Relationship among recent CORE-SINEs in marsupial genomes. A hypothetical evolutionary scenario of the relationships among short CORE-SINEs, particularly WSINE1 and WALLSI2, found in marsupials. The short CORE (beige) is only found in a few SINEs, suggesting a common evolutionary origin. Insertions into the tRNA-related part (green) of CORE-SINEs are rare; thus, the 7-nt insert (black) shared between WSINE1a/1b and WALLSI2 is likely to have a common evolutionary origin. Elements in parentheses are those responsible for the retroposition of the respective SINES. Green: tRNA-related sequence, beige: CORE sequence, dark grey: LINE3-like tail sequence, purple: RTE-like tail sequence, pink: origin unknown of the tail sequence, black: 7-nt insertion, red: 11-nt insertion, red AAAA: indicates that the SINE uses a poly(A)-tail for propagation via LINE1.