Yellowface II budgerigar mutation
Encyclopedia
The Yellowface II budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigar
s. In combination with the Blue
, Opaline
and Clearwing
mutations, the single factor Yellowface II mutation produces the variety called Rainbow.
The double factor (DF) Yellowface II Skyblue variety is very similar to the Yellowface I Skyblue, but the yellow pigmentation is brighter, and tends to leak into the body feathers to a greater extent.
A contemporary report
of his breeding says, "Mrs Lait mated a dark green cock to a greywing mauve hen, and in their third nest was a pale greywing mauve hen with a distinct (light lemon yellow) mask and bib, with the under tail feathers yellow and with yellow on the wings in the places where the normal blue bird is white. This hen ... was mated with a cobalt/white cock and they have produced five youngsters, all having yellow masks like their mother. Mr Long's birds were bred from a dark green of a somewhat olive shade mated to a rather unusually coloured hen, which appears to be a green but has a turquoise suffusion on the breast, etc. The first nest produced 3 cobalt birds with yellow masks, etc, like Mrs Lait's birds described above, and one green-blue bird like the mother. The second nest produced exactly the same result."
The description of the birds suggests that Mr Long's birds were a DF Yellowface II Cobalt cock and a SF Yellowface II Cobalt hen, but the breeding of Cobalts with yellow masks places this in doubt.
are not yet fully and definitively understood.
Much confusion and misunderstanding have arisen because the popular names given to these mutations are misleading. These mutations do not generate a yellow face, as the names might suggest. Rather the action of all these mutations is to reduce the yellow pigmentation, either entirely or to some degree, with respect to the wild-type Light Green. Had these mutations been named 'Yellow-less' rather than 'Blue' or 'Yellowface' their action might have been more easily understood from the outset. But the traditional names are engrained and are retained here.
The prevailing view is that the Yellowface II mutation, together with the Yellowface I
and Blue mutations
, are members of an allelic series situated at the Blue locus
. Although some breeders still dissent from this view it is the one followed here.
On its own, the Yellowface II is a simple autosomal recessive with respect to the wild-type. Visibly, its action appears to be similar to that of the Blue mutation. The heterozygote or Light Green/yellowface II with one Yellowface II allele
and one wild-type allele is visibly indistinguishable from a Light Green, and the homozygote with two Yellowface II alleles is like a Skyblue with a variable green suffusion on the breast.
The SF Yellowface II Skyblue variety, described in Appearance above, is a composite of the Blue and Yellowface II mutations, having one allele of each.
The loci of the Dark budgerigar mutation
and the Blue allelic series are situated on the same autosome
, so the Dark mutation is linked to the Blue allelic series (see genetic linkage
). The cross-over value (COV) or recombination frequency between the Dark and Blue loci is commonly stated to be about 14%, but some experiments have found much smaller values (see Genetics in the Dark budgerigar mutation
).
Budgerigar
The Budgerigar , also known as Common Pet Parakeet or Shell Parakeet informally nicknamed the budgie, is a small, long-tailed, seed-eating parrot, and the only species in the Australian genus Melopsittacus...
s. In combination with the Blue
Blue budgerigar mutation
The Blue budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Skyblue, Cobalt, Mauve and Violet.- Appearance :...
, Opaline
Opaline budgerigar mutation
The Opaline budgerigar mutation is one of approximately 30 mutations affecting the colour or appearance of budgerigars. It is the underlying mutation of the Opaline variety...
and Clearwing
Clearwing budgerigar mutation
The Clearwing budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Clearwing variety, often known as Yellowwings in the green series and Whitewings in the blue series. When combined with the Greywing mutation the...
mutations, the single factor Yellowface II mutation produces the variety called Rainbow.
Appearance
The single factor (SF) Yellowface II Skyblue variety is like a normal Light Green but has a very bright body colour midway between blue and green — a shade often called sea-green or turquoise. The body feathers of the SF Yellowface II Cobalt are bottle-green and in the SF Yellowface II Mauve they are a mixture of mauve and olive.The double factor (DF) Yellowface II Skyblue variety is very similar to the Yellowface I Skyblue, but the yellow pigmentation is brighter, and tends to leak into the body feathers to a greater extent.
