BrackAdapt · Using genomics to understand how freshwater fishes turned a lethal environment into an ideal habitat

Ongoing climate change leads to rising sea levels and changes in local precipitation volume and regularity which will reshape estuarine ecosystems across Earth. As current climate change dramatically alters estuarine ecosystems, fish populations must adapt to the novel environment, or they will go extinct. Understanding how past environmental changes led to genomic adaptations is the key to predicting the adaptive potential of fishes facing ongoing climate change and could be the difference between protecting and losing locally adapted biodiversity. Perch (Perca fluviatilis) and pike (Esox lucius) are two freshwater fish species inhabiting freshwater ecosystems across the northern hemisphere. Nevertheless, in the Baltic Sea, which is the world’s largest estuary, each species have developed brackish water ecotypes capable of thriving at salinities exceeding their internal salinity. This requires fundamentally different cellular functions and is lethal to non-adapted freshwater individuals. However, their evolutionary histories and functional genomic adaptations are unknown. Through deep sequencing of brackish water and freshwater ecotypes of perch and pike, Project BrackAdapt aims to identify the demographic and evolutionary history of each species. The project will identify genomic regions under selection for salinity tolerance and investigate whether genomic adaptations to environmental changes are parallel in function, time and space within and between species. The training and project management experience I will gain during the project will be a stepping-stone for my career to advance and make me an independent researcher.