TERRITORIAL BEHAVIOR AND SOCIAL-ORGANIZATION AS A FUNCTION OF THE LEVEL OF AGGRESSIVENESS IN MALE-MICE

Territoriality and social organization were examined in relation ro di fferent genetic dispositions for aggressive behaviour. The animals use d in the study were male mice of the 51st and 52nd generation of selec tion for high (Turku Aggressive, TA) and low (Turku Non-Aggressive, TN A) levels of aggressiveness. The level of aggressiveness of the animal s was assessed by means of individual tests with non-aggressive standa rd opponents, after which they were allowed to form individual territo ries in a 102 x 204 x 90 cm enclosure. TA and TNA males were placed in different enclosures. After 2 wk, when the partitions between individ ual pens were removed, the behaviour of the animals was observed for a 7-d period. Excessive fighting between the highly aggressive TA males occurred, resulting in the formation of dominant-subordinate relation ships. A great number of attacks inflicted were found to be associated with dominance in the colony, and correlated with a high level of agg essiveness when the animals were individually tested for aggression af ter having been in colony environments. The level of aggressiveness of the TA males that had become subordinates had significantly decreased . The TNA males fought less and were more often found to stay in their original territory for the entire period of observation. The results suggest that different genotypes for aggression are related to differe nces in territoriality, and social organization in mice.