Phylogenetic relationships of the 58 Daphnia pulex Grs to each other and a representative set of insect Grs. This is a corrected distance tree, with the highly conserved CO2 receptor lineage designated as the outgroup to root the tree. Bootstrap values from 10,000 replications of uncorrected distance analysis are shown on major branches, followed by Bayesian posterior probabilities. DpuGr (D. pulex) lineages are highlighted in red. Major groups of insect Grs whose ligands are known or which are mentioned in the text are highlighted in blue (Ag – Anopheles gambiae, Am – Apis mellifera, Bm-Bombyx mori, Hv- Heliothis virescens, and Tc- Tribolium castaneum).