Functional relationships between genotypes and environments in behavior. Effects of different kinds of early social experience on interstrain fighting in male mice.

Comparisons are made of the interstrain fighting behavior of adult male mice from two inbred strains (ST-albino; CBA-black-agouti), raised in one of three postweaning social situations: 1) isolated from other males, 2) reared with males of the same strains, or 3) reared with males of the opposite strain. Using the fighting behavior of isolated males as a baseline, it is found that each type of early social experience affects the fighting behavior of the males from each of the two inbred strains differently, indicating that the functional relationships between genotype and environment studied in these experiments are nonadditive. The importance of these results in describing the norm of reaction of a behavioral phenotype and in extrapolating data from one experiment to another is discussed.