rickmoss95
New member
we were discussing co-dominant and incomplete dominant in another thread in this section, so i looked it up, because there was some confusion on the actual definition, so here goes.
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co dominant versus incomplete diminant
- Thread starter rickmoss95
- Start date
rickmoss95
New member
incompleate dominant..
these quotes are from vince russo on page 15,16, and 17, in his book "the complete boa constrictor"
incomplete dominance
"For many years, reptile breeders have erronously used the term "co-dominant" when in reality they ae referring to INCOMPLETE DOMINANCE. Incomplete dominance is similar to a recessive trait, in that the heterozygous offspring are gene carriers for a specific trait. However, in breedin scenarios where incomplete dominance is involved the heterozygous animals have a visual indicator therefore are referred as "visually heterozygous". This means the offspring exibit another type of color or pattern that is halfway between the normal appearance and the "super" or more exaggerated dominant form. So if you breed boas to each other that have an incomplete dominant trait and that are visually heterozygous for an extreme trait, you will have a one in four chance of producing the super, exaggerated form which will be dominant. When this dominant boa is then bred to a normal, all of the litter will be visually het. offspring. And finally if you breed these visual hets to a normal you will get half visual hets and half normal appearing boas.
With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of both parental traits. An example of the incomplete dominant trait in boas is hypomelanism. This trait is quite common amongst Central American boas and the best known example was popularized by Rich Ihle. He named this trait "salmon hypo boa" for its underlying salmon colors. This trait is incompletely dominant because the super form is very light and exhibits very little or no black at all, and the visually het is a little darker an is visually distinguished as being something between the normal and a super."
these quotes are from vince russo on page 15,16, and 17, in his book "the complete boa constrictor"
incomplete dominance
"For many years, reptile breeders have erronously used the term "co-dominant" when in reality they ae referring to INCOMPLETE DOMINANCE. Incomplete dominance is similar to a recessive trait, in that the heterozygous offspring are gene carriers for a specific trait. However, in breedin scenarios where incomplete dominance is involved the heterozygous animals have a visual indicator therefore are referred as "visually heterozygous". This means the offspring exibit another type of color or pattern that is halfway between the normal appearance and the "super" or more exaggerated dominant form. So if you breed boas to each other that have an incomplete dominant trait and that are visually heterozygous for an extreme trait, you will have a one in four chance of producing the super, exaggerated form which will be dominant. When this dominant boa is then bred to a normal, all of the litter will be visually het. offspring. And finally if you breed these visual hets to a normal you will get half visual hets and half normal appearing boas.
With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of both parental traits. An example of the incomplete dominant trait in boas is hypomelanism. This trait is quite common amongst Central American boas and the best known example was popularized by Rich Ihle. He named this trait "salmon hypo boa" for its underlying salmon colors. This trait is incompletely dominant because the super form is very light and exhibits very little or no black at all, and the visually het is a little darker an is visually distinguished as being something between the normal and a super."
rickmoss95
New member
..again these following quotes are from vins book, "the compete boa constrictor" on page 18 and 19
co-dominant traits
When the recessive and dominant traits appear togeather in the phonotype of hybrid organisms, the expression is called CO-DOMINANT. When working with co-dominant traits, crossing organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear togeather. This genetic scenario works in much the same way as incomplete dominance. A hybrid organism shows a third phenotype; not the usual dominant one and not the usual recessive one...but a third, different phenotype. With co-dominance we get a blending of the dominant and recessive traits so that the third phenotype exibits both traits togeather. AT the time of writing i am not aware of any boa traits that have been proven to be co-dominant.
co-dominant traits
When the recessive and dominant traits appear togeather in the phonotype of hybrid organisms, the expression is called CO-DOMINANT. When working with co-dominant traits, crossing organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear togeather. This genetic scenario works in much the same way as incomplete dominance. A hybrid organism shows a third phenotype; not the usual dominant one and not the usual recessive one...but a third, different phenotype. With co-dominance we get a blending of the dominant and recessive traits so that the third phenotype exibits both traits togeather. AT the time of writing i am not aware of any boa traits that have been proven to be co-dominant.
