Quantitative characters of potential value in studying mutagenesis.

The use of polygenic characters in testing for mutagenicity appears promising. Characters chosen should be easily measured and highly heritable, with a reasonable proportion of the genetic variance being of the additive type, as this implies that polygenic mutations affecting the character would be detectable in the heterozygous state. Changes in such characters may arise as a result of pleiotropic effects of major gene mutations that affect early steps in metabolic pathways.--No single character is likely to be entirely satisfactory; rather a diverse group of biochemical, anatomical and physiological characters, including growth and behavior, should be studied. Mandible shape appears to be particularly promising. The characters may be analysed simultaneously using multivariate techniques. Special attention should be paid to the detection of outliers, which may then be investigated by more classical methods for the presence of mutants. Thus, easily measured, highly heritable polygenic characters may be useful in screening animals for the presence of mutations.