Are there really any CoDomiant Morphs in Leopard Geckos?

I am of the opinion that if you use the correct definition of Co-Dominant, there aren't any Co-Dominant Morphs in Leopard Geckos. By the reactions I get when I say this, I think that I am probably in a very small minority that believes this. I posted some of my thoughts on this, on another forum, and for the most part, nobody has said flat out that I am wrong, but I don't have many that say I am right either. So I thought that I would try this forum, and see if I can get some peoples thoughts on the subject. Later, Jim

well i thought every1 was saying mack snows were co-dom. but i dont know what is the part that is. we learned about co-domanince in school, and i dont know what is being "shared" in a way. i really dont know. soooo... ya. hope u find some answers.

ReptilianGems said:

I am of the opinion that if you use the correct definition of Co-Dominant, there aren't any Co-Dominant Morphs in Leopard Geckos. By the reactions I get when I say this, I think that I am probably in a very small minority that believes this. I posted some of my thoughts on this, on another forum, and for the most part, nobody has said flat out that I am wrong, but I don't have many that say I am right either. So I thought that I would try this forum, and see if I can get some peoples thoughts on the subject. Later, Jim

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Why do you think that? Just curious, I'd love to hear your side of it.

Kyle,

Glad you are curious. Rather than retype everything again, I will paste some stuff that I posted on another forum.


Incomplete Dominance: When there is a blending of the two parental phenotypes, producing third phenotype different than either parent. One classic example of Incomplete Dominance, is when breeding some flowers, crossing a red flower with a white flower, produces a pink flower. In this case, one allele dominates the other, but only partially, producing a third intermediate phenotype, intermediate between those of the parents.

Co-Dominance: Is when both parental traits are FULLY expressed in the offspring. An example of Co-Dominance often given, is in cattle when one parent has red fur, and the other has white fur, the offspring is born with both red and white fur. As with Incomplete Dominance, a third phenotype is produced, but there is no blending. In other words, the red fur is still red, and the white fur is still white, but they are both present together. There is no blending with Co-Dominant traits. Because neither Allele dominates the other, they are both expressed fully in the first generation. In the example of the red and white cattle, the red hair is still red, and the white hair is still white, but they are both present together (hence the term Co-Dominant). You don't have to breed offspring together to get a Co-Dominant trait.

To put it in a nut shell, going by the correct definition of Co-Dominance, there aren't any Co-Dominant traits in Leopard Geckos that I know of. Which leads me to the term "Super". I am not sure who made up the term, but it is being used in conjunction with an incorrect definition of Co-Dominance by many people. They seem to be substituting it for the word homozygous when breeding the offspring of a particular trait being called Co-Dominant. When in reality, Co-Dominance occurs in a heterozygote, not a homozygote. If you look through any book on genetics, or look at any web page posted by a university or high school, on a course on genetics, you will not find the term Super, because it is not a genetic term.

The main thing to remember when thinking about Dominant, Incomplete Dominant, and Co-Dominant traits, is that these three terms describe the relationship between two DIFFERENT alleles. If an animal has two copies of the same allele, then it is just homozygous for that trait, no different than when a Tremper albino has two copies of of the Tremper Albino gene. I haven't ever heard of anyone calling a gecko a super Albino.

To give some examples, using two parent flowers, one Red, and one White.

Co-Dominant... Red + White = Offspring that are BOTH Red and White, or in other words are White with spots of Red, or Red with spots of White.

Incomplete Dominant... Red + White = Offspring that are Pink. In other words, there is a blending of the two parental phenotypes.

simple Dominance... Red (being the dominant allele) + White = Offspring that are all Red.

I have not proven yet whether my snows are dominant or incomplete dominant. I hate to outbreed a nice animal just to prove a point, but I am pretty sure that mine are incomplete dominant, just because of the blending that occurs as they age when they are outbred to a non-snow. I have some Gem to Gem offspring that I suspect are Homozygous, but I have not proven it yet. They are much whiter than the outbred ones.

I have one question. Is there anybody out there that gets this, or am I just beating a dead horse, lol? I didn't want to come across as a Mr. Smarty pants know it all, but I have spent a lot of time on individual emails, trying to help people on this, and I have yet to have a person that I think really got a handle on it because of anything I wrote. I honestly hope that this helps somebody. Now, let the chastising begin, lol.

On my web page (www.reptiliangems.com), I have links on all of my genetic terms and definitions, that will connect you to Wikipedia, Answers.com, and thefreedictionary.com. You can get to them from a link on my About our Snows page, for those who think I am just making this stuff up as I go,lol.

Just previewed this post, and that was a rather large nutshell. Sorry, I tend to ramble sometimes. Old age I think.

The term co-dominant is improperly used a lot in the discussion of reptile morphs. Incomplete dominance is much more common especially in relation to color morphs of ball pythons and the expression of the Mack snow mutation in leopard geckos.

