Transcriptome Response of Atlantic Salmon to Competition with Non-Native Ecologically Similar Species

Non-native salmonid species provide economic value, however they can also have detrimental impacts on the native species. For example, introduced salmonids are thought to be a significant barrier to the reintroduction of Atlantic salmon (Salmo salar) into Lake Ontario due to interspecific competition. Although transcriptomic methods are not traditional for quantifying competition effects, it is a promising approach to identify genes that underlie fitness-related changes during competition. Such an approach will not only improve our understanding of the effects of interspecific competition at the molecular level, but will also help to identify individuals and stains with higher competitive ability. In this study, we conducted semi-natural stream challenges to quantify how competition with non-native salmonids (Chinook salmon, Rainbow trout and Brown trout) affect the fitness of two Atlantic salmon strains. Within each strain we created four treatments: Atlantic salmon alone and Atlantic salmon reared with each of the three non-native species. We compared genome-wide transcription among the four treatments for each Atlantic salmon strain using RNA-Seq. We identified specific genes that differentially responded to interspecific competition, as well as transcriptional differences between the two strains. This work highlights the potential value of transcriptional profiling for conservation of sensitive ecosystems and species.