Neighbor-joining phylogenetic tree of LTR retroelements in the D. pulex genome. The RT sequences are from the newly-identified elements (an element from each family) in the D. pulex genome along with previously known retroelements; (a and b) the elements in gypsy group, (c and d) the elements in BEL/Pao group, and (e and f) the elements in copia group, and (g) the elements in DIRS group. D. pulex retroelements were named after the family name and element name without underscores. For example, in Dpul B1 104 3, Dpul B1 is the family name and 104 3 is the element name. Previously known retroelements follow their annotated names such as SURL and Maggy. The bootstrap value for main branches and a divergence scale are indicated. The families that have transcriptionally active elements are marked with black circles. The D. pulex elements identified are marked in gray circles.