The influence of the Y-chromosome of Rb/1Bg mice on agonistic behaviors

Males of the Rb/lBg and C57BL/10Bg strains, as well as of the Bl0RblF, and RblBlOF1, reciprocal hybrids, were tested for aggression over three daily trials beginning at 50 days of age. The BlORblF, hybrids were sired by Rb/lBg males, and the RblBlOF, hybrids were sired by C57BL/10Bg males. The mean scores for the agonistic acts of chase, wrestle, flank‐bite (but not tail rattle or attack), and the mean “aggression” score (but not mean latencies to first agonistic act or first attack) were significantly higher for BlORblF, than for RblBlOF, hybrids. These findings are consistent with the hypothesis that some aspect(s) of the Rb/lBg Y‐chromosome strain can influence the occurrence of some of the motor patterns of offense but not defense. The Y‐chromosomes of the DBA/1, DBA/2, CBA, and PHH inbred strains have a similar effect on agonistic behaviors.