Figure 3

Phylogenetic relationships of SRs in insects. This corrected distance tree was rooted with the AmGr2/NvGr2 and HvCr5/BmGr4 lineage as the outgroup, based on their apparent basal clustering in larger analyses of the entire Gr family. Bootstrap support above 50% from 1000 replications of full heuristic uncorrected distance analysis, 1000 bootstrap replications of full heuristic maximum parsimony analysis, and 25000 maximum likelihood quartet puzzling steps are shown above relevant branches. Intron gains and losses are indicated by light blue upper case and lower case letters, respectively, above branches to which they are mapped by simple presence-absence Dollo parsimony. Drosophila SRs are shown in shades of red, mosquito green, beetle brown, moth blue, and hymenopteran purple. Only the D. pseudoobscura SRs are included along with those from D. melanogaster to help balance the dipteran SR analysis. Inferred orthologous relationships within the three mosquito species are indicated by bars on the right. The large orange 1 and purple 2's indicate the two major tandem duplications hypothesized at the base of the dipteran SR evolution (see Figure 4). The blue 3 indicates the origin of the novel exon and hence also intron "q" in the expanded moth SR lineage.