Peafowl Genetics for Dummies (in other words us)

[AugeredIn]

Yep, thats easier.

 

[Rosa moschata]

OK, I'm back.

First, I want to add how to properly use the term "split". What you see you write down first, then "split", then anything that the pea has but only as one copy. With incompletely- or partially-dominant mutations, "split" birds can show some effects of having one copy of the gene, but the "normal" India Blue type will also show through. But in recessive birds, you can't tell just by looking. Thus a pea that looks like a regular India Blue but carries a copy of Bronze will thus be properly termed "India Blue split to Bronze". This means you "see" India Blue, but don't "see" Bronze. Saying "Bronze split to India Blue" is incorrect, because if there is one copy of the "normal" version of the gene, you will "see" the "normal" India Blue coloration.

Remember how I said that Pied and White are different mutated versions of the same gene? That means that a White bird can't be "split" for Pied, and a Dark Pied bird can't be "split" for White. Why is this? Chromosomes come in like-pairs (except for Z and W, which are different but pair up in females). This means that a bird can have either two copies of the same version of a gene, or one of each of two different versions. Pied and White being two different versions of the same gene (the third version is the "normal" version), then a bird can be one of the following possibilities:

2 copies "normal" = India Blue
1 copy "normal" and 1 copy Pied = India Blue split to Pied
1 copy "normal" and 1 copy White = India Blue split to White (note that this and the previous one will look rather similar in real-life)
2 copies Pied = Dark Pied
2 copies White = White
1 copy White and 1 copy Pied = Pied

Note that in each case, the total number of copies = 2. We can't have an India Blue split to White and Pied because that would = 3. Similarly, Whites can't be split to Pied, and Dark Pieds can't be split to White. And Dark Pied, White and Pied do not have a "normal" version of the gene at all -- thus even if bred to a pure "normal" India Blue, these last three will have offspring which are split to Pied or split to White.

< Note -- for those who are familiar with other species, you may think "but my ducks can be split to White AND Pied..." but in those cases, Pied and White are NOT alleles -- they are mutations of DIFFERENT genes. >

How does that work? Remember, chromosomes are maintained as pairs in peas (and all other diploid organisms). When sperm and eggs are produced, only one of each pair gets passed on. Which one will be random. And this is where we get the percentages given when crossing different mutations -- they are based on probabilities. A peacock which is called Pied will have half of his sperm carrying the chromosome with the Pied version of the gene, and the other half of his sperm will carry the chromosome with the White version of the gene. Pied peahens will similarly produce eggs that are either carrying Pied or White in equal probabilities. If you look up a Punnett Square, you'll see that this chart shows how to figure out the probabilities of offspring from these crosses. And that's how you get the 1:2:1 ratio of Dark Pied : Pied : White -- a chick has a 25% chance of getting the Pied version from Dad AND the Pied version from Mom; a chick has a 50% chance of getting Pied from one parent and White from the other (since this can happen either way -- Dad/White + Mom/Pied, or Dad/Pied + Mom/White); and a chick has a 25% chance of getting the White version from Dad AND the White version from Mom.




OK, so what about different mutations that AREN'T alleles? This means that these deviations from the "normal" versions are of different genes. Thus a pea CAN be split to two different non-allele mutations -- or even SHOW two different non-allele mutations. We already see this -- as an example, consider a Bronze Blackshoulder. Such a pea will have two copies of the Bronze version (and thus no copies of the "normal" version) of ONE gene, and two copies of the Blackshoulder version (and thus no copies of the "normal version) of ANOTHER gene.

How would one go about putting that together? Well, let's start with a Bronze peacock with "normal" barred wings, and a Blackshoulder peahen with "normal" India Blue coloration. The peacock has two copies of the mutated Bronze version of that particular gene, and two copies of the "normal" version of the barred wing gene. The peahen has two copies of the "normal" India Blue version of the "Bronze" gene, and two copies of the mutated Blackshoulder version of the wing pattern gene. Since neither are "splits", their respective sperm/eggs can pass on only one "version" of each respective gene.

