Figure 1.

Phylogenetic trees of subfamily structure based on LTR nucleotide sequence data. The 32 elements of Osr26 family fall into at least 5 clades, with Osr25 as the outgroup. To better exhibit tree structure, all Osr27 elements were removed. Insertions/deletions were ignored while performing phylogenetic analyses. Values on individual branches are bootstrap percentages using 1000 bootstrap repetitions. Each LTR in the tree is named by the genomic clone in which it was found. For elements with two LTRs, the 3' LTR is labeled by a lower case "b" while the 5' LTR is labeled by a lower case "a". Each tree is exhibited with a scale bar determined by the number of nucleotide substitutions per site between two sequences. The tight clustering seen in both families represents a high degree of nucleotide identity between elements within a subfamily.