Phylogenetic relationships of the Ae. aegypti and An. gambiae odourant receptor (Or) families. Corrected distance tree generated using paup* v4 using distances corrected in TreePuzzle v5 using a maximum-likelihood model and the BLOSUM62 amino acid matrix [(Hill et al., 2002; Robertson et al., 2003; Robertson & Wanner, 2006) for methods]. The tree is rooted using the AaGPRor7and AgGPRor7 pair based on the basal position of their highly conserved ortholog DmOr83b in the Orfamily in a phylogenetic tree of the entire superfamily (Robertson et al., 2003). Bootstrap support from 1000 replications of neighbour-joining with uncorrected distances is shown on the relevant branch points. Ae. aegypti (bold branches) and An. gambiae (thin branches) gene expansions are indicated by vertical black bars. Brackets indicate apparent orthology between Ae. aegypti and An. gambiae OR proteins. Protein names are abbreviated to AaOr and AgOr, with suffixes: (P) – pseudogene; (C) (N) – lacking sequence at C- or N-terminus, respectively. Introns are named according to Fig. S3, and their presence within a lineage is indicated by bold letters. Inferred intron losses are indicated by italicized letters on the relevant branches.