The Autosomal recessive mutation


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


Lorikeets we see many mutations who are auto. recessive, blue, turqouise, fallow, dilute, faded, blue-fronted, rec. pied, rec. greygreen. (note; from the pied and greygreen also exist a dominant form)

Autosomal means that the changed gene is located on an Autosome chromosome (non-sex chromosome), so males and females are equally likely to be affected.

Recessive means that both copies of the gene must be changed in order for a bird to have the condition.

In the development of an Autosomal recessive mutation are the parents usually related to each other (therefore not always directly brother x sister, but can also x cousin or even further away in the bloodline.)

Now is it not the case that each inbred brings a mutation, the parents should both carry the same mutation gene.

A carrier of a mutation (also called split) is a normal coloured bird that have an abnormality in his gen. If both parents have the same abnormality in the gene than can come from this pairing a Visual mutation.

It is definitely not good for just inbred to try to get a new mutation, because beyond the chance that a desired mutations occurs is extremely small, the chance that you breed disabled, blind, small size or lethal, are going to get is much larger, So don't do it!

Simply said, is that you need 2 x the abnormality in the gene to get the colour, when you have only 1 abnormality in the gene  you have a split or carrier.

For a Autosomal recessive mutation we don't have to deal with the Sex chromosomes.

For calculation the outcome we use the Law of Mendel. with the punnett square.



A split or carrier we wright with a slash /  , normal / blue = normal split for blue


In my examples I use blue but you can change it to any Autosomal recessive mutation. 



pairing up blue x normal gives:

So you see the outcome is 100% the same, all are (normal and blue) = normal but have the recessive gene in them for blue . So pairing a normal  x blue gives 100 % normal split (or carrier for) blue.






pairing up blue x normal / blue gives

Here you have 2 different outcome so

50% the mutation(blue blue) = blue

50% split (normal blue) . = normal / blue

So pairing  normal/blue x blue gives 50% blue and 50% normal/ blue





So pairing up normal / blue x normal / blue gives

So you get

50 % Split ( normal  blue) = normal / blue

25% normal (normal  normal) = normal (pure wildtype)

25% mutation (blue  blue). = blue

The split and the normal looks the same so 75% of this pairing is normal but  25% not for blue! But the biggest part of the normal are split for blue , you cannot see any difference in the birds, only by breeding you can find out if they are split or not.

These birds we call possibly split in advertisements we wright a double slash // means possible split. so normal // blue means normal possibly split for blue.


Below some examples of pairing outcome, which are explained above.

The examples with the punnett square,  explain the procent in the outcome of the mutations, but its theoretically, in practice its often different, unless the outcome is 100% then it cannot be something else

It is the same as in humans you have 50% chance to have a boy and 50% to have a girl. But how many big families have almost or all boys or only girls.

In this mutation form (autosomal recessive), it does not matter if the male or female is the mutation or split the outcome is the same.





normal ( pure wildcolour) X split (= carrier) gives:


•  50%  normal = pure wildcolour 

•  50% split

you cannot see any difference between them, only by pairing you can find out if they are split are not. these are called "possibly split"



split X split gives:


 •  25% normal = pure wildcolour

•  50% split

•  25% mutation. 


Just as the first pairing , you cannot see which is the pure wildcolour or the split, only by breeding you can find out.


split X mutation gives:


•  50% split 

•  50% mutation


mutation X normal gives:


100% split


mutation X mutation gives:


•  100% mutation


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