The Sex-linked Dominant mutation


When you only want to know the outcome just scroll down!


The Sex-linked Dominant mutation, is a Dominant mutation on the Sex-chromosome Z.

A Sex-linked Dominant mutation we see in the stella lorikeet, the black (melanistic) form.

Some are saying it is the red stella who is the mutation, Sex-linked recessive against the black. However this doesn't make sense, as we see the red in other Charmosyna's as well but no black.

So now with this article I was thinking a bit deeper into this matter, and find out that you get the same outcome, when you make the red stella the recessive Sex-linked mutation or the black the Dominant Sex-linked mutation. But only call it different, black split red (when red is Sex-linked recessive), or (when black is the Dominant Sex-linked) SF black.

Also there is sometimes a visual difference between a single factor and double factor, certainly when you can see them in the sun, the SF have a reddish shine over the black colour. So maybe we are dealing with the Sex-linked Incomplete Dominant mutation.

But in my first pair I didn't see the reddish shine. So it's not always the case.


Also here is it a Dominant mutation so they never  can be a split (or carrier) for the mutation . 

A female  is hemizygous so she have only 1 Z chromosome, and therefore she never can be double factor or single factor, just red or black (melanistic)


So here some examples of pairings. As there are no other mutations in lories this way I already use the names in the punnett square, so it's easier to understand.


SF = Single Factor (= 1 Z red and the other  Z Black)  SF means Single Factor for Black the other factor is red, but as red is the wildtype you don't say split for red. Black is dominant so the colour is black and not red. Only males can be single factor. 


DF = Double Factor (= 1 Z black and the other Z also black)

Only males can be a double factor as it have 2 Z chromosome.


A female got 1 Z and 1 W sex-chromosome , the W chromosome don't contain colour , so we don't write anything behind the W chromosome.



SF Black male  x red female


You get:


male (ZZ) 50% SF Black

male (ZZ) 50% red


female (ZW) 50%  Black

female (ZW) 50% red



red   male x  Black  female


As you can see you get


Male (ZZ) 100% SF Black


Female (ZW) 100% red




SF Black male x  Black female


As you can see you get


Male (ZZ) 50% DF  Black

Male (ZZ) 50% SF Black


female (ZW) 50%  Black

female (ZW) 50% red


As you can see , it is still possible to breed a red female out of a black pair, but only if the male is single factor, when it is a double factor only black come out, as you can see below.



I'm not going to write everything with the Punnett square. But here are all the outcomes of all pairings.



red male X  red female gives:

 

•  100% male red


•  100% female red



red male X  Black female gives:                                             


•  100% male SF Black


•  100% female red


SF Black male X red female gives:


•  50% male SF Black

•  50% male red


•  50% female red

•  50% female  Black


SF Black male X  Black female gives:

 

•  50% male SF Black

•  50% male DF Black


•  50% female red

  50% female Black


DF Black male X  Black female gives:


•  100% male DF Black   


•  100% female  Black


DF Black male x red female gives:


•  100% male SF Black


•  100% female  Black



Or you can look at the picture below. small letter is red, 1 big letter is SF and 2 big letters is DF.

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