Inherited and rearing components of aggressive dominance and autonomic reactivity in the rat

Abstract

On the basis of their scores in the open field test apparatus and 'limited access' competition, rats were divided into high and low aggressive and high and low reactive lines. Intrastrain breeding experiments were conducted across 3 generations to determine the heritability of aggressive behaviour and reactivity. In each generation, the animals of each strain were reared under 'normal', 'crowded' and 'food restricted' conditions to determine the extent of the influence of rearing environment on these behaviours. The genetic and environmental contributions to aggression and reactivity were further investigated through reciprocal cross matings and foster rearing. In most of the cases, environmental factors showed significant but varied and unpredictable influences, whereas the genetic factors were more consistent in their effects.