Slate budgerigar mutation
Encyclopedia
The Slate budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigar
s. It is the underlying mutation of the Slate variety.
The Light Green Slate is intermediate in shade between a Light Green and a Light Grey-Green. In both blue- and green-series Slates the cheek patch is purplish-grey or deep violet, somewhat like the cheek patches of Mauves. The long tail feathers are a little darker than the corresponding non-Slate. Other features are unaffected by this mutation.
The Dark
mutation produces a more noticeable effect in combination with Slate than it does with Grey
, but these darker Slate shades differ from one another very much less than Skyblue, Cobalt and Mauve differ. The Cobalt Slate and Mauve Slate are distinctly darker than the Skyblue Slate, with the Mauve Slate being very dark. When Violet
is also introduced the resulting Violet Mauve Slate is said to be extremely dark, of a dense blue-black colour.
As we know now that the Slate mutation is a sex-linked recessive, presumably the cock was split for Slate. In a series of articles
published in the Budgerigar Bulletin, Mr Bowman described the establishment of the Slate mutation. After breeding a few Slates of the blue series, he deliberately paired a Cobalt split Slate cock to a Light Yellow hen to produce Slates of the green series, and in 1937 he succeeded in breeding both Light Green Slates and a Dark Green Slate.
In 1938 Mr Bowman paired a Slate to a Cinnamon, producing split Cinnamon Slate Type II cocks, and in 1939 he intended breeding from these to produce Cinnamon Slates, but no results appear to have been reported. It was, however, reported
that Cinnamon Slates had been bred in 1939 by both W G Roderick of Purley
and Len Trevallion of Loughton
in Essex. Mr Roderick paired a Light Green split dilute cinnamon slate cock to a Cinnamon Cobalt split dilute hen and they produced a Cinnamon Dilute Slate in the first round. Mr Trevallion paired a Skyblue split cinnamon slate cock to a Dilute Mauve hen and they produced a Cinnamon Slate Cobalt split dilute hen. These Slates are likely to have been obtained from Mr Bowman, as he reported that several other breeders had Slates.
Little was heard of Slates during and immediately after the war, but a few appeared again in the early 1950s, most or maybe all of which were Opaline Slates. It seems to have been quite difficult to separate the Opaline and Slate genes and it was not until 1962 that A F Fullilove reported
that non-Opaline Slates had finally been obtained.
After that, Slates almost vanished entirely, but in 1970, after a visit to Cyril Rogers, a Dutch couple obtained a pair of Slates, and later the only Slate they had left was passed to Inte Onsman. Then, in 1992, Inte Onsman sent two Slates cocks to Cyril Rogers. Mr Rogers died in August 1993 and his Slates were passed to Ken Gray, a member of the Rare Variety and Colour BS. Several members of that society then instigated a breeding programme designed to ensure the survival of the Slate variety.
There has always been an interest in producing a completely black budgerigar, so far without success, and the darkening effect of the Slate mutation prompted attempts to combine this mutation with other darkening agents to achieve this. W H James, of Flixton
, near Manchester
, was one of the first to cross-breed Violets and Slates, attempting it first in 1955, and Cyril Rogers also investigated the effect of combining several darkening mutations in one bird in the late 1950s and early 1960s. These attempts certainly produced dark budgerigars, but because the pale grey to white colour of the barbules
of the body feathers is unaffected by any mutation known to date, the admixture of their colour with the colour of the underlying barbs would still produce a grey appearance, even if the barbs themselves were jet black.
, the locus
of its gene
being carried on the X chromosome
. It is recessive
to wild-type. The gene locus has the symbol sl. The wild-type allele
at this locus is notated sl+ and the Slate allele is notated sl.
In birds, the cock has two X chromosomes and the hen has one X and one Y chromosome. So in hens whichever allele is present on the single X chromosome is fully expressed in the phenotype
. Hens cannot be split for Slate (or any other sex-linked mutation). In cocks, because Slate is recessive, the Slate allele must be present on both X chromosomes (homozygous) to be expressed in the phenotype. Cocks which are heterozygous for Slate are identical to the corresponding Normal. Such birds are said to be split for Slate, usually written '/slate'.
