* Text taken from the AELR website
In genetics a character represents the visible, measurable, or quantifiable expression of one or several genes. The set of chromosomes that carry the genes form the genotype of the individual, while the expression of those genes influenced by the environment constitutes the phenotype.
To understand the inheritance of color it is essential to define several terms. First of all we should know that there is a relation of dominance and recessivity between the genes that determine the color. The dominant genes will be represented by uppercase letters, and the recessive ones by lowercase, whenever a recessive gene is paired with a dominant the latter will prevent the expression in the phenotype of the recessive gene, although this gene will appear in the genotype of the individual. Genes are formed by pairs of alleles that are inherited independently from each parent, and that are located on the chromosome at a given loci. Between these alleles are going to establish epistatic or hypostatic type relationships as they let express or plug the genes to which they refer.
The genes that transmit color are two pairs, and their relations of dominance / recessivity and epi / hypostatic are the following:
- Gen B: transmits the color black, is dominant over chocolate and recessive with respect to yellow.
- Gen b: Hypostatic allele that allows the transmission of chocolate color and is recessive with respect to black and yellow.
- Gen E: This gene does not transmit a certain color, it is the epistatic allele that acts by canceling the dominance of the yellow color, and therefore allows the expression of chocolate or black.
- Gen e: Hypostatic allele with respect to E, which allows the expression of the dominant yellow color over black and chocolate.
The combination of these genes in terms of color (Bb) and transmission (Ee) will produce 9 different specimens with the following genetic maps:
EE BB : Pure dominant black
EE Bb: Black chocolate carrier.
Ee BB: Black carrier of yellow.
Ee Bb: Black carrier of yellow and chocolate.
ee BB: Pure yellow, with normal pigmentation.
ee bb: Yellow carrier of chocolate, with lack of black pigmentation in mucous membranes.
ee Bb: Yellow with normal mucosal pigmentation, carrier of black and chocolate.
EE bb: Pure chocolate.
Ee bb: Chocolate that puppies of the three colors can produce according to their crossing.
Of all the possible combinations of these nine genotypes, 44 different crosses are obtained, which we specify below with their types and percentages:
A continuación encontraran varios enlaces de interes sobre las distintas caracteristicas y tipicidades de la raza Labrador Retriever.