Body Color Inheritance

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Gouldian hens come in four body colors: green, yellow, blue, and silver. Gouldian cocks come in six body colors: green, dilute, yellow, blue, pastel, and silver. Note: Certain body colors affect the expression of certain head colors: the yellow gene suppresses the expression of black coloration, and the blue gene suppresses the expression of red and yellow coloration. This will be explained more in detail below.
 

Green body is a sex-linked gene which is incompletely dominant to yellow body (also a sex-linked gene). Green body is dominant to blue body (which is autosomal). Because it is a sex linked gene, cocks can be double-factor (DF) or single-factor (SF) for green body (the other factor being yellow body) while hens can only ever be single-factor (SF). Green body can occur in combination with any head or breast color; however, when a cock bird is single-factor for green body and single-factor for yellow body, and he also has a purple chest, he appears dilute (as explained below). If he is single-factor for green body (or, equally, single-factor for yellow body) with a white or lilac chest, he appears yellow. This occurs because body color is a polygenic trait which is influenced not only by the color coded for on the sex chromosomes, but also by the autosomal breast color (and blue body) genes. Therefore only the white breasted single factor yellow body cock could be considered "split" for green body, because he would appear to be a yellow bird even though he is carrying a green gene.
 

Yellow body is a sex-linked gene which is incompletely dominant to green body (also a sex-linked gene). Yellow body is dominant to blue body (which is autosomal). Because it is a sex linked gene, cocks can be double-factor (DF) or single-factor (SF) for yellow body (the other factor being green body) while hens can only ever be single-factor (SF). Yellow body can occur in combination with any head or breast color; however, when a cock bird is single-factor for yellow body and single-factor for green body, and he also has a purple chest, he appears dilute (as explained below). If he is single-factor for yellow body (or, equally, single-factor for green body) with a white or lilac chest, he appears yellow. This occurs because body color is a polygenic trait which is influenced not only by the color coded for on the sex chromosomes, but also by the autosomal breast color (and blue body) genes. The yellow gene suppresses the expression of the color black on the birds, so any area which would normally be black on a green bird appears white or off-white on a yellow bird. This is why genetically black headed yellow birds appear to have white or near-white heads.

 

Dilute is the phenomenon of combining a 'yellow' Z (sex-linked) chromosome with a 'green' Z (sex-linked) chromosome in a purple-breasted bird. (Obviously since two Z chromosomes are required for this to occur, dilute birds can only be cocks.) Hens can never be dilute. The single yellow body gene "battles" with the green body gene for expression, and so a little of each gene is expressed making the bird not green nor yellow but a shade in between. This is the hallmark of incomplete dominance. Dilute will never occur in a white breasted cock (since then the bird who is SFYB will appear yellow), but dilute birds can be split for white breasted. Because the yellow gene suppresses the expression of black coloration and because the green gene mutes the effects of the yellow gene, any normally black area on the bird will appear grey (as opposed to white), so black headed birds will have grey heads.
 

Blue body is an autosomal recessive gene, so both cocks and hens can be double-factor (DF) and express the color blue or single-factor (SF) and be "split" for blue body. Birds will appear blue in color only when a bird carrying only "green" sex chromosome(s) (as opposed to yellow) is also DF for the blue body gene. This body color can occur in combination with any head or breast color, however, because the blue gene suppresses the expression of red and yellow, any bird with a genetically red or yellow head will appear to have a salmon colored head, and the normally yellow belly will appear off-white.

 

Pastel is the phenomenon of combining a 'yellow' Z (sex-linked) chromosome with a 'green' Z (sex-linked) chromosome and double-factor blue genes in a purple-breasted bird. (Obviously since two Z chromosomes are required for this to occur, pastel birds can only be cocks.) Hens can never be pastel. Pastels can be thought of as "blue dilutes." Pastel will never occur in a white breasted cock (instead the bird who is SFYB and DF blue body will appear silver as explained below), but pastel birds can be split for white breasted. Because the yellow gene suppresses the expression of black coloration and because the green gene mutes the effects of the yellow gene, any normally black area on the bird will appear grey (as opposed to white), so black headed birds will have grey heads. Also because the blue genes suppress the expression of red and yellow, any areas of the bird which would normally be red or yellow (such as the head or yellow belly of the bird) appear salmon or off-white, respectively, in color.
 

