Improved estimate of the Gm-Pi linkage.

The Gm-Piota linkage group is firmly established. A heterogeneity of recombination fraction amongst males of different Piota types has now become very likely. The major differences seem to be between the Piota (z) and other alleles of the Pi system. A chromosomal deletion, inversion or a regulatory (rec) locus in linkage disequilibrium with the Piota locus offer possible explanations.