Brown trout (Salmo trutta) WGS anadromous & resident Irish populations

Migration in animals and associated adaptations to contrasting environments are underpinned by complex genetic architecture. Here we explore the genomic basis of facultative anadromy in brown trout (Salmo trutta), wherein some individuals migrate to sea whilst others remain resident in natal rivers, to better understand how alternative migratory tactics (AMTs) are maintained evolutionarily. To identify genomic variants associated with AMTs, we sequenced whole genomes for 194 individual trout from five anadromous-resident population pairs, situated above and below waterfalls, in five different Irish rivers. These waterfalls act as natural barriers to upstream migration and hence we predicted that loci underpinning AMTs should be under similar divergent selection across these replicate pairs.