

I'm interested in your opinions about pastel and the data that supports them, too. Any issues I have with pseudogeneticists are confined to their vocabulary, not their eyesight or reasoning powers.

Paul Hollander

"I considered it until the Sutherlands told me that pastel mated to several normals produced only pastels and normals. A combination would come apart in that sort of mating."

Have you ever heard of "Pastel siblings"...???
That term arose based upon the fact that many "normal" siblings to Pastels have certain "Pastel-like" characteristics...
Varying degrees of yellow visible on the sides of so-called "Pastel siblings" is evidence of both an "increased yellow" and a "decreased black"...
Pastel does, in fact, "come apart"...
As do Salmon boas...

"However, if many homozygous pastels cannot be distinguished from heterozygous pastels at all ages, then we will have to change the classification of the pastel mutant gene from "codominant" to "dominant and showing variable expressivity"."

Again, you are assuming that Pastel is a 2-allele trait...
Upon what do you base that assumption...???

"The variable expressivity is most likely caused by modifier genes and environmental factors."

It couldn't possibly be anything to do with polygenes...???

"Salmon in the boa constrictor has had to be reclassified that way."

And one of these days Salmon in the boa constrictor may also be reclassified, as a combination of multiple polygenic traits...
I have been classifying it that way for several years...
Ask Rich Ihle...

"Any issues I have with pseudogeneticists are confined to their vocabulary, not their eyesight or reasoning powers."

Any issues I have with you are confined to you basing your assumptions on what you clearly regard as flawed vocabulary...
You express a condescending attitude to the vocabulary utilized by the herping community...
And yet you base every statement you make on an implicit assumption expressed through that very same vocabulary...
That Pastel is a 2-allele trait...

As I stated earlier, I have yet to see any direct evidence that Pastel is a 2-allele trait...

That's an interesting idea, however I think that the fact that pastel X normal brredings result in approximitly 50% pastel offspring rules out the possibility of the trait being polygenic. If it were control by multiple genes, the result would be far less pastels.

My "pastel siblings" look absolutely normal. I view this as just marketing to illustrate that the babies are captive bred. (or an worst, trying to sucker somebody who does not understand genetics).

Good healthy discussion though, Dave

My "pastel siblings" look absolutely normal. I view this as just marketing to illustrate that the babies are captive bred."

If you produce enough of them...
And inspect them carefully...
You will find significant variation...

"Good healthy discussion though"

I agree...
I usually try to stay away from this subject...
The usual logic that is presented in support of the "codominant" theory goes something like this...
"I know it's codominant because I read it on such-and-such a website"...

Not sure what "enough" is, I've produced 14 pastels and about the same number of normals (pastel siblings). I closely examined them all and although there are individaul differnces, I see no consistent differences when compared to het for albinos and possible het for caramels.

I'll have to disagree with you (respectfully) on the polygenic theory (for the pastel trait)as well. I think it is pretty clear that the trait is an example of incomplete dominance. Though your right, the codominant term is widely misused.

I've had a few classes in this area and feel fairly comfortable with genetics, though there is always more to learn. I have a brother though that is a microbiologist and taught college genetics. He's not into snakes (but can talk for hours about drosophilia) so I'll have to sit down to a few beers and run this by him. Take care, Dave

Which pastel lines/types are you two working with?

Graziani line...... n/p

>Have you ever heard of "Pastel siblings"...???
>That term arose based upon the fact that many "normal" siblings to Pastels have certain "Pastel-like" characteristics...
>Varying degrees of yellow visible on the sides of so-called "Pastel siblings" is evidence of both an "increased yellow" and a "decreased black"...
>Pastel does, in fact, "come apart"...

No one has mentioned such "pastel siblings" to me. How many groups can these pastel siblings be broken into? How does each grouping differ in appearance from a normal ball python and from other groupings of pastel siblings? What are the results from mating two of those pastel siblings? How many such matings have been done with how many babies showing what phenotypes? Are there any F2s from such a mating? If so, how many and with what phenotypes? How many matings have been done between a pastel sibling and a normal and what are the results in the F1 and F2?

>Again, you are assuming that Pastel is a 2-allele trait...
>Upon what do you base that assumption...???

Occam's razor. Pastel being a single codominant mutant gene is the simplest explanation for the reports available to me. That assumes that the data is accurate.

Paul Hollander

"Occam's razor. Pastel being a single codominant mutant gene is the simplest explanation for the reports available to me. That assumes that the data is accurate."

So why do we have the "gray area" of high-grade Pastels / low-grade "Super" Pastels...???

Perhaps you should consider the meaning of the term "Pastel"...
"Pastel" is a term that is used to describe multiple phenotypic attributes...
Not just a single attribute...

