Reptile & Amphibian Forums

Makes sense that albinoism is a recessive gene. Are there any dominant patterns/morphs?

Are there any morphs that are inherently only seen in males or females, such as calico in cats and possibly calico retics?

I have been doing the snake thing for many years and have come across two types of people. One type (thankfully the majority)is open, well-mannered, up front, and generally good person, who happens to understand and can sympathize that not everyone appreciates snakes. The other person is the scammer. We've all seen them at shows. They're in it for the buck. My question is, how can you trust at the end of the day that the snake you are getting is indeed some percentage

Trust. If you purchase 100% pair of hets you should produce on average one morph per four eggs.
The 66% and 50% can not be guaranteed as a 100% het therefore it is luck or statistical to prove them out. I am working on two projects now. I have four possible dh for snow males and five 50% het for clowns.
Be real nice if I produce a clown or snow for such a "cheap" price.
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RicK BbI

Ball Boutique,Inc.

Codom

pastel ball
red axanthic

Dom

spider
lesser platty
coral glow (might fall here)
black (another one I am not sure one)

And on the possible het thing it is always a crap shoot. You can probably trust the big breeders. But the big breeders do not produce many possible hets, besides for dbl homozygous traits (snow, caramel glow, and the ones that are sure to follow)
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Derek Affonce
DeKeAff Exotics
dekeaffexotics.com

I don't know of any sex linked mutations in ball pythons.

I'm not up on the Calico Retics, have they been proven genetic and if so how is it inherited?

With snakes the sex chromosomes are W and Z and the females are WZ and the males are ZZ. Since it's the female that has the unmatched pair it's her contribution that determines the gender of the offspring and not the father's as in humans.

Someone once told me that in humans the male Y chromosome doesn't have information on it (except in the case of some porcupine guy who's sons where all porcupine guys). I vaguely remember someone mentioning that this might be the case with one of the snake chromosomes but I don't remember the details (i.e. was it “W” or “Z” or neither).

Presumably if there where a mutation on the W chromosomes (if this is possible) then it would only be seen in females. If it were on the Z chromosome then you would probably have different rules for how it shows up in a female that can only have up to one copy vs. a male that can have either one or two copies. It might be that only male snakes could be calico.

That's really interesting. I didn't know that people were thinking there was a Barr body type effect controlling calico in retics. For those who don't know how this works, in genders where the sex chromosomes are the same, a common "strategy" is to simply turn of one copy of the chromosome, but this happens independently in different cells during development, so in some cells one copy is turned on, in others a different copy. The end result in cats say, is that some hair cells wind up developing one pignet color, while others are developing another, and you get this hodgepoge of a cat. I've never heard of this chromosome deactivation in reptiles before though. If someone has more concrete infromation on this please let me know. I know a few people who would be very interested.

Luis Bonachea
UF Department of Zoology

Sorry, I don't know much of anything about the calico retics. I think it's just that since "calico" is in the name people start thinking sex linked after the mammal examples but I don't have any information indicating that's the case. I think NERD works with calico retics so perhaps can fill us in while we are on the subject.

Calico Syrian hamsters are created similarly to calico cats, using a yellow gene on the X chromosome in combination with non sex linked genes to make black and white. Since females can have two X chromosomes they can have one with the yellow gene and one without so have spots of yellow and spots where the base black (recessive in hamsters) shows through. Throw in a white band (dominant in hamsters) or white spots (co-dominant, fatal when homologous) and you can get a calico. Since males only have one X chromosome the yellow gene ones are all yellow (seems to cover the black completely). In fact, I didn't have the eye to pick a yellow gene male since it looks like a fairly normal animal to me so the only way I found out what they looked like was when I produced some of them from a calico female to a black male.

So, back to snakes, it sounds like you are saying we can't just assume that should there be any appearance genes (or any genes at all) on the Z chromosome that male snakes (ZZ) will have this rationalization effect where when they have only one copy of the mutant Z they will show it in some places and not in others.

Does anyone happen to know if both the W and Z sex chromosomes have information on them? I was really shocked to hear that the Y chromosome doesn't (or at least not info that is used). I would like to understand more about how this absence of the information from a 2nd X chromosome creates a male in humans. I wonder if the W in snakes to create a female (WZ) is a similar thing or if both sex chromosomes in snakes are used. It would help us know what sort of things to look out for as possible sex linked genes in snakes. If a mutation was on the W it would only ever be seen on females and males could not even carry it. If it was on the Z it might be dominant in females but perhaps recessive, co-dominant, or dominant in males or even seen in spots on the males.

