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  • Zebrafinch genetics : Instructions

    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.

    Genetics of zebrafinch 4

    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.

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  • Genetic transmission of physical characteristics

    If you ask at a meeting of zebrafinch lovers a question about the genealogy of the masked, the pastel, or a black cheek, you are sure to receive the right answer.
    But if we ask the genealogy question about the format (size), the shape of the head or the length of the beak, the answers will be multiple and different.
    Some will say intermediaries, others dominant, etc.

    Nevertheless these characteristics follow Laws of Mendel. Many breeders do not believe this explanation, but it is true. It seems that the laws no longer behave in a strict way as for the mutations of colors. A wider variation in the format (size), shape of the head, etc... seems normal.

    Law of independent assortment

    In nature, zebrafinch have the same variation in size. And, in the process of domestication, this difference in variation has increased. Our cultivated zebrafinch are on average two centimeters wider than their ancestors in nature.
    In the articles, we always recommend a hard selection at the level of format and model taking into account the differences between the parts such as the head, the body, etc.

    But the format and the model are driven by genealogy. The body shapes are driven by factors.
    The question that arises is: Is there a relationship between the different factors that govern the format, the model, the shape of the head and the beak ?

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  • Illustrated glossary of mutations in zebrafinch

    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.

    Gris male Gris femelle

    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)

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