Transcriptional responses to changing environments: insights from salmonids

Abstract Understanding the molecular basis of plasticity and physiological tolerance to environmental changes is crucially important in the era of global change. Salmonids, a diverse family of fishes that includes salmon, trout, and charr, are emerging as powerful models for studying molecular responses to such changes. These species inhabit a wide range of aquatic environments, including freshwater and marine ecosystems, and are known for their remarkable adaptability to varying environmental conditions and for their variety of life history strategies. This review synthesizes current research on some of the major molecular mechanisms underlying transcriptional responses to important environmental changes. We discuss key studies that have applied state-of-the-art genomic tools in salmonids to uncover some of the gene expression changes underpinning plastic or acclimatory responses due to changes in temperature, salinity, oxygen levels or pH. By presenting examples of genes involved in these processes in salmonids, this review aims to provide insights into the broader implications of these findings, namely for conservation strategies and management. We also consider the potential of salmonids as emerging model species for monitoring the impacts of climate change on aquatic ecosystems, and their capacity to cope with rapid and inevitable environmental change. Finally, we outline future research directions to further elucidate the molecular pathways underlying plastic responses to environmental changes, with potential implications for evolutionary adaptation in these species.