Alternate Author Name(s)

Dr. Alan Treiber, MA '74

Document Type

Dissertation

Date of Award

1977

Keywords

Aggressive behavior in animals, Gerbils, Animal behavior, Mongolian gerbil, Intraspecific and intergeneric agonistic behavior

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

John L. Fuller

Second Advisor

Richard G. Burright

Third Advisor

John J. Christian

Abstract

Although the agonistic patterns of behavior of the adult male gerbil (Meriones unguiculatus) have been examined in previous work, the behavior of the female gerbil has not been given careful examination. Understood to an even lesser extent is the plasticity of the agonistic response in terms of intergeneric encounters or the effects of prior experience during an extended adolescent developmental period (approximately 30 to 100 days of age).

The first of two experiments was concerned with similarities or differences in the behavior of the adult male and female gerbil. Six adult female and six adult male gerbils were established in individual home cages. Over a period of 4 weeks, individual intruders (either a male or female gerbil or a male or female SJL mouse) were placed in the home cage. The resulting outcomes of the social interactions between the resident gerbils and the intruders revealed three important findings: (1) that SJL mice are subject to more agonistic behavior on the part of the residents; (2) that the female resident gerbils tend to be more aggressive than the male resident gerbils; and (3) that female resident gerbils direct more aggression toward female gerbil intruders than against male gerbil intruders.

The second experiment was concerned with the effect of postweaning experience with conspecifics and/or members of another species on adult patterns of agonistic behavior. At weaning (30 days of age), male gerbils were placed in one of three rearing condition cages: SG – a single gerbil and a single SJL mouse, MG – 3 gerbils and one SJL mouse, and AG – 4 gerbils. At 95 days of age, the test subject gerbils (8 from each condition) were placed in a neutral arena and observed for agonistic response to both an individual gerbil and SJL mouse during a 10 minute period. Following the neutral arena tests, the test subject gerbils (residents) were placed into individual home cages. At 121 days of age the resident gerbils were tested for agonistic response to strange individual gerbils and mice (intruders) placed into their home cage.

Contrary to expectations, the gerbils (SG, MG) with the post-weaning social experience with SJL mice proved to be more aggressive toward mice and more dominant over mice in both the neutral arena and in the home cage test trials than were the gerbils (AG) without post-weaning experience with mice. In addition, the gerbils (SG) without post-weaning experience with other gerbils exhibited deficiencies in social interaction with other gerbils both in the neutral arena and home cage trials.

The results of both experiments suggest that the patterns of social behavior in the Mongolian gerbil, and by extrapolation other rodent species, may be more complex and plastic than previously thought in that: (1) the role of the female in maintaining population structure and dominance hierarchies has been underestimated, (2) intergeneric agonistic behavior is an important aspect of the gerbil’s social behavior repertoire, (3) previous experience with another species can modify the intergeneric agonistic behavior patterns, and (4) the extent of the plasticity in patterns of social behavior can depend on the context of the testing situation (e.g., neutral arena or home cage).

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