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• Albinism in Japanese Quail (from Crawford, R. D., 1990. Poultry Breeding and Genetics. Elsevier Amsterdam, The Netherlands.):
Types:
• Complete Albinism (autosomal recessive; completely white bodies with bright red eyes)
• Incomplete Albinism (sex-linked recessive; pink eyes with white to light yellow bodies, light barring may occur on some feathers)
• Dominant White (incomplete autosomal dominant; white bird with black skin; partially lethal; few birds survive to adulthood)
• Recessive White (autosomal recessive; white bird with a few WT feathers splashed on the head, neck, and back)
• White Feathered Down (autosomal recessive; lethal in the homozygous form; white feathers and down and black eyes)
• Brown Splashed White (autosomal recessive; white splashed with WT feathers predominantly on the head, back, wings, and breast)
• Panda (autosomal recessive; WT splashed with white; breast feathers and primaries are always white)
• White Breasted (autosomal recessive; white fronted birds-from eyes to vent)
• White Crescent (possibly autosomal recessive; white crescent on the chest of a WT colored bird)
• White Bib (possibly autosomal recessive; white bib on the chest of a WT colored bird)
• White Primaries (autosomal recessive; white primary feathers only)
Q: Why can some of these mutations be classified as albinos?
A: Albinism is the complete lack of pigment in the feathers, eyes, or skin and all of these mutations exhibit at least one of those criteria. Some have white feathers, but normal skin and eyes - they are albinos for feather colour. The mutations that exhibit a mix of feather colours are partial albinos for feather colour. Several genes (maybe more) are responsible for feather colour in birds and a mutation in at least one of these genes is leading to white feathers. These birds are an albino for the gene(s) causing the white feathers and wild type at the genes where there has been no mutation.
Albinism in Pheasants (from Crawford, R. D., 1990. Poultry Breeding and Genetics. Elsevier Amsterdam, The Netherlands.):
Types:
• Pied Spotting (autosomal recessive; pied with white feathers; dirty blue eyes)
• Blue Eyed White (autosomal recessive; completely white feathers and blue eyes; pearl white shanks and beak)
• Brown Eyed White (autosomal recessive; completely white feathers and brown eyes; buff beaks and shanks)
• Incomplete Albinism (sex-linked recessive; white bird and pink eyes; reduced viability)
• Albino (inheritance unknown; white feathers and red eyes)
• White Skin (autosomal dominant; white skin [pinky hue])
• In conclusion, albinism is not a very well studied mutation in genetics so there isn't very much information out there and the definition of an albino is disputed among geneticists. If you take the most common definition "Albino = a pigmentless "white" phenotype determined by a mutation in a gene coding for a pigment synthesizing enzyme.", you have to interpret an albino as anything where there is a mutation in a gene which results in a pigmentless phenotype. This means that any mutation leading to a pigmentless phenotype (white hair, feathers, OR skin or red eyes) should be classified as an albino. This can be extended to animals expressing these phenotypes for only part of their body (e.g. lacking pigment in their toes, have splashes of white feathers, only have red eyes). These may not be complete albinos (red eyes, white skin, & white feathers/hair), but they are partial albinos. |
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