A Morphometric Discriminant Analysis of Agouti Genotypes in C57BL/6 House Mice

Abstract

Leamy, L. and S. S. Sustarsic (Department of Biology, California State University, Long Beach, Long Beach, California 90840) 1978. A morphometric discriminant analysis of agouti genotypes in C57BL/6 house mice. Syst. Zool. 27:49–60.—Multivariate discriminant and canonical analysis techniques were applied to suites of six (A) and eight (B) morphometric characters, respectively, in two separate inbred populations of C57BL/6 house mice. Each population consisted of six classes of male mice which differed only in the particular allele present at the agouti locus. The six genotypes (aa, a^ta, a^ta^t, Aa, A^vya, A^ya) were previously found to exert significant pleiotropic effects on most of the characters, the dominant alleles in general causing a decrease from the standard aa genotype. Among the A characters, the width of the first upper molar was the most powerful genotype discriminator, whereas interorbital width was most important among the B characters. Contributions of the characters to the canonical variates generally reflected known correlation patterns as seen from the results of principal component analyses. Discrimination plots and phenograms of the six genotypes consistently showed the a^ta^t and A^va genotypes as distinctive. The percentage of correct classification in the discriminant analysis classification matrices was similar (55% and 60%) for both sets of characters. The implications of the results for topics of interest to systematists (pleiotropy, subspeciation, natural selection) are discussed.