Mutation

1. Introduction

First and foremost, I would like to thank the people I have worked with on the evolution of white cheek zebra finches over the past few years.
This text therefore not only tells about my experiences but also their experiences. Thanks to Paul Chabot, Jan Van Looy and Wessel Vermeulen. When I use the term "I" later, you must understand "we". We do not agree on all the details. Fortunately, because then we can discuss it. And we continue to encourage each other on the results to improve and the conclusions to be made.
At our zebra finches, everyone knows the cheeks and the black cheeks. In these two mutations, both males and females have colored cheeks. We now also have the white cheeks. So we have white, brown and black cheeks.



2. Historical

The first time a white-cheeked zebra finch appeared was when Jacques Vanduren wondered if he had bred a new mutation. Some of its birds could be admired in the exhibitions of the B.Z.C. (Belgian Zebrafinch Club).
Jacques also wrote an article on this subject in our magazine, illustrated with photos of details. It was the end of the 90s of the previous century. Jacques was unlucky enough to lose his breeding and eventually the white cheek zebra finch disappeared. However, he had even given birds to other hobbyists in order to avoid the risk of extinction. But these other amateurs couldn't build a strain. Result: the white cheeks are returned to square one.
A few years ago, the founding president of B.Z.C., Paul Chabot, discovered a "special" zebra finch. Paul Chabot is the one who, in his time, took the first steps with a male of the orange breast mutation. So he had experience building a "special" strain.
This bird also had black in its cheeks, which is why Paul went in search of a black-cheeked partner for this zebra finch. His mindfulness was good for the white cheeks. For he directly raised white cheeks !
That's why he decided the white cheek factor was dominant. But Paul also used other zebra finches besides the gray black cheeks. When Jan and I went to interview Paul, we saw White Cheeks combined with masked, Black Chest Mutation and even crested. Paul explained to us that he had had many deaths among his birds, he knew of Jacques's experience and he was betting on a lethal factor in white cheeks.
Paul gave each of us a zebra finch because he was afraid the next breeding season would be disastrous. His secret hope was that we would help him. Then it turned out that the health of his birds was the cause of his growing problems. So we were able to eliminate the lethal factor from our reasoning.
In Dordrecht Paul met Wessel Vermeulen who also had zebra finches with partially white cheeks. Wessel even bred zebra finches having three colors in the cheeks. They show white (the tear line is absent), then comes black and normal brown in the posterior arch of the cheeks.



In the meantime Jan and I have started breeding with our white cheeks. Our goal was to understand the inheritance of white cheeks.
When Jan and I started breeding many told us they thought it was a combination. Some thought of the black chest mutation, others of the black chest black cheek jumpsuit. Several had already seen traces of white cheeks. And indeed, we did not speak of white cheeks only with us. The internet, as we know, makes contacts all over the world. I know that in other countries we talk about white cheeks: Israel, Italy, France.
Let's take a more in-depth look at the white cheeks. What is important: we make a distinction between combinations of white cheeks with black cheeks and those without black cheeks. This distinction will be the common thread of this story.

Since we will be discussing the orange breast zebrafinch (PO) in this article, it is certainly interesting to dwell a bit on the history of this mutation first.
The orange breast mutation (PO) is believed to have originated in Belgium. I consciously write "supposed" because the first orange breast (PO) was actually found at a bird merchant. In Dutch literature in particular, long before the discovery of the first orange breast (PO) in Belgium, zebra finches were described there with characteristics that we can now attribute to orange breast (PO) wearers.
What we are certain of anyway is that the honor of the discovery of the orange breast (PO) goes to a certain Mr. De C. who in 1978 noticed a rather special gray male in a store. This male had an orange breast bar when normally it should have been black. Mr. DE C. bought this copy, but at the breeding nothing came out of what he had hoped for. At the end of 1978, Paul CH., President of the BZC at that time, acquired this male. There were good and bad surprises with this subject, because unfortunately this male did not live very long. Fortunately Paul CH. had been able to get some young people before. Orange breast (PO) is inherited autosomal recessively compared to the wild form. The orange factor must therefore be doubly present to become visible. He therefore crossed young people between them and quickly took out the first orange breasts (PO).

