The Basics of Cockatiel Color Genetics

Every living creature is formed from cells. Cells contain chromosomes that are formed from DNA – deoxiribonucleic acid. And the DNA contains the genes. Genes contain the hereditary information. Their role is to guide the functioning of cells.

Genetics examines how various characteristics of the legacy is inherited. These properties can be, for example Cockatiel colors, size, or even length of the crest. All inherited properties, however, are not always good, and therefore some of the genetical information of cockatiels are particularly important to to realize, especially for a breeder. Since genetics is not very simple thing, many parts of it need to be explained from the very beginning.

The main roles in genetics are played by the following units:

1. CELLS form the tissues of living creatures. Most of the cells have a centrum called the nucleus.

2. NUCLEUS contains the chromosomes.

3.CHROMOSOMES are settled up in pairs. The other one is from mother, the other comes from father.

4. DNA CHAINS that are clinged tightly together, form the chromosomes.

5. DNA forms a replicating double helix structure. DNA parts that contain the genetical formula of making a certain proteine, are called

GENES.

DNA and chromosomes

Human women have two sex chromosomes that are both named as X. Men have only one X and also an Y chromosome. With birds it’s the opposite. The sex chromosomes of birds are named Z and W, whereas the Z is the same as X and W is comparable with the Y. Cockatiel males have ZZ-chromosome pair, females have ZW.

Because of the comparability we often hear people talking about cockatiel chromosomes X and Y. This site aims to use the correct terms and I would encourage hobbyists to do the same to avoid any misunderstandings.

Sex chromosomes

Human women have two sex chromosomes that are both named as X. Men have only one X and also an Y chromosome. With birds it’s the opposite. The sex chromosomes of birds are named Z and W, whereas the Z is the same as X and W is comparable with the Y. Cockatiel males have ZZ-chromosome pair, females have ZW.

Because of the comparability we often hear people talking about cockatiel chromosomes X and Y. This site aims to use the correct terms and I would encourage hobbyists to do the same to avoid any misunderstandings.

Sex determination

The fertilized egg cell type orders the gender of the chick. If the cock’s sex cell that contains of course the chromosome Z, fertilizes the hen’s edd cell that contains the chromosome W, the chick gets Z and W chromosomes and becomes a female. If the cock’s cell (still containing the chromosome Z) fertilizes the hen’s egg cell that has also has the chromosome Z the chick will have two Z-chromosomes – as in, ZZ-pair – and becomes a male.

Eli:

1) Male cockatiel’s spermatozoon containing the chromosome Z fertilizes the female’s egg cell containing the chromosome W -> ZW chromosome pair -> the chick is a female.

 

2) Male cockatiel’s spermatozoon, that contains the chromosome Z fertilizes the female’s egg cell containing the chromosome Z -> ZZ chromosome pair -> the chick is a male

 

Geenit, alleelit ja lokus

Genes are specific sequences in DNA. Genes determine the type of protein that the cell starts to produce. Genes determine partially for example the appearance, the characteristics and health-related issues. Genes are located in the DNA, which in turn forms from the chromosome strings.Anything that is affected only by the genes is called the genotype. Genotype means then the individual’s genome, or all of its genes. Things that are caused by the interaction of the environment and the genotype, is calle the phenotype, ie the individual’s dress – all that specimen is shown outwardly.

Each chromosome has a certain place for a certain type of gene. This place is called locus. Chromosomes are always as couples, so the individual may own maximum of two copies of one gene. If the gene is mutated, the gene may arise as a new version that is called the allele. Allele is a variant of a gene. For example, the whiteface color is an allele of the so called blue gene. This means that once the blue gene mutated and produced a new allele. It has done this more than once, resulting also the goldcheek, pastelface and creamface – all off them that are alleles of each other and alleles of the blue gene. If a bird has two identical alleles the bird is called homozygous. If the individual has two different alleles of the same gene, the bird is said to be heterozygous.

For example the pastelface color (caused by the parblue gene) and the whiteface color (caused by the blue gene) are alleles of each other. So, they have both mutatated from the wild type located in particular locus. And you should of course remember that also the gene that we see as wild-type has been mutated originally from something else due to evolution.

The alleles form a gene family and each of them are located in the same locus in the chromosome. Because there are two of each chromosome, one cockatiel can offer two locus of the same type. And because every locus can take one gene, one cockatiel can have two alleles of one gene. They can be similar (homotsygous) or different (heterotsygous). The term heterozygous is the term for what we often call a split. An example: The wild-type of the recessive pied locus dominates over the pied mutation allele. If the cockatiel has one wild-type allele and one pied mutation allele the bird is heterotsygous pied. Or as we call it, split to pied.