Dilute budgerigar mutation
Encyclopedia
The Dilute budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigar
s. It is one of the constituent mutations of several recognised varieties: the Light, Dark, Olive, Grey and Suffused Yellows and the Grey and Suffused Whites.
when adult. There is considerable variation in the intensity of the green suffusion, but the best exhibition birds of the 1930s showed very little and also had very faint wing markings. These are the Dilute Light Greens, usually known as Light Yellows.
The green suffusion becomes progressively darker when single and double factors of the Dark mutation
are present. These are the Dilute Dark Greens and Dilute Olives, usually known as Dark and Olive Yellows. When the suffusion is particularly heavy the bird is known as a Suffused Yellow.
In the blue series the absence of the yellow pigment turns the body colour to white, although this is usually suffused with blue, often quite heavily. When the suffusion is light, Dilute Skyblues are known as Whites; when it is heavy they are known as Suffused Whites. Dilute Cobalts and Mauves are usually known as Suffused Whites.
, in 1840
, when he imported to England a pair which had been bred by his brother-in-law, Charles Coxon
. They grew steadily in popularity. For the first thirty years of their domestication only the wild-type Light Green budgerigar was known, but in 1872
birds with greenish-yellow bodies and very pale wing markings were reported from Belgium (in both Brussels
and Antwerp) and Germany (in both Kassel
and Berlin
). This, now known as the Dilute mutation, was the first mutation observed in the domesticated budgerigar.
Joseph Abrahams obtained some of these new yellow birds from Belgium and bred the first Yellow, as it was called, in Great Britain in 1884. These strains, in both Britain and Europe, laid the foundations for the very popular exhibition Light Yellow of the 1920s and 30s, which were often known by the alternative names of Buttercups or Buttercup Yellows. The popularity of the variety declined after the Lutino
became available in the late 1930s.
In 1896, Mr Keartland of the Calvert expedition to Australia, observed a yellow budgerigar flying wild in a flock on three occasions. This suggests the Dilute mutation is relatively common in heterozygous form among the wild populations, as two such heterozygous individuals would need to mate in order to produce a visible Dilute.
Although the Blue mutation
was first seen soon after the first Dilutes, in 1878, and had become established by 1890 in Europe, the first combination of the Blue and Dilute mutations in double homozygous form did not appear until around 1920, some 30 to 40 years later. This combination was the White (known as Silver in Australia), and it was first bred in England by H D Astley in September 1920 from a pair of Skyblues. A White was also reported in Paris in the same year. Whites were never as popular as the Yellows, as it was much harder to approach the exhibition ideal of a pure white bird.
, so a bird possessing a single Dilute allele (the heterozygote) is identical in appearance to the wild-type Light Green. That is, the presence of a single wild-type allele is sufficient to permit the production of the normal number of melanin
granules. Among the budgerigar fancy such a bird is said to be a Light Green split dilute, usually written Light Green/dilute, although Light Green/yellow has been used.
In a bird which has two Dilute alleles (the homozygote) the number of melanin granules is greatly reduced, to around 5% of the normal amount. This results in a much reduced intensity of the black markings, and less absorption of light which passes through the cloudy layer in the medulla of barbs. As this absorption of light is a necessary part of the process which generates the blue colouration the intensity of blue is also greatly reduced.
The Dilute mutation is one of a series of multiple alleles at the same locus
, called dil+ in the wild-type. The others are the Clearwing
(dilcw) and Greywing
(dilgw) mutations. The Dilute allele (dild) is recessive to all other alleles at this locus, so for the Dilute character to be expressed in the phenotype
the genotype
must be homozygous for this allele.
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. It is one of the constituent mutations of several recognised varieties: the Light, Dark, Olive, Grey and Suffused Yellows and the Grey and Suffused Whites.
Appearance
The Dilute mutation changes the body colour of the wild-type Light Green to yellow, with a variable amount of light green suffusion. The suffusion is deepest on the rump and around the vent. The spots and markings on the wing, head and neck, which are black in the wild-type, are pale grey. The cheek patches are pale lavender and the long tail feathers are pale bluey-grey. The eyes remain normal, with white iridesIris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
when adult. There is considerable variation in the intensity of the green suffusion, but the best exhibition birds of the 1930s showed very little and also had very faint wing markings. These are the Dilute Light Greens, usually known as Light Yellows.
