Maximum-likelihood dendrogram based on protein sequences of candidate odorant receptors (ORs) and gustatory receptors (GRs). Included are ORs and GRs from Ips typographus (Ityp), Dendroctonus ponderosae (Dpon), Tribolium castaneum (Tcas) and Megacyllene caryae (Mcar). The branch containing bark beetle GRs was used as outgroup to root the tree. The different subgroups (numbered 1–7 according to [29, 53], and 7a-7b) are discussed in the main text. Originally, TcasOr339 and TcasOr340 were found within group 4 and 6 , as indicated here by the numbers in brackets. Numbers at nodes refer to support values, which are only displayed when <; 0.9.