Figure 1.

Phylogeny of the subgenus Sophophora, showing estimates for divergence times and the distribution of both canonical (complete, active elements similar to those in D. melanogaster) and noncanonical P elements. The relationships among the four principal species groups is indicated, and within each species group a major split among subgroups is shown. Phylogeny and divergence times were estimated from a number of morphological, cytogenetic, biogeographical, and molecular studies. Each species group is identified by a particular color, which allows the origin of particular sequences in Fig. 3 to be easily discerned. ∗ in the canonical column for the melanogaster subgroup identifies the P element transferred horizontally to D. melanogaster.