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  Basic genetics
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  Post new topic   This topic is locked: you cannot edit posts or make replies. The United Peafowl Association - www.peafowl.org Forum Index » Breeding and Genetics     
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peahen52
UPA MEMBER
UPA MEMBER


Joined: 30 Oct 2007
Posts: 9
Location: Kansas
PostPosted: Fri Feb 01, 2008 6:39 pm Reply with quote

I have been asked by our moderator, Kat, to "teach" a very elementary genetics class. This will be an on-going column, solely to help the very new breeders. There are no dumb questions, so if you read something you don't understand, please don't hesitate to ask. We'll begin with the bird most people are familiar with--the India blue. In the following matings, it doesn't matter which color bird is the male or female.
Blue bred to white: all chicks will be blue, usually with a white wing feather
Blue bred to pied: same as above, but chicks will be split to pied. This means the chicks are carrying the pied gene.
Blue bred to blackshoulder: I sound like a stuck record. All chicks are blue, again carrying the blackshoulder gene. In simple terms, blue is dominant--meaning it will win no matter what you throw at it. The exception to this rule is the sex-linked colors. If, for example, you breed a blue cock to a cameo hen, all chicks will be blue. The male offspring will carry the cameo gene--female chicks will not. If you reverse this mating, and breed a cameo cock to a blue hen, then you will get cameo colored hens, and blue male chicks carrying the cameo gene. This is the same law that will apply to purple and peach, whether in a barred-wing pattern, or the blackshoulder pattern.
Genetics is not an exact science, and since most of us don't have documentation into our birds' backgrounds for the last six generations, there can always be something unexpected turn up. For the purpose of this forum, however, I am trying to deal in probabilities, only. Please don't email me with stories about having a pied chick with only one pied parent. It's happened to me, also, but, again, I'm trying to play the odds here. The whiteeye gene seems to be one that can sometimes overtake the dominant blue gene. This means that if you have one parent that is carrying a strong enough whiteeye gene, and the other parent carries none, you can still have whiteeye chicks. For those of you unsure of what the whiteeye gene is, I'll elaborate. This is another pattern variety that can be put on all the colors we now have. It generally shows up as a white throatlatch, a white wing feather, and "snowflakes" on the back. In a "good" whiteeye male, most of the eyes in his tail will be white in the center of the eye. This is quite striking when he struts. The back of the hens will have an overall gray cast. For education purposes, let's say you have decided you want a bronze whiteeye. How will you do that? (If you answered, go buy one, you're learning!) No, just kidding. You're going to start by breeding a bronze to a blue whiteeye. If the whiteeyed gene is strong enough, then the chicks should all be blue whiteeyes--SPLIT to (remember--carrying the gene) bronze. Even if it doesn't show up, the chicks are still carrying both the whiteeye and bronze gene, but look like a blue bird. This is why record keepiing is very important. In two years, if you take one of those chicks and breed back to the bronze parent (this is an example--don't start yelling about inbreeding), then you will still have some blue chicks, some blue whiteeye chicks, and, hopefully, some bronze whiteeyes. This is the conclusion of this lesson. I will try and cover some of the other patterns in future discussions. If there is something you would like to see next, let me know. Thanks, Gwen Hibler, UPA President
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Kevin
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Joined: 01 Nov 2007
Posts: 196
Location: Riverside, CA
PostPosted: Sat Feb 02, 2008 3:32 am Reply with quote

This is a good idea. I do have some comments, unfortunately they don't agree with you but we are all here to learn and discuss, right?

Blue is not dominant, nor is it a gene. It is the whole genotype(genetic make up) of the Indian Blue, the wild type for Indian peafowl.

How to determine a mutant is dominant, recessive or "in-between" which has several terms, a commonly used one is Co-dominant.. is to breed a mutant to a wild type of the same species. From a mating to a wild type, if the mutant gene does not express itself in any way in the offspring, it gets the Recessive label. If it completely expresses itself, masking all(or nearly so) expression of the wild type, it gets the Dominant label. If it shows visibly but not quite completely yet expresses itself completely in a homozygote(pure) then it gets the Co-dominant label.

For example, Black shoulder is a mutant found in Indian peafowl. To determine if it is recessive, dominant or co-dominant is to breed a Black shoulder to a pure Blue, because Blue is the wild type for this species. We already know the result is 100% Blue looking birds. This proves BS is recessive so it gets that label. This is not a matter of "Blue gene dominanting BS gene" because there is no such thing as a "Blue gene".. the only specific thing is the BS mutant gene that somehow affects a single specific part of the Blue genotype.

The sex linked genes known so far in peafowl still get the Recessive label for this reason.. but the breeding results also prove they are a sex linked gene. So Purple is labeled "properly" as a Recessive Sex Linked mutant, nothing more.

White eyed isn't "strong or weak", it has what's called "variable penetrance" which means the physical expression of the gene varies from bird to bird, with the reasons for such variety in appearance being unknown.

It's mostly a coincidence that so far all mutants proved to be recessive in Indian peafowl, with the exception of possibly white eyed and white. White is an interesting one.. it seems to be mostly considered "co-dominant" however people regularly speak of "split white" which is exactly how you speak of a recessive gene.

Give a lot of time and many many more birds, someday a dominant mutant WILL show up. Unfortunately, peafowl, compared to other birds and some domestics are rather slow to breed and don't exactly breed in huge numbers, require a lot of room and most people cannot or want to keep them so the occurrence and discovery of a new mutant in peafowl is always going to be on the low side.

I say genetics really isn't a hazy mystery for the most part.. yes it is a challenging,seemingly overly complicated subject for many(I don't pretend to understand all of it myself).. actually genetics in peafowl are pretty straightforward and simple compared to genetics in other animals- because they are few in number and have rather clear cut and already well-known inheritance patterns for the most part(silver pied and peach seem to be not too well understood). Peafowl actually could be a good starter lesson in understanding genetics.

Birds suddenly showing up with X to me just gives me more information about that bird and its lineage. That can be a very valuable understanding/information. Like last season I hatched two black shoulder spalding chicks which was a total surprise to me as I'd bred some of them for several generations with no black shoulders or known splits but that information tells me there are at least two split birds(unfortunately these eggs hatched when I was not home, didn't get to note whose eggs they hatched from..). But if I find out exactly who produces the BS chicks, it might be possible for me to figure out which ancestors were splits or likely splits.
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connerhills
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Joined: 31 Oct 2007
Posts: 368
Location: Mo.
PostPosted: Wed Mar 17, 2010 3:23 pm Reply with quote

Kevin,, as you can see there has been no input on the thread for over 2 yrs.. Would you be willing to start and continue posting info on genetics? As there are always new people showing up that would appreciate your help and info and here would be a good place to find it.. thanks George A Conner
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