Causes and consequences of variation in the hippocampus of individuals utilizing different spatial strategies

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Spatial memory use has been associated with many behaviors such as territoriality, mate choice, navigation and acquisition of food resources. Differential demands on spatial abilities have been shown to affect the hippocampus, the region of the brain thought partially responsible for spatial processing. Although many studies have found a positive association between space use strategies and hippocampal structure, little is known about the causes of variation in the hippocampus and if or how genetics, experience, hormonal and maternal effects influence this variation. More importantly, while most studies assume fitness consequences based on hippocampal variation, there have been no tests of this assumption. The primary goal of this research is to look at the genetic, maternal, hormonal, and experiential basis of variation in the volume, number of neurons and neurogenesis in the hippocampus, as well as the fitness consequences of variation in the hippocampus of male side-blotched lizards (Uta stansburiana). Consequently, this study has 5 primary goals: (1) to determine whether changes in the hippocampus are genetically encoded and relate to particular genetic combinations, (2) to explore if maternal effects, in the form of estradiol deposition in egg yolk, can cause variation in the hippocampus, (3) to manipulate testosterone in males to gauge if differences in gonadal hormones mediate underlying changes in hippocampal morphology, (4) to explore if changes in the hippocampus can be induced or enhanced by spatial use experiences, and (5) to assess if natural and lesion-induced variation in hippocampal attributes relate to fitness, namely survival. Thus, this research links the mechanism, developmental and fitness consequences of variation in the hippocampus. This study will provide interdisciplinary research training to underrepresented undergraduate students, as well as educating the general public via K-12 scientific videogames, popular print, visual media and presentations at community colleges.