Does diet drive the evolution of head shape and bite force in chameleons of the genus Bradypodion?

The head is a complex integrated system that is implicated in many vital functions. As such, its morphology is impacted by different and sometimes conflicting demands. Consequently, head shape varies greatly depending on the environment and dietary ecology of an organism. Moreover, given its role in territory defence and mating in lizards, it is also subjected to strong sexual selection in these animals. We investigated the relationships between head shape, bite performance and diet in 14 of the 17 extant Bradypodion species to determine whether variation in diet can explain the observed diversity in bite force and head shape in this genus. We also evaluate differences between sexes in terms of the relationships between head shape, bite force and diet and predict tighter relationships in females given that the head in this sex is principally under natural selection. Our results show that there is indeed a correlation between head shape, diet and bite force, but the direction and magni...头部是参与多项关键生命功能的复杂整合系统。正因如此，其形态会受到多重甚至相互冲突的需求影响。因此，头部形态会因生物所处的环境与饮食生态的差异而产生极大变异。此外，鉴于蜥蜴的头部在领地防御与交配行为中发挥的作用，这类动物的头部同时也承受着强烈的性选择（sexual selection）压力。 本研究针对17个现存侏儒变色龙属（Bradypodion）物种中的14个，分析了头部形态、咬合性能（bite performance）与饮食之间的关联，旨在验证饮食差异能否解释该类群中观察到的咬合力（bite force）与头部形态多样性。此外，我们还针对头部形态、咬合力与饮食之间的关联，评估了两性间的差异，并预测雌性个体间的关联更为紧密——鉴于该性别的头部主要受自然选择（