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The black hole of corn snake genetics

J

Jack B

New member
I can't believe it sucked me in.

I've been reading this forum and then had to google corn snake genetics and read a bunch of stuff out there and now I'm getting obsessed with all of this what X what = what business.

I've gained a basic understanding of the dominant and recessive traits, what the hets are and how the Punnet square can be used to predict what morphs can be produced in what percentages.

2 things I'm wondering about that I haven't been able to find out yet are:

What's the difference between (anery A) and (anery B). It seemed to me that if the neonate had the aa pairing as opposed to the AA or Aa it would be anerythristic period. I don't get where the anery A and B nomenclature comes from.

The other thing I'm wondering about is hypomelanism. How does that happen? I understand how amelanism happens but hypo and hyper melanism are not clear to me.

Also does anyone know of a good book on the subject that does not go too deep into biochemistry and the like?
 
The difference between anery A and anery B, aside from the "minor" phenotypical differences, is that they are caused by two separate genes. Breeding an anery to a charcoal will result in all normal offspring het for both traits.

Hypomelanism is caused by a single recessive gene and causes a reduction in the amount of black pigment seen. That amount can vary between individuals. There are currently 5 different hypos, each caused by it's own recessive gene...hypo A (most commonly seen and the one referred to when a snake is called a hypo), Sunkissed (which may also be a pattern gene), lava, ultra and Christmas. Hypermelanism would be an increase in the amount of black pigment. To date, there is no known genetic mutation that causes hypermelanism in cornsnakes.

An excellent book on cornsnake genetics is the Cornsnake Morph Guide which can be purchased at www.cccorns.com.

Here are some comparison pics:
Hypomelanistic
Hypo_82_-_close_up.JPG


Normal
Normal_31_-_2.JPG


Anerys and Hypo Anerys (Ghosts)
Anery_Mot_Plus_babies_July_05.JPG
 
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Very good questions and Susan answered them perfectly for you. If you really want to take advantage of a bevy of information I would suggest these three books. PJ and I call them the "Holy Trinity" as they are a must have for any serious Cornsnake keeper/breeder. This site is the place to be if you have a Cornsnake. This place is crammed full of information and very cool people. You should try to take advantage of the F.A.Q. and the Search functions found on the top of the page. Hope this helps.
Jay & PJ :cool:

Cornsnake%20Morph%20Guide,%202006%20COVER.jpg


Corn%20Snakes%20-%20The%20Comprehensive%20Owner's%20Manual,%20COVER.jpg


Soderberg%202006%20book%20cover.jpg
 
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That, Jack, was an excellent set of questions. The Hypo traits are really hard for me to "get"/automatically understand. And then Susan cam along with PICTURES and explained it.

The clouds have parted....

Thank you!!

SaulsMom
 
SaulsMom said:
The clouds have parted....
Click to expand...
.....and it's usually at this point that you get sucked in like an iron filing to a magnet.

There is no turning back. Resistance is futile. :grin01:

regards,
jazz
 
PJCReptiles said:
Very good questions and Susan answered them perfectly for you. If you really want to take advantage of a bevy of information I would suggest these three books. PJ and I call them the "Holy Trinity" as they are a must have for any serious Cornsnake keeper/breeder. This site is the place to be if you have a Cornsnake. This place is crammed full of information and very cool people. You should try to take advantage of the F.A.Q. and the Search functions found on the top of the page. Hope this helps.
Jay & PJ :cool:

Cornsnake%20Morph%20Guide,%202006%20COVER.jpg


Corn%20Snakes%20-%20The%20Comprehensive%20Owner's%20Manual,%20COVER.jpg


Soderberg%202006%20book%20cover.jpg
Click to expand...

All 3 of which I got for Christmas under the tree this year from the husband, I asked for them after I found myself completing The Corn Snake Manual for the 20th time or so :rolleyes: :grin01:
 
jazzgeek said:
.....and it's usually at this point that you get sucked in like an iron filing to a magnet.

There is no turning back. Resistance is futile. :grin01:

regards,
jazz
Click to expand...
Yep, there is NO way out once you are in... this addiction only grows, no matter what limitations you set, the snakes will slither right over the lines without glancing at them and into your hearts until suddenly one day you wake up and they are in your house.

Just when you think you have no more space for yet ANOTHER snake, you will find the room in the most unlikely of places and manage to fit three more in there instead of just one.

Susan - brillaint answer! Very clear and concise, something that would have helped me earlier last year when I was once a genetic noob myself... is great for refreshing my knowledge too!

Jenn
 
Susan, thanks for the explanation. The anery A & B and hypomelanism questions are clearer to me now. It seems then that there are separate alleles that could reside at a specific locus which can cause different forms of anerythrism and the same with hypomelanism.

I'm thinking that one would have to know the lineage of the snake or just make an educated guess based on phenotype to determine if their snake was anery A or B.

I was surprised to learn that there are so many genes for hypomelanism but at least it seems to me the differences in phenotype among the different hypo genes is greater than the differences present in anery A & B.