Historical Notes
Although not recognised as such at the time, it is possible that the first Yellowface II birds to be reported in the UK were bred by Jack Long of Gorleston-on-Sea in 1935.A contemporary report
of his breeding says, "Mrs Lait mated a dark green cock to a greywing mauve hen, and in their third nest was a pale greywing mauve hen with a distinct (light lemon yellow) mask and bib, with the under tail feathers yellow and with yellow on the wings in the places where the normal blue bird is white. This hen ... was mated with a cobalt/white cock and they have produced five youngsters, all having yellow masks like their mother. Mr Long's birds were bred from a dark green of a somewhat olive shade mated to a rather unusually coloured hen, which appears to be a green but has a turquoise suffusion on the breast, etc. The first nest produced 3 cobalt birds with yellow masks, etc, like Mrs Lait's birds described above, and one green-blue bird like the mother. The second nest produced exactly the same result."
The description of the birds suggests that Mr Long's birds were a DF Yellowface II Cobalt cock and a SF Yellowface II Cobalt hen, but the breeding of Cobalts with yellow masks places this in doubt.
Genetics
The genetics of the several Yellowface mutations and their relation to the Blue mutationBlue budgerigar mutation
The Blue budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Skyblue, Cobalt, Mauve and Violet.- Appearance :...
are not yet fully and definitively understood.
Much confusion and misunderstanding have arisen because the popular names given to these mutations are misleading. These mutations do not generate a yellow face, as the names might suggest. Rather the action of all these mutations is to reduce the yellow pigmentation, either entirely or to some degree, with respect to the wild-type Light Green. Had these mutations been named 'Yellow-less' rather than 'Blue' or 'Yellowface' their action might have been more easily understood from the outset. But the traditional names are engrained and are retained here.
The prevailing view is that the Yellowface II mutation, together with the Yellowface I
Yellowface I budgerigar mutation
The Yellowface I budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars.- Appearance :The Yellowface I Skyblue variety is the same in appearance as a normal Skyblue except that the forehead and mask, which is white in the normal Skyblue, is replaced by bright...
and Blue mutations
Blue budgerigar mutation
The Blue budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Skyblue, Cobalt, Mauve and Violet.- Appearance :...
, are members of an allelic series situated at the Blue locus
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
. Although some breeders still dissent from this view it is the one followed here.
On its own, the Yellowface II is a simple autosomal recessive with respect to the wild-type. Visibly, its action appears to be similar to that of the Blue mutation. The heterozygote or Light Green/yellowface II with one Yellowface II allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
and one wild-type allele is visibly indistinguishable from a Light Green, and the homozygote with two Yellowface II alleles is like a Skyblue with a variable green suffusion on the breast.
The SF Yellowface II Skyblue variety, described in Appearance above, is a composite of the Blue and Yellowface II mutations, having one allele of each.
The loci of the Dark budgerigar mutation
Dark budgerigar mutation
The Dark budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Dark Green and Olive in the green series and Cobalt, Mauve and Violet in the blue series.- Appearance :Budgerigars...
and the Blue allelic series are situated on the same autosome
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
, so the Dark mutation is linked to the Blue allelic series (see genetic linkage
Genetic linkage
Genetic linkage is the tendency of certain loci or alleles to be inherited together. Genetic loci that are physically close to one another on the same chromosome tend to stay together during meiosis, and are thus genetically linked.-Background:...
). The cross-over value (COV) or recombination frequency between the Dark and Blue loci is commonly stated to be about 14%, but some experiments have found much smaller values (see Genetics in the Dark budgerigar mutation
Dark budgerigar mutation
The Dark budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Dark Green and Olive in the green series and Cobalt, Mauve and Violet in the blue series.- Appearance :Budgerigars...
).