Albino - What's in a Name?
by Robert J. Mangile
What is an “albino” and what is not? Problem!
My perception of the term albino suggests to me that we are referring to the entire being; whether it be a pigeon, a wolf or bison. The animal is an albino - period! Assuming that my perception of the word is correct, it follows that the animal being referred to can not be classified as anything else, with regards to that condition. The following is a definition from the Internet web site, Encyclopedia.com:
"albino - animal or plant lacking normal pigmentation. The albino body covering (skin, hair, and feathers) and eyes lack pigment. In humans and other animals albinism is inherited as a recessive trait. Breeding has established albino races in some domestic animals."
Albinos are unique in that none of their pigment producing cells contain pigment (melanin); i.e., the pigment cells are present but lack pigment. If any pigment cells of an individual contain pigment (melanin), it should not be considered an albino. The genetic "mechanism" that produces white plumage on a Great White Heron or a Snow Goose is different than the one that produces the white plumage of an albino. White plumage lacks pigment, but for various reasons.
If an animal breeder raises an albino, it is most certain that both parents are carriers (heterozygous) for the albino gene. The odds of the spontaneous mutation of both genes in the offspring would be astronomical! A plumage displaying only some white, or a light coloration cannot be an albino by definition because it contains some pigment; whereas, an albino has none. Generally, scattered white or patch-pied plumage differ from the white of an albino in that they lack pigment cells; whereas, the albino has pigment cells but lacks pigment in the cells. Consequently, in either case the lack of pigment lends to the production of white. Complicating matters - in at least one case involving pink-eyed, all white pigeons, it was found that the albino-like appearance was due to a combination of mutant genes and proved not to be albino.
Being involved in both pigeon raising and bird watching it is interesting to compare how each community views and discusses the issue of albinism. Those in the bird watching (birding) community refer to all pied or dilute coloration as either "partial albinos", "imperfect albinos", "incomplete albinos", or "leucistic". A birder might label the White King pigeon as an albino; or a imperfect albino - if they notice that they have dark "bull" eyes? Any breed with a pattern-pied plumage, e.g., Magpies, gazzi Modenas, etc., might be referred to as incomplete or partial albinos. Ironically, they don't refer to the snow goose, the bald eagle or the wild magpie in such related terms.
Loose usage tends to distort or transpose the meaning of terminology. For example: the term “true albino” might be used to make a distinction between an albino and a bird that is all or partially white but not considered an albino. If the bird is albino it needs no further description by adding a qualifier to declare it a "true" albino. If a qualifier is required it is something different. Of course, birders cannot test-breed wild species to establish the genetic basis for various phenotypes.
Unknowingly, birders adhere to the concept of "wildtype" as the standard of reference; a concept that pigeon fanciers struggle to understand. Birders would consider it ridiculous to apply a name to the black-flighted phenotype of the mostly-white Snow Goose; but feel comfortable with the term of "blue morph" or "blue goose" for another plumage variation found in that species. Apparently it is assumed that the wildtype is the white form; labeling the variations as the "blue form"? Similarly, the blue barred pigeon should be considered the "wild type", labeling only the variations.
With regards to the understanding of plumage variations, the community of pigeon fanciers seems much more advanced. For example: fanciers know that a dilute (d) and a reduced (r) are different plumage expressions produced by different genes that promote the dilution of pigmentation (pigment reduction). Birders would refer to both phenotypes as “leucistic”, “partial albino” or “incomplete albino”, depending on who you talk to. Identifying each plumage variation and the mutated gene(s) that produced it is no importance to birders. The opposite is true with pigeon and ring-necked dove fanciers.
Understandably, birders have little regards for domesticated variations; however, many mutations that have occurred in wild species have been preserved in domesticated forms. In domestic pigeons the stork-mark, bald-head, and magpie plumage are "look-alikes" of wild species; possibly even sharing a genetic base, albeit they are found in unrelated species. Fanciers adopt names for every plumage variation - which are often misleading, with regards their relationship to the genetic state of the bird. Instead of labeling the expression of each gene (mutation) on the “wildtype” plumage, they apply names to gene combinations - often producing confusion. Unlike birders who have few classifications for variations - which is equally confusing or misleading.
Unlike keepers of domesticated
animals,
ornithologists (bird scientists) assign great significance to seemingly
minor
plumage (and behavioral) variations. However, the significance is
that
such variations in wild species may occur in specific regions and the
selection of these variations, even within a species, is done by the
forces of Nature; and not by Man. And over the millennium Nature
forges a new species, while Man forges a new breed.
But regardless of whether Man or
Nature does the selecting, the end result will most likely be
considered an
advancement - by Man. Nature makes no judgment calls!
--
Selected terms and definitions:
albescence
= The act of becoming white.
albinism
= Congenital absence of normal pigmentation.
heterochroism
= An increase or decrease in the normal amount of pigment.
leucism
(dilution)
= A reduction in the intensity of all pigments.
melanism
= An excess of black or brown pigment.
schizochroism
= Absence of one or more normally occurring pigments.
xanthochroism (flavism) = An excess of yellow pigment.
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