Back pale, masked and masked old type, three allelic versions

Male dos pale gris

Explanations and couplings

Why, these three mutations combined are so difficult to predict ?


Simply because we can not speak at the genetic level of different mutations but rather allelic versions of a single gene. The pale back, the masked and the old type mask (OT) are due to the same gene but which has three allelic versions. You can find the phenotype of each one in photo in this article : Illustrated glossary of mutations in zebrafinch.

In order to understand well, let us make the parallel with the man, the color of the eyes for example, whatever the color of our eyes, our color of the iris and coded by the same gene, but this discomfort has many different versions (alleles) that allow us to have the color panel that we know.

Now that we know a little more, let's see how each allele behaves in relation to each other.

A small table to illustrate all this :

Allèle \ allèle Back pâle Masked Masked OT*
Back pâle X Dos pâle Back pâle
Masked Back pâle X Masked
Masked OT* Back pâle Masked X

* OT = old type

In this double-entry chart you can see that it allele dominates the other, so the bird will have the phenotype of the allele that dominates. Be careful, it's not because the allele is dominated that it does not influence. See also the pale back / OT mask : The back is more diluted because of the masked OT allele.

From this result we can draw the first conclusions :

- The pale back may be masked or mask OT.
- The masked can be masked OT but can not be bearer of pale back (pale back dominates the masked).
- The masked OT can not be bearer of pale back, nor masked because these last two dominate it.

Femelle masque gris ancien type anglaise 2016
Female masked gray old type

To know :

- Each bird has two chromosomes so it has twice the same gene (but not necessarily the same allele).
- The pale back, the masked and the masked OT are mutations linked to the sex, they are thus carried by the sex chromosomes. In birds, the male has twice the same sex chromosome (ZZ) and the female has two different sex chromosomes, one of which bears the genes linked to the phenotype (ZW, the W carries the genes related to the phenotype).
 
Now let's detail each possible coupling. Let's start with the pale back and the masked below.

Male pale back X masked female

Female\Male ZBp* ZBp
ZM ZBpZM* ZBpZM
W ZBpW ZBpW

*Bp = Back pâle; *M = masked

 

 

This coupling gives :

- 50% male back pale / masked
- 50% female pale back
 
Male masked X female pale back

Female\Male ZM ZM
ZBp ZBpZM ZBpZM
W ZMW ZMW


This coupling gives :

- 50% male back pale / masked
- 50% female masked

Male pale back / masked X female pale back

Female\Male ZBp ZM
ZBp ZBpZBp ZBpZM
W ZBpW ZMW


This coupling gives :

- 25% male back pale
- 25% male back pale / masked
- 25% female pale back
- 25% female masked

Male pale back / masked X female masked

Female\Male ZBp ZM
ZM ZBpZm ZMZM
W ZBpW ZMW

 
This coupling gives :

- 25% male back pale / masked
- 25% male masked
- 25% female pale back
- 25% female masked

Male masque gris 1
Gray masked male

Now let's take a look at the case of the coupling between pale and masked OT backs, the results will be identical to the masked X-ray back coupling, we just have to replace in the results masked by masked OT.

Male pale back X masked female

Female\Male ZBp ZBp
ZM ZBpZm ZBpZM
W ZBpW ZBpW


This coupling gives :

- 50% male back pale / masked
- 50% female masked

To finish, let's take a look at the case of mating between masked and masked OT, the results will be identical to the masked X-shaped back coupling, it is enough to replace in the results back pale by masked and masked by masked OT.

Masked male X masked female OT

Female\Male ZM ZM
ZMOT ZMZMOT ZMZMOT
W ZMW ZMW


This coupling gives :

- 50% male masked / masked OT
- 50% female masked
 
Femelle dos pale gris
Female pale gray back

Place a few different cases :

Male pale back / masked X female masked OT

Female\Male ZBp ZM
ZMOT ZDpZMOT ZMZMOT
W ZBpW ZMW


This coupling gives :

- 25% male back pale / masked OT
- 25% male masked / masked OT
- 25% female pale back
- 25% female masked

Male pale back / masked AT X female masked

Female\Male ZBp ZMOT
ZM ZBpZM ZMZMOT
W ZBpW ZMOTW


This coupling gives :

- 25% male back pale / masked
- 25% male masked / masked OT
- 25% female pale back
- 25% female masked OT

Hoping that this article makes you more comfortable with the three mutations that are the pale back, the masked and the old masked type.

Mutation Allele Pale Back Masked Masked OT