morph names and my opinions.

[paulh]

Interesting definitions for partial dominance, overdominance, and no dominance. I've also heard of transdominance, semidominance, lack of dominance, less than dominance, incomplete dominance, and several others that I don't remember at the moment.

In all of these definitions, the heterozygous type can be distinguished from both homozygous types.

Another set of definitions: With incomplete dominance, the heterozygous type can be distinguished from both homozygous types, and one allele has a nonfunctional product. The phenotype depends on whether there is one or two copies of the allele producing a functional product. In codominance, the heterozygous type can be distinguished from both homozygous types, and both alleles have functional products. Using these definitions, we'd need biochemical information to decide which term to use. At this time, we have insufficient data to make the determination for any reptile mutant.

My old genetics prof said that, FOR SIMPLICITY, we should just call all such cases codominance. We are primarily interested in the breeding results. The breeding results are the same whether a given mutant is called a partial dominant or a codominant. So there is no point in splitting hairs over this particular point of terminology.

 

[Paco]

Interesting definitions for partial dominance, overdominance, and no dominance. I've also heard of transdominance, semidominance, lack of dominance, less than dominance, incomplete dominance, and several others that I don't remember at the moment.

In all of these definitions, the heterozygous type can be distinguished from both homozygous types.

Another set of definitions: With incomplete dominance, the heterozygous type can be distinguished from both homozygous types, and one allele has a nonfunctional product. The phenotype depends on whether there is one or two copies of the allele producing a functional product. In codominance, the heterozygous type can be distinguished from both homozygous types, and both alleles have functional products. Using these definitions, we'd need biochemical information to decide which term to use. At this time, we have insufficient data to make the determination for any reptile mutant.

My old genetics prof said that, FOR SIMPLICITY, we should just call all such cases codominance. We are primarily interested in the breeding results. The breeding results are the same whether a given mutant is called a partial dominant or a codominant. So there is no point in splitting hairs over this particular point of terminology.

Paul... I was wondering when you were going to chime in. Great stuff and very interesting as usual.

It kinda funny I think I am finally starting to get a grasp on genetics then BAM 100's of new things come flying at you!!!

So you are saying to truly determine wether or not an animal is Incomplete-Dom or Co-Dom some sort of chemical test would need to be performed? Is this correct?

 

[paulh]

So you are saying to truly determine whether or not an animal is Incomplete-Dom or Co-Dom some sort of chemical test would need to be performed? Is this correct?

It could be a chemical test, as in blood typing. Or it could involve some other characteristic, like the speed of migration through a medium when influenced by an electrical current (electrophoresis). Whatever is used, the test is far more sensitive than the Mark I eyeball.

 

[paulh]

Codominance is when two alleles of a gene which result in distinctly different phenotypes, but when they are both inherited together in an individual (one from the mother and one from the father - called heterozygosity), the individual has both of the phenotypes.

For example: if one allele is for red skin and the other allele is for blue skin, then the individual will have patches of blue skin and patches of red skin. (This is in contrast to incomplete dominance, where the individual would inherit a blend of the two alleles and have purple skin).

The word "codominance" was originally coined for the relationship between human blood types A and B. If the example above was an accurate description of how things work, red blood cells from a type AB human could be separated into type A cells and type B cells. They cannot be so separated. So this type of scaling up from cellular effects to the whole body is not what happens.

 

[herpencounter]

The word "codominance" was originally coined for the relationship between human blood types A and B. If the example above was an accurate description of how things work, red blood cells from a type AB human could be separated into type A cells and type B cells. They cannot be so separated. So this type of scaling up from cellular effects to the whole body is not what happens.

So what is the true name for “codominance” for the example I gave?

 

[Paco]

My old genetics prof said that, FOR SIMPLICITY, we should just call all such cases codominance. We are primarily interested in the breeding results. The breeding results are the same whether a given mutant is called a partial dominant or a codominant. So there is no point in splitting hairs over this particular point of terminology.

Well this quote right here leads me to believe that people have been using the proper terminology for years for Co-dom traits and it makes sense why we see it used the way it used today for many morphs.