The following definition of "Pastel" is provided on the NERD Web site...
"Yellow/Orange, Black and White animals with pale eyes and pale tongues. The black saddling appears faded and hypo."

What you appear to be suggesting, therefore, is that a "single codominant mutant gene" is responsible for all of the following pnenotypic attributes...
- Intensity of yellow/orange coloration.
- Degree of fading of black pattern.
- Intensity of eye coloration.
- Intensity of tongue coloration.

The term "Pastel" is not used to describe a single trait...
It is used to describe the appearance of an animal that exhibits multiple traits within certain boundaries...
Stating that "Pastel" is controlled by a "single codominant mutant gene" is akin to stating that whether or not a person is Caucasian is controlled by a "single codominant mutant gene"...

I am going to coin a new term for tall people who have blue eyes and red hair...
I am going to call such people "Oreo Cookie" people...
Would you now suggest that whether or not someone is an "Oreo Cookie" is controlled by a "single codominant mutant gene"...???
We cannot simply state that a "single codominant mutant gene" controls "Oreo Cookie" people just because this is a simple explanation...
We need to break the appearance down into its components, and examine each component individually...

If we were to break the Pastel trait down into its individual attributes, perhaps we could attempt to determine whether each of those attributes are controlled by 2-alleles, or whether by polygenes...

An arbitrary term, "Pastel", was coined to describe a particular appearance...
You are now attempting to form a one-to-one correspondence between that term and various genetic terminology...
This simply cannot be done...

So how many genes does it take to make a spider? They have both reduced pattern and white on the sides.. Do all spider X normal offspring fall neatly into categories of full-fledged spider (with both traits) and normals and is the long term ratio around 50/50? I think if that is the case it would be good evidence that both the spider’s reduced pattern and it’s white sides are caused by a single gene.

A single gene could also cause all the pastel traits. They could all be results of a single biochemical cause. If all the pastel traits tend to stay together I would think it likely that a single gene causes the mutation.

Do you feel that there is a gray area on distinguishing pastel from non-pastel when breeding a pastel (het) to a normal? I've heard varying things about if the high quality "normal" siblings make this difficult. If there is a clear line between the ones that are pastel and the ones that aren't then we need to get a good sample size and look at the numbers as to what percentage are pastel from pastel X normal. If it's right around 50% then it almost has to be a single gene. There would still be the possibility that "pastel" is a group of closely linked genes on the same chromosome and sometimes the linking is broken in the nicer siblings.

If your basic pastel is a polygenetic combination then I would think that it would break apart in the many generations of outbreeding that have taken place and there would be a lot of incomplete pastels out there being sold. Do you feel that many people are selling pastels without the entire minimum package of traits to qualify for being a pastel?

I would suspect that ya'll are working with some of the premium pastel lines (i.e. lemon, blond, stonewashed) and that those may well be combinations of a single pastel gene and other genetic but not well known traits for high yellow and/or fading. The other traits by themselves fall into the realm of “normals” so haven't been tracked but might be showing up in the nicer siblings causing the appearance that pastel it's self is polygenetic. My theory is that these other traits have been picked up by the premium pastel lines from line breeding with exceptional "normal" females.

So basically my theory is that there is a single pastel gene that causes all the basic pastel traits but that the premium pastel lines are polygenetic in the sense that they are combinations of pastel and other complementary but not well understood genes.

If we knew more about the genes that cause variations in the color and pattern of normals we could probably predict the quality of premium pastel lines better and explain the sibling effect. I think the multiple individual genes responsible for human skin, hair, and eye color and height while certainly complex are well understood by some experts. While it may not be possible to narrow the variation in normal humans in the Caucasian group to a specific genotype it might be possible to narrow your "Oreo Cookie" people down to a group of several genotypes. Perhaps these would be analogous to several possible combination genotypes that make a lemon looking pastel vs. a regular pastel that has just the pastel gene without any particular helper/enhancer genes. To take the analogy further there are human single gene mutations which have multiple symptoms which seem to correspond with multi trait but single gene snake morphs like spider. There are also broader groups of human appearances such as racial types which might correspond to polygenetic and harder to predict types of normal ball pythons. It’s helpful for our breeding goals to narrow down the individual single gene mutations when possible but when they coincide with polygenetic variations in normals it can confuse things.

There are quite a few questions and quite a few interesting discussion items packed into your post.

I would be more than happy to discuss my views on these matters, but it would be very difficult to condense into a forum post. In order to present and discuss my views completely, it is necessary to explain things from the beginning. In other words, I can't fully explain my views without explaining the reasons behind these views.

If you are interested, perhaps we could chat about it over the telephone. It would need to be a time when we each had several hours free. If Paul is interested, perhaps we could arrange a conference call?

Anyway, if you are interested, send me an e-mail and we can see about arranging a mutually convenient time.

