URoL: Epigenetics 2: Collaborative Research: Bumble bee cold tolerance across elevations - From epigenotype to phenotype across space, time, and levels of biological organization

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Understanding how organisms cope with environmental variability is of fundamental importance in ecology and evolutionary biology. Adaptation to environmental variation has commonly been inferred by examining how the appearance of organisms (phenotypes) and their DNA sequences (genotypes) vary across a broad range of climatic conditions. However, there has been increasing recognition of additional layers of complexity along the genome-to-phenotype spectrum that influence responses to the environment by altering expression of genetic variation. Epigenetic, or non-DNA sequence based, DNA modifications under different environmental conditions are increasingly considered to be a potent mechanism that may drive how organisms respond to different environments. Likewise, the different molecules associated with metabolic activity (metabolome) can vary among individuals or populations in different environments or can change under stressful conditions to alter organism function. Species that occur across altitudes experience rapid shifts in conditions, especially temperature, over short spatial scales, which provides advantages for teasing apart how different mechanisms influence tolerance of environmental variation. This project will focus on thermal tolerance across elevations in wild and laboratory reared bumble bees, an important group of pollinators that are threatened by environmental pressures. The project will provide valuable tools to understand how bee populations overcome environmental stress that will help predict the stability of bee populations. Post-doctoral fellows, graduate students and undergraduates at the University of Alabama, Tuscaloosa and University of Wyoming will be broadly trained in molecular biology, physiology and computational modeling approaches. A strategy game app to demonstrate how molecular changes can affect populations and ecosystems under different thermal conditions will be developed for K-12 students. Results of the study will be disseminated through an exhibit at a native bee garden within the Stokes Nature Center in Utah to increase awareness of wild pollinators.The major research goal of the project is to address the question: How does information flow from genetic and epigenetic variation through expression of this information to produce intraspecific phenotypes adapted to abiotic extremes? Thermal physiology experiments on field-collected and laboratory-reared bumble bees from elevation gradients in the Oregon Cascade Mountains will be combined with genomic, transcriptomic, methylomic, and metabolomic analyses. Computational modeling will be employed to integrate data sets and test how variation in epigenetic modification of DNA in different populations influences gene expression, and ultimately physiology, under cold temperature exposure. Specific research questions include: (1) are bumble bees capable of withstanding similar cold stress exposure regardless of geographic origin, or do individuals, social castes, and populations exhibit constitutive variation in cold tolerance associated with local climate? (2) to what degree do populations exhibit structured variation in DNA methylation, transcription, and metabolomics across environments versus plastic regulation of processes in response to cold stress?, and (3) how do epigenetic changes within individual organisms influence transcription and in turn production of small molecules to explain variation in cold tolerance across individuals, castes, colonies, and environments?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.