Data from: Enemy at the gates: rapid defensive trait diversification in an adaptive radiation of lizards

Adaptive radiation, the product of rapid diversification of an ancestral species into novel adaptive zones, has become pivotal in our understanding of biodiversity. While it has widely been accepted that predators may drive the process of adaptive radiation by creating ecological opportunity (e.g. enemy-free space), the role of predators as selective agents in defensive trait diversification remains controversial. Using phylogenetic comparative methods, we provide evidence for an ‘early burst’ in the diversification of antipredator phenotypes in Cordylinae, a relatively small adaptive radiation of morphologically diverse southern African lizards. The evolution of body armour appears to have been initially rapid, but slowed down over time, consistent with the ecological niche-filling model. We suggest that the observed ‘early burst’ pattern could be attributed to shifts in vulnerability to different types of predators (i.e. aerial versus terrestrial) associated with thermal habitat partitioning. These results provide empirical evidence supporting the hypothesis that predators or the interaction therewith might be key components of ecological opportunity, though the way in which predators influence morphological diversification requires further study.

适应辐射（Adaptive radiation）指祖先物种快速分化为多个全新适应生态位的演化过程，如今已成为我们解析生物多样性的核心议题。尽管学界普遍认为捕食者可通过创造生态机遇（如天敌自由空间）推动适应辐射进程，但捕食者作为防御性状分化的选择因子，其作用仍存在争议。本研究采用系统发育比较方法（phylogenetic comparative methods），对绳蜥亚科（Cordylinae）——一类形态多样、分化规模相对较小的南非蜥蜴类适应辐射类群——的反捕食表型（antipredator phenotypes）分化进行分析，为其分化呈现"早爆式（early burst）"模式提供了实证依据。躯体装甲的演化最初速率较快，但随时间推移逐渐放缓，这与生态位填充模型的理论预期一致。我们认为，观测到的"早爆式"分化模式可归因于与热生境分区相关的、对不同类型捕食者（即空中捕食者与陆生捕食者）的易感性转变。本研究结果为"捕食者或其与生物的相互作用可能是生态机遇的关键组成部分"这一假说提供了实证支持，不过捕食者影响形态分化的具体路径仍有待进一步探究。