Sex-linked Clearbody budgerigar mutation
Encyclopedia
The Sex-linked Clearbody budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigar
s. It is the underlying mutation of the Texas Clearbody variety.
Over the years many mutations have been reported which produce a (relatively) clear yellow or white body with normal black or dark wing markings, approximating to the beautiful painting of a (hypothetical) "laced Yellow" by R A Vowles shown in Dr M D S Armour's book, "Exhibition Budgerigars"
. In an article published in Cage and Aviary Birds Dr T Daniels summarised those that were known in 1981. Many of these failed to become established, and others, reported separately, may have been the same mutation which appeared in different parts of the world. The Sex-linked Clearbody was one which was established successfully in the USA.
, but the normally coloured cheek patches distinguish the Sex-linked (Texas) Clearbody. For photographs of Sex-linked Clearbodies,
see.
and Mr John Papin of Long Beach
, both in California, obtained respectively a pair and a hen, and showed that the mutation is a sex-linked recessive.
Jeff Attwood brought the variety to Britain in 1989.
and recessive
to wild-type. It is a further mutation of the ino locus with the symbol inocl. Together with the Ino mutation
, it forms a series of multiple alleles. The order of dominance is ino+, inocl, ino, with ino being the most recessive. Mutations which are allelic to Ino and cause partial albinism are known as Par-ino mutations in parrot species.
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 Sex-linked Clearbody (or any other sex-linked mutation). In cocks, because Sex-linked Clearbody is recessive to wild-type and dominant to Ino, the Sex-linked Clearbody allele must be present on both X chromosomes (homozygous) or present on one with an Ino allele on the other to be expressed in the phenotype.
Cocks which are heterozygous for Sex-linked Clearbody with the wild-type allele are identical to the corresponding Normal. Such birds are said to be split for Sex-linked Clearbody, usually written '/SL Clearbody' or '/Texas Clearbody'.
Cocks which are heterozygous for Sex-linked Clearbody with the Ino allele are visually similar to homozygous Clearbodies, although possibly with clearer bodies.
Such birds are said to be split for Ino, usually written 'SL Clearbody/ino' or 'Texas Clearbody/ino'.
The table on the right shows the appearance of all possible genetic combinations involving the Sex-linked Clearbody and the Ino mutations.
As the ino locus is on the X-chromosome the Sex-linked Clearbody gene is linked to all other sex-linked mutations, including Opaline
, Slate
, and Cinnamon
. Because Sex-linked Clearbody is an allele of Ino, the cross-over
values between Sex-linked Clearbody and other sex-linked mutations are identical to those between Ino
and those mutations. For these cross-over values, see the Genetics section in the Ino budgerigar mutation
article.
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 Texas Clearbody variety.
Over the years many mutations have been reported which produce a (relatively) clear yellow or white body with normal black or dark wing markings, approximating to the beautiful painting of a (hypothetical) "laced Yellow" by R A Vowles shown in Dr M D S Armour's book, "Exhibition Budgerigars"
. In an article published in Cage and Aviary Birds Dr T Daniels summarised those that were known in 1981. Many of these failed to become established, and others, reported separately, may have been the same mutation which appeared in different parts of the world. The Sex-linked Clearbody was one which was established successfully in the USA.
Appearance
In the green series the Sex-linked (Texas) Clearbody has a yellow body with a pale greenish cast, and white in the blue series with a pale bluish cast. The cast is palest on the breast, increasing towards the vent and rump. The variety has normal wing marking in grey-black, off-white to grey flights, a tail rather lighter than usual, and normal violet cheek patches. The appearance is rather similar to the Dominant (Easley) ClearbodyDominant Clearbody budgerigar mutation
The Dominant Clearbody budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Easley Clearbody variety....
, but the normally coloured cheek patches distinguish the Sex-linked (Texas) Clearbody. For photographs of Sex-linked Clearbodies,
see.
Historical notes
The details of the first appearance of the SL (Texas) Clearbody have been lost, but the Clearbodies being bred by Floyd Guelker in 1958 were probably of this type. The original mutation is thought to have originated in a colony aviary in Texas around 1955. In 1958 Mrs Gay Terraneo of WilmingtonWilmington, Los Angeles, California
Wilmington is a district of Los Angeles, with industry as its primary economic activity. It lies adjacent to the Port of Los Angeles, San Pedro, and Harbor City. Wilmington is the site of Banning House and Drum Barracks, or Camp Drum, the only major American Civil War landmark in California. The...
and Mr John Papin of Long Beach
Long Beach, California
Long Beach is a city situated in Los Angeles County in Southern California, on the Pacific coast of the United States. The city is the 36th-largest city in the nation and the seventh-largest in California. As of 2010, its population was 462,257...
, both in California, obtained respectively a pair and a hen, and showed that the mutation is a sex-linked recessive.
Jeff Attwood brought the variety to Britain in 1989.
Genetics
The Sex-linked Clearbody 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...
and 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. It is a further mutation of the ino locus with the symbol inocl. Together with the Ino mutation
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 :...
, it forms a series of multiple alleles. The order of dominance is ino+, inocl, ino, with ino being the most recessive. Mutations which are allelic to Ino and cause partial albinism are known as Par-ino mutations in parrot species.
| Sex | Genotype | Phenotype |
|---|---|---|
| Cocks | ino+/ino+ | Normal |
| ino+/inocl | Normal (/SL clearbody) | |
| inocl/inocl | SL Clearbody | |
| ino+/ino | Normal (/ino) | |
| inocl/ino | SL Clearbody (/ino) | |
| ino/ino | Ino | |
| Hens | ino+/Y | Normal |
| inocl/Y | SL Clearbody | |
| ino/Y | Ino |
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 Sex-linked Clearbody (or any other sex-linked mutation). In cocks, because Sex-linked Clearbody is recessive to wild-type and dominant to Ino, the Sex-linked Clearbody allele must be present on both X chromosomes (homozygous) or present on one with an Ino allele on the other to be expressed in the phenotype.
Cocks which are heterozygous for Sex-linked Clearbody with the wild-type allele are identical to the corresponding Normal. Such birds are said to be split for Sex-linked Clearbody, usually written '/SL Clearbody' or '/Texas Clearbody'.
Cocks which are heterozygous for Sex-linked Clearbody with the Ino allele are visually similar to homozygous Clearbodies, although possibly with clearer bodies.
Such birds are said to be split for Ino, usually written 'SL Clearbody/ino' or 'Texas Clearbody/ino'.
The table on the right shows the appearance of all possible genetic combinations involving the Sex-linked Clearbody and the Ino mutations.
As the ino locus is on the X-chromosome the Sex-linked Clearbody gene is linked to all other sex-linked mutations, including 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...
, Slate
Slate budgerigar mutation
The Slate budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is the underlying mutation of the Slate variety.- Appearance :...
, and 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 :...
. Because Sex-linked Clearbody is an allele of Ino, the cross-over
Crossover (genetic algorithm)
In genetic algorithms, crossover is a genetic operator used to vary the programming of a chromosome or chromosomes from one generation to the next. It is analogous to reproduction and biological crossover, upon which genetic algorithms are based...
values between Sex-linked Clearbody and other sex-linked mutations are identical to those between 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 those mutations. For these cross-over values, see the Genetics section in the Ino budgerigar mutation
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 :...
article.