Patterns, maintenance and the evolution of behavioral variation and covariance: the presence of personalities in kangaroo rats

Abstract

My dissertation examined patterns of variation and covariation among multiple behaviors in Merriam's kangaroo rats (Dipodomys merriami). I also examined the mechanisms that may be responsible for the maintenance of variation within and between natural populations of D. merriami and investigated the mechanisms that may lead to the evolution of behavioral syndromes or "personalities". I used a structural equation modeling and information-theoretic approach to demonstrate that D. merriami exhibits personality structure between behaviors measured in the laboratory. I evaluated the mechanisms that may maintain variation between and within populations of D. merriami and demonstrated that D. merriami exhibit behavioral covariance in natural populations and that D. merriami behavior was repeatable. Natural populations of D. merriami also exhibited relatively discrete behavioral strategies in aggression and behavioral responses were bimodally distributed. Using individually based modeling, I demonstrated that fluctuating selective pressures led to the evolution of personality structure in populations. This research project developed novel quantitative approaches for the study of the ecological consequences of personality structure, broadened the understanding of the ecological role of within population variation and increased our theoretical understanding of the evolution of personality structure.