ORGANIZATION OF SEX-TYPICAL PATTERNS OF DEFENSE DURING FOOD PROTECTION IN THE RAT - THE ROLE OF THE OPPONENTS SEX

Feeding rats defend a food item from an approaching conspecific by tur ning away, laterally, about 180 degrees. Females and males use a diffe rent composition of movements and stepping patterns to perform these d efensive dodges. This study was designed to examine the role of the ro bber's sex on the execution of sex-typical patterns of dodging. All su bjects were tested with a partner of each sex. During dodging, females used the female-typical pattern of pivoting around the pelvis, and ma les used the male-typical midbody pivot, irrespective of the robber's sex. These findings show that the sex-typical patterns of dodging are not determined by the sex of the partner. Females and males however di ffered in how they were oriented towards a same sex robber at the end of the dodge. This suggests that while male and female robbers must po se different defensive problems, these differences are dealt with by m odifying the sex-typical pattern of dodging rather than by switching t o the dodge pattern of the opposite sex. This further suggests that th e differences in the composition of the dodge pattern in males and fem ales are not due to extrinsic contingencies, but rather, are due to in trinsic differences in the sex-typical organization of defensive motor patterns. (C) 1997 Wiley-Liss, Inc.