Mangile's Pigeon Pages

Pigeon Genetics, News, Views & Comments
Issue #7
August 1984, pages 3-6.

EVIDENCE SUGGESTS ALLELISM OF
"GAZZI" AND "RECESSIVE WHITE" IN PIGEONS

By Robert J. Mangile
816 E. Atkinson Ave.
Pittsburg, Kansas 66762

The inheritance of white plumage in pigeons can be a very complex matter. Through the decades many attempts have been made to gain insights into some of the more common piebald patterns and their genetic make-up. It is not the aim of this paper to explain the numerous aspects of the inheritance modes that produce white plumage in pigeons, but rather to focus on two of the better understood genetic traits, i.e., "gazzi" and "recessive white".

Gazzi

Perhaps the best understood piebald pattern in pigeons is called "gazzi". Modenas and Strassers are breeds that have examples of the gazzi piebald pattern. Outcrosses of gazzi on colored* pigeons generally produce colored* offspring, with the gazzi pattern being reproduced in the F2's. Hollander gave the symbol "z" to represent the autosomal recessive gene that produced gazzi (see Levi page 343). My breeding experiments agree with previous researchers, i.e., that "gazzi" can be produced from colored parents that are considered to be heterozygous for gazzi, and from backcrosses to gazzi stock. I shall accept the symbol "z" for the autosomal recessive gene for gazzi and make no further comment on the inheritance mode of this pied pattern.

Recessive White (Bull-eyed white)

Solid (self*) white pigeons have been held in high esteem for Centuries. As common as they are, one would think that the genetics of solid white plumage would have been worked out many years ago, but due to the complexities involved, it has remained a mystery until the more recent past.

Solid white plumages are produced from various genetic combinations. Extreme piebaldness may produce solid white, as will ash-red (B^A) combined with grizzle (G). To list all the known and suspected possibilities of genetic combinations that will produce solid white plumages in pigeons will serve no purpose in this paper.

The usual solid white plumage with bull eyes has been suspected of being under the control of a single recessive gene. Over the past ten years or so, students of pigeon genetics have come to call it "recessive white". The work to establish this idea has never been done on a large scale to establish "recessive white" as a single gene unit.

Kings, as well as other pigeon breeds, have demonstrated the likelihood of having "recessive white" in their genetic make-up, and many breeders have suspected and mentioned this fact in personal letters, some of which were published (see ref.). Quinn mentions recessive white briefly and makes the connection to the inheritance mode of "gazzi", in his book "Introduction To Pigeon Science". Levi discusses white and all of its forms at great length in 'The Pigeon", but no conclusions are made with respect to solid white being a single gene unit or its possible allelism to gazzi.

* The term "colored" is used to describe a plumage coloration that is basically without white, sometimes referred to as "self", i.e., one color. Some individuals may have had a few white flights or a small amount of white in their rump or vent, but in no cases did the birds appear to be spotted with white or "splashed", as termed by pigeon fanciers. Such birds may or may-not have been "wildtype" (blue). This researcher considers these white areas to be under other genetic influences.

**The term "intermediate" used by Hollander describes birds that are between the solid white plumage and the gazzi piebald pattern. Such plumage labeled "intermediate" are variable but are definitely not the typical gazzi pattern, and are mostly white.

In 1972 I acquired four (4) Runts from R. C. Fitch, in exchange for some Racing Homers bred for various genetic traits. The Runts were colored birds, of which one cock and one hen were brown (b), one hen was faded blue (St ^F) and one cock was blue (wildtype) with white flights. To my surprise I raised some solid white birds from them, and learned that White Kings were crossed into the Runt stock in the not too distant past. I assumed that the solid white birds produced were recessive white as suspected to occur in the King breed. Subsequent testing with Racing Homer stock soon made it apparent that "recessive white" was indeed being demonstrated in my breeding results (see Table-1). All offspring from pairings with one solid white parent and one colored parent were colored. Pairings with colored parents and considered to be heterozygous for recessive white produced both solid white and colored birds.

 
There seems to be enough evidence, despite the small numbers produced, to support the idea that the solid white plumage in this study is a simple recessive. The expected 3:1 ratio for a simple recessive gene of 41.25:13.75 for the fifty-five (55) birds produced is reasonably close to the 39:16 ratio actually produced. As shown in Table-1, solid white birds were produced in both sexes, ruling out sex-linkage. Only solid white hens would have been produced if sex-linkage were operating.

Gazzi//Recessive White Allelism

In personal communications with Dr. Hollander, he suggested that "gazzi" and "recessive white" might be allelic. In an article entitled "On The Origins Of Domestic Genes. XXX. White & Pied", he points out that "Crossing gazzi with bull-eyed white commonly gives Fl intermediate**, suggesting allelism of the two." Also, in the periodical "Pigeon Science & Genetics Newsletter", Chrisler (1977, see ref.) makes the statement "Have new indications that recessive white may be allelic to gazzi." Engrossed with such possibilities I decided to make direct tests to help clarify this matter.

I paired a blue gazzi Modena cock to a recessive white hen (Pair 482) and produced six (6) Fl's, all of which were "intermediate" in plumage coloration as Hollander suggested. Of these six F1's, two (2) cocks and two (2) hens were kept for further breeding tests. The resulting data are shown in Table-2.

 
By combining the data from Table-1 and Table-2 the totals show that of ninety-one (91) offspring produced twenty-eight (28) were solid white, or just under 3l%, which is slightly above the 25% expected.