Silver body occurs when yellow body genes are combined with blue body genes. A genetically yellow bodied blue bird will appear silver in phenotype. (A SFYB DF blue cock will ONLY appear silver if he is white breasted, otherwise he will appear pastel.) Because the yellow gene suppresses the expression of black coloration and because the blue genes suppress the expression of red and yellow, the entire body of the bird appears white or off-white in color. The purple of the chest is not affected, however, and red or yellow headed birds will have salmon colored (not white) heads. Therefore, in order to achieve a bird which is nearly all white, one would need to produce a genetically black headed, white breasted, yellow bodied blue bird. Cocks should preferably be DFYB to get the brightest silver coloring.


Here are some breeding charts which will give you a list of all potential outcomes from a given cock - hen pairing. Recall that Z and W denote the sex chromosomes of avian species (whereas X and Y denote the sex chromosomes of mammalian species), and that unlike mammals, the male finch is the homogametic sex (ZZ) and the female is the heterogametic sex (ZW).
 

× Green cock × Green hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
All offspring will have a green body.

 

× SFYB cock × Green hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
Theoretically, half of the cocks produced will be green and the other half will be SFYB (appearing dilute if they have a purple breast); half of the hens will be green and half will be yellow.

 

× DFYB cock × Green hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
All of the cocks produced will be SFYB (appearing dilute if they have a purple breast); all of the hens will be yellow.

 

× Green cock × Yellow hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
All cocks produced will be SFYB (appearing dilute if they have a purple breast) & all hens will be green.

 

× SFYB cock × Yellow hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
Theoretically, half of the cocks produced will be SFYB (appearing dilute if they have a purple breast) and the other half will be DFYB; half of the hens will be green and half will be yellow.

 

× DFYB cock × Yellow hen
Male Offspring	D a m   S i r e        Z Z Z ZZ ZZ W ZW ZW	Female Offspring
All cocks produced will be DFYB & all hens will be yellow.

 

DF-blue cock × DF-blue hen
	D a m   S i r e        B B B BB BB B BB BB
All birds produced will be DF-blue. The blue gene "transforms" a green bird to a blue one, a dilute cock to a pastel cock, and a yellow bird to a silver one.

 

DF-blue cock × SF-blue (/blue) hen (or visa versa)
	D a m   S i r e        B B B BB BB B BB BB
Half of the birds produced will be DF-blue, half will be split to blue (SF-blue or /blue). In DF-blue birds, the blue gene "transforms" a green bird to a blue one, a dilute cock to a pastel cock, and a yellow bird to a silver one.

 

SF-blue (/blue) cock × SF-blue (/blue) hen
	D a m   S i r e        B B B BB BB B BB BB
A quarter of the birds will be DF-blue, a quarter will not carry any blue at all; the other 50% of the birds will be split to blue (SF-blue or /blue), but there is no visual way to distinguish between /blue and birds not carrying any blue at all. In DF-blue birds, the blue gene "transforms" a green bird to a blue one, a dilute cock to a pastel cock, and a yellow bird to a silver one.

 

SF-blue (/blue) cock × non-blue hen (or visa versa)
	D a m   S i r e        B B B BB BB B BB BB
Half of the birds will be split to blue (SF-blue or /blue) & half will not carry any blue at all, but there is no visual way to distinguish between /blue and birds not carrying any blue at all.

 

DF-blue cock × non-blue hen (or visa versa)
	D a m   S i r e        B B B BB BB B BB BB
All birds produced will be split to blue (SF-blue or /blue).