The Bronze barred-wing peacock passes on Bronze and barred wing. The IB Blackshoulder peahen passes on "normal" IB color and Blackshoulder wing pattern. The result? All offspring will be split for both -- they will "look" like regular barred-wing IBs, but each will have one copy of each of the mutated versions of the Bronze and Blackshoulder genes.

So it sounds like crossing these two is pointless, right? We don't have any Bronze Blackshoulder peafowl from this first cross. Well, these cases require what's called a "dihybrid cross" -- there are two different mutations we are considering when crossing these peafowl. In order to get Dad's color to be seen with Mom's wing pattern, we need to get to cross their offspring together (or, to avoid inbreeding, one could set up two unrelated pairs consisting of the same cross, and then cross the offspring from the different pairs) to get peas with two copies of each mutated gene in order to "show" both mutations. In basic Mendelian genetics, how this happens is referred to as "independent assortment" and would be worth looking up if this step isn't clear the way I'm explaining it.

OK, so let's look at the offspring from the Bronze Dad and the Blackshoulder Mom. They'd be called IB split to Bronze and Blackshoulder. Being splits, their sperm and eggs can carry either the "normal" OR "mutated" version of each gene. The "independent assortment" part refers to the genes which occur on different chromosomes, and thus don't "travel together" (linked genes are those which DO occur on the same chromosome, but at different parts -- that's another lesson for next time). So while the "normal" India Blue color came along with the Blackshoulder wing pattern from Mom, they don't have to "travel together" in her daughters' eggs or her sons' sperm -- they can "independently assort" into new combinations with what Dad passed on. And this is where the fun part of breeding happens.

Sons and daughters of the original pair will thus make sperm and eggs (respectively) which can carry one copy each of either:

(A) India Blue color with barred wing
(B) India Blue color with Blackshoulder
(C) Bronze color with barred wing
(D) Bronze color with Blackshoulder

Each has an equal probability in sperm and egg. So when we figure out what you get when sperm and egg meet, we get the following combinations, each pair with an equal probability of occurring:

AA
AB
AC
AD

BA
BB
BC
BD

CA
CB
CC
CD

DA
DB
DC
DD



Remembering back about recessive mutations needing two copies to "show", we'll see that the only Bronze Blackshoulder peafowl will be those that get two copies of each mutation -- one each from each parent. Anytime there's a "normal" version for either gene, the "normal" variation will be seen -- barred wing pattern or India Blue color. So let's repeat the list of possibilities and add what they represent with respect to which version of each gene will be had, and after the = will be how to term what we see.


AA = 2 copies IB color + 2 copies barred wing = IB barred wing
AB = 2 copies IB color + 1 copy barred wing + 1 copy Blackshoulder = IB barred wing split to Blackshoulder
AC = 1 copy IB color + 1 copy Bronze color + 2 copies barred wing = IB barred wing split to Bronze
AD = 1 copy IB color + 1 copy Bronze color + 1 copy barred wing + 1 copy Blackshoulder pattern = IB barred wing split to Bronze and Blackshoulder

< Before I continue, note one thing -- if you see AB, it will be the same as BA. The same goes for AC and CA, AD and DA, etc. You'll also see the same results from other combinations. But I'll continue, even if it seems repetitive -- you'll see why in the end, if you can follow along. >

BA = 2 copies IB color + 1 copy barred wing + 1 copy Blackshoulder = IB barred wing split to Blackshoulder
BB = 2 copies IB color + 2 copies Blackshoulder = IB Blackshoulder
BC = 1 copy IB color + 1 copy Bronze color + 1 copy barred wing + 1 copy Blackshoulder = IB barred wing split to Bronze and Blackshoulder
BD = 1 copy IB color + 1 copy Bronze + 2 copies Blackshoulder = IB Blackshoulder split to Bronze

