Collaborative Research: Does responding to stressors prime greater resilience? Testing the long-term effects of challenges on behavior, physiology, epigenetic state, and fitness.

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When faced with a major challenge – severe weather, the attack of a predator, an injury – organisms mount a coordinated physiological and behavioral stress response. This response can be vital for surviving and recovering from immediate threats. This project will test whether activating the stress response system has another overlooked benefit that operates over much longer time-scales: priming the system to respond better to future challenges. Coordinated experiments will address fundamental questions about when and how environmental challenges prime greater resilience to future challenges, and examine whether those effects persist across generations. This study will also adapt and refine newly developed sensor technology that enables non-invasive monitoring of heart rate in free-living animals – a tool that could yield considerable advances across fields. A more comprehensive understanding of the lingering impacts of challenges will also be valuable for other fields, including conservation and human health. Additionally, the team will lead a career development program that combines a field research internship – in which students participate in addressing the research objectives outlined in this proposal – with a laboratory- and classroom-based skills development program for students from underrepresented groups who are interested in careers in STEM fields. This opportunity is designed to foster interactions among students from a small liberal arts college and from a large research-intensive university.This project will test the hypothesis that transient challenges experienced in adulthood prime greater resilience or robustness to future challenges, defined as the ability to return to or maintain a stable state. Research will use a long-term study population of tree swallows (Tachycineta bicolor) in which large-scale behavioral and physiological data can be collected from free-living individuals. In the first year of study adult females will be exposed to either an ecologically relevant challenge or a simulated glucocorticoid stress response. In the following year(s) a diversity of phenotypic traits, and context-dependent performance and fitness, will be measured. This study design will enable comparison of the direct effects of exposure to a challenge with the effects of exposure to a mediator of the response to that challenge. These experiments will also reveal whether the long-term effects of stressors on behavior, physiology, and fitness are mediated by glucocorticoids and by glucocorticoid-induced changes in DNA methylation. This research will also test whether parental exposure history carries over to affect the phenotype and fitness of offspring produced in the year(s) after the challenge. By combining targeted experiments in a free-living population with integrative methods of behavioral, physiological, and epigenetic assessment this project will provide insights important for developing and revising conceptual models of stress and phenotypic plasticity. It will also broaden our understanding of the mechanisms of behavior, how organisms are shaped by their environments, and how sub-organismal responses contribute to organismal resilience and robustness.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.