D3030: Geographical patterns of thermal tolerance and genome-wide methylation in a widespread bumble bee (Bombus vosnesenskii)

An organism’s ability to mount a physiological response to sudden environmental shifts is crucial to its individual survival but is also important for determining evolutionary phenomena such as species range limits and potential to withstand changing climates. Phenotypically plastic responses to stressors, such as shifts in temperature, will often require changes in gene expression, although we still know little about whether such responses differ among populations within a species range and what might regulate such differences. Epigenetic modifications such as DNA methylation can govern transcriptomic changes in response to environment, however, methylome patterns can vary geographically due to climatic differences, potentially leading to regional variation in interspecific thermal tolerance thresholds. We examine lab-reared colonies of the bumble bee Bombus vosnesenskii to investigate the relationship between methylation, geographic variation, and exposure to thermal stress. Previous research showed that workers reared from queens collected at different latitudes and elevations across the western US display region-specific differences in thermal tolerance and thoracic gene expression when subjected to thermal stress experiments. We generated whole genome methylation profiles from 44 samples from this study to characterize differentially methylated regions with respect to population and thermal stress treatment. Our results suggest the primary driver of differential methylation was region of queen origin, findings that help contribute to our understanding of the epigenetic patterns that potentially influence differential geographic thermal tolerances in bumble bees.