Dominant-Recessive

 

An allele is dominant when in heterozygous modality (allele paired to dissimilar) it is able to express the characteristic for which it stands. A recessive allele will only express the corresponding characteristics when it is in homozygous modality, (paired to alike)

Genotype and Phenotype

 

The genotype is the whole of the genetic charge that an individual carries in its genes. The phenotype is the  characteristics that the genes are able to visually express on a subject.

Codominance and Incomplete Dominance

 

When codominance exists both alleles in a heterozygote will express their corresponding characteristic with equal strength, in which case both characteristics may be visible.

 

Example: a cross of a melanic X lipochrome will give variegated birds, both characters are expressed.

 

In the case of incomplete dominance, the alleles are unable to fully express their characteristics, an amalgamation of both characters occurs.

 

Example: a cross of Red X Yellow will give some orange birds.

             

Multiple Alleles

 

Refers to the case of wild type subjects which have suffered more than one mutation or change.

 

Examples:

           Wild Type>Opal>Onyx

             Wild Type>Phaeo>Topaz

Genetic Exchange “Crossover”

 

 

During the meiosis process, in Prophase , when homologous chromosomes align in synapsis, the chromatids become entangled and segments are exchange between chromosomes, this segment exchange is an important event in bird breeding because it occurs frequently and affords genetic variability to many species.

 

 

 

 

 

 

 

 

 

 

Isabelle canaries are the product of  crossover.

 

 

· When we cross a Brown X Agate we obtain Black carriers of Brown and Agate.

 

· When we cross these F1 known as “Passepartouts” with any Classic colored female we can obtain Agate, Brown or Black female descendants and if crossover occurs we can also obtain Isabelle females.

 

 

 

 

 

 

 

 

 

 

 

 

 

· In theory we could obtain...

 

1. One Black male carrier of Brown and Agate

2. One Brown female

3. One Brown male

4. One Agate female and in case of        crossover Isabelle

 

Black/Brown/Agate

X

Brown female

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