Behavioral genomics in the white-throated sparrow

Most behavioral traits are complex and are the product of interactions between multiple genes and/or environments. Therefore, ideal models in which to examine the relative roles of genetic effects should have, 1) variation in behavioral phenotypes, 2) the potential to identify the genetic bases of these behavioral traits, 3) an obvious association between phenotype and genotype, 4) the potential to identify relevant environmental conditions contributing to the establishment of behavioral phenotypes so that partitioning of gene-by-environment effects is possible, and 5) a strong understanding of the evolutionary forces influencing the system. Given these desires, an unexpected new animal model emerges for the study of behavioral genomics – morphs of the white-throated sparrow (Zonotrichia albicollis) exhibit alternative strategies of monogamy/high parental effort vs. promiscuity/low parental effort. These behaviors are absolutely correlated with the presence or absence of a large chromosomal rearrangement. We have amassed 22+ years of detailed behavioral, physiological, ecological, and evolutionary data on this species making it possible to identify the genetic, epigenetic, and environmental bases of behavior. Here we further outline the utility of the species, as well as present current cytogenetic and molecular data showing that rearrangements and linkage in multiple chromosomes are key to the evolution of alternative phenotypes. In addition, comparative analyses among the Zonotrichia suggest an interesting and slightly counterintuitive evolutionary pathway in this group. Genomic studies in the white-throated sparrow will identify the gene(s) associated with complex behaviors, as well as provide us with information on how environment interacts with genetic architecture to affect aggressive, social, sexual, and parental phenotypes. Morphs of the sparrow provide us with a unique opportunity to study intraspecific genomic differences, which have resulted from two separate, yet linked evolutionary trajectories. Such results can transform our understanding of the evolution of genomes.