Reptile & Amphibian Forums

hey everyoen i was just wondering why no co dom for corn snakes. everything seems recessive out there and that can be costly. imagine if hypo or lavander or lava or bloodred was co-dom then imagine the possibility you have. in bp's they are a lot of co-dom morphs to work with. but in corn snakes not enough. is there even a co-dom in corn snake? why not more?

Ultra is co-dominant (isn't it?)
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0.1 Snow Corn "Hope"
1.0 Ball Python "Wilson" (Castaway)
1. Orange Albino Black Ratsnake "Chunk" (Goonies)
.1 Orange Albino Black Ratsnake "Peaches"
0.0.1 Mexican Black Kingsnake "Onyx"

Ultra is a recessive mutant gene because it is recessive to its normal allele. The most one can say is that ultra is codominant to amelanistic and that amelanistic is codominant to ultra.

I have noticed that the pro geneticists seem to be restricting dominant/codominant/recessive to the comparison with the normal allele and actually specifying the appearance of the two mutant gene heterozygote. In this case, both ultra and amelanistic are recessive mutant genes. A corn snake with an ultra mutant gene paired with an amelanistic mutant gene (an ultramel) is more or less intermediate in appearance between a homozygous ultra and a homozygous amelanistic corn snake.

As for why there aren't any dominant or codominant mutant genes in corns but are in ball pythons, the most likely reason is that mutant genes are likely to be more or less deleterious. Corn snakes with such mutant genes die or get killed off before they can reproduce. While the snakes that are heterozygous for a recessive mutant gene don't get killed off more rapidly than the normals. The normal-looking heterozygotes are more likely to survive and reproduce than the snakes with dominant or codominant mutants.

As I understand it, ball pythons are ambush hunters that spend much of their times in holes waiting for prey to come to them. Corn snakes are much more active hunters making them more likely to get into situations where an abnormal appearance would be a survival disadvantage.

As corn snakes are being bred in captivity now, dominant mutants of various flavors are more likely to survive than in the wild. We just have to have the patience to wait for them to occur spontaneously and the eye to recognize them when they do occur.

Paul Hollander

There is some argument that 'bloodred' is a codominant trait. Hets for bloodred (or diffuse as some call it) sometimes have a bit of plain striping down the middle of their belly.

Actually, to get technical, 'codominant' means that both genes are expressed. What most people in the snake world think of as codominant really is 'incomplete dominant', where both genes are partially expressed.

Ultra is an incomplete dominant when paired with amel. Diffuse is an incomplete dominant when paired with the wild-type.

-Kat
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This Space For Rent

>Actually, to get technical, 'codominant' means that both genes are expressed. What most people in the snake world think of as codominant really is 'incomplete dominant', where both genes are partially expressed.

To be really technical, in both cases, both genes are fully expressed biochemically, and both genes affect whatever test is used to detect the gene expression. "Incomplete dominant" means that the heterozygote can be distinguished from the two homozygotes and that one gene produces a functional product while the other gene produces a nonfunctional product. And "codominant" means that the heterozygote can be distinguished from the two homozygotes and that both genes produce functional products.

By the way, a homozygote is an individual animal that has a gene pair in which the two genes are the same, such as an amelanistic corn snake or an ultra corn snake or a genetically normal corn snake. A heterozygote is an individual animal that has a gene pair in which the two genes are not the same, such as a het amelanistic corn snake or an ultramel corn snake.

As most of the time we have no clue to the biochemistry, it is advantageous to skip that part and just say that "incomplete dominant" and "codominant" are synonyms. Then both can mean that the heterozygote can be distinguished from the two homozygotes. Especially as the breeding results are the same for both and for the dozen or so other more-or-less synonyms (transdominant, less than dominant, partial dominant, semidominant, etc.). "Codominant" simply has the fewest letters of any of these terms.

Paul Hollander

I once had a super bloodred, I kept one of her babies but unfortunately is free roaming at this time.

I spoke to Kathy Love when I had my first blood several years ago, as I had no idea what it was. I got it on somewhat of an accident. Kathy did say that the genetics are very uncertain. But I do recall us talking about multiple alleles. Such as skin pigmentation in humans, as I recall from my 1 genetics class there are 16 alleles for our skin.

I am NOT a geneticist, but I do know there is a difference between co-dom and incomplete. But with out DNA mapping, or an extensive SCIENTIFIC breeding plan, I just think there are to many options to lay claim to fully understanding this area.

As a lay person with a little knowledge, it seems it would take years of study to deduce genetic makeup's in these areas. Then we can do what Mendel did and cheat, and go backwards. I'm going to catch heck for that one.

Also after many generations of breeding albino rats, a colony can still produce a agouti (wild color).

There are obviously some very knowledgeable people in here. I wish I knew as much , or more to help more. But I do appreciate the time and energy to post their thoughts. As it helps me to understand more. Even if it gives me a migraine. lol
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Tom

www.herpzilla.com

We could go backwards.... but snakes are more fun than pea plants!
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0.1 Snow Corn "Hope"
1.0 Ball Python "Wilson" (Castaway)
1. Orange Albino Black Ratsnake "Chunk" (Goonies)
.1 Orange Albino Black Ratsnake "Peaches"
0.0.1 Mexican Black Kingsnake "Onyx"

I agree, but lizards are more fun than snakes. OH MY, did I say that? lol

1.3 Bearded Dragons
2.4 Ball Pythons,
6 baby female Western hognose, 3.5 adults some friend some mine,,,building breeding stock)
1 Corn snake (bloodred) MIA
Rats, Degus,
2.0 Dogs,
0.2 Cats,,
0.1 Wives,
1.1 Kids (Paininthearsius takamemonii) J/K great kids
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Tom

www.herpzilla.com