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Basic color genetics.

Genotype = the genetic makeup of the organism.
Phenotype = the physical appearance of the organism.


There are 18 color genes loci : e+e+ co+co+ db+db+ pg+pg+ ml+ml+ Cha+Cha+ mh+mh+ di+di+ Ig+Ig+ cb+cb+ i+i+ bl+bl+ Lav+Lav+ C+C+ Mo+Mo+ b+b+*b+/- s+s+*s+/- Choc+Choc+*Choc+/-


Gene = a unit of hereditary , a section of DNA found on a chromosome that codes for a particular protein.

Allele = one of two alternate forms of a gene that has the same locus on homologous chromosomes.

Locus (plural=Loci) = the location of an Allele on the Chromosome


You can see a gene contain always 2 alleles, ex. : gene = "e+e+", allele = "e+".
You can see ALL the alleles are written with a "+" behind it, this means the allel is NOT mutated, in other words she is original.
You can see the 3 last genes are written a little different, there is a "*" in between = sexlinked genes. The cock have 2 alleles, the hen have 1 allele and a "-"


A gene can take 3 different forms:

Homozygous = where alleles of a locus on homologous chromosomes are the same. Ex. : e+e+
Heterozygous = where alleles of a locus on homologous chromosomes are different. Ex. : Ee+

Hemizygous = a genetic locus present in one copy only. Of females, in reference to the only one allele at each locus on the single Z chromosome (only one allele possible, as only one Z chromosome in females, therefore not heterozygous or homozygous as no chromosome pair). Ex. : s+/-


A gene can inheritance in 2 different ways:

In a Dominant way = producing the same phenotype whether its allele is identical or dissimilar

In a recessive way = producing its characteristic phenotype only when its allele is identical


You can see I wrote "Dominant" with a capital ex. : EE
You can see I wrote "recessive" with a little letter ex. : ebeb

The 2 MOST important genes loci in breeding :

E-locus : can be expressed in 15 different ways:
(I write in the gene with a "/" to be more clear between the 2 alleles)


E/E = Extended black
E/ER
E/EWh
E/eb
E/e+

ER/ER = Birchen crowwing
ER/EWh
ER/eb
ER/e+

EWh/EWh = Wheaten
EWh/eb
EWh/e+

eb/eb = Partridge/brown
eb/e+

e+/e+ = duckwing/lightbrown

S-locus : can be expressed in 5 different ways :
(is a sex-linked gene, the cock have 2 alleles, the hen have 1 allele and a "-")

For a cock:

S/S = Silver (= Dominant, homozygous)
S/s+ = "golden (= Dominant, heterozygous)
s+/s+ = gold/wildtype (= recessive, homozygous)

For a hen:

S/- = Silver (= Dominant, hemizygous)
s+/- = gold/wildtype (= recessive, hemizygous)