gene expression and thermal stress

Trout Thermal Stress

Studies of organismal response to climate change typically focus on the effects of long-term changes in average weather conditions. However, shorter-term heat waves can dramatically influence individual fitness and local species abundance. Predicting organismal response to heat waves, understanding the mechanistic basis for this response, and identifying which populations and species are under threat represent key challenges in organismal biology and conservation ecology. Here, we focus on a cold-adapted fish, brook trout, that serves as a keystone species in its community. We conducted two separate studies in which we collected gill transcriptomes from wild trout. In the first experiment, we sampled fish from nine populations and found associations between expression of >100 genes and thermal conditions at the time of sampling. In the second experiment, we sampled fish at eight time points across two successive heatwaves in four streams, two of which were warmer and more variable and two of which were cooler and less variable. This resulted in a natural experiment that allowed us to examine the temporal dynamics of gene expression induced by thermal stress. This study identified genes whose expression tracked stream thermal conditions. In both studies, genes identified included candidate genes known to be associated with heat stress, but also suggested several molecular pathways that have not been studied previously with respect to thermal stress response. Future work will experimentally validate our findings as well as integrate transcriptomic data into physiologically guided abundance models – models that fuse data from experimental studies with landscape-level monitoring of species abundance and environmental conditions – to better predict how brook trout will respond to future climate change. Together, these studies add critical information about the response of organisms to rapidly changing environments and provide applications for fisheries conservation and management.