Effects of alleles at the albino locus on odontometric traits in coisogenic mice

The widths of all six molars were examined in coisogenic house mice of strain 129/J to determine whether they were being influenced by chinchilla alleles at the albino locus. Although genotype differences did not reach formal significance in the analyses of variance for any molar (or body weight) in either sex, the molar means for chinchilla homozygotes were less than those for the albinos in 11 of the 12, and for heterozygotes in 12 of 12 combinations. The difference between the two homozygous genotypes within each molar and sex averaged 0.25 standard deviations. Static allometry coefficients were calculated for each genotype and sex from partial regressions of the logarithms of each of the molars on the logarithms of the cube root of body weight, adjustment being made for the effects of litter size and the day the litter was born. These coefficients all were low in magnitude (negative allometry), and multivariate analyses of covariance showed that they differed significantly among genotypes in males, but not in females.