Sex-linked Genetics

[Sally]

I decided to do a thread on sex-linked genetics and make it a sticky. There are often questions about what results to expect with this type breeding, and this will give you an idea of what to expect. Remember that the percentages listed are just a guide--these percentages were the result of studying a large number of birds, so our one clutch will not have these exact results. However, it will help you in setting up breeding pairs when aiming for a certain result--i.e. if you are trying to produce mutation males, this will help you in reaching that result. Remember that mutation to mutation is the worst possible pairing you can make, resulting in possible defects.

This chart can be used for those breeding fawn Owls, fawn Shaft-tails, fawn Cherry finches, Yellow-faced Stars--any sex-linked mutation. This chart has nothing to do with Gouldian genetics. And I know nothing about Zebra genetics, so I have no idea how this might apply.

SEX-LINKED GENETICS

Male normal + Female mutation gives you
normal split males 100%
normal females 100%

Male normal split + Female normal gives you
normal males 50%
normal split males 50%
normal females 50%
mutation females 50%

Male normal split + Female mutation gives you
mutation males 50%
normal split males 50%
mutation females 50%
normal females 50%

Male mutation + Female normal gives you
normal split males 100%
mutation females 100%

Male mutation + Female mutation gives you
mutation males 100%
mutation females 100%
This is not a good pairing because the birds go down in size, color, health, and could even have defects. One breeder in NFSS posted that he got blind babies from this pairing.

I forgot to add my thanks to rayray for getting this information for me from some of the fawn mutation breeders in Europe.

[L in Ontario]

Great post/sticky, Sally! Straight forward and easy (for me) to understand information.

I believe you can add the Blue-faced & Lutino Blue-faced Parrot Finches to the list as well. Not sure about the Red-throated and Seagreen Parrot Finches or the Forbes. Probably all in the same family...?

[finchmix22]

Great Sticky Sally! Thanks. Now, I can refer to this when I'm breeding my Owls or Stars.

[cindy]

It works the same for zebras...the sex linked are fawn, lightback and CFW. Females are only visual, do not carry the gene but give split to the mutation males. The mutation to mutation (last one listed) it does not make weak babies or blind babies in zebras.

[Sally]

I think the mutation to mutation breeding is bad when it is a new mutation, as new mutations are almost always weaker than normals anyway, so breeding mutation to mutation then just increases the tendency towards problems. As mutations become stronger, then it would probably be alright to breed mutation to mutation one time, then outcross the babies with normals.

Before I knew anything about sex-linked mutations, I was breeding a YF Star male to a YF Star female, and all the babies were just fine. I then sold all of them to a friend, who outcrossed with normals, and she had great success with the YF Stars.

[finchmix22]

O.K. on another thread someone posted that the female finch only has one sex chromosome and the male has two, which is the opposite of human genetics. Is this correct? If so, how do we chart the genetic pairing and offspring? For example, I would normally use XY for male and XX for female, as I learned in biology in school. I read finch genetics is written as ZX for female and XX for male? I am confused by this different labeling. So, for a mutation that is sex linked, are they all on the female sex chromosome? Is that for all finches or just certain species?
Sorry for all these questions, but I really want to understand this finch genetics.

[Sally]

I am fairly clueless when it comes to genetics, but there is a brief article at the FIC. See if this helps answer any of your questions.

http://www.finchinfo.com/genetics/definitions.php

[finchmix22]

I found out that all bird species have the ZX and XX genetic, but the male is the one with the XX and the hen is the ZX, go figure!! So, that makes bird genetics confusing.

[debbie276]

I believe the male birds are ZZ and females ZW

[SandyinLargoFL]

Yes, bird genetics are the opposite of humans. It really doesn't matter what letters you use so long as you remember that. 20 yes ago when I was breeding cockatiels, I had a program that would track my birds and give me all the possible outcomes of the pairings. Does anyone know if something like this is available for finches?

[Fahim_147]

I paired my fawn diamondfiretail female with a white male..
I got 1fawn baby n 2 normal..As male is white n female fawn I didn't expect normal baby..can anyone explain what could be the reason for normal colour baby ? TIA

[Sally]

I'm not sure about genetics with Diamond Firetails. wildbill works extensively with this species, so maybe he can help.

[Smurf]

Fahim_147 , for you to have got a fawn youngster from your pair then the white father is split for fawn, on average your pair should produce 50% fawns and 50% normals with all youngsters being split for white and the normal cocks also being split for fawn.

White (split fawn) Cock x Fawn Hen (your pair) gives
25% normal (split fawn+white) cocks
25% Fawn (split white) cocks
25% normal (split white) hens
25% fawn (split white) hens

White is autosomal recessive inheritance which works different to fawn which is sex linked inheritance, split means bird is visualy one colour but carrying hidden genes for another colour

[Fahim_147]

Thanks a lot Smurf I forgot to mention that they broke their first egg maybe that was also a fawn..thanks again

[wildbill]

true -the normal cock bird you have is spit/fawn. that is what they don't like about birds here in oz now. visually they look normal but with these hidden gene factors -what appears to be of pure stock at times is not the case.
enjoy the breeding -very easy to breed