The green suffusion becomes progressively darker when single and double factors of the Dark 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...
are present. These are the Dilute Dark Greens and Dilute Olives, usually known as Dark and Olive Yellows. When the suffusion is particularly heavy the bird is known as a Suffused Yellow.
In the blue series the absence of the yellow pigment turns the body colour to white, although this is usually suffused with blue, often quite heavily. When the suffusion is light, Dilute Skyblues are known as Whites; when it is heavy they are known as Suffused Whites. Dilute Cobalts and Mauves are usually known as Suffused Whites.
Historical Notes
Budgerigars were first introduced into Europe by the ornithologist and bird artist, John GouldJohn Gould
John Gould was an English ornithologist and bird artist. The Gould League in Australia was named after him. His identification of the birds now nicknamed "Darwin's finches" played a role in the inception of Darwin's theory of evolution by natural selection...
, in 1840
, when he imported to England a pair which had been bred by his brother-in-law, Charles Coxon
. They grew steadily in popularity. For the first thirty years of their domestication only the wild-type Light Green budgerigar was known, but in 1872
birds with greenish-yellow bodies and very pale wing markings were reported from Belgium (in both Brussels
Brussels
Brussels , officially the Brussels Region or Brussels-Capital Region , is the capital of Belgium and the de facto capital of the European Union...
and Antwerp) and Germany (in both Kassel
Kassel
Kassel is a town located on the Fulda River in northern Hesse, Germany. It is the administrative seat of the Kassel Regierungsbezirk and the Kreis of the same name and has approximately 195,000 inhabitants.- History :...
and Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
). This, now known as the Dilute mutation, was the first mutation observed in the domesticated budgerigar.
Joseph Abrahams obtained some of these new yellow birds from Belgium and bred the first Yellow, as it was called, in Great Britain in 1884. These strains, in both Britain and Europe, laid the foundations for the very popular exhibition Light Yellow of the 1920s and 30s, which were often known by the alternative names of Buttercups or Buttercup Yellows. The popularity of the variety declined after the Lutino
Ino budgerigar mutation
The Ino budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Albino and Lutino varieties and, with Cinnamon, a constituent mutation of the Lacewing variety.- Appearance :...
became available in the late 1930s.
In 1896, Mr Keartland of the Calvert expedition to Australia, observed a yellow budgerigar flying wild in a flock on three occasions. This suggests the Dilute mutation is relatively common in heterozygous form among the wild populations, as two such heterozygous individuals would need to mate in order to produce a visible Dilute.
Although the Blue mutation
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 :...
was first seen soon after the first Dilutes, in 1878, and had become established by 1890 in Europe, the first combination of the Blue and Dilute mutations in double homozygous form did not appear until around 1920, some 30 to 40 years later. This combination was the White (known as Silver in Australia), and it was first bred in England by H D Astley in September 1920 from a pair of Skyblues. A White was also reported in Paris in the same year. Whites were never as popular as the Yellows, as it was much harder to approach the exhibition ideal of a pure white bird.
Genetics
The Dilute mutation is recessive to its wild-type alleleAllele
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...
, so a bird possessing a single Dilute allele (the heterozygote) is identical in appearance to the wild-type Light Green. That is, the presence of a single wild-type allele is sufficient to permit the production of the normal number of melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
granules. Among the budgerigar fancy such a bird is said to be a Light Green split dilute, usually written Light Green/dilute, although Light Green/yellow has been used.
In a bird which has two Dilute alleles (the homozygote) the number of melanin granules is greatly reduced, to around 5% of the normal amount. This results in a much reduced intensity of the black markings, and less absorption of light which passes through the cloudy layer in the medulla of barbs. As this absorption of light is a necessary part of the process which generates the blue colouration the intensity of blue is also greatly reduced.
The Dilute mutation is one of a series of multiple alleles at the same 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...
, called dil+ in the wild-type. The others are the 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...
(dilcw) and Greywing
Greywing budgerigar mutation
The Greywing budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Greywing variety...
(dilgw) mutations. The Dilute allele (dild) is recessive to all other alleles at this locus, so for the Dilute character to be expressed in the phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
the genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
must be homozygous for this allele.