Effectiveness of Selection in Producing Laboratory Stocks Genetically Uniform for Resistance or Susceptibility to Dental Caries

¹ Michigan State University, East Lansing, Michigan, and Ohio State University, Columbus, Ohio

Inbreeding is not the best method for producing a homozygous resistant or susceptible stock of small mammals for studying the causes of dental caries. It is better to breed within a closed population, mating animals that are no more closely related than second or third cousins, preferably the latter. Select as breeders animals that are themselves resistant (or susceptible), but an additional requirement is that they be from resistant (or susceptible) sibships. The method used for identifying dental caries should be as exacting as possible under the conditions of the experiment, but even if the method of selection is not highly accurate, homozygosity will be approximated in time. The production of genetic uniformity by selection is not significantly influenced by genetic equilibrium in the foundation stock.