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Further Data on the Inheritance of Blue in Poultry

1921; University of Chicago Press; Volume: 55; Issue: 639 Linguagem: Inglês

10.1086/279815

1537-5323

William A. Lippincott,

Microbial Metabolism and Applications

1. It has been shown that the development of black pigment in the blue-splashed, blue and black races of the Andalusian and Orpington breeds, and of black Langshans, depends upon the action of a dominant hereditary factor P, for which they are normally homozygous. 2. The allelomorph of P is p. Individuals homozygous for p are white, as in the white Wyandotte and white Plymouth Rock breeds. 3. The extension of black pigment to all feathers of the body, resulting, if no pattern factors are present, in self-colored individuals, depends upon a dominant factor E. This factor has been found in the Andalusian, Orpington, white Plymouth Rock, white Wyandotte and black Langshan breeds. Some evidence is presented which indicates its presence in white Leghorns. 4. The blue appearance of blue and blue-splashed Andalusians and Orpingtons, is due to the arrangement and restriction of black pigment, the result of a dominant factor R. This factor has also been found in individuals of the white Wyandotte and white Leghorn breeds, though its presence is probably not usual in these breeds. 5. No individuals of the Andalusian, Orpington, white Plymouth Rock, white Wyandotte or black Langshan breeds have been found which did not carry R, E or both. 6. The mutual relations of R and E are such that they have never been found together in the same gamete. This indicates that they are allelomorphic, i.e., occupy identical loci on homologous chromosomes, or, each is so closely linked to the recessive allelomorph of the other, (Re) and (rE), that crossing-over rarely, if ever, occurs. 7. No evidence of crossing-over between R and E has been found and the tentative conclusion must be in accord with that previously held, that R and E are allelomorphs. 8. Both R and E are independent of P in their hereditary behavior, though dependent upon its presence for their manifestation. 9. The cooperative influence of the ovary is necessary for a full expression of R in the regions of the neck, back and saddle. 10. On the basis of the evidence presented in the body of this paper the genetic formulae of the breeds and varieties employed, with respect to the factors under observation, are usually as follows: blue-splashed Anabaena and orangeade PC (Re) (Re); blue Andalusians and Orpingtons PP (Re) (rE); black Andalusians, Orpingtons and Langshans PP (rE) (rE); and white Plymouth Rocks and Wyandottes pp (rE) (rE). 11. The possibility of the occurrence of factors which duplicate the somatic effects of R and E is pointed out, and the relation of this possibility to the production of constant-breeding blues briefly discussed.