Genetic relationships between sublines of inbred strains of mice as assessed by mandible analysis.

Abstract

Genetic relationships between sublines of inbred strains of mice were investigated by using mandible measurements. (1) Canonical discriminant analysis (discriminant analysis with reduction of dimensionality) was applied to the investigation of genetic relationships between sublines on two kinds of dimensionality. As a result, it was made clear that all the sublines of the same strains mapped closer to each other than they were to other strains on the plane of z1--z2, except the sublines of strain AA. (2) According to the result of discriminant analysis, misclassification among the sublines of the other strains was only 0 head/302 head, or 0%, for the male mice and 6 head/302 head, or 1.99%, for the female mice. Misidentification between the sublines of the same strain was also of low rate; that is, 28/302, or 9.27%, or the males and 9/302, or 2.98%, for the females. These results suggested that the mice of the sublines of the same strain might be genetically different from one another. (3) The cause for the occurrence of such subline divergence as this seemed to be mainly due to the spontaneous mutation of each colony after the separation of mice. It appeared that the subline divergence of strain AA might be due to the genetic heterozygosity of an original stock before the separation of mice.