Thanks again Paul. That quote right there makes things very simple for the novice to understand. I like "FOR SIMPLICITY" Sakes sometimes.:main_thumbsup:

 

[preacherman]

"There are few examples of true codominant traits in reptiles...So is a trait incompletely dominant or codominant? ...many if not all reptile morphs called codominant are actually incompletely dominant. However, this distinction in terms rarely makes a difference in practice--at least until a true codominant morph appears. A good rule of thumb is that if there is a "super" form, the mutation is incompletely dominant." (Vincent J. Lynch. "Genetics 101". Reptiles Magazine. August, 2007. pg. 83)

"An allele is dominant if it has the same phenotypic effect in heterozygotes as in homozygotes--that is, the genotypes Aa and AA are phenotypically indistinguishable. Sometimes, however, a heterozygote has a phenotype different from that of either of its associated homozygotes. Flower color in the snapdragon, Antirrhinum majus, is an example. White and red varieties are homozygous for different alleles of a color-determining gene; when they are crossed, they produce heterozygotes that have pink flowers. The allele for red color (W) is therefore said to be incompletely, or partially, dominant." (Snustad, Simmons, Jenkins. Principles of Genetics. John Wiley & Sons, Inc. New York, New York. 1997. Pg 61.)

I could be way off base here, but it seems to me that while it may indeed be splitting hairs to make a distinction between co-dominance and incomplete-dominance, it is appropriate in the reptile world, especially in regards to morphs that have "super" forms, i.e. the heterozygote is indeed distinguishable from both homozygotes. Is this not what distinguishes incomplete-dominance from co-dominance? Please correct me if I'm misunderstanding this distinction.

 

[Gregg M]

I am a genetics major at the University of Alberta.

:main_rolleyes:

Here we go... Another know-it-all genetics major...

It might do you well to sit back and learn from people who have been doing this for many years... Honestly if you are here to try and prove people wrong who have been at this for longer than you are alive, you will not go very far and you really are not offering anything... Try not to "talk down" to respected members of the community...

Your definitions on genetic mutations from your text book are nothing the entire community has not already seen...

I think Paulh is the voice of reason in this thread... Good posts Paul..

 

[Gregg M]

Super Snows may be anery, and Blizzards may be a true leucistic, I`ll agree.

This I do not agree with at all...

 

[herpencounter]

This I do not agree with at all...

Explain?

I have no stand on this just curious to why you say they are not.


I would also like to mention that some people are happy enough with the fact that you can distinguish the difference from the het form to the homo form, weather we call it codom, incomplete dom or what ever.

Other people (myself included) want to know more. Based on what we know with out getting any test done it is incomplete dominance.

Just my 2 cents.

 

[Gazz]

So with Mack snow/super snow being incomplete dominant.Do this better explane how mack snow/super snow bred to GEM/TUG/LB snows throw super snows.Dose GEM/TUG/LB snows maybe have a dormant gene'etc that's unlocks/express's the super snow with in.Or its it all on the Mack side of things.And if you breed a mack snow/super snow to a GEM/TUG/LB snow are all offspring snows technically MACK-(HET) super snow.I wonder if NON MACK snow's are carrying a dormant gene for super snow.That can only be opened/Express by a homo type gene(preasant in mack snow or super snow).I've used caputal a small letters in the example.And below is theory but this is my line of thinking if it makes sences to you.


TUG/GEM/LB-sS
&
Mack-SS.

Snow-sS X wild = Snow-sS & wild.

Snow-SS X wild = Snow-SS & wild.

Snow-sS X Snow-sS = Snow-sS.

Snow-SS X Snow-SS = wild & Snow-SS & (25%Super snow).

Snow-sS X Snow-SS = Wild & Snow-SS & (14.5%Super snow).

Snow-SS X Super = Snow-SS & (50%Super snow).

Snow-sS X Super = Snow-SS & (25%Super snow).

Super snow X Super snow = Super snow.

 

[paulh]

I could be way off base here, but it seems to me that while it may indeed be splitting hairs to make a distinction between co-dominance and incomplete-dominance, it is appropriate in the reptile world, especially in regards to morphs that have "super" forms, i.e. the heterozygote is indeed distinguishable from both homozygotes. Is this not what distinguishes incomplete-dominance from co-dominance? Please correct me if I'm misunderstanding this distinction.

In both incomplete dominance and codominance, the heterozygote can be distinguished from the two homozygotes. That's the difference that splits both of them off from dominant and recessive genes. That is as far as we need to go as breeders. However, most of the texts try for further subdivisions, which is an unnecessary complication for us, in my opinion.

