Fig. 2

Contractions of olfactory receptors (ORs) in L. dimidiatus. Phylogenetic tree of ORs subfamily δ gene sequences with 100 bootstraps and the non-ORs as the outgroup. T. bifasciatum and N. celidotus exhibited more ORs δ gene than L. dimidiatus. The leaf nodes with back, grey and light grey square mean obligate cleaner, facultative cleaner and non-cleaner. The bold branches in the left phylogenetic tree indicate the internal nodes with bootstraps ≥ 80, and only the internal nodes with bootstraps ≥ 80 showed in the right phylogenetic tree