However, if in fact the giant mutation is inherited the way that it is believed, I would say that there is a good chance that it is a true co-dominant trait. This is because of the likely biochemical and/or physiological changes that result in the expression of the "giant" form. If the genes that express the giant mutation are in fact genes that control some other physiological function, that once altered, lead to the expression of the trait. Then I would think that it could be compared to human blood type (A,B,AB).

Right now no one knows what really causes the expression of the giant mutation so it cannot be said for sure. However if it is biochemical then it will almost certainly be best described as a co-dominant trait, like most biochemically expressed traits.

But I would have to agree that I cannot think of one color mutation in reptiles that is a true co-dominant trait. But then again I don't now them all either.

Matthew,

Thanks for your input, I appreciate it very much. I think you are probably right about the Giants, even though I don't have any in my collection. The human blood types (A,B,AB) are often mentioned when defining Co-Dominance.

I can't believe how many very nice reptile web pages have a totally screwed up definition for Co-Dominance on their Genetics page. It gets a little frustrating sometimes when people ask for help with understanding Co-Dominance, or Incomplete Dominance, and what I tell them is contradicted by dozens of well meaning people that have a wrong definition stuck in their heads.

I know there have to be more people like you that get it, but just don't want to waste your time bucking the trend. That is why I started this thread. I was hoping that some people that do get it would post, and cause others to stop and think about it.

By the way, if there is anybody that thinks that I am way off base, I would also like to here from you too, and why you think I am wrong.

Hey Jim,

First of all I wanted to thank you for what you've put together. I read through the thread on the other forum. I've seen it on there, just haven't had time to read it, till I saw this one.

Anyways, I think you are spot on that Mack Snows are not Co-Dom but are Incomplete-Dominate.

As for the other, 3 lines of snows, have any of the Gem x Gem, Urban x Urban, or Line x Line been able to produce Super Snows?

I have heard though if a Mack is thrown into the mix of any of those, Supers (aka the Homo form of the trait) show up. Based off of that, I believe there is some sort of relationship between all 4 different lines of snows.

To complicate things a little bit, Albey crossed his Linebred/Fasciolatus with Macks (not sure if they were Homo or Hetero for the Mack Gene), and to my knowledge no Super Snows were produced. I picked one of the offspring up, when she is ready to breed, I will be breeding her to my Tremper Hybino Male. I'll post my results from the cross once I have offspring to help prove anything out.

Sorry if I rambled and it became jambled. I had a lot of ideas running through my head.

A lot of biological terms are misused every day, and not just when it comes to animals. I figure that even geneticists will argue with each other on the use of terms related to the inheritance of traits, what's the use in arguing it on a forum. As long as everybody understands what is generally trying to be conveyed, I don't really care to try to correct it.

Besides, nobody really knows the pathway from a gene to the visible expression of that gene for the majority of expressed traits. If we did then we would be able to use more than just the outward expression of a trait to determine the best way to classify different modes of inheritance.

Hey Kyle, good luck on that Linebred/Fasciolatus project. Keep us posted on that. As far as the Gem x Gem, Urban x Urban, or Line x Line producing supers, I haven't heard of it yet. I am pretty confident that Gem x Gem won't.

I see your point Matthew, about not wanting to bother with trying to correct it. And I wasn't wanting to argue the point, I was just curious if anybody even cared, and so far I think it is safe to say that most people don't.

I was just thinking about what it must be like to be new to the hobby, or trying to understand the genetics of a gecko you were interested in, and hearing 2 or 3, or more different definitions. That has to be really confusing. I guess it might be the way I was raised, but I always felt like if there was a right way, and a wrong way, why not do it the right way. Just some more rambling thoughts.

ReptilianGems said:

Hey Kyle, good luck on that Linebred/Fasciolatus project. Keep us posted on that. As far as the Gem x Gem, Urban x Urban, or Line x Line producing supers, I haven't heard of it yet. I am pretty confident that Gem x Gem won't.

I see your point Matthew, about not wanting to bother with trying to correct it. And I wasn't wanting to argue the point, I was just curious if anybody even cared, and so far I think it is safe to say that most people don't.

I was just thinking about what it must be like to be new to the hobby, or trying to understand the genetics of a gecko you were interested in, and hearing 2 or 3, or more different definitions. That has to be really confusing. I guess it might be the way I was raised, but I always felt like if there was a right way, and a wrong way, why not do it the right way. Just some more rambling thoughts.

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Thanks!

I'm not new to the hobby, but I'm new to the whole genetic approach. I've had Leopard Geckos for 10 years, and I'm getting into my first year of breeding and Leopard Genetics. I get what you're saying about the confusion. I think it should be done the right way. On my website, when I get my genetics/morphs section up, I will represent Macks the right way

I have a question about your Gems though. Since you say Gem x Gem hasn't produced any Super Snows yet, would they be considered just Dominate?

Thanks again!