rickmoss95
New member
i know this if from a boa book, but the definition is the exact same no matter what the species. i hope this clarifies things for you. (it better because after all that typing, my wrists and fingers are about to fall off!) lol! anyway, that is the actual definition from vince russo....who i must thank for both taking the time to help me out in my early boa constrictor ventures, and writing such a wonderful and in depth book! THANK YOU VINCE!
Tom Tuttle
Fightin the C
rickmoss95
New member
after i typed all of that tom!!! im gonna choke you next time i see you! lol just kidding bro.
Good info.
I was discussing this with a certain breeder (who is into balls and some other snakes), awhile back (a couple/few years ago?), and told him that one thing that was kind of "funny" (not "haha" funny), to me, was how co-dominant was being improperly "used" in the Boa/Ball world... that "co-dominant" is a misnomer and that it is actually an "incomplete dominant".
I have years of experience in horse color genetics (plus have done/helped some research and have written an article). Yes, it is, actually, "incomplete dominant" ... where just one gene, of a pair, will give a certain phenotype and two of those same genes (the pair being of the same gene) will give you another phenotype (usually an enhanced version of the single gene phenotype).
Just one example, of an incomplete dominant in horses, is the Cr gene. Without the Cr gene, you will have a Chestnut but, with just one Cr gene it will be a Palomino ... and with two Cr genes it will be a Cremello (a very enhanced version, of the Palomino, that is a very light cream, to white, horse with blue eyes).
I was discussing this with a certain breeder (who is into balls and some other snakes), awhile back (a couple/few years ago?), and told him that one thing that was kind of "funny" (not "haha" funny), to me, was how co-dominant was being improperly "used" in the Boa/Ball world... that "co-dominant" is a misnomer and that it is actually an "incomplete dominant".
I have years of experience in horse color genetics (plus have done/helped some research and have written an article). Yes, it is, actually, "incomplete dominant" ... where just one gene, of a pair, will give a certain phenotype and two of those same genes (the pair being of the same gene) will give you another phenotype (usually an enhanced version of the single gene phenotype).
Just one example, of an incomplete dominant in horses, is the Cr gene. Without the Cr gene, you will have a Chestnut but, with just one Cr gene it will be a Palomino ... and with two Cr genes it will be a Cremello (a very enhanced version, of the Palomino, that is a very light cream, to white, horse with blue eyes).
Tom Tuttle
Fightin the C
Carpet pythons
A good example of incomplete using the jaguar carpets. Here are the three phenotypes:
(1) normal looking sibs
(2) Jaguar
(3) White snakes that don't survive (some refer to them as a super form) I call it the death gene.
Same scenario for the spider balls
(1) normal
(2) Spider
(3) dead snakes
A good example of incomplete using the jaguar carpets. Here are the three phenotypes:
(1) normal looking sibs
(2) Jaguar
(3) White snakes that don't survive (some refer to them as a super form) I call it the death gene.
Same scenario for the spider balls
(1) normal
(2) Spider
(3) dead snakes
Not all homozygous "incomplete dominants" lead to death, of course. However, it is true that some do (as you have illustrated).
While incomplete dominants will work to give a certain phenotype, in the homozygous form, there can be others that are lethal.
Again in horses
... there is one (called "Frame Overo Pinto") that, in the single form will give you a Frame Overo Pinto but, in the homozygous form, will give you "Lethal White" (foal is born white and soon dies).theroadwarrior
New member
So for example, would Tessera (appear to) be an incomplete dominance, while motley/stripe or ultra/ultramel would be an example of codominance?
Tessera is not a good example as it has not been shown to be an incomplete Dominant. So far, Tessera has shown itself to be a Dominant.