Already the first orange breast breeder (PO) made the mistake of not combining and developing the orange breast (PO) with classic colors (gray, brown, pale back, masked) but he rushed directly on the combination of the orange breast with black breast (PN) and other mutations. From that moment on, every orange breast breeder’s dream was born to produce an all-orange zebra finch.
Due to having burned the breeding stage in the classic colors, the following question remained :

Are there any specific characteristics that we see in our classic orange breasts, are they just annoying derivatives of the presence of the black breast mutation (PN) or are these specific effects of the orange breast mutation ?

What do I mean by that? Often the orange chest gray or orange chest brown reveal not well defined cheeks. Likewise, there is often an orange hem on the fenders. Also, the chest frequently flows upwards and the belly shows patterns. All these observed characteristics are quite disturbing.

Why are the mutations in zebrafinch of pale back, masked (new type) and masked old type combined with each other so difficult to predict !?
Quite simply because we cannot speak at the genetic level of different mutations but rather of allelic versions of a single gene. The pale back, the masked and the old type mask are due to the same gene but which has three allelic versions.
To understand well let's make the parallel with man, the color of the eyes for example, whatever our eye color, our iris color and coded by the same gene, but this gene has many different versions (alleles) which allow us to have the color panel that we know.

Now that we know a little more about what complicates these crosses, let's take a look at how each allele behaves in relation to each other.
Everything is a story of dominance and co-dominance or recessivity.

A small table to illustrate all this :

*OT = Old type

In this double entry table you can see that it allele dominates the other, the bird will therefore have the phenotype of the allele which dominates, be careful, it is not because the allele is dominated that it does not not influence. See 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 can be masked or OT masked.
• The masked can be a masked OT split but cannot be a pale back wearer (pb dominates masked = pb / masked). *pb = pale back
• The masked OT cannot carry a pale back, nor a masked person because the latter two dominate him.

Small practical software allowing to have the probabilities of the results of a mating according to the mutation (s) of the respective parents. It can be put on USB sticks, no need for an internet connection to use it.

Before that, we will obviously need to know the genotype of each parent. To help you determine the mutation or combination of mutations to which your zebrafinch belong, you can refer to: Illustrated glossary of mutations in zebrafinch.
That said, I would say that this application is only an aid. The best thing will always be to understand how each mutation is transmitted. For this, I also advise you to have a good basis to consult the article: Zebrafinch genetics : Instructions.

Here is a site, also available in application, dedicated to the calculation of the genetics of zebrafinch. ZebraCalc allows you to have the probabilities of results depending on the mutations of the respective parents.

Before that, we will obviously need to know the genotype of each parent. To help you determine the mutation or combination of mutations to which your zebrafinch belong, you can refer to: Illustrated glossary of mutations in zebrafinch.
That said, I would say that this application is only an aid. The best thing will always be to understand how each mutation is transmitted. For this, I also advise you to have a good basis to consult the article: Zebrafinch genetics : Instructions.

It was in 1960 that the first zebrafinch pale Brown back appeared in Belgium.
Let us try to understand how such a combination of colours could have been born.

It is known that the brown and pale back factors, related to sex, are located on X chromosomes, but different and at different locations (loci): (1) and (2).
They are therefore not normally linked (otherwise all the browns would also be pale backs: which is not the case).
How could they get linked on the same chromosome ? (3)



When you mate a brown male with a pale grey back female (or vice versa), each time you get grey males, carriers of brown and pale backs. Each male therefore has two different X chromosomes: One carries the "brown" "no light back" genes, the other carries the "no brown" and "light back" genes. Being recessive, none of these genes can be expressed since they are in a single copy; being non-alleles, neither can dominate the other; It is therefore a natural grey colour that is expressed.

How will these genes be transmitted by the male to his offspring ? To understand it, some explanations are necessary.