So what is the true name for “codominance” for the example I gave?

Codominance. Not because there is a patchwork phenotype but because the heterozygous type can be distinguished from the two homozygous types. There are codominant mutants that produce a patchwork phenotype, such as spot in cats. But a patchwork phenotype is not a requirement for a codominant mutant.

 

[paulh]

So with Mack snow/super snow being incomplete dominant. Do this better explane how mack snow/super snow bred to GEM/TUG/LB snows throw super snows.Dose GEM/TUG/LB snows maybe have a dormant gene'etc that's unlocks/express's the super snow with in.Or its it all on the Mack side of things.

I think this sort of super snow is a combination effect. Add the effect of the Mack snow gene to the effects of some of the genes required to make a GEM/TUG/LB snow and the result is a super snow. If so, then mating a pair of this sort of super snow would not produce all super snows. Some babies could be super snows, some could be Mack snows, and some might not be anything special.

 

[herpencounter]

Codominance. Not because there is a patchwork phenotype but because the heterozygous type can be distinguished from the two homozygous types. There are codominant mutants that produce a patchwork phenotype, such as spot in cats. But a patchwork phenotype is not a requirement for a codominant mutant.

OK thanks.

For fun.

http://www.users.csbsju.edu/~wlambert/bio115/vocab/vocab2.htm

 

[preacherman]

In both incomplete dominance and codominance, the heterozygote can be distinguished from the two homozygotes. That's the difference that splits both of them off from dominant and recessive genes. That is as far as we need to go as breeders. However, most of the texts try for further subdivisions, which is an unnecessary complication for us, in my opinion.


Codominance. Not because there is a patchwork phenotype but because the heterozygous type can be distinguished from the two homozygous types. There are codominant mutants that produce a patchwork phenotype, such as spot in cats. But a patchwork phenotype is not a requirement for a codominant mutant.

Thanks for the information. Just a couple more questions:

First, you're saying that for all practical purposes there is no need for us as reptile breeders to make any distinction between co-dominance and incomplete-dominance, correct? Second, what is the distinction between the two, and could you give us an example of each? Finally, why do some in the reptile field insist on making a distinction if the distinction is not a profound one?

 

[nevinm]

what ever i said befor makes no diff. this is the outcome i wanted by starting this thread. i just wanted people who were afraid to say something about whatever they wanted to acccually say something. in fact in my first post there are only 2 things that i do believe. everything else was just me getting people to speak their minds.

 

[Gazz]

First, you're saying that for all practical purposes there is no need for us as reptile breeders to make any distinction between co-dominance and incomplete-dominance, correct? Second, what is the distinction between the two, and could you give us an example of each? Finally, why do some in the reptile field insist on making a distinction if the distinction is not a profound one?

In a nut shell i beleave like below.It's the HET example that are visually differant.

 

[cassadaga]

I agree, the difference between co-dominance and incomplete dominance are almost irrelevant to standard hobbiests. That's also how I feel about the difference between albino and amelanistic in fat-tails and leopard geckos.

I wonder though...

I agree with the way Gazz illustrated the difference between incomplete and codominance. So where does that leave morphs like mojave and lesser ball pythons? Incomplete dominance? I would imagine if they were codominant it'd be more like a piebald. I don't really see either morph as an intergrade between a wild type ball and a blue eyed leucistic though, either.

 

[Paco]

Codominance. Not because there is a patchwork phenotype but because the heterozygous type can be distinguished from the two homozygous types. There are codominant mutants that produce a patchwork phenotype, such as spot in cats. But a patchwork phenotype is not a requirement for a codominant mutant.

Cassadaga it is right here. You are not always going to have a patch work look to the animals. Who is it that says thats the way both traits always have to display themselves? Patchwork look that is. This is where the problem comes in. Everyone thinks there is supposed to be some sort of Patchwork look that happens but it is not always the case.

 

[DarthGekko]

Interesting stuff guys/girls. I am really curious about the different snow morphs and how they interact with one another. Possible Polygenic? Don't quote me but I'm just posing the idea

Also, I would like to see a Dominant gene that allowed for first year females to lay 14+ eggs! I have 2 projects that need this gene like right now!!!!