# Is the morph colour in Corns sex linked.



## dani11983 (Mar 17, 2007)

This is bugging me now. 

I know about mendelian genetics, I teach it at A-level but does anybody know if the genes for the morph in corn snakes is located on the sex chromosomes? E.g. in people its XX for females and XY in males.

Stephen Sharp indicated that males have an extra chromosome so therefore their colouring is generally brighter. But if it is sex linked in the same way as some traits in humans then, as I understand it, surely the males only have one????

Someone help!!!!


----------



## rachel132002 (Dec 4, 2006)

Male brightness seems to only show in certain morphs such as lavenders that i've seen so i don't know really, i've never heared of extra chromosomes for males before though?


----------



## cornmorphs (Jan 28, 2005)

hypo bloods are very obvious.


----------



## dani11983 (Mar 17, 2007)

So the genes for colour are located on the sex chromosomes? And if so why are males brighter?


----------



## cornmorphs (Jan 28, 2005)

i dont go that deep scientifically i'm afraid dani


----------



## mark97r1 (Feb 9, 2007)

Snakes arn't really my thing so cant help you here. Though i would guess at not as snakes arnt supposed to be able to be visually sexed are they? This would lead me to beleve that no phyisical attributes are located on the sex chromosomes. just a guess though.
But there could be something in it.

Also correct me if im wrong, but arnt these chromosomes the same but the male 'Y' is 'missing' the 'branch' which would make it an 'X'? If this is the case the male couldnt have an extra gene on there could he? Only she could, or am i way off here? 

Sorry its been a long time since i did any chromosome genetics.

Do the 'Z' and 'X' in snakes work just the same?

Mark


----------



## dani11983 (Mar 17, 2007)

I don't usually! I studied genetics for a couple of months at uni but it wasn't applied to corns! Just flat worms and humans! Its bugging me. I just want to know!


----------



## cornmorphs (Jan 28, 2005)

nerys, or sisthico


----------



## dani11983 (Mar 17, 2007)

mark97r1 said:


> Also correct me if im wrong, but arnt these chromosomes the same but the male 'Y' is 'missing' the 'branch' which would make it an 'X'? If this is the case the male couldnt have an extra gene on there could he?


You are correct in that Y chromosomes have a bit missing. With some traits the female ends up with two genes, males one. The other was lost on the missing branch. 

However because the female has double the copies of the gene, one may be 'turned off' and not expressed so the amount proteins produced from the genes are the same in males and females.


----------



## mark97r1 (Feb 9, 2007)

dani11983 said:


> You are correct in that Y chromosomes have a bit missing. With some traits the female ends up with two genes, males one. The other was lost on the missing branch.
> 
> However because the female has double the copies of the gene, one may be 'turned off' and not expressed so the amount proteins produced from the genes are the same in males and females.


Ok, yeah i get that. Do you know if the sex chromosomes in snakes work the same way? I suppose 'Z' and 'W' amounts to the same theory. Its still just 3 and 4 'branches' at the end of the day.


----------



## dani11983 (Mar 17, 2007)

mark97r1 said:


> Ok, yeah i get that. Do you know if the sex chromosomes in snakes work the same way? I suppose 'Z' and 'W' amounts to the same theory. Its still just 3 and 4 'branches' at the end of the day.


Thats what I'm thinking too. At the end of the day we're both vertebrates so can't be that far off!!!

If I google corn snake genetics all I get is loads of stuff about crosses. 

I what to know the mechanisms of the inheritance.

I'm a geek, I know!!!


----------



## SnakeBreeder (Mar 11, 2007)

dani11983 said:


> This is bugging me now.
> I know about mendelian genetics, I teach it at A-level but does anybody know if the genes for the morph in corn snakes is located on the sex chromosomes? E.g. in people its XX for females and XY in males.
> Stephen Sharp indicated that males have an extra chromosome so therefore their colouring is generally brighter. But if it is sex linked in the same way as some traits in humans then, as I understand it, surely the males only have one????
> Someone help!!!!


Maybe I worded it wrongly. 
I am sure if you teach it as "A" level you will know more than I.
Simply I was stating the male has a "Y" chromosomes which the female does not have. They may have the same number but the female has two copies of the "X" chromosomes while the male is "x" and "Y" in people.
Apparently it is the information on Loci on chromosomes that make the difference.
In snake it is the opposite way around in that the female has "w" and "Z" chromosomes and the male has two "Z" chromosomes that produce the different sexes.
In different chromosomes the loci may not have a corresponding loci to pair with. If a trait is only on the "Z" chromosomes it will only be expressed in males as there are two copies of the "Z" chromosomes. The females single copy would not "express" the trait.
However I am not an expert in genetics, I just dabble.
Stephen.


----------



## dani11983 (Mar 17, 2007)

That makes it a little easier!!! i didn't know that females carried the two different chromosomes. 

The females must express the trait though. May be the two loci of the male in some corn morphs codes for a brighter visual morph that the females single locus.

I appologise if I mis-quoted you, Stephen. It wasn't intentional!


----------



## SnakeBreeder (Mar 11, 2007)

Hi Dani.
Sometimes a little knowledge leads me to wrong interpretations or conclusions.
I see a difference that is expressed more in one sex and think it is sex linked.
I have heard of the lighter male Lavenders from a few sources and seen brighter colors in male Opals, which are also just Lavenders, and associate the two events as a being linked.
However some of my Opals are het Caramel and this may also have something to do with the color differences.
I am only working with the offspring of one clutch, so don’t have a massive amount of observation to base it on.
: victory:
Stephen


----------



## Ssthisto (Aug 31, 2006)

There are, at this point, no TRUE 'sex linked' colour morphs (certainly, not like tortoiseshell/ginger in cats, anyway).

Yes, males tend to be brighter in colour and show MORE colour than a female of the same morph - but this isn't an absolute. I've noticed it in a sibling pair of Anery het glacier stripes that I own - the male has peachy-brown tones in his saddles and a lot more yellow than the female, who is still pretty black-and-grey.


----------



## dani11983 (Mar 17, 2007)

Ssthisto said:


> There are, at this point, no TRUE 'sex linked' colour morphs (certainly, not like tortoiseshell/ginger in cats, anyway).


Thanks for that. So female corns don't have the Barr body (condensed inactive X chromosome) in their skin cells then. 

If its not sex linked then, why is there a difference between the sexes of some morphs?


----------



## Ssthisto (Aug 31, 2006)

dani11983 said:


> Thanks for that. So female corns don't have the Barr body (condensed inactive X chromosome) in their skin cells then.
> 
> If its not sex linked then, why is there a difference between the sexes of some morphs?


Probably for the same reasons that there are differences in overall body shape - something like "females may not have some "modifiers" on the W gene that a male has on both Z genes." 

Having lighter-brighter colours within the same morph isn't necessarily quite the same as having a genuine sex linked colour pattern, a colour that ONLY occurs in one sex or the other (unless there's something abnormal).


----------



## dani11983 (Mar 17, 2007)

Thats solved it! When people on here talk about sex linked they are just pointing out generalisations between sexes of morphs. 

Its the biologist in me that naturally thought of it as 'sex linked' in the proper genetic terms.

So has anyone published any scientific journal studies on corn snake genetics?


----------

