Sensory sensitivity to different concentrations of the stimuli varies in the different nematode species. (A) Concentration curves for octanol avoidance. We tested concentrations ranging from 0% octanol to 100% octanol on the species and found that Panagrellus redivivus did not avoid this noxious chemical to the same extent as the other species. Caenorhabditis elegans and Cruznema tripartitum displayed similar trends in avoidance and Caenorhabditis briggsae, Caenorhabditis sp. 3 and Pristionchus pacificus responded very similarly. Data for each species is represented as normalized avoidance index (see Methods for details). (B) Concentration curves for glycerol avoidance. Concentrations ranging from 0.1 M to 4 M glycerol were tested on the different nematodes. We found that P. redivivus showed least avoidance of glycerol at concentrations wherein the other species fully responded to glycerol. At the highest concentration tested, P. redivivus also responded strongly to glycerol. All the other species displayed similar avoidance of different concentrations of glycerol. Data for each species is represented as normalized avoidance index (See Methods for details). (C) Behavioral dendrogram for osmotic avoidance and octanol avoidance and its relation to the phylogenetic tree. The dendrogram was generated using hierarchical clustering for these two sensory behaviors. This data set incorporated all the different ablations done in the different species for the different behavioral assays. As expected P. redivivus and C. tripartitum exhibited the most different behavioral repertoire compared with the other species. (D) Phylogenetic tree of the species used in our analysis.