Fig. 2

Landscape and comparison of SKLA1.0 MHC. a The arrangement order of genes in the duck MHC. The duck MHC is about 1.82 Mb and encodes 183 coding genes. MHCI, MHCII, MHCIII, BTN, and NKC gene families are colored in blue, pink, purple, yellow, and green respectively. The D-P and the C-D block are in green and brown dotted rectangle, respectively. b Comparison of MHC map in amphibians, reptiles, waterfowls, landfowls, and mammals. The MHC map includes seven blocks, namely MHCI, MHCII, MHCIII, BTN, NKC, D-P, and C-D. These blocks may not necessarily be completely separate, and in some species, one block may overlap with another block. The proto-MHC represents the ancient MHC map in vertebrates, which was inferred based on alignment of MHC gene maps from duck and 22 other species as well as previous ancient MHC map. Dash line denotes that BTN and NKC blocks are found in amphibian MHC, but the location is not consistent among these amphibian species