| For behavior to evolve, behavioral differences among animals must be influenced by genetic variation. In general, we do not know which genes contribute to behavioral variation in natural populations. The close relationship between behavior and the nervous system, however, allows us to infer that genetic, neural, and behavioral variation are likely to be both correlated and causally related. Unfortunately, the intricate interactions between genes, the brain, and complex behavior make understanding these relationships difficult. Recently, two advances in genetics have made it possible to link these phenomena like never before. First, natural animal species are quickly becoming mainstream model systems in which we can investigate genetic and behavioral traits that have evolutionary relevance. Second, advances in quantitative genetics have made it possible to identify the genetic contributions to complex traits, including behavior. These two developments have enabled new investigations into the genetic and neural underpinnings of behavioral variation in evolutionarily relevant systems.;In the following body of work, I present a study of the genetic and neural contributions to social behavior in threespine sticklebacks (Gasterosteus aculeatus). Using information theoretic analysis techniques as well as original behavior assays, I show that stickleback populations exhibit quantifiable differences in shoaling and schooling behavior. I also identify unexpected amounts of variation in a neural system that contributes to these behaviors, the lateral line sensory system. I find evidence for heritable contributions to both the lateral line system and schooling behavior, enabling a genetic analysis of these traits. Although my quantitative trait locus (QTL) analysis for schooling behavior is unsuccessful, I find many QTL contributing to variation in the lateral line. My findings suggest that this sensory system is influenced by loci exhibiting independent (modular), pleiotropic, and epistatic modes of action, all of which have important implications for the evolution of the lateral line in sticklebacks. |