So I got off my butt and read the NERD page on calico retics.

Could the male calico's be a different mutation than the female ones? What was the mother of the male calico who's father was also a calico?

On theory is that the female white phase calicos could be a mutation on the W gene and if so then a mother would pass it to all of her daughters but none of her sons (no male could even be a carrier, but the daughter to daughter passing would continue indefinitely each generation regardless of what father was used).

The male retic might be a completely different line with a mutation on the Z chromosome, perhaps rationalized (displayed in some spots and not in others). In this theory the original male calico caries one copy of the mutant Z and one normal Z. He passes the mutant Z to half of his offspring (both male and female). However, it might look different in the males that get it than in the females. Perhaps the females will be all odd colored and not just in spots. Alternatively, perhaps the W has a corresponding gene that will cover it over in the females so the best you can hope for in the females is an invisible het with the ability to produce about 50% calico sons. Eventually you could breed one of those het females to a male line calico male and produce a 25% chance male homozygous for the mutant Z (both of his Z genes having the male line calico mutation). Maybe this snake would be all white or whatever color the spots are in the male line calico and all of his sons would be calicos and all of his daughter’s carriers.

>Does anyone happen to know if both the W and Z sex chromosomes have information on them? I was really shocked to hear that the Y chromosome doesn't (or at least not info that is used). I would like to understand more about how this absence of the information from a 2nd X chromosome creates a male in humans. I wonder if the W in snakes to create a female (WZ) is a similar thing or if both sex chromosomes in snakes are used. It would help us know what sort of things to look out for as possible sex linked genes in snakes. If a mutation was on the W it would only ever be seen on females and males could not even carry it. If it was on the Z it might be dominant in females but perhaps recessive, codominant, or dominant in males or even seen in spots on the males.

From what I've found, boa constrictors (maybe all Boidae) do not have different sized sex chromosomes. Colubrids do have different sized Z and W chromosomes, but the W isn't as small as the mammalian Y chromosome. And there was an article on the evolution of the Y chromosome in Scientific American in the last few years. As I recall, it said that there was originally information on the Y chromosome that was slowly lost over millions of years. So I'd assume that there could be information on snake W chromosomes.

My impression is that the mammalian Y chromosome is required to make a male. As I recall, an X human is a poorly developed female, XY is male, and XXY is also male.

Birds have a large Z and small W sex chromosomes. A male is ZZ, and a female is ZW. My understanding is that sex is additive in birds, with one Z producing a female and ZZ producing a male.

The only possible candidate I know of for a sexlinked mutant in snakes is brindle in the black rat snake. And that hasn't been proven to my satisfaction.

I've messed around a little with genetics of pigeons and ringneck doves. Both have sexlinked mutants on the Z chromosome. Pigeons, for example, have three alleles at the b locus. In males, the mutant brown is recessive to both ash red and normal, and the mutant ash red is dominant to both normal and brown. A male pigeon that has an ash red mutant gene paired with a normal gene is just ash red, not with patches of ash red and patches of normal coloration. And we can tell what the female's genotype is at the b locus from her appearance. If snake sexlinkage is analogous to pigeon sexlinkage, a sexlinked mutant could be dominant, codominant, or recessive to normal in a male snake. And I'm not expecting an analog of calico in snakes.

BTW, here's another bit of genetics terminology: hemizygous. It means that a gene is present on one chromosome but has no match on the other chromosome. So a brown female pigeon is hemizygous brown because it has only the one brown gene on the Z chromosome and no match on the W chromosome.

Paul Hollander

Aww my heart sank a little when i read that. I had been hearing that only male retics showed calico. Couple that with the fact that theyre the homogametic sex and no two calicos seem to be same, it was a good recipe for a possible deactivation complex.

And as far as how much and what information is on the W, it seems to be highly variable. Some species seem to have nearly identical W and Z. Some seem to have a tiny W. It varies. I think there was a post in the is thread about the theory that W is just a degenerated form of the z chromosome that has gone losing genetic information through evolutionary time. I wonder if some of these Uropeltids tend to be the ones that have near equal sized chroms.

Its nice to see a lot of academic discussion here to. Ive noticed that often times, people in academia can learn so much about the natural history of reptiles from husbandrists and vice versa.
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