Mapping of the genes for pea comb, blue egg, barring, silver, and blood groups A, E, H, and P in the domestic fowl.

Five chromosomal rearrangements involving chromosome 1 were utilized to test linkage relationships of the blue egg--pea comb--naked neck (O-P-Na) linkage group. An F1 stock was created by crossing rearrangement carriers with individuals carrying the traits being studied. The F1 was then backcrossed to recessive, normal chromosome tester stocks. Chromosomal and phenotypic descriptions were made for each of the segregating progeny. Significant linkage relationships were shown for blue egg and pea comb on the proximal one third of the short (p) arm of chromosome 1. No linkage was found for naked neck. Barring and silver were tested against the two arms of the Z (sex) chromosome, and the linkage values suggest that these loci are on opposite arms. Blood group loci linkages between Ea-H and W4, Ea-P and Na, and Ea-A and Ea-E were confirmed. However, no linkage was observed between these loci and the marker rearrangements on the p arm of chromosome 1.