Reptile & Amphibian Forums

The DEFINITION of:
co-dominant- "Of or relating to two alleles of a gene pair in a heterozygote that are both fully expressed"

Incomplete dominance- "A heterozygous condition in which both alleles at a gene locus are partially expressed, often producing an intermediate phenotype."

As i said before the term "co-dominant" when used in defining reptile morphs is wrong. What is "co-dominant" is really an example of incomplete dominance. In reptile "co dominance" there is the normal and the "super" form. With the normal being homozygous for normal and super being homozygous for the trait. When you breed a "super" to a normal you come with an intermediary phase which is like when you mix the "super" and normal together. If it really was co-dominant then you would get parts that were normal and parts that were "super".

ie. In flowers
Red flower and white flower make pink flower. That is incomplete dominance.
Red flower and white flower make red or white with red or white spots. That is an example of co-dominant.

ie. In Ball pythons
"super" pastel and normal make pastel. That is an example of incomplete dominance.
Leucistic and normal make piedbald (normal and leucy expressed). That is an example of co-dominant. (that is THEORETICALLY if leucistic was a co-dominant morph).
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0.1 "Tremper" looking Albino Leopard gecko (Lex)
0.0.1 tiger crested gecko (peachs)
0.1 Red blood python (Rhianon)
0.0.1 ball pythons (FELIX!!!!!)
2.1 Feral cats that we adopted (Fuzzy, Bear, and Tony)

"scientia est vox"

>The DEFINITION of:
co-dominant- "Of or relating to two alleles of a gene pair in a heterozygote that are both fully expressed"
>
>Incomplete dominance- "A heterozygous condition in which both alleles at a gene locus are partially expressed, often producing an intermediate phenotype."

IOW, when two alleles are codominant, the genes present can be identified from the phenotype. And when two alleles are incomplete dominants, the genes present can be identified from the phenotype.

>As i said before the term "co-dominant" when used in defining reptile morphs is wrong. What is "co-dominant" is really an example of incomplete dominance. In reptile "co dominance" there is the normal and the "super" form. With the normal being homozygous for normal and super being homozygous for the trait. When you breed a "super" to a normal you come with an intermediary phase which is like when you mix the "super" and normal together. If it really was co-dominant then you would get parts that were normal and parts that were "super".
>
>ie. In flowers
>Red flower and white flower make pink flower. That is incomplete dominance.

Red and white and pink four o'clock flowers. The classic example of incomplete dominance.

>Red flower and white flower make red or white with red or white spots. That is an example of co-dominant.

What species of flower does this occur in?

>ie. In Ball pythons "super" pastel and normal make pastel. That is an example of incomplete dominance.

I will agree that pastel is neither a dominant nor a recessive gene.

>Leucistic and normal make piedbald (normal and leucy expressed). That is an example of co-dominant. (that is THEORETICALLY if leucistic was a co-dominant morph).

As piebald is a recessive mutant gene, you are making the results up. Please use examples that exist. White spotting in cats might fit better. Though I think the spotting mutant is usually called an incomplete dominant or partial dominant.

The classic example of codominants is human blood type A and human blood type B. With human blood type AB produced by the heterozygote. Note that this is on the biochemical level while the four o'clock example is on the whole plant level. As each cell in the heterozygote has one of each allele, transitioning from the biochemical level to the whole organism level is likely to produce an intermediate effect in the whole animal.

The four o'clock example comes out of the field of plant breeding while types A, B, and AB come out of blood typing. A classic case of independent discovery and giving different names to the same thing.

Please note that I am not saying that "incomplete dominant" is wrong and "codominant" is right. I am saying that at the level we are working on, the two terms are synonyms. I happen to prefer "codominant" because it has fewer letters to write.

Paul Hollander

What species of flower does this occur in?
I totally forgot. We had to learn it for science last year, but i forgot.

As piebald is a recessive mutant gene, you are making the results up. Please use examples that exist.
Sorry, i couldn't think of any true co-dominant genes in ball pythons. So i used a visual representation of a "theoretical" possiblity.
-----
0.1 "Tremper" looking Albino Leopard gecko (Lex)
0.0.1 tiger crested gecko (peachs)
0.1 Red blood python (Rhianon)
0.0.1 ball pythons (FELIX!!!!!)
2.1 Feral cats that we adopted (Fuzzy, Bear, and Tony)

"scientia est vox"

OMG! It was Mendel's most famous experiment! Graden peas of course!

http://library.thinkquest.org/20830/Textbook/Genetics.htm

However great his life was and how amazeing the discoveries he made. I will always not like him for putting me through like the worst 3 weeks of my life. Genetics is boring enough....genetics with pea plants= uber boring.
-----
0.1 "Tremper" looking Albino Leopard gecko (Lex)
0.0.1 tiger crested gecko (peachs)
0.1 Red blood python (Rhianon)
0.0.1 ball pythons (FELIX!!!!!)
2.1 Feral cats that we adopted (Fuzzy, Bear, and Tony)

"scientia est vox"

.

This site has it exactly backwards from that. And it I looked around and found lots of sites contradicting each other as well. My opinion= who cares.

"Not all alleles are dominant and recessive like the ones Mendel studied in his pea plants. Some alleles are equally strong and neither are masked by the other. When both alleles are present, they are both expressed in the phenotype. The hybrid is a blend of both alleles. Alleles which are equally strong are said to be "codominant". An example of this is found in carnations. When purebred white carnations are crossed with purebred red carnations, the result is a pink carnation. When expressing codominant alleles, both alleles are represented by different capitalized letters.

Incomplete dominance, is a situation in which both alleles are equally stong and both alleles are visible in the hybrid genotype. An example of incomplete dominanceis found in chickens. When white chickens are crossed with black chickens, the result is not a grey chicken, but a chicken with both black and white feathers. Incomplete dominant genes are written as superscipt capital letters placed above the letter"i"."

http://www.cccoe.net/genetics/codominant.html

Okay, I guess I'll take a shot at trying to explain clearly...

If that's what's on the site, then it's definately backwards. It's the opposite, though it's not always apparent in the phenotype which is which. It might be easier to think of it this way - say you have a flower and there's a gene that creates an enzyme that produces red coloration (let's call it R, and let's call a defective gene that doesn't produce the enzyme r).

Dominant - having either one or both copies of R will produce visually indistinguishable red flowers (enough enzyme is produced by one copy to give red flower, possibly because a limiting factor exists somewhere else in the steps of color production, etc.)

Recessive - In this case, let's say that the homozygous r gene would give a lack of color because it would have both copies of the defective gene that doesn't produce the enzyme required. Flower would be white.

Incomplete Dom - Having one copy of R and one of r produces half the required enzyme and in this case, the amount of enzyme is directly related to the amount of pigment produced. Flower would be pink.

CoDominant - Now we have to add another allele to the mix - let's say it's one that produces blue flowers, B. Now, if blue is dominant to red, then a BR would be blue. If red is dominant to blue, BR flowers would be red. If they were codominant, than both blue and red pigment producing enzymes would be produced. You'd get purple flowers, though I guess I'm not sure how many cells are required to produce a petal and how easily it would be to see that both red and blue are there. Maybe spotted? Who knows.

In this case, incomplete dominance is determined by the visual differences caused by the differing amounts of a single pigment produced, while codominance has two separate pigments being expressed at the same time, thus giving the appearance of a blend between two phenotypes. This also applies to other features, whether it be pattern, color, etc.

This message is probably more confusing than anything else, but it's not always apparent what the difference is when looking at something visually which it would be - codom or incomplete.
Of course, there are MANY other inheritance patterns, but I don't need to add to the confusion...