Multiple effects of coat color genes in the Norway rat, with special reference to temperament and domestication.

On the origin of domesticity: A test of Keeler’s “black-gene” hypothesis

“…Ultimately, how does one account for the differences between the findings of this study and those of Keeler (1942)? The origin of the "gene pool" for each study cannot be determined.…”

“…Robinson (1965) stated that Keeler's black rats were a substrain of King's (1939) rats. In any case, the female albino rats would have contributed 50% of the domestic genes to the offspring, and this could have accounted for a substantial portion of the domestic characteristics that Keeler (1942) reported, in spite of the effects of 12-14 generations of laboratory rearing.…”

“…Keeler (1942) stated that his black rats were derived from segregants from a cross of three Wistar albino females with a brown Norway rat. There is no indication of whether the brown Norway male was recently trapped or an inbred laboratory variety left from King's (1939) work.…”

Genetic Architecture of Tameness in a Rat Model of Animal Domestication

“…Possible explanations include direct selection for coat color variants by humans (e.g., Pielberg et al 2008) and removal of selective pressures for camouflage. It is further conceivable that coat color variation is a pleiotropic effect of alleles influencing other traits and particularly behavior, including the level of tameness (Keeler and King 1942;Cottle and Price 1987;Hayssen 1997).…”

“…Prominent examples include the white color variants in dogs, pigs, cows, horses, and chickens. In laboratory rats, it has been proposed that ''coat color genes'' may account for many of the differences associated with domestication (Keeler and King 1942). It is thus interesting that individuals with white spots appeared in both the tame foxes (Trut 1999) and the tame rats (Trut et al 2000) at higher frequency than in the corresponding aggressive lines, although they were absent or rare in the founding fox and rat populations, and although they were not selected for.…”