ERV orthologous insertions in cetaceans.

( A ) Examples of orthologous insertions for the SHS and the LTW ERV lineages. The phylogenetic relationship of cetaceans is shown on the left. The dotted boxes in red and blue show orthologous ERV insertions for the SHS and the LTW scenarios, respectively. The white and mauve rectangles represent 500 bp sequences flanking complete ERVs. The deep purple rectangles represent complete ERVs. Illustrations of cetacean species courtesy by Chris Huh. ( B ) ERV orthologous insertions between cetaceans and H . amphibious . Rectangles from left to right represent 1,000 bp flanking sequence, 5’-LTR, internal genes of an ERV, 3’-LTR, and 1,000 bp flanking sequence, respectively. Dashed boxes indicate missing of the corresponding regions. ( C ) ERV orthologous insertions between mysticetes and odontocetes. Rectangles from left to right represent 500 bp flanking sequence, ERV, and 500 bp flanking sequence, respectively. Dashed boxes indicate missing of the corresponding regions. ( D ) ERV and cetacean phylogeny congruence test. The event cost scheme (0, 1, 2, 1, 1) is for cospeciation, duplication, duplication with host switch, loss, and failure to diverge, respectively.