The table on the right shows the appearance of all possible genetic combinations involving just the Slate mutation.
The Slate gene is linked
to other genes located on the X chromosome, i.e. to the genes of other sex-linked mutations. These sex-linked mutations include the Cinnamon
, Ino
and Opaline
mutations. The cross-over
or recombination
values between Slate and these linked genes have not all been measured, but the opinion has been expressed
that there is a close link between Opaline and Slate. As several Cinnamon Slates were bred without difficulty, it seems likely that the linkage between Cinnamon and Slate is not close. However, these opinions are not borne out by the only measurements to date
. In these, Inte Onsman found 22 crossovers between Opaline and Slate in 54 hens bred, which gives a cross-over value of 41±9%, almost no linkage at all. He provides no figures, but suggests the linkage between Cinnamon and Slate is around 5%.
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 the underlying mutation of the Slate variety.
Appearance
The name 'Slate' is derived from the appearance of blue-series Slates, particularly the Skyblue Slate, which is close in colour to a Light Grey but with a more bluish tone.The Light Green Slate is intermediate in shade between a Light Green and a Light Grey-Green. In both blue- and green-series Slates the cheek patch is purplish-grey or deep violet, somewhat like the cheek patches of Mauves. The long tail feathers are a little darker than the corresponding non-Slate. Other features are unaffected by this mutation.
The Dark
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...
mutation produces a more noticeable effect in combination with Slate than it does with Grey
Dominant Grey budgerigar mutation
The Dominant Grey budgerigar mutation, often called the Australian Grey or simply Grey, is one of approximately 30 mutations affecting the colour of budgerigars. It is the basis of the Grey-Green and Grey standard varieties.- Appearance :...
, but these darker Slate shades differ from one another very much less than Skyblue, Cobalt and Mauve differ. The Cobalt Slate and Mauve Slate are distinctly darker than the Skyblue Slate, with the Mauve Slate being very dark. When Violet
Violet budgerigar mutation
The violet budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is one of the constituent mutations of the violet variety.- Appearance:...
is also introduced the resulting Violet Mauve Slate is said to be extremely dark, of a dense blue-black colour.
Historical Notes
Only one discovery of the Slate mutation appears to be documented in the budgerigar literature. In 1935 T S Bowman of Carlisle bred a Skyblue Slate and a Cobalt Slate, both hens, from a Cobalt cock and a Skyblue hen.As we know now that the Slate mutation is a sex-linked recessive, presumably the cock was split for Slate. In a series of articles
published in the Budgerigar Bulletin, Mr Bowman described the establishment of the Slate mutation. After breeding a few Slates of the blue series, he deliberately paired a Cobalt split Slate cock to a Light Yellow hen to produce Slates of the green series, and in 1937 he succeeded in breeding both Light Green Slates and a Dark Green Slate.
In 1938 Mr Bowman paired a Slate to a Cinnamon, producing split Cinnamon Slate Type II cocks, and in 1939 he intended breeding from these to produce Cinnamon Slates, but no results appear to have been reported. It was, however, reported
that Cinnamon Slates had been bred in 1939 by both W G Roderick of Purley
Purley
- in England :*Purley, London**Purley Way, out-of-town retail area*Purley-on-Thames, in Berkshire- People :*David Purley , British race driver*Purley, several members of a fictional family in 1996's Secrets & Lies...
and Len Trevallion of Loughton
Loughton
Loughton is a town and civil parish in the Epping Forest district of Essex. It is located between 11 and 13 miles north east of Charing Cross in London, south of the M25 and west of the M11 motorway and has boundaries with Chingford, Waltham Abbey, Theydon Bois, Chigwell and Buckhurst Hill...
in Essex. Mr Roderick paired a Light Green split dilute cinnamon slate cock to a Cinnamon Cobalt split dilute hen and they produced a Cinnamon Dilute Slate in the first round. Mr Trevallion paired a Skyblue split cinnamon slate cock to a Dilute Mauve hen and they produced a Cinnamon Slate Cobalt split dilute hen. These Slates are likely to have been obtained from Mr Bowman, as he reported that several other breeders had Slates.
