A central challenge in the study of behavior is to understand the mechanisms by which genetic changes can cause behaviors to vary. Though nesting is a heritable, tractable behavior with profound consequences for survival and reproduction in rodents, the genes that influence this trait and the precise neural circuitry governing this behavior are unknown. This research project will complement an ongoing genetic study and bridge the gap between our understanding of genetic, neurobiological and behavioral variation by identifying the neurons that are active during nesting and characterizing gene expression patterns in these cells. These are crucial steps in understanding how genetic changes can alter the structure and function of a mammalian nervous system, an area of inquiry with implications beyond nesting behavior. Moreover, this is a unique opportunity to identify a genetic change that contributes to a behavioral difference in naturally evolving populations, examples of which are very rare, especially in mammals. As this genetic variant is segregating in wild rodent populations, the results of these experiments will provide insights into the evolution of mammalian behavior that may be broadly applicable to other species, including humans. Finally, of the researchers will create videos and educational materials including activities, problems sets, and exam questions to complement the videos that will be made freely available to educators and the public through the Hoekstra Laboratory website, the Harvard Museum of Comparative Zoology Teacher Resource Page, and the National Association for Biology Teachers.
This project focuses on two sister species Peromyscus polionotus (the oldfield mouse) and P. maniculatus (the deer mouse) that differ in their latency to build nests of thermoregulatory value to further understand how genetic changes can alter the structure and function of a mammalian nervous system and, ultimately, behaviors important for fitness. Cross-fostering experiments between the two species demonstrated that this difference is heritable, and a Quantitative Trait Locus (QTL) mapping experiment identified 3 genomic regions that contribute to interspecific variation, including one locus containing only 62 candidate genes. This research will significantly extend and improve upon this existing body of work. First, the researchers will use Immediate-Early Gene (IEG) expression patterns to identify the cell populations in the brain active during nesting, which will itself be a novel finding and will additionally allow subsequent experiments to focus on the brain regions and cells most relevant for the behavioral difference. Following this the researchers will characterize the transcriptomes of those neurons specifically active during nesting using a cutting-edge phosphorylated ribosome profiling technique. Together, these aims will both narrow the list of candidate genes generated by the genetic mapping approach and provide insights into how those genetic changes modify neural circuits to produce behavioral differences. The researchers will also make short educational videos tailored to a high school/undergraduate audience using VideoScribe (www.videoscribe.co/) to explain basic concepts in genetics and neuroscience and their application to the study of behavioral evolution.
