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.化学感官对于有鳞类（squamates，即蜥蜴与蛇类）而言至关重要。然而，有鳞类对化学感知系统的利用程度，在不同类群以及物种的觅食策略间差异显著，且这一差异对有鳞类的演化产生了重要影响。在蜥蜴类中，硬舌亚目（Scleroglossa）演化出了物种依靠化学信号搜寻食物的特征（即主动觅食者），而鬣蜥亚目（Iguania）则保留了利用视觉捕猎的模式（即伏击觅食者）。然而，这种严格的二分法存在缺陷，因为所有演化支中都发生过觅食模式的转变。本研究尝试厘清觅食生态与系统发育性状保守性这两个因素，分别作为有鳞类化学感知投入差异的主导成因所产生的影响。为此，我们以物种在无生态相关化学刺激下的弹舌频率，作为其基础化学感知探究水平的替代指标，即基线弹舌频率。我们基于近100个物种的文献数据，并运用系统发育比较方法，检验了觅食模式与食性是否以及如何影响基线弹舌频率。研究结果显示，主动觅食者的基线弹舌频率高于伏击觅食者。尽管部分蜥蜴类群的基线弹舌频率在系统发育上表现出稳定性，但这实则是觅食模式同步稳定的结果：当类群内的觅食模式发生转变时，基线弹舌频率也会随之改变。此外，基线弹舌频率可较好地预测猎物化学识别能力，因为我们发现基线弹舌频率与猎物响应弹舌频率之间存在显著的正相关关系。基线弹舌频率与食性并无关联。本质而言，驱动有鳞类化学感知探究水平趋同演化的是觅食模式，而非系统发育亲缘关系。