Pekin Genes -- Hidden Silver Appleyard Coat?

[ANightPerson]

I'm completely familiar with the genetics behind the Pekin masking gene and how it hides the true coat that the duck carries, but I have a few questions on the inheritance patterns of some other coats.

When I first got ducks, I started out with a Cayuga/Blue Swedish mix and her brother and sister. I lost both the brother and sister over the years and got some more Ducks, and my original Cayuga/Swede hen ended up having a half Pekin daughter. She was black like her mom, with a tiny bit of Pekin leakage & some wildtype leakage. There was an incident a few months ago in which I lost both my original hen and her daughter, so I popped all of their eggs that I could find in the incubator to continue her bloodline in my flock. My only drakes are both Pekin.

Three hatched: one was my original hen's, and two were her daughter's. One of her grandducklings & her duckling were black with white leakage, as you'd expect. I was expecting some black ones, some white ones, some wildtype, and any mix of the three, but the third duckling (3/4 Pekin, 1/8 Cayuga, and 1/8 Blue Swede) came out with the characteristic black tail & mohawk of a Silver Appleyard. She's 7-8 weeks & has a lot of her feathers now, and she looks just like a Silver Appleyard to me, albeit a bit dark.

Video attached to show what she looked like as a duckling, I don't have any good pictures.

I wasn't sure that she had the SAY coat until I saw what SAYs look like as ducklings, now I'm sure of it. Obviously she got it from her Pekin father & grandfather, but that seems a bit strange to me. Firstly, is the SAY coat an actual gene or two, or a combination of many genes? Also, why would Pekins carry it? SAYs are so rare, were they even bred into Pekins? It's possible that my Pekins are a little mixed, they're just hatchery ducklings. The strange thing to me is also that her grandfather & her father came from completely different strains from different hatcheries. I thought that most Pekins carry a wildtype or black coat, since a major component of the breed was the Rouen, but somehow both of these Drakes passed on SAY. Is the SAY coat dominant to a regular wildtype coat?

Is this strange, or am I just not familiar with this?

 

[Pyxis]

What you're calling the 'pekin masking gene' is just white in ducks. It works the same in all breeds, it's not specific to pekins. In ducks, white is epistatic to all other colors. It's also recessive, so a duck needs two copies of it for it to express.

This duck does look like it is restricted mallard, which is part of what gives a silver appleyard its coloration. The other part is light phase, which to me not something I'm seeing in her - and it's also why you think she looks a bit dark. She does look a bit dark, because she's missing the light phase component that a silver appleyard has.

Restricted mallard is, of course, a wildtype aka 'mallard base' color. Black is dominant to all mallard colors, so really it could have come in with the cayuga cross OR with the pekins, since both the extended black and the white could hide it.

So basically, one of the ducks was carrying it, somewhere in her lineage, and it passed down until this one finally did not inherit a copy of extended black and also did not inherit two copies of white and thus it is finally visible in this duckling.

 

[ANightPerson]

What you're calling the 'pekin masking gene' is just white in ducks. It works the same in all breeds, it's not specific to pekins. In ducks, white is epistatic to all other colors. It's also recessive, so a duck needs two copies of it for it to express.

This duck does look like it is restricted mallard, which is part of what gives a silver appleyard its coloration. The other part is light phase, which to me not something I'm seeing in her - and it's also why you think she looks a bit dark. She does look a bit dark, because she's missing the light phase component that a silver appleyard has.

Restricted mallard is, of course, a wildtype aka 'mallard base' color. Black is dominant to all mallard colors, so really it could have come in with the cayuga cross OR with the pekins, since both the extended black and the white could hide it.

So basically, one of the ducks was carrying it, somewhere in her lineage, and it passed down until this one finally did not inherit a copy of extended black and also did not inherit two copies of white and thus it is finally visible in this duckling.

Yes, I know that it isn't just Pekins. I'm fully versed in the genetic principles behind it, I was just curious as to the coat color, since it's just so similar to SAPs and I've never seen it before. Sorry if my phrasing was unclear. I'm sure it came from the Pekins, since it's not only more plausible with the white masking, but my original Cayuga/Swede hen bred true for black.
So it's a wildtype coat with some sort of modifier or dilution gene? How many genes are responsible for the restricted mallard phenotype? What would the pattern of inheritance be if I bred her back to a wildtype or even one of her Pekin cousins? I just think she's beautiful, I'd love to breed out more like her! It's a shame that I lost her mom. Thank you for your identification!

One more question-- is it possible that whatever modifier/modifiers that result in the restricted phenotype came from the Cayuga mix line? Would the modifier/modifiers not affect the black coat color, and therefore stay hidden?

 

[Pyxis]

So it's a wildtype coat with some sort of modifier or dilution gene? How many genes are responsible for the restricted mallard phenotype? What would the pattern of inheritance be if I bred her back to a wildtype or even one of her Pekin cousins?

It's one gene - instead of having regular M+ wildtype mallard, she has M^R, which is restricted mallard. It's dominant to regular M+.

Since it's dominant, theoretically breeding her to a wildtype mallard, which would result in a phenotype of M+M^R, would result in more restricted mallard ducklings. Breeding her back to the pekins depends on what's going on under the white, but if it's just basic wildtype mallard, then it should be the same thing.

One more question-- is it possible that whatever modifier/modifiers that result in the restricted phenotype came from the Cayuga mix line? Would the modifier/modifiers not affect the black coat color, and therefore stay hidden?

Yes, and yes. Extended black covers up all the mallard genes.