At the moment I cannot think of an incomplete dominant that exists in Cornsnakes. In fact, I am not sure that it exists (or, at the very least end, not sure that it has been found/proven) to date.
CoDominant does exist, in Cornsnakes, though. An example, of CoDominant (in Cornsnakes), is, yes, the Ultramel. This is where the Ultra gene, and the Amel gene, are both expressed (and blended) in the phenotype (giving you the Ultramel).
Heterozygous genes -- Requires two copies, of a particular (same) allele, to produce a certain phenotype... only one copy does not have an affect upon the phenotype.
Dominant genes -- Requires only one copy, of a particular allele, to produce a certain phenotype ... and, if two copies are present, does not change the phenotype of a one copy individual.
Incomplete Dominant genes -- Requires only one copy, of an allele, to produce a certain phenotype ... and two copies, of that same allele, produces yet another/different phenotype (an enhanced version of the single allele phenotype).
CoDominant genes -- This is where the alleles are different but work together &/or are expressed together ... producing/expressing a blending, of both of those alleles, in the phenotype.
theroadwarrior
New member
Ah yes I see what you mean about the Tessera. Thank you for the clarification. BTW, what are either of us doing up at this hour, and discussing genetics?
BTW, what are either of us doing up at this hour, and discussing genetics? BTW, what are either of us doing up at this hour, and discussing genetics?
:rofl:
Dunno, should be happily snoozing in bed. Guess that the snakes must be rubbing off, on us, more than we thought... what, with the nocturnal thing & all.
The best example i was given for co-dominance was human blood types. A and B are dominant to O, so when your genotype is AO or BO bloodtype your phenotype is A or B. But when your genotype is AB your phenotype also shows AB. Hence the term co-dominant. Both A and B are dominant to O, but not towards each other.
Dreamsnake
New member
Corn snakes helped me pass the heredity chapters in biology.
Simple dominance is the wild type over the recessive genes. The tesseras are only dominant non wild type morph yet to be discovered that is not a locality.
Incomplete dominance are when the recessive genes share an allele like the amel and ultra or the hypo and strawberry. A mating will produce a third codominant phenotype in the first generation.
Simple dominance is the wild type over the recessive genes. The tesseras are only dominant non wild type morph yet to be discovered that is not a locality.
Incomplete dominance are when the recessive genes share an allele like the amel and ultra or the hypo and strawberry. A mating will produce a third codominant phenotype in the first generation.
theroadwarrior
New member
:rofl:
Dunno, should be happily snoozing in bed. Guess that the snakes must be rubbing off, on us, more than we thought... what, with the nocturnal thing & all.
Yes, and I'm burning the midnight oil again... Yes, I'll blame the snakes. Define irony- one's actually snoozing in my lap right now...
Anyways I'm confused. Is sharing the same allele (motley/stripe, or amel/ultramel) a codominance or incomplete dominance thing? I re-read the responses several times, and I'm pretty sure people are saying two different things.
theroadwarrior
New member
Wait let me clarify: are the Motley/Stripe, and/or Amel/Ultramel SPECIFICALLY examples of codoninance or inomplete dominance? Has anyone already seen a thread that definitively answers this question?
theroadwarrior
New member
And furthermore, would diffusion be a potential example of incomplete dominance, since many "het diffused" animals show some phenotypic signs of diffusion? (Going by the definition posted on this thread?) LOL or why not?
LOL That is funny.
Although some responses are simply confusing ... that may be true too.
It would be allelic, &/or, CoDom. See my other post on what "incomplete dominant" is. One primary difference is that Incomplete Dominant are same alleles and CoDom are different alleles.
No, diffusion would not be an example of incomplete dominant. Not all het diffused express that they are het, there is variability, does not follow the "incomplete dominant" phenotype inheritance, etc. IMO Diffused, aside from having the het/hom inheritance, ~seems~ to follow something akin to having Polygenic traits/inheritance as well.