Document Type



Doctor of Philosophy



Date of Defense


Graduate Advisor

Zuleyma Tang-Martinez


Lon Wilkens

George Taylor

Stan Braude


Individual differences in behavior are significant because they serve as the substrate for natural selection. Within the Behavioral Syndromes framework, researchers study individual differences in behavior of animals. Behavioral Syndromes are defined as correlations between behaviors in different environmental contexts or testing situations. In this study, I examined the effects of litter size and sex ratio, familial relationships, and age and sex on exploratory behavior of prairie voles, Microtus ochrogaster. Exploratory behavior, defined as spontaneous behavioral responses to unfamiliar stimuli, was examined in three novel situations: an open-field with novel objects, a two-way novel choice apparatus, and a complex maze. Each test was found to measure a different exploratory behavior axis: the open-field test with novel objects measured interactive behavior, the exploratory maze measured general activity behavior, and the two-way novel choice test measured proactive/reactive behavior in response to novel environments. No correlation of behavioral responses across the three tests was found, thus providing no evidence of an overall exploratory behavioral syndrome in this species. On the other hand, there was considerable individual variation in behavior within each test and some of this variation could be explained by the independent variables examined. Litter size and, to a smaller degree, age explained exploratory behavior in the open-field. Subjects from large, socially complex litters and young subjects were less interactive in the open-field with novel objects than subjects from smaller litters and older subjects. In the maze, subjects who were the only ones of their sex in a litter entered the maze sooner than subjects from all other litter compositions; there also was a tendency for females to travel longer distances within the maze than males. However, I found no relationship between behavior in the two-way novel choice apparatus and the independent variables of interest. Across all three tests, most subjects across families demonstrated similar behavioral tendencies; as a result I concluded that the general character of this population of prairie voles includes being highly interactive, more active, and proactive. Overall, the results of this study raise questions about the interpretation of behavioral responses and the identification of behavioral syndromes.

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Biology Commons