SOME SUBORDINATES ARE MORE EQUAL THAN OTHERS - PLAY FIGHTING AMONGST ADULT SUBORDINATE MALE-RATS

Adult male rats living together form dominance relationships, with one dominant and the remainder adopting subordinate roles. In previous st udies, it was shown that in adult male pairs, the subordinate rat init iates more playful contacts and retains a more juvenile response to th e playful contacts by the dominant. In this experiment, triads were us ed to examine the play between subordinate males. The subordinates dir ected fewer playful contacts to each other than to the dominant rat, a nd there was a symmetrical play relationship between the subordinates. After the dominant was removed from the colony, one subordinate becam e the dominant. Playful interactions amongst these pairs increased, wi th the subordinate initiating more playful contacts than the dominant. Furthermore, from a similarly low frequency of juvenile-type response to playful contact to each other when in triads, the subordinate in t he dyads increased its frequency of juvenile responses to the dominant partner. This supports the hypothesis that the playful behavior of su bordinate male rats towards the dominant is an adaptive response, serv ing a ''friendship maintenance'' function. Finally, when in triads, on e subordinate was more playful with the dominant than the other subord inate. It was the least playful subordinate that was the most likely t o become the dominant. This suggests that within a colony, not all sub ordinates are the same. (C) 1993 Wiley-Liss, Inc.