Inherited activation-inactivation of the star [piebald spotting] gene in foxes. Its bearing on the problem of domestication

A frequency of more than 10(-2) of the de novo appearance of piebald spotting (star) was established in silver-black foxes selected for domestic behavior. The star phenotype is determined by the autosomal semidominant gene S. Ten genealogical groups of foxes, in which star arose independently, were analyzed. Of these, the star character is determined by S alleles in at least seven groups. The S gene is located in a linkage group other than the earlier described W (Georgian white) locus. The star gene is incompletely penetrant, but its penetrance is significantly higher in offspring from tame mothers than from aggressive ones, or when S is received from a heterozygous vixen (Ss). There was a notable shortage of homozygous (SS) offspring from Ss X Ss crosses, which cannot be adequately explained by selective embryonic mortality, differential zygotic and gametic death, or transgression of homozygous and heterozygous phenotypes. Some foxes, proven carriers of a homozygous (Ss) genotype, showed the phenotype and mode of inheritance characteristic of heterozygotes (Ss). Presumably, the mechanism responsible of these observations is a heritable functional activation-inactivation of the star gene. Some implications of this concept in terms of destabilizing selection are discussed.