The Goodale white-spotted mice: a historical report.

After tracing the history of Dr. Goodale's selection study of white-spotted mice, it appears that the white spotting selected for was controlled by a complex of genetic factors. Spot occurrence was controlled by a single gene pair, causing small white areas on the forehead. The size of head spot was determined by a few modifier gene loci, among which some nonadditive gene action may have taken place. The B locus appeared to be associated with head-spot size, either through linkage or pleiotropic effects. There may also have been some maternal effects on head-spot size. Selection for increased head-spot size was successful, the heritability of the trait being between 0.1 and 0.2. The increase in spot size was fairly slow; a total score of about 13 units was reached over 16 years of selection. Accumulation of factors favoring increased head-spot size led eventually to the appearance of body spots, and selection began to concentrate on these. Body-spot size was controlled by a larger number of gene pairs; gene action appeared to be more nearly additive, and there appeared to be no maternal effect or association with B locus alleles. Heritability of body-spot size was 0.3 to 0.5. Total score increased from 13 to 56 units over the 11 years of selection.