Using my snake as an example I would say she is a crimson corn, hypomelanistic Miami phase (het for anery). Her mother was crimson and her father was ghost ( I know this from the breeder). So I could probably assume that she is hypo A as a dominant trait and anery A as a recessive trait since her father was a ghost and not charcoal.I don't know if she's 100% het or what so the only way to determine that if I wanted to know would be to pair her with a snake 100% het anery or a shake that is anery. Is that right?

Also, thanks for the link and book suggestion. That site is currently sold out of the 2006 edition but I'm going to a show in NY to get some frozen pinks this weekend so I'll keep an eye out for that book as well as the Don Soderberg book recommended by PJC. I already have the Comprehensive Owners Manual.

Thanks again.
 
Jack B said:
IWhat's the difference between (anery A) and (anery B). It seemed to me that if the neonate had the aa pairing as opposed to the AA or Aa it would be anerythristic period. I don't get where the anery A and B nomenclature comes from.
Click to expand...

Basically, a snake displaying the "Anerythrism" phenotype (lack of red pigment) is a process like "Car won't run" - it's a physical effect which can have lots of different genetic causes.

You could have:
"Car Won't Run - No Petrol" (Anerythrism A) or
"Car Won't Run - Starter Motor's Dead" (Anerythrism B AKA Charcoal)
"Car Won't Run - No Engine" (Anerythrism C AKA Caramel)

... and so on.

One problem is that Anery A doesn't have an AKA name, it's just called Anerythristic - so it's a little misleading - it implies that all other 'anery' effects should be compatible!
 
Jack B said:
Susan, thanks for the explanation. The anery A & B and hypomelanism questions are clearer to me now. It seems then that there are separate alleles that could reside at a specific locus which can cause different forms of anerythrism and the same with hypomelanism.
Click to expand...

As you'll see in my previous reply... no, the Anery alleles don't HAVE to exist on the same locus - and since they're not compatible (a Charcoal X an Anery = normal het charcoal and anery) they're probably not on the same locus at all.

Using my snake as an example I would say she is a crimson corn, hypomelanistic Miami phase (het for anery). Her mother was crimson and her father was ghost ( I know this from the breeder). So I could probably assume that she is hypo A as a dominant trait and anery A as a recessive trait since her father was a ghost and not charcoal.I don't know if she's 100% het or what so the only way to determine that if I wanted to know would be to pair her with a snake 100% het anery or a shake that is anery. Is that right?
Click to expand...

I think this one might have gotten garbled.

Anerythristic and hypomelanistic are both recessive genes - you need two copies to produce either physical appearance, because a "not anery" or "not hypo" gene would make the snake look normal.

You might be confusing "dominant" with "homozygous" and "recessive" with "heterozygous".

"Homozygous" means that both genes of a pair are the same - EE (homozygous not anery, visually normal) and ee (visual anery) are both homozygous gene pairs.
"Heterozygous" means that both genes of a pair are different - Ee (visually normal, invisibly carrying anery AKA "het anery") is a heterozygous gene pair.

"Dominant" and "Recessive" refer to the visual expression of a gene pair. In the example above, an Ee snake will LOOK visually not-anery, because the "not-anery" gene "E" is dominant to the "anery" gene "e".

Hypo is not dominant to Anery simply because Hypo is part of a different gene pair than Anery is - if the pair "not-Anery"/Anery is expressed as E/e then "not-Hypo"/Hypo could be H/h :)

If Dad was a Ghost, he is homozygous Anerythristic A + homozygous Hypo.
If Mom was a Crimson, she was homozygous hypo, selectively bred for a miami-like appearance.

That means that you will get 100% hypo offspring (neither mom NOR dad can give a non-hypo gene to the offspring) and they will be 100% het anerythristic (because dad can't give a non-anery gene to the offspring). That means yours is definitely het for Anery (100% het) - she can't be anything but - and her genetics could be expressed as hh Ee ... and that doesn't take into account any of the thousands of other gene pairs that make up the snake you have in your hands.
 
Ssthisto said:
One problem is that Anery A doesn't have an AKA name, it's just called Anerythristic - so it's a little misleading - it implies that all other 'anery' effects should be compatible!
Click to expand...
. . . and to add to that (and the other great information), Anery B and Anery C are not commonly used any longer in favor of Charcoal (Anery B) and Caramel (Anery C) and Lavender (Anery D?) and Dilute (Anery ??).

D80
 
Ssthisto said:
As you'll see in my previous reply... no, the Anery alleles don't HAVE to exist on the same locus - and since they're not compatible (a Charcoal X an Anery = normal het charcoal and anery) they're probably not on the same locus at all.

Yes, I see. Thanks for clearing that up. I didn't follow the motor not running analogy that well.

I think this one might have gotten garbled.

Anerythristic and hypomelanistic are both recessive genes - you need two copies to produce either physical appearance, because a "not anery" or "not hypo" gene would make the snake look normal.

You might be confusing "dominant" with "homozygous" and "recessive" with "heterozygous".

"Homozygous" means that both genes of a pair are the same - EE (homozygous not anery, visually normal) and ee (visual anery) are both homozygous gene pairs.
"Heterozygous" means that both genes of a pair are different - Ee (visually normal, invisibly carrying anery AKA "het anery") is a heterozygous gene pair.

