PREDATORY AGGRESSION IN MALE-MICE SELECTIVELY BRED FOR ISOLATION-INDUCED INTERMALE AGGRESSION

Male mice differing in their genetically determined disposition for is olation-induced intermale aggression were compared on behaviors relate d to predatory aggression. An ongoing sequence of selective breeding e stablished high-aggressive (Turku Aggressive: TA) and few-aggressive ( Turku Non-Aggressive: TNA) lines from an outbred Swiss albino foundati on stock. The parental strain, designated the Normal (N) strain, has b een kept as a control line and is bred without regard to aggressivenes s. Testing consisted of dropping a live cricket into the home cage of the individually housed experimental mice. Results showed that the TA males displayed shorter latencies to attack and spent more time in cha sing, attacking, and consuming crickets than did TNA and N males. The TNA males displayed significantly less predatory aggression than both the TA and N males. When brothers of the males tested for predatory ag gression were tested for intermale aggression, a similarly significant effect of breeding line was obtained for the latency to attack. Testi ng consisted of placing an intact male mouse into the cage of the male to be tested. The results suggest that there may be parallels in gene tic variation between intermale and predatory attacking.