Proximate causes of variation in dermal armour: insights from armadillo lizards

Although it is widely assumed that body armour in animals evolved to thwart predator attacks, assessing the role that predators may play in shaping defensive morphologies has proven to be difficult. Recent studies suggest that body armour might be influenced by additional factors besides predation, and/or even by sexual selection. We investigated variation in dermal armour in 13 populations of armadillo lizards (Ouroborus cataphractus), spanning the entire distribution range of the species. We obtained thickness measurements of osteoderms – bony plates embedded in dermal layer of the skin – using micro- and nano-computed tomography. Using these data, we examined the effects of predation pressure/risk and climatic variables on dermal armour variation and addressed sexual and ontogenetic influence. Our results show that climate is the only factor affecting variation in dermal armour. Populations inhabiting more arid environments, characterized by low summer precipitation and mild winter t...

尽管学界普遍认为，动物的躯体装甲演化的初衷是抵御捕食者的攻击，但要明确捕食者在塑造动物防御形态过程中所发挥的作用，却始终颇具挑战。近期相关研究表明，动物躯体装甲的演化或许并非仅受捕食压力调控，还可能受到其他额外因素的影响，甚至与性选择存在关联。本研究以覆盖犰狳蜥（Ouroborus cataphractus）全分布范围的13个种群为研究对象，对其真皮装甲的变异情况展开了调查。我们利用显微计算机断层扫描（micro-computed tomography）与纳米计算机断层扫描（nano-computed tomography）技术，获取了该物种真皮骨板（osteoderms）——嵌入皮肤真皮层的骨质甲板——的厚度数据。基于上述数据，本研究分析了捕食压力/风险与气候变量对真皮装甲变异的影响，并探讨了性选择以及个体发育阶段对装甲变异的作用。本研究结果显示，气候是唯一影响真皮装甲变异的因素。栖息于以夏季降水匮乏、冬季温和为典型特征的干旱程度更高环境中的种群...