TITLE: Effects of Operational Sex Ratio on Spatial Learning Ability in Prairie Voles Introduction: Prairie voles (Microtus ochrogaster), are a commonly used model of nonhuman social monogamy. Traditional monogamous systems

Introduction: Prairie voles (Microtus ochrogaster), are a commonly used model of nonhuman social monogamy. Traditional monogamous systems are comprised of male-female pairs that share territory and care for offspring. Operational sex ratio (OSR), the relative ratio of males to females that are sexually receptive, can affect sexual selection, and in monogamous systems, OSR tend to be about 1:1. However, population densities with male-biased OSR generate more male-male competition, thereby increasing variance in reproductive success and mating tactics. Cognitive characteristics, such as navigational skills, may increase males reproductive success by increasing their ability to navigate the social world. We hypothesized that prairie voles placed in a complex social and spatial environment will have better navigation skills and perform better in the Morris water maze (MWM).