Data from: How phylogeny and foraging ecology drive the level of chemosensory exploration in lizards and snakes

The chemical senses are crucial for squamates (lizards and snakes). The extent to which squamates utilize their chemosensory system, however, varies greatly among taxa and species’ foraging strategies, and played an influential role in squamate evolution. In lizards, Scleroglossa evolved a state where species use chemical cues to search for food (active-foragers), while Iguania retained the use of vision to hunt prey (ambush-foragers). However, such strict dichotomy is flawed since shifts in foraging modes have occurred in all clades. Here, we attempted to disentangle effects of foraging ecology from phylogenetic trait conservatism as leading cause of the disparity in chemosensory investment among squamates. To do so, we used species’ tongue-flick rate in absence of ecological relevant chemical stimuli as a proxy for its fundamental level of chemosensory investigation, i.e. baseline tongue-flick rate. Based on literature data of nearly 100 species and using phylogenetic comparative methods, we tested whether and how foraging mode and diet affect baseline tongue-flick rate. Our results show that baseline tongue-flick rate is higher in active than ambush foragers. Although baseline tongue-flick rates appear phylogenetically stable in some lizard taxa, that is a consequence of concordant stability of foraging mode: when foraging mode shifts within taxa, so does baseline tongue-flick rate. Also, baseline tongue-flick rate is a good predictor of prey chemical discriminatory ability, as we established a strong positive relationship between baseline tongue-flick rate and tongue-flick rate in response to prey. Baseline tongue-flick rate is unrelated to diet. Essentially, foraging mode, not phylogenetic relatedness, drives convergent evolution of similar levels of squamate chemosensory investigation.