| Abstract: | The aggressive behavior of two selectively bred rat strains (high “H” and low “L” emotional reactivity) and their reciprocal F1 and F2 hybrids were measured during three consecutive days in home-cage intruder tests. In terms of biting, bite latency, on-top-of and aggressive grooming, L males were more aggressive than H and F1 males. There was no difference between H and F1, nor between HLF1 and LHF1 with the exception that LHF1 showed more on-top-of. About one fourth of F2 males were equal to or more aggressive than L in terms of bite latency and number of bites. These findings suggest that aggressiveness was inherited as a recessive, monogenic trait in these rats. |