Birds in pairings number 516 and 517 were switch-mated and bred the following year in pairings numbering 581 and 587. One cock, when used in pair number 581, became sterile or failed to fertilize eggs for many successive clutches, explaining the production of only one offspring in that mating.

Discussions And Conclusions

The intermediate phenotypic expression produced when gazzi is crossed with bull-eyed recessive white is clear evidence of an interaction. If gazzi and recessive white were located on different chromosomes the 9:3:3:1 ratio of a dihybrid cross would be altered due to the phenotypic expression produced by the interaction. With the use of Punnett Squares, it can be shown the 25% of the F2's should have been solid white, 31.25% colored and the remaining 43.75% either gazzi and/or intermediate.

Even if gazzi and recessive white were linked, we would expect a percentage of the F2's to be colored relative to the linkage.

Of the thirty-six (36) F2's produced, none were colored and the closest coloration to a wildtype colored plumage was a "gazzi" piebald pattern. This fact suggests strongly that the genes that control gazzi and recessive white are allelic, as Hollander suggests.

If the allelism of gazzi and recessive white is accepted, there must be consideration given to the phenomenon that when gazzi and recessive white occur in the same bird, as demonstrated in the Fl's in the original cross of a gazzi Modena and a recessive white Homing Pigeon (pair 482), the phenotypes are intermediate as Hollander pointed out. The combined effects of these two genes apparently produce a plumage coloration that is mostly white with some colored feathers, but in my experience the colored feathers occur in the areas of those colored areas in the gazzi pattern. Recessive white in its heterozygous state with gazzi assists in the production of whitening of the plumage. Some birds of this genotype approach near solid white, but with some colored feathers, particularly in the tail and on the head and face. Perhaps a solid white plumage could be produced from this genotype with wildtype background, and almost certainly a solid white could be produced with the addition of other genes as ash-red (B^A), grizzle (G) and almond (St). Clearly, there is a connection of gazzi to recessive white.

If the assumption is made that gazzi and recessive white are allelic, and the heterozygous condition of gazzi and recessive white produces an "intermediate" expression of the two plumages, the anticipated expected ratio would be 1:2:1. Comparing the results of the F2's in Table-2, to the proposed 1:2:1 ratio, it must be pointed out that the nine (9) gazzi phenotypes produced is exactly the 25% expected from the thirty-six (36) F2's produced.

At this point it must be made clear that my judgment comes into question because the classification of the gazzi pattern in some cases may have been arbitrary. The segregation of gazzi does not always express itself phenotypically as clearly and neatly as one wished, therefore, error in judgment is to be considered. The same comments may be applied to the intermediate phenotypes. Perhaps some were miss-classified and should have been classified as gazzi.

Of the thirty-six (36) F2's produced, fifteen (15) were classified as "intermediate". This is three (3) short of the expected 50% in the 1:2:1 ratio. The twelve (12) classified as solid white were three (3) over the 25% expected ratio. There was no error in the classification of white plumage. No pigment is visible in recessive white plumage, or in the skin, feet or bills of young squabs; nor does down length appear to be affected.

Though the numbers included in the F2's are small, they appear to fit the 1:2:1 ratio. It is my opinion that Hollander was correct in his guess that "gazzi" and "recessive white" are allelic. The data shown reflects clearly, by the failure to produce wildtype/colored offspring in the F2's that independent assortment as expected in a dihybrid cross was not confirmed in the thirty-six (36) F2's produced.

The proposal that "gazzi" and "recessive white" are allelic appears sound enough to be accepted at this time. The symbol "z" for "gazzi" as an autosomal recessive gene has been given by Hollander (see Levi, page 343). Therefore, with "recessive white" being labeled as an allele of "z" scientific tradition necessarily dictates that the symbol should begin with a z. In personal correspondence, Hollander suggests the symbol "z^wh" for "recessive white". This suggestion seems acceptable to this researcher.

The genotypic expression of recessive white would be expresses as (z^wh//z^wh), and the phenotype would be solid white with bull eyes. Offspring from birds with z//z genotypes (gazzi) paired to birds with z^wh//z^wh genotypes would (as in pair 482) have "intermediate" phenotypes and z^wh//z genotypes.
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Literature Cited:

Chrisler, T.S.-------Pigeon Genetics News Letter, issue #70, p. 3-6. April 1974. Personal communications.

------------------------Pigeon Science & Genetics Newsletter, issue #4, p. 30. January 1977. Personal communications.

Fitch, R.C. ---------Pigeon Genetics News Letter, issue #57, p. 68 & 69. January 1970. Personal communications.

Graefe, C. ----------Pigeon Genetics News Letter, issue #54, p. 13, April 1970, and issue #64, p. 11, October 1972. Personal communications

Hollander, W. F. --Pigeon Science & Genetics Newsletter, issue #1, p. 12 & 13. January 1976. Series - "On The

Origins Of Domestic Genes. XXX. White & Pied".

Levi, W.M.-----------"The Pigeon", 667 pp., 1957 ed. Chapter V, Genetics-Variation and Inheritance, paragraphs 524 thru 531.

Mangile, R. J. ------Pigeon Genetics News Letter, issue #69, p. 27. January 1974. Personal communications.

Quinn, J.W.---------"The Pigeon Breeders' Notebook--An Introduction To Pigeon Science", 144 pp., 1971. (Page 107)

Rinehart, D. A. -----Pigeon Genetics News Letter, issue #72, p. 23. October 1974. Personal communications.

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