CA = 1 copy IB color + 1 copy Bronze color + 2 copies barred wing = IB barred wing split to Bronze
CB = 1 copy IB color + 1 copy Bronze color + 1 copy barred wing + 1 copy Blackshoulder = IB barred wing split to Bronze and Blackshoulder
CC = 2 copies Bronze color + 2 copies barred wing = Bronze barred wing
CD = 2 copies Bronze color + 1 copy barred wing + 1 copy Blackshoulder = Bronze barred wing split to Blackshoulder

DA = 1 copy IB color + 1 copy Bronze color + 1 copy barred wing + 1 copy Blackshoulder pattern = IB barred wing split to Bronze and Blackshoulder
DB = 1 copy IB color + 1 copy Bronze + 2 copies Blackshoulder = IB Blackshoulder split to Bronze
DC = 2 copies Bronze color + 1 copy barred wing + 1 copy Blackshoulder = Bronze barred wing split to Blackshoulder
DD = 2 copies Bronze color + 2 copies Blackshoulder = Bronze Blackshoulder



WHEW!!!! Kind of exhausting, isn't it? This is why it becomes easier to use genetic calculators when trying to determine probabilities beyond monohybrid (i.e. crosses involving only one gene -- "normal" versus "mutated" -- as opposed to di- or tri-hybrid, or more). But as an exercise, let's see what we actually get, and how many times we get each:

IB barred wing = 1
Bronze barred wing = 1
IB barred wing split to Blackshoulder = 2
IB Blackshoulder split to Bronze = 2
IB barred wing split to Bronze and Blackshoulder = 4
IB barred wing split to Bronze = 2
Bronze barred wing split to Blackshoulder = 2
IB Blackshoulder = 1
Bronze Blackshoulder = 1


Remember the 1:2:1 ratio with Pied X Pied? Think of that as 2 X 2 = 4, but 2 of the 4 are the same result appearing twice, thus giving 1:2:1 (otherwise known as 25%, 50%, 25%). When we cross birds with two different mutated genes, and then cross the offspring, we're moving up to 4 X 4 = 16, but once again, some results appear more than once. Now, instead of 1:2:1, we have 1:1:2:2:4:2:2:1:1. I know, the numbers are getting crazy, and again, this is why genetic calculators come in handy.

You'll see that getting a Bronze Blackshoulder in the grandchildren of the original pair has only a 1/16 chance of occurring, the rest being mostly various combinations of splits. If that's disconcerting, here's something worse -- most of the offspring will LOOK like "regular" IB barred wings. Huh? But isn't that only 1/16 as well? Right -- as far as GENOTYPES go, yes, only 1/16 will be PURE IB barred wing, not split to anything else. But many others will LOOK IB barred wing, being split to other stuff. The tricky part is that the IB barred wing will look the same as the IB barred wing split to Bronze, and the same as the IB barred wing split to Blackshoulder, and the same as the IB barred wing split to Bronze and Blackshoulder. So while as far as GENOTYPE, you'll have only 1/16 IB barred wing and split to nothing else, other GENOTPYES will look the same. And that's why I colored the text -- same color text means these will LOOK the same in "real life" (i.e. PHENOTYPE) despite their different GENOTYPES.

< Note -- males split to Blackshoulder will develop some dark feathers on their wings over time, but still ALSO display the barred wing pattern, so in males, IB appears to be an incompletely- or partially-dominant trait. >

So let's see how the PHENOTYPES add up:

Peas that look like "normal" IB barred wing = 9/16
Peas that look like IB Blackshoulder = 3/16
Peas that look like Bronze barred wing = 3/16
Peas that look like Bronze Blackshoulder = 1/16


OK, I know that for some this may seem overwhelming, but trust me -- once you get the basic concepts down, you will be able to answer all your "what do I get if I cross this with that?" questions yourself. It's like learning how to use a new tool. And remember that any term or concept still unclear can simply be googled. There's also plenty of videos on YouTube providing better visual examples of how to figure out basic Mendelian genetics. It's far easier in the long term to invest some short term learning than to try and "reinvent the wheel" to explain how it works using inaccurate terms and definitions which will reduce the accuracy of your predictions of future offspring from controlled pairings.

Next time, I'll go over how the sex-linked mutations work, and how, too, they can be combined with the non-sex-linked AND with other sex-linked mutations.

