Chromosomal locations of Atlantic salmon major histocompatibility complex (MHC) class I and class II genes, in addition to PSMB8-10 and TAP1/2 genes based on data from [18,19]. Atlantic salmon MHC class I genes are shown with pink shading, while class II genes are shown with orange shading on individual chromosomes (NCBI genomes, GCA_000233375.4). Total size of each chromosome (Chr.) is shown below in megabases (Mb), while location of MHC genes are shown within each box. Centromeres and telomeres are shown with grey (tentative position) or black oval shapes. MHC-containing chromosomes known to be homologous or share regional homology due to the unique salmonid Ss4R WGD event [39,40] are shown with cyan boxes where the presumed shared homology between Chr.09 and 20 is tentative and thus shown using a dotted line.