Thanks...

I would love to be able to just listen in on that. Lots of good info and theories and debate on this thread, with lots of things to think about!

>What you appear to be suggesting, therefore, is that a "single codominant mutant gene" is responsible for all of the following pnenotypic attributes...
>- Intensity of yellow/orange coloration.
>- Degree of fading of black pattern.
>- Intensity of eye coloration.
>- Intensity of tongue coloration.

No.

Normal genes at dozens and dozens of loci are required to produce the normal color phenotype. IMHO, replacing the normal allele at the pastel locus with pastel, a single codominant mutant gene, changes the phenotype from normal to one with a less than normal amount/intensity/whatever of melanin everywhere that melanin occurs. That includes, but is not limited to, the skin, eyes, and tongue. Reduced melanin in the yellow areas of the skin allows the normally-occurring yellow/orange to seem more intense.

Here is a parallel case. Albino, a recessive mutant gene, prevents formation of melanin everywhere it would occur in a normal snake. That includes, but is not limited to, the skin, eyes, and tongue. Lack of melanin in the yellow areas of the skin allows the normally-occurring yellow/orange to seem more intense.

Please note that I am NOT claiming that pastel and albino are alleles. That question would be nice to test, but I think the odds are against it being true.

Randy Remington has an excellent post next to this one.

Got any data on "pastel siblings"?

Paul Hollander

You bring up some interesting points on the genetics of pastel.

To me the best test as to if it's a single gene is the ratio of pastels when breeding pastel to normal. Of course there may also be a gray area in this experiment with some on the border between pastel and normal. However I would think there is a huge pool of data out there if just a few of the bigger pastel producers would post their numbers for pastel vs. normal production out of pastel (heterozygous) X normal breedings. If it comes out to 50% then I would think we have good evidence that it's a single gene.

I suppose it could still be a pair or more of closely linked genes though. If they where close together on the same chromosome they would tend to stay together and be inherited like a single gene.

Good question though and it will be interesting if we can get a good sample size together to test it.

So that still leaves the question as to why the variation in quality inside both the homozygous pastel (i.e. super pastel phenotype) and the heterozygous (normal) pastel groups and the possible phenotype overlap of the two genotypes. I think the possibility of overlap where the lowest quality homozygous pastels might look the same as the best quality heterozygous pastels maybe factors more into the argument of how to classify the mutation (i.e. co-dominant/incomplete dominant etc.)

One genetic explanation that I can think of is that while pastel it's self might well be a single gene there may be other genes that can be combined with it to effect the quality of the pastel or super pastel. Perhaps some of the premium pastel lines are combinations of a single pastel gene with undescribed genetic high yellow or high blushing morphs. It’s known that “normals” vary considerably in color and some of that variation could be due to one or more genes that we haven’t described yet. Over the years I would suspect that really interesting females (high yellow ect.) have been selected for breeding to pastel males so quality might be complicated and polygenetic but probably not pure chance. This theory would also explain the occasional report of extra nice looking non pastel siblings.

So the idea of polygenetic pastels might apply to some of the premium pastel lines but I believe the data will support a single “pastel” gene at the root of the morph. So, lets here some data!

I'd love to see the results of it too.

This is a fascinating thread, BTW! I've been reading about genetics since I was in the 6th grade and first heard the phrases "Mendel" "sweet peas" and "fruit flies" and have read books on the genetics of mice, dogs, and horses, but I don't think I have found any on snakes. And no, I am not going to say just how many years ago that was...

Katrina

The thing is there have already been many many pastel X normal breedings. I guess the problem would be getting a scientifically random sampling of results (i.e. we might be more likely to get volunteer reports from people who had high pastel ratios). If we could just hear pastel vs. normal sibling ratios from a handful of the breeders who have produced say 30 or more pastels we could get a good feel in a hurry for if the ratio is coming out 50/50 as predicted by the currently accepted understanding of pastel or not. Of course breeders of that size might be less likely to spend the time to keep records of production numbers or less likely to frequent or post on this forum but I think there are enough of them out there to get a sample size of a several hundred pastel X normal offspring.

I started a monster
-----
0.0.1 Chrysemys picta picta (Eastern Painted Turtle)
0.0.1 Teliqua gigas (Indonesian Blue Tongue Skink)
0.2.0 Eublepharis macularius (Leopard Geckos)
0.0.1 Nerodia sipedon (Northern Water Snake)
0.0.2 Rhacodactylus ciliatus (Crested Geckos)
0.0.1 Python regius (Ball Python)
?.?.? Assorted goldfish, minnows and guppies
1.0.0 Ferret
1.1.0 Cats
1.0.0 Aussie Cattle Dog/ Border Collie Mix

Thank you everyone who posted!!!!!!!!!!!!!!!!