DEFENSIVE REACTIONS OF WILD-TYPE AND DOMESTICATED WILD RATS TO APPROACH AND CONTACT BY A THREAT STIMULUS

Selective breeding of wild rats over many generations on the basis of low or high defensive threat and attack to human approach and contact has produced highly polarized ''domesticated'' and ''wild type'' anima ls. Because the selection procedure selectively involves these two def ense patterns, and these clearly differ in the two groups, it is of in terest to determine if other, nonselected, defensive behaviors to thre at stimuli also change. '' Domesticated'' and ''wild-type'' rats of th e thirty-fifth generation were run in a fear defense test battery (F/D TB) to systematically evaluate defensive behaviors to a variety of pre sent threat stimuli. ''Domesticated'' rats showed reduced avoidance an d slower flight speed to an approaching experimenter, reduced jump/sta rtle response to handclap and dorsal contact, less vocalization and bo xing to vibrissae stimulation or to an anesthetized conspecific, and r educed defensiveness to an attempted pickup by the experimenter These results indicate that selective bi-directional breeding for defensive threat and attack to human approach and contact produces group differe nces in a variety of defensive behaviors, and in defensiveness to stim uli other than those on which the selection was based. (C) 1994 Wiley- Liss, Inc.