Breeding Zebras - unexpected results

[Finchy123]

Hi,

I recently purchased a number of Zebra Finches after about 10 years of not having any pet birds. The colours I bought are as follows:

2 x OB Fawn males
1 x OB Fawn female
1 x Fawn female
1 x CFW male
1 x CFW female

I keep them in an aviary, so it was to be expected that there would no control over pairing. They all paired off immediately, and started nesting straight away.

Pair 1: OB Fawn Male + Fawn Female
Offspring: 2 x Fawn males, 2 x CFW females

Pair 2: OB Fawn Male + CFW Female
Offspring: 1 x CFW Male

Pair 3: CFW Male + OB Fawn Female
Offspring: 1 x Normal Grey Male

I'm not too sure how Zebra Finch genetics work, but I was surprised to get CFW babies from the Fawn pairing (Pair 1) and a NG male from Pair 3.

Can someone who understands Zebra Finch genetics explain how I could get these results? I suspect due to the lack of control in an aviary setting, that my male CFW has been a bit promiscuous with all the females!

[cindy]

Fawn and CFW are sex linked, males can be split to fawn and split to CFW... they can also carry both mutations http://www.efinch.com/species/cfwzeb.htm

"The combination with fawn requires a genetic phenomenon known as crossing over to occur before CFW and Fawn can be combined. Crossing over is a random occurrence so one cannot predict how long, if ever, before the combination will occur. Fawn-CFWs look similar to gray series CFWs, but all the black markings will be dark brown instead. Once combined the two mutations are linked and will act as one. Some sources have erroneously indicated that the Continental CFW was a combination of CFW and Fawn. This error is probably due to a belief that the cream cast to the back was caused by the Fawn mutation rather than the new mutation. There is also some evidence that points to a modifier gene that causes a cream cast to the back of Regular CFWs that is more commonly seen in CFW-Fawns. Again, this should not be confused with the Continental CFW mutation."

If you want specific results from your zebras breed select pairs in cages only

[Sally]

I don't know anything about Zebra genetics, but I wanted to welcome you to the forum! There's lots of good reading at www.finchinfo.com, where you will find many articles on breeding, housing, and especially the Zebra finch. If you put your general location in your profile, it makes it easier to answer locale-specific questions later on.

[jamezyboo21]

Welcome to the forum! I don't know anything bout genetics

[lovezebs]

Finchy123

Welcome to the Forum, and congratulations on new babies.
Cindy, can explain Zebra genetics very well.

We are all looking forward to getting to know both you and your birdlings. Would love to hear about what brought you back to Finches, and to see some pictures of your Zebbie crew.

Best wishes.

~Elana~

[Aspen]

Like Cindy said, both CFW and fawn are sex linked - the females only have one gene so they have to show what they have. The male has two genes so they can carry either of these mutation (and lightback as well) and not show them. (These mutations are recessive as well as being sex linked, so males can be carriers and not show it. You can have dominant sex-linked mutations, where the males would show it but carry a normal gene as well, but I can't think of a mutation of this type in zebra finches.)

So here's a more detailed explanation of the cause of your results.

Pair 1: OB Fawn Male + Fawn Female
Offspring: 2 x Fawn males, 2 x CFW females
The male has to carry CFW. He could have given you fawn females as well, 50/50 chance, but you happened to get two CFWs. The two males look fawn because they got fawn genes from both parents, but they have a 50/50 chance of carrying CFW. No way to know until they have chicks of their own.

Pair 2: OB Fawn Male + CFW Female
Offspring: 1 x CFW Male
This male also has to carry CFW because a male has to have two CFW genes (one from each parent) to show that mutation. You had a 50/50 chance of having a fawn or a CFW male.

Pair 3: CFW Male + OB Fawn Female
Offspring: 1 x Normal Grey Male
This one gets more complicated. While both CFW and fawn are sex linked (so same chromosome), they are different genes. This baby carries a fawn gene from mom, but only one, so he doesn't show fawn. (Dad must be from the grey line or else the baby would be fawn.) The baby also carries a CFW gene from dad, but only one, so he doesn't show CFW. The corresponding genes of these two mutations are normal - so he looks NG. However, all his female chicks will be either fawn or CFW (50/50 chance) as he doesn't have one normal sex chromosome - unless crossing over occurs, as Cindy's quote says, but that is uncommon and complicated. This situation isn't as uncommon as might be thought. I have a NG male gives fawn and lightback females.

Hope this explains it a bit.

Or - maybe the chicks aren't really from the fathers that look to be paired up. That's also a possibility...

[Colt]

Zebra genetics confuses me immensely, but I would also say there is a chance that the hens laid eggs in multiple nests. It certainly isn't unheard of so it is possible that some of the unexpected babies are from different parents. To be sure you'd want to isolate the pairs to be sure. Also some birds will mate with multiple individuals so one clutch may have different fathers if the eggs did indeed all come from hen.