Chromosomes are very long molecules (2 millionths of a mm thick, average 5 cm long in humans) that are normally entangled with each other in the nucleus of the cell. At the time of meiosis (cell division allowing, in males, the formation of spermatozoa from the mother cells of the testes), these chromosomes split into two rigorously identical chromatids linked together by a centromere.
Each chromatid then spirals. Only then does the chromosome become visible under the optical microscope. The chromosomes group together and join two to two homologous pairs.

During this phase, two chromatids of the two joined chromosomes can cross, break and then join together by exchanging more or less important segments. This is the phenomenon called spanning.
The “brown” gene could thus be found linked to the “pale back” gene on the same X chromosome. A grey male with brown back and pale back can (but only this way) produce pale grey, grey, brown back and pale brown back females. (12.5% of each).

With this crossing over, this same male could also have:

• Crossed with a pale back female: 12.5% of pale grey back males split brown.
• Crossed with a brown female: 12.5% of brown males split pale backs.

By mating one or the other of these with their "pale brown back" sister, it is possible to obtain (in 3rd generation): 25% pale brown back males and 25% pale brown back females.



CHROMATID

A : Normal
B : Spirally contracted
C : Schematized

1. Introduction

The breeding and competition of zebrafinch has grown considerably over the past fifteen years. In order to improve the size of the new mutations, breeders also have recourse to conventional "split" birds.
Some manage to combine several mutations. All this made it essential to know a minimum of applied genetics. It is this minimum that I would like to present to novice breeders.
This is not a complete course in genetics, but a simple presentation of the method I use preceded by some basics.

2. The zebrafinch and its mutations

A zebrafinch has a number of visible characters (size, shape, designs, color, sex) that constitute its phenotype. It can have, in addition to other unexpressed traits (it is said to be a split). The set of traits, expressed or not, is called the genotype.

A young zebrafinch grows out of an egg cell, the result of the fusion of the nucleus of a father's sperm and the nucleus of the female's egg. The bird's genetic program is already there: A series of cell divisions and coded information will (or not) trigger the appearance of the characters. The encoded information is carried by genes located on long filaments contained in the nucleus: chromosomes.
All chromosomes go in pairs: each chromosome therefore has its counterpart.

There are two categories of chromosomes :

- Sex chromosomes :
• XX in the male
• XY in the female

- Autosome chromosomes.

The gray zebrafinch living in Australia is the source of all of our farmed zebra finches. It has a whole set of genes distributed in its chromosomes.Whenever a new mutation has appeared, there has been a change in an original gene (and it has been shown to be hereditary). The original gene and the mutated gene are located in the same place called a locus on each of the homologous chromosomes.
Both genes are alleles.



A bird is pure (homozygous) when all of its alleles carry identical information.
A bird is heterozygous when at least one pair of alleles carries different information about the same trait.

We currently know about twenty different mutations of the gray zebrafinch.

The objective of this article is not to impose a management of breeding or create a controversy, but to share my experience of breeding, my observations as well as the difficulties I have encountered for about fifteen years of breeding zebrafinch in this combination of mutations.

The black breast is a mutation of design due to a different distribution of eumelanim in the plumage of the bird. The orange breast mutation is a color mutation: The eumelanin of the designs is transformed into brown orange phaeomelanin, which pulls towards the red-rust color for the best subjects. I do not think it is important to specify in detail how each mutation we already know alters on the mutated bird.

The ideal competition male, in addition to a correct shape and size such as a classic, must have no black discharge into the chest, must have a parotic zone (the color: between the beak and the cheek) white, a chest that rises as high as possible under the beak, a strong extension of the cheeks (the cheeks meet at the back of the skull) without running on the back (which for me represents a non-selective extension of the color), a gray back and not loaded with brown veil as is often the case, drawings on primary and secondary remiges (white+orange), the most intense red/rust color possible, the largest belly design (orange flames). To this it is necessary to add that the drawings of blanks must be marked with white ovals on orange background; The drawings of the tiles of tails are of course elongated.

The female as the male must be gray of back, shape and size correct, have a belly drawing (the flames)( note that this drawing is not orange as on the males but rather pulls towards the gray-brown), back drawings (on the outer edge of the remiges), a chest that rises very high, drawings of orange cheeks, flanks marked with dots and orange color also.

