Jill M. Mateo - US grants

DESCRIPTION (provided by applicant): Adrenal hormones (glucocorticoids) regulate the body's responses to stress, but also influence cognition. Glucocorticoids can either improve or impair memory formation and retrieval, depending on the severity and length of stress. Despite extensive research on the effects of these hormones on cognition in laboratory rodents, little is known about how glucocorticoids influence biologically relevant learning by animals in natural contexts. This information has clinical applications because high levels of glucocorticoids are associated with depression, Alzheimer's disease and addiction behaviors, and because synthetic glucocorticoids are often prescribed for people with arthritis or adrenal dysfunctioning. Knowledge how long-term changes in glucocorticoids influence learning and memory would aid in the development of pharmacological treatments for such patients. The proposed studies extend this body of research to investigations of learning and memory in a free-living animal model, Belding's ground squirrels (Sperinophilus beldingi). In particular, these studies will focus on the role of glucocorticoids in enhancing or impairing the development of antipredator behavior, and whether variation in glucocorticoids early in development has long-term effects on adult behaviors. Many of the studies will use non-invasive fecal hormone assays to monitor adrenal functioning. This research will enhance our understanding of both the mechanisms underlying cognition as well as the ecological and developmental factors that influence it. In addition, the development of species-typical behaviors, especially those critical to survival, has been a relatively unexplored area of learning and memory, and this research will provide a rare example of how adrenal functioning affects cognition in freely behaving, outbred animals.

Many species, including humans, can discriminate among individuals according to genetic relatedness. Yet how this kin recognition is accomplished remains largely unexplored. Belding's ground squirrels, Spermophilus beldingi, are group-living squirrels that exhibit many forms of nepotism (preferential treatment of relatives), including cooperative territory defense and predator avoidance, which require the ability to identify relatives. The PI's previous NSF-supported research showed that S. beldingi produce at least six individually distinct odors which can be used for social recognition, as well as several odors that vary with relatedness. The proposed research seeks to demonstrate for the first time a direct, causal association between odors, recognition mechanisms and preferential treatment of relatives. These studies will determine how this species uses odors for recognition, examine the limits of kin discrimination, and describe how kin-recognition abilities facilitate inbreeding avoidance. The ability of animals to use different recognition mechanisms in different contexts would be favored in unpredictable social environments; thus this research will test the hypothesis that if S. beldingi lose all memories of kin during hibernation they must later rely on their own odors to help them recognize their kin in the spring. Theory also predicts that animals will avoid mating with close kin; these studies will therefore determine whether kin-recognition abilities also function in mate choice, using observational and genetic techniques. They will test whether the recognition abilities used to treat particular kin classes favorably are the same as those used to avoid close inbreeding. This research program is among the first to examine if particular odors have numerous, overlapping functions and whether there are commonalities between the mechanisms of recognition in multiple contexts. Given the importance of social relationships for understanding speciation, population dynamics, mating systems and reproductive success, the proposed research offers a unique opportunity to integrate both mechanistic and functional levels of analysis for an understanding of kin recognition in both mating and nepotistic contexts. Recognition abilities can either promote or limit adaptive responses to kin, and the combined field and laboratory components of this research will facilitate exploration of these outcomes. The results of the proposed research can be applied to studies of social recognition in a variety of taxonomic groups, and can also be applied to captive breeding and re-introduction programs, particularly if social recognition influences the formation and stability of social groups or their mating success. This project will support the interdisciplinary training of a postdoctoral scholar and, indirectly, 2-3 graduate students from several programs on the University of Chicago campus. Students will be trained in theory and concepts as well as field and experimental techniques, integrating proximate and ultimate approaches to behavior, ecology and evolution. Each year of the award will also support participation of 4-5 undergraduate field assistants, giving them an opportunity to experience field biology regardless of income or prior experience. Historically, assistantships have been offered to females and ethnic minorities, as both groups tend to be discouraged from fieldwork. The award will also be used to promote further development of a multi-user molecular genetics facility, as well as to produce lectures and lay articles for the local communities near the field site.

Animals can benefit from living in social groups for many reasons. For example, individuals living in a group can share the burden of finding food resources, watching for predators and caring for offspring. However, we know very little about the physiological mechanisms that contribute to social advantages. This project will address this deficiency by evaluating the relationships among stress hormones, immune function, behavior, survival and kinship in Belding?s ground squirrels. Specifically, this project will test how living near kin or non-kin affects stress hormones and immune function as well as how increased stress hormones change predation risk. Captive experiments will be conducted with wild-caught squirrels and will measure genetic relatedness, hormone levels and immune function with laboratory assays. It is predicted that individuals living with kin will exhibit reduced stress hormones, increased immune function and will perceive reduced predation risk. It is also predicted that individuals with experimentally increased stress hormone levels will perceive greater predation risk. This research will have broader impacts because it will improve our understanding of how physiology shapes social benefits. This is relevant to all social vertebrates, including humans, because they all share the hypothalamic pituitary adrenal axis that regulates stress responses. In addition, this research program has a strong history of outreach. Two undergraduates and two field assistants will be trained in behavioral, ecological and laboratory techniques. In addition, the results of this research will be used to teach urban Chicago youth about behavioral research and the scientific method.