gouldian question

isabella · Post by **isabella** » Sat May 12, 2007 12:59 pm

hello
I have a complicated question and also i am new to owning gouldians so please bear with any words that dont suit.
Ok currently i have a young gouldian hen, she is i think a double mutation, her coloring is yellow body, yellow wings and underside, yellow & a light grey to white head, she alos has a lilac or purple breast.
I have come across a breeder who has exactly the same in a cock bird but tells me if i buy the cock bird and the two exact colors eventually breed that the chicks that are hens will not live. Thus i am saying this colour of gouldian finch will only produce cock birds, would you agree with this or have you heard this before as i do not want to make the mistake of buying this cock bid. Thankyou and i would appreciate any help.
warm regards
isabella

Crystal · Post by **Crystal** » Sat May 12, 2007 11:30 pm

I know Australia has a few different mutations than we have in the US, so this might not apply to your situation, but none of the mutations I am aware of in the states are lethal in hens. You are likely to have greater losses overall when breeding mutation to mutation as the birds tend to be more inbred and the chicks tend to be a little weaker, but so far I haven't encountered a color mutation which is lethal every time.

I guess the one question I would pose to you is: if your hen and the cock you are considering breeding to are the same mutation, but the mutation can only produce live cocks, how do you have a live hen of that mutation?

If you have a picture of your hen, I could look up more information for you, too.

isabella · Post by **isabella** » Sun May 13, 2007 1:23 pm

hello
Yes!! I have been thinking about that question too-how could the breeder that sold me the hen have the hens, so i had my husband call him and after a long conversation it diesnt seem to be true, in fact the original breeder told us that some breeders tell you this to up the price of their own birds-and the advice i received about not producing hens was from another breeder we went to look at to buy another pair of gouldians). So i guess it isnt true but time will tell and since they are only young i dont want to breed them quite yet-but it is sad that i was told this just to get a few more dollars out of me. BTW i dont have a picture of them yet.

Thalia · Post by **Thalia** » Sun May 13, 2007 3:36 pm

I don't know anything about goulds, but I did take some genetics in university. I'd say the guy is trying to swindle you. If the hens produced from pairs of the same colours are lethal then that would indicate that the trait is sex linked, since it is the sex of the bird that determines lethality. However since female birds have 2 different sex genes ZW and it's the males that have two of the same ZZ, then the guy is still wrong, it'd be the males that would be double dose lethal.
So I suppose it could work the same way the manx gene in cats works, one gene gives a shortened tail but two is lethal, however these kittens with two of the genes die in utero.
In theory if the trait is dominant and your hen is unizygous (one gene for that colour since she can only have 1 sex gene) for the trait (according to the guy she'd have to be) and your male only has one copy since he's alive, then you would end up with half the females looking like mom and dad, half would display the colour dad's carrying and all the males would be heterozygous for that colour because the double dose is lethal. Basically, even if the trait is lethal when present on both sex chromosomes not all the males would die, only half of them.
(edited to correct chromosome configuration)

Crystal · Post by **Crystal** » Mon May 14, 2007 3:13 am

Thalia, bird genetics is the 'opposite' of mammalian genetics in that the Male carries two copies of the sex chromosomes (ZZ or "XX") and the female/hen carries only one copy (ZW or "XY").

Thalia · Post by **Thalia** » Tue May 15, 2007 10:32 am

Oh darn it! I knew that something wasn't adding up about what he was telling her. Then he's definitely full of it, since it'd be the males that would be double dose lethal.

LOL I guess I have my genetics stuff down, just not my biology, some vet I'll make

I do know that birds and some reptiles are backwards from mammals, my brain just wasn't fully functional that day lol.

Crystal · Post by **Crystal** » Tue May 15, 2007 10:46 am

It's an easy mix up to make! Especially since emphasis is usually placed on mammalian genetics during biology classes, etc.

Thalia · Post by **Thalia** » Tue May 15, 2007 10:59 am

I bet the guy doesn't know that females are ZW and Males are ZZ, I bet that's why he said that females will die... Well at least we've established that the guy is definitely trying to pull one over on you isabel!
I'll go edit my post now so it makes more sense lol