Little was heard of Slates during and immediately after the war, but a few appeared again in the early 1950s, most or maybe all of which were Opaline Slates. It seems to have been quite difficult to separate the Opaline and Slate genes and it was not until 1962 that A F Fullilove reported
that non-Opaline Slates had finally been obtained.
After that, Slates almost vanished entirely, but in 1970, after a visit to Cyril Rogers, a Dutch couple obtained a pair of Slates, and later the only Slate they had left was passed to Inte Onsman. Then, in 1992, Inte Onsman sent two Slates cocks to Cyril Rogers. Mr Rogers died in August 1993 and his Slates were passed to Ken Gray, a member of the Rare Variety and Colour BS. Several members of that society then instigated a breeding programme designed to ensure the survival of the Slate variety.
There has always been an interest in producing a completely black budgerigar, so far without success, and the darkening effect of the Slate mutation prompted attempts to combine this mutation with other darkening agents to achieve this. W H James, of Flixton
Flixton, Greater Manchester
Flixton is a village and electoral ward within the Urmston area of the Metropolitan Borough of Trafford in Greater Manchester, England. It lies about six miles to the southwest of Manchester city centre, within the historic county boundaries of Lancashire.Flixton's present-day population is...
, near Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...
, was one of the first to cross-breed Violets and Slates, attempting it first in 1955, and Cyril Rogers also investigated the effect of combining several darkening mutations in one bird in the late 1950s and early 1960s. These attempts certainly produced dark budgerigars, but because the pale grey to white colour of the barbules
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
of the body feathers is unaffected by any mutation known to date, the admixture of their colour with the colour of the underlying barbs would still produce a grey appearance, even if the barbs themselves were jet black.
Genetics
The Slate mutation is sex-linkedSex linkage
Sex linkage is the phenotypic expression of an allele related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosomal chromosomes, where both sexes have the same probability of inheritance...
, the 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...
of its gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
being carried on the X chromosome
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
. It is recessive
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
to wild-type. The gene locus has the symbol sl. The wild-type 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...
at this locus is notated sl+ and the Slate allele is notated sl.
| Sex | Genotype | Phenotype |
|---|---|---|
| Cocks | sl+/sl+ | Normal |
| sl+/sl | Normal (/slate) | |
| sl/sl | Slate | |
| Hens | sl+/Y | Normal |
| sl/Y | Slate |
In birds, the cock has two X chromosomes and the hen has one X and one Y chromosome. So in hens whichever allele is present on the single X chromosome is fully 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...
. Hens cannot be split for Slate (or any other sex-linked mutation). In cocks, because Slate is recessive, the Slate allele must be present on both X chromosomes (homozygous) to be expressed in the phenotype. Cocks which are heterozygous for Slate are identical to the corresponding Normal. Such birds are said to be split for Slate, usually written '/slate'.
The table on the right shows the appearance of all possible genetic combinations involving just the Slate mutation.
The Slate gene is linked
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:...
to other genes located on the X chromosome, i.e. to the genes of other sex-linked mutations. These sex-linked mutations include the Cinnamon
Cinnamon budgerigar mutation
The Cinnamon budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Cinnamon variety and, with Ino, a constituent mutation of the Lacewing variety.- Appearance :...
, Ino
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 :...
and 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...
mutations. The cross-over
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:...
or recombination
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...
values between Slate and these linked genes have not all been measured, but the opinion has been expressed
that there is a close link between Opaline and Slate. As several Cinnamon Slates were bred without difficulty, it seems likely that the linkage between Cinnamon and Slate is not close. However, these opinions are not borne out by the only measurements to date
. In these, Inte Onsman found 22 crossovers between Opaline and Slate in 54 hens bred, which gives a cross-over value of 41±9%, almost no linkage at all. He provides no figures, but suggests the linkage between Cinnamon and Slate is around 5%.