 

[AugeredIn]

Well, at least you got the answer right.

 

[Arbor]

Next time, I'll go over how the sex-linked mutations work, and how, too, they can be combined with the non-sex-linked AND with other sex-linked mutations.

Ok, I'm jumping ahead into you next topic, so is there a possibility of two sex-linked traits being passed on to the offspring at the same time without crossover? It's been suggested and discussed before that the peach colour is the result of a crossover in the genes of a male split to purple and cameo, is this the same case with cinnamon-pearl in cockatiels?

On a separate note, it has also been suggested that taupe is a combination of Opal and purple. If this is the case, this would mean that it's a partial sex-linked combination, meaning you should be able to hatch out more taupe hens by breeding a taupe male to any hen that carries at least one Opal gene. I challenge anyone with the colour to attempt this. The best hen choice would be an opal hen, which should produce all taupe hens. I think that it is very important to keep the facts in the open, as it will help create a more genetically diversified population if it's a combined effort between more than one breeder. I understand many peoples views on "how the first breeder had put in a lot of time and done a lot of work to achieve this", but to prevent inbreeding problems, after the first couple years, getting others to repeat the same thing with separate lines is only beneficial. I'm currently working on at least 1/2 dozen combinations not yet available in the market. Info on breeding will be available as soon as I manage to produce adult birds in these combinations, reason being is I need to make sure that they are going to be different enough to make it worth the while for others to do the same. My only fear is that many combinations will look like washed out versions of their parents (or each other), and not different enough for most people to care. Sorry to veer this...

 

[connerhills]

Rosa , I would be interested in your opinion on silver pied and how they were made.. I don't think you can make a real silver pied without the silver pied gene, which is a gene mutated out of the first white eye developed as the breeder was trying to make a white bird with dark eye. Your thought when you have time. connerhills

 

[Rosa moschata]

Ok, I'm jumping ahead into you next topic, so is there a possibility of two sex-linked traits being passed on to the offspring at the same time without crossover? It's been suggested and discussed before that the peach colour is the result of a crossover in the genes of a male split to purple and cameo, is this the same case with cinnamon-pearl in cockatiels?

On a separate note, it has also been suggested that taupe is a combination of Opal and purple. If this is the case, this would mean that it's a partial sex-linked combination, meaning you should be able to hatch out more taupe hens by breeding a taupe male to any hen that carries at least one Opal gene. I challenge anyone with the colour to attempt this. The best hen choice would be an opal hen, which should produce all taupe hens. I think that it is very important to keep the facts in the open, as it will help create a more genetically diversified population if it's a combined effort between more than one breeder. I understand many peoples views on "how the first breeder had put in a lot of time and done a lot of work to achieve this", but to prevent inbreeding problems, after the first couple years, getting others to repeat the same thing with separate lines is only beneficial. I'm currently working on at least 1/2 dozen combinations not yet available in the market. Info on breeding will be available as soon as I manage to produce adult birds in these combinations, reason being is I need to make sure that they are going to be different enough to make it worth the while for others to do the same. My only fear is that many combinations will look like washed out versions of their parents (or each other), and not different enough for most people to care. Sorry to veer this...

If two different sex-linked traits are each found on separate chromosomes, it is not possible (barring spontaneous new mutation) for both to be passed down via the same parent to one offspring. Remember, eggs and sperm contain just one copy of each chromosome, so if a trait exists on one or the other of a pair, then only one or the other will be passed on -- UNLESS crossover between both members of the pair occurs, in which case a newly-formed chromosome with either BOTH or NEITHER will be passed on. This could occur ONLY in a male split to both mutations, as such a male will have one Z with mutation A, and the other Z with mutation B, which are NOT alleles -- or in a pea with an already recombined Z containing both mutations together. If crossover occurred at some point on the Z between mutations A and B, then newly-formed Z chromosomes would be 1) a Z with NEITHER mutation, and 2) a Z with BOTH mutations.

