Electrophoretic, skeletal, and behavioral divergence of two C3H substrains of mice.

Two C3H substrains of mice, one Australian and one English, were reared under identical conditions in the same laboratory. Electrophoretic and morphometric studies indicated there were genetic differences between the substrains. There were skeletal differences for both metrical and nonmetrical traits of the skeleton scored, and the substrains differed for two of 29 biochemical markers screened electrophoretically. In combination, these results indicate that the two substrains have diverged genetically. A comparison of nest-building behavior indicated that the substrains also differed from one another for the weight of material used to build a nest and the shape of the nest built. The demonstration of genetic divergence in biochemical and morphological traits makes it plausible that these behavioral differences also are due to genetic differences. The implications of these findings for animal studies, especially behavior-genetic studies, are discussed.