Kyle

Well Kyle, with simple Dominance, the animal will look the same whether it has one copy of the gene, or two. With Incomplete Dominance, and Co-Dominance, the Hets (one copy) will looks different than the homozygotes (two copy).

Since I did mostly outbreeding with my snows, before I started to understand them, I have lots of one copy snows (visible hets). I produced several last year that I suspect are homozygous (two copy), but the only way to prove for sure that they are two copy, is to breed them to a non snow, and then if they procuce all snows, they have two copies of the gene.

Since there is some variability on the amount of yellow that creeps in, even in my one copy snows, I would have to say they are probably Incomplete Dominant. I probably won't try to prove it this breeding season, but I hope to do so next year. But I can say for certain that mine are not Co-Dominant, so they would have to be either Incomplete Dominant, or Dominant like you mentioned. I know that is a rambling explanation, but hope it helps. If you need help with getting your genetics page together, feel free to borrow anything you think you can use from my genetics page.

Jim

ReptilianGems said:

Well Kyle, with simple Dominance, the animal will look the same whether it has one copy of the gene, or two. With Incomplete Dominance, and Co-Dominance, the Hets (one copy) will looks different than the homozygotes (two copy).

Since I did mostly outbreeding with my snows, before I started to understand them, I have lots of one copy snows (visible hets). I produced several last year that I suspect are homozygous (two copy), but the only way to prove for sure that they are two copy, is to breed them to a non snow, and then if they procuce all snows, they have two copies of the gene.

Since there is some variability on the amount of yellow that creeps in, even in my one copy snows, I would have to say they are probably Incomplete Dominant. I probably won't try to prove it this breeding season, but I hope to do so next year. But I can say for certain that mine are not Co-Dominant, so they would have to be either Incomplete Dominant, or Dominant like you mentioned. I know that is a rambling explanation, but hope it helps. If you need help with getting your genetics page together, feel free to borrow anything you think you can use from my genetics page.

Jim

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Thanks for the input Jim. I think I might have to pick a Female Gem Snow from you to match up with my Tremper Hybino I'll let you know when I have the space and money.

I love the thread an appreciate the work you've put into it. Keep up the good work!

Very fascinating thread. I have spoken with another breeder about this a couple weeks ago (my belief that Mack Snows are not Co-Dom).

You are 100% correct that a lot of reptile hobbiests do not use genetics terms properly.

TripleMoonsExotic said:

Very fascinating thread. I have spoken with another breeder about this a couple weeks ago (my belief that Mack Snows are not Co-Dom).

You are 100% correct that a lot of reptile hobbiests do not use genetics terms properly.

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I just wish more people would talk about it. It seem like the consensus is that we have been wrong for so long, we might as well stay wrong. Really it would take only a few of the big name breeders to get it fixed, but most of them have been using the wrong terminology themselves, and seem to hate to change. Thanks for expressing your opinion.

I know where you're coming from, Jim. Most just do not like change. It's also a shame that some will follow people like Tremper whom blatantly use terminology wrong and don't care.

I did not talk about the Mack issue publicly because when I had questioned Tremper's description of the RAPTOR (mainly the "het" part) here on Fauna, I got ripped a new one. What amusing is that what I said back then, they're saying now...

Stephanie,

I think for the most part, the people that think there are Co-Dominant Snows, are probably thinking that if they just ignore this thread, it will go away, and we can just go about doing things they way we have. And I would have to say they are probably right.

The bad thing is that for those that really don't understand the difference, this thread might have confused them more than enlightened them. I hope that it might have helped a few people though. That was my intention anyway.

Jim

www.ReptilianGems.com

I agree. To put it bluntly, they will be the ones whom look silly in the end.

Charles Pritzel (Author of the Cornsnake Morph Guide) just released "Genetics for Herpers" a guide that teaches how to apply genetics terms correctly. I believe the book would greatly benefit the Leopard Gecko Community.

http://cornguide.com/genetics.php

I'm fairly new to Leos but I have had a fairly rigorous science education and was totally thrown for a loop with the miss used terms. The term Mack "Co-Doms" really was confusing, I guess In-Dom is more propper. I always just preferred describing the Genotype as homo dom, hetero, or homo recessive. And describe the phenotype. Ex Mack snow: the "super snow" genotype: homozygous dominant and phenotype: no yellow present, regular mack snows genotype: heterozygous and phenotype: faded yellow present, mack siblings genotype: homozygous recessive and phenotype: normal yellow coloring

Mack Snow siblings are not recessive for Mack Snow if that is what you are implying.

Are you sure?
If "M" represents the mack snow gene, upper case since Mack snow is a dominant trait. Then "m" would be the resessive gene representing not a Mack snow.
Then If a Mack snow is bread the result could be
MM is a Mack super snow,
Mm Regular Mack Snow, and
mm normal type (Mack snow sibling)
There is a very good chance I have this wrong, this is the way I thought it would work if the Mack snow where the result of a single gene. Which I thought it was. Is the Mack snow trait polygenetic?