And yes, I've previously used the example of Cinnamon-Pearl or Lutino-Pearl cockatiels resulting from crossover, being as those three mutations are sex-linked and thus all occur on the Z chromosome. Cinnamon-Lutino is also genetically possible, but birds would appear simply Lutino, since that mutation erases melanin, leaving none to be diluted by the Cinnamon mutation. It's like a white-colored pea being also genetically Bronze, but you can't "see" the Bronze because being homozygous for (i.e. having two copies of) White simply erases all the melanin.

If a phenotype results from the combination of two mutations, then it is not proper to call it one mutation. Take, for example, solid-white cockatiels, sometimes called Albinos. They are genetically Whiteface Lutino. It is incorrect to say "they are sex-linked" or "they are not sex-linked" because the phenotype results from the interaction of two different mutations, not simply one "Albino" mutation. You can say "the Lutino part is sex-linked, but the Whiteface part is autosomal recessive". You have to look at the individual parts. Getting back to peafowl, the same would be applied to Purple Blackshoulders. Are they a sex-linked mutation? No. They are a two-mutation phenotype -- one mutation is sex-linked (Purple) and the other is autosomal recessive (Blackshoulder).

I agree about the benefits of understanding how multiple-mutation phenotypes can be bred, allowing for more to be bred "from scratch" by using birds carrying or showing only one or the other. In the case of Peach resulting from Purple and Cameo, we know that some Cameo peafowl display the "turning-white" problem -- but not all. If some Peach peafowl develop the same issue, new lines of Peach could be created by using Cameo lines which have no history of the "turning-white" problem. The formula is simple, and can be found by researching the history of Peach peafowl. The original breeder bred a Cameo male to a Purple female. All sons thus had one Z from Dad with the Cameo mutation of that gene, but the "normal" version of the Purple gene (i.e. "not-Purple"). From Mom, the sons inherited a Z with the "normal" version of the Cameo gene (i.e. "not-Cameo") and the Purple version of that gene. During sperm formation, cells divide and paired chromosomes separate -- but before they do, they often twist over each other, and may "break" and "reunite" at the points where they touch, resulting in a reshuffling of genes between members of each pair. That means that some sperm can contain Z chromosomes with BOTH the Cameo and Purple mutations, and others with Zs with NEITHER mutation (i.e. the "normal" versions of each). That's how the second-generation included an India Blue (i.e. NEITHER Purple NOR Cameo) hen, and a Peach (i.e. BOTH Purple AND Cameo) hen.

It's not as straightforward of a probability as basic Mendelian genetics, but I would definitely place money on the eventual outcome of a Peach hen from an IB split to Purple and Cameo cock with NO history of Peach in either's ancestry. Such a cock could be bred to a hen of ANY other color to have such a daughter. Any of you with both visual Purple and Cameo peas can try it yourself -- cross one color to the other (doesn't matter which parent is which color), and save one of the sons (which will look IB but be split to both Purple and Cameo). When that son matures, set him up with a regular IB hen that isn't split to anything -- and, eventually, you'll get a Peach hen "from scratch". To up your odds, you could pen him up with SEVERAL normal, IB split-to-nothing hens.

If this isn't clear, I'll do something more about sex-linked and crossover tomorrow.

 

[Rosa moschata]

Rosa , I would be interested in your opinion on silver pied and how they were made.. I don't think you can make a real silver pied without the silver pied gene, which is a gene mutated out of the first white eye developed as the breeder was trying to make a white bird with dark eye. Your thought when you have time. connerhills

From anything I've read about the three white-spotting genes in peafowl (White, Pied and White-Eyed), it doesn't seem that there is any one "Silver Pied gene". Rather, the Silver Pied phenotype is the result of an interaction between three genes, each acting as "erasers" and working together to result in an almost totally "erased" pea. From reading breeding information posted in many areas, I would say that the Silver Pied phenotype results from a bird having one copy of White, one copy of Pied, and two copies of White-Eyed. Perhaps there is an amplifying "eraser" effect when these three genes are present together, but such an effect would not require a separate "Silver Pied gene" -- though I can't completely dismiss the possibility of subtle effects of modifiers, maternal versus paternal inheritance of White/Pied and degree of expression, etc. I think that the first White Eyed peas were Single-Factor (i.e. they had only one copy of the White Eyed gene) and, perhaps, breeders were assuming a simple autosomal recessive mode of inheritance. When birds "even whiter" resulted from further breeding, it seems more likely that Double-Factor (i.e. they had two copies of the White Eyed gene) birds started appearing. These "even whiter" birds may have given rise to the idea that a new, separate "Silver Pied gene" also came about, but I don't think that's the most likely explanation.