Should the female have the darkest possible cheeks and flanks ? I have no answer.
What is certain is that the first female orange breast had no orange cheeks and that the Dutch standard required females without cheeks a few years ago (now there are two standards accepted and judged differently: with drawing and without drawing…: type 1, type 2 in competitions). The female without drawn cheeks keeps the tail tiles as orange as possible. Most of my breeding females do not have cheeks, it is a character that I do not select specially.
I sometimes read on the internet that to release a good intensive male in color it is absolutely necessary a female with very orange cheeks, it is not true. We come out very good colored birds with females without cheeks if they are very grey. By “very grey” I mean birds whose eumelanin supersedes phaeo. This does not mean that certain characters should not be present (belly drawing, caudal overlying, eyelid etc.). I can say that the female without cheek has no influence on the intensity of the color on the males.



Some peculiarities are specific to the mutation combination

The orange breast seems to intensify the extension of the orange color of the drawings. We often observe subjects with a complete extension of the cheeks at the back of the skull, and this with a chest that goes up very high under the beak (compared with a pure black chest). This extension, when important, tends to color the color. I do not agree with those who say that orange-colored birds are black-faced birds. This coloration appears as well on black breast orange breast without the black face mutation for several generations.

I do not select the orange color of the color. Certainly it is a defect present in my birds but raising black face black breast orange breast, I do not pay attention to it.
In competitions, it depends a lot on the judges but in general, if the bird is good, they do not get heavily punished. Note that there are several kinds of orange colors, which a photo does not show well. Rusty orange colors like the chest and that come to blend with the cheek (not good) or an orange veil, lighter than the cheek and that stands out again (it goes better). But on big competitions, this is what the beautiful bird will miss to rank against the best.

The aim of this article is not to establish an unstoppable rule for the recognition of a gray male split (carrying) the black breast mutation. Rather, it aims to gather the clues that will allow you to identify it.
For this, every detail of the mutation is taken over, according to what I observed during the selection of my strain of gray black chest.

Before starting to analyze each possible clue, it seems important to me to bear in mind that the black chest mutation changes the shape of the drawings. To identify a split of the black chest mutation, I also advise you to take into account all the clues described in this article.

Let’s proceed and analyze the phenotype of a gray black breast from the head to the rectrices in comparison to a gray split the black breast mutation. To identify each descriptive term used, you can use this diagram : Descriptive terms in zebrafinch.

1. Mustachial line

Black chest : The moustachial line will be pronounced and intense black.
Split (/) Black chest : The moustachial line may be more pronounced than on a gray, however this does not constitute for me a sufficient clue.

2. Tear line

Black chest : The tear line disappears (ideally according to the standard) or only a fine line remains.



Split (/) black chest : Different cases depending on the force of expression of the mutation in the split.

- The tear line is present and fine :



- Tear line is present and wide :



- In some cases, the tear line of a split black chest may also be absent. It will be necessary to rely on the other clues to know if it is a split or a black breast in its own right.

3. Cheeks

Black chest : The drawing of the cheeks will extend up and back of the head.

I made this glossary to illustrate in photos the existing mutations in the zebrafinch.
He can help you identify the mutation (s) of your zebra finches.

Important precision :To identify the genotype of your zebrafinch, it will be necessary to take into account that a zebra finch can carry a mutation without being mutant.
Being a carrier (/, split) of a mutation means that it is partially present (genetically speaking). From the visual point of view the partially carried mutation will not be seen or only by some clues present in the appearance of the bird.
In this case, it will be necessary to have a trained eye to determine the genotype. Sometimes check couplings will be necessary.
Your zebra finch can also have several mutations, the possible combinations are numerous.

This glossary is based solely on the phenotype (visual characteristics) and single mutations (not combined).

Grey (GR)

The gray zebrafinch is not a mutation, it is the original (wild) type.



1. Gender-related mutations

The female can never be a split, so she is either mutant or non-mutant.
The male can be a split of the mutation.

Brown (Br)