"Dominant" and "Recessive" refer to the visual expression of a gene pair. In the example above, an Ee snake will LOOK visually not-anery, because the "not-anery" gene "E" is dominant to the "anery" gene "e".

Hypo is not dominant to Anery simply because Hypo is part of a different gene pair than Anery is - if the pair "not-Anery"/Anery is expressed as E/e then "not-Hypo"/Hypo could be H/h :)


I was confusing dominant and recessive with homo and hetero zygous. I think that was causing me a bit of confusion.

If Dad was a Ghost, he is homozygous Anerythristic A + homozygous Hypo.
If Mom was a Crimson, she was homozygous hypo, selectively bred for a miami-like appearance.

That means that you will get 100% hypo offspring (neither mom NOR dad can give a non-hypo gene to the offspring) and they will be 100% het anerythristic (because dad can't give a non-anery gene to the offspring). That means yours is definitely het for Anery (100% het) - she can't be anything but - and her genetics could be expressed as hh Ee ... and that doesn't take into account any of the thousands of other gene pairs that make up the snake you have in your hands.
Click to expand...

Thanks for stepping through that example for me. It seems so clear when you break it down logically like that. I think I need to mull it over a bit until more of the fog begins to lift at this point. If I look at the individual morphs and determine what each is homozygous for might help.
 
Jack B said:
I'm thinking that one would have to know the lineage of the snake or just make an educated guess based on phenotype to determine if their snake was anery A or B.
Click to expand...
Breeding trials will always have the final say, but the "educated guess" for visually determining between anery A or B is the amount of contrast between ground and saddle color:

Anery "A" -


Ansel122806-1.jpg



Charcoal -

Mary071906-2.jpg


regards,
jazz
 
Jazz, thanks for the pictures. That gives me a great visual reference for anery A and B.

At this point I think I need to get my head around what the individual morphs are homozygous for. What makes them "show what they show". Then I think what X what = what will become clearer to me.

Thanks again.
 
Susan said:
To avoid some confusion, anery C is not another name for the caramel gene. It may have been used briefly quite a few years ago, but more recently, anery C is also known as Morph Z. Here is a link to info on anery C from the gene's "founding father", Rich Z.
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Thanks for the clarification Susan! One of the reasons I personally prefer 'trade'-like names as opposed to Anery A-B-L-X! :crazy02:

Jack, I haven't seen it referenced yet, but play around with THIS program for a a few minutes (days!!) and things will get clearer as well! It's great because you can do crosses and ask for genotype results OR phenotype results!

D80
 
Drizzt80 said:
Thanks for the clarification Susan! One of the reasons I personally prefer 'trade'-like names as opposed to Anery A-B-L-X! :crazy02:

Jack, I haven't seen it referenced yet, but play around with THIS program for a a few minutes (days!!) and things will get clearer as well! It's great because you can do crosses and ask for genotype results OR phenotype results!

D80
Click to expand...

Thanks for the link. That will be very useful. It will help me familiarize with the products from various crosses and also as I get better with the genetic nomenclature and playing around with Punnet squares, this will help me check if I've got it right or not.

I didn't even know there was anery C until Susan's post.
 
Dale belted out the following...

.....and it's usually at this point that you get sucked in like an iron filing to a magnet.
Click to expand...

The best advice given... :laugh01:

Regards.. Tim of T and J
 
Jack B said:
Yes, I see. Thanks for clearing that up. I didn't follow the motor not running analogy that well.
Click to expand...

Think of it this way. A corn snake that is 'running correctly' looks wild-type/normal. It produces black pigment, red pigment, yellow pigment and has a normal blotched pattern. Any alteration in the visual look is because there's something that isn't 'running as normal' (but is not necessarily BROKEN) inside the snake's genetics.

So, the "Car won't run" analogy is the idea that you get a visual result ("car won't start" or "looks like a grey snake") but that visual result can have multiple underlying causes.

In the case of a car, the car might not start if the starter motor's blown, or if there's no petrol, or if there's no engine. They all have the same end result, but they're for entirely different reasons.

In the case of a 'grey snake' there are lots of different processes that can prevent the snake's body from correctly producing the red or yellow pigments. These processes are determined by genetics, and they don't have to be related in any way. It could be "unable to make red pigment at all" or it could be "no red pigment cells in the skin" or "delayed development of red pigment cells in the skin" - and each gene that creates the visual look of 'grey snake' could be doing it for a very different reason.

That's why, when you breed a Charcoal to an Anery (and neither are het for the other), you get a normal - because a gene with effect of "Can't create red pigment" from the Charcoal is counteracted by the gene of "Creates red pigment normally" from the Anery; the "Normal number of Red Pigment Cells in the Skin" that comes from the Charcoal overrides the "No red pigment cells in the skin" from the Anery....

Just like if you combined the "dominant" working as normal parts of "This car won't start because there's no petrol, but it's got a working starter motor" with "This car won't start because it has a broken starter motor, but it has a full gas tank" you'd get a car that will start - because you've got gas (from one car) and a working starter motor (from the other)!
 
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