Dynamics of Agonistic Interaction between Paired Animals in Three Gerbil Species

Pairing in neutral territory is a common method for studying aggressive behavior in rodents [7, 9, 10]. Agonistic interactions in most rodent species follow the same pattern [13]. During the first several minutes after pairing, the animals inspect the place and each other and then begin to demonstrate postures that can be interpreted as threats, since this demonstration usually precedes acts of direct aggression. An animal often attacks the other immediately after demonstrating the threatening posture; sometimes, the opponent capitulates before being attacked and demonstrates this by assuming submissive postures. After the phase of mutual threats, one of the partners attacks, and the attack is followed by fighting. Later, stable asymmetry in the relationships is achieved: one of the partners continues to threat and attack, while the other only defends, assumes submissive postures, and flees. Thus, four phases can be identified: investigation and evaluation of the situation, mutual threats, direct aggressive actions, and, at last, contest asymmetry. The goal of this study was to compare three gerbil species in duration of the first three phases preceding the formation of the winner-loser asymmetry, and in the strain of agonistic interaction between the animals during the last phase. Based on a general model of behavioral interaction [2, 11], we considered the fighting phase in agonistic encounters of two animals as a period of mutual attempts to inhibit agonistic activity of the partner. Obviously, fighting leads to psychological and physical exhaustion, and the longer the fighting phase, the greater resistance to pressure from the opponent is required. This paradigm makes it possible to consider interspecific differences in the dynamics of agonistic behavior as a manifestation of varying resistance of species to inhibition of behavioral activity.