Figure 2.

Phylogenetic tree of cartilaginous fish and other selected vertebrate class I molecules. The tree was constructed using the neighbor-joining (NJ) method with the α1 and α2 domains (PBR), and rooted with CD1. Bootstrap support values are shown as percentages on the branches. The boxes indicate the four distinctive MHC class I lineages in cartilaginous fish. GeneBank accession numbers for all the sequences are listed in Supplemental Table I, and the corresponding alignment is found in Supplemental Figure 1. Common names are shown followed by abbreviation of the scientific name (two letters of the genus and two letters of species). The scale bar indicates the number of amino acid differences per sequence.