 

[connerhills]

Has anyone ever done this ? Made a silver pied with 100 % WY and a back that turns a silvery color ( That is where the name comes from ) from scratch, no silver pied gene ? Please provide photos. thanks ,, connerhills

 

[Rosa moschata]

Has anyone ever done this ? Made a silver pied with 100 % WY and a back that turns a silvery color ( That is where the name comes from ) from scratch, no silver pied gene ? Please provide photos. thanks ,, connerhills

That would take a couple generations, but one possible way would be the following:

IB Double Factor White Eyed male penned with two females: one White but not carrying any White Eyed, and the other IB Dark Pied and also not carrying any White Eyed.

First generation offspring would be:
1) IB Single Factor White Eyed split to White (from first hen)
2) IB Single Factor White Eyed split to Pied (from second hen)

Breed half-sibs together -- male from 1) and female from 2), or vice versa -- and there's a potential 1/16 chance for Silver Pied phenotype if my assumptions are correct. You'll also get some Whites (but won't be able to tell by looking if they have 1, 2 or 0 copies of White Eyed), some Dark Pieds (with either 1, 2 or 0 copies of White Eyed), etc.

If you used hens which also had White Eyed (either Single or Double Factor), you'd increase your odds of getting Pied Double Factor White Eyes, but you wouldn't exclude the possibility of also transmitting the possibly non-existent "Silver Pied gene", since most birds carrying White Eyed with Pied or White genes will descend from Silver Pied ancestry. In order to demonstrate that the possibly non-existent "Silver Pied gene" isn't necessary to achieve the Silver Pied phenotype, you'd have to start with birds that don't descend from Silver Pied birds.

 

[AugeredIn]

Rosa , I would be interested in your opinion on silver pied and how they were made.. I don't think you can make a real silver pied without the silver pied gene, which is a gene mutated out of the first white eye developed as the breeder was trying to make a white bird with dark eye. Your thought when you have time. connerhills

Now this is a conversation I would like to have. I have had multiple different answers from folks that should definitely know. Are you saying that the silver pied mutation is a different mutation than white eye on the same gene pair? If so do you have a picture of a bird that is pied white eye that does not have a silver saddle? What does a bird split to silver pied look like? Is it different than a dark pied bird or a bird split to white eye? Or, how do you know a bird is split to silver pied or can you even tell?

I produced what I believe, but cannot yet prove, is a spading bronze silver pied peacock from a visually bronze bird that had a few white flights and a few white eyes. The hen is actually spading split bronze with white flights but really does not appear to be white eye. They were sold to me as a spalding bronze split white and white eye cock and spading split bronze & split white hens. I will not mention names but they came from one of the biggest. Spring of 2012 this pairing produced an almost all yellow chick that shocked me as it should not have happened. I ASSUMED that I had mislabeled the egg. That bird certainly appeared to become a bronze silver pied hen but I lost it at about 9 months (broken neck).

This year the pairing produced four mostly yellow chicks and I dang sure did not mis-label these. One died at about three weeks. One is what I now call loud pied bronze hen. She is 60-70% or more white and obviously split white eye from the "dusted grey" color. One is a spading loud pied and the male is, from all appearances, silver pied. He is not old enough, however, to have the adult saddle feathers to see if they are silver. I stupidly traded this bird before thinking about the implications as I had ASSUMED from previous information that there was a silver pied gene. It was part of a trade that was so beneficial to me that I had to do it and I already had a bronze silver pied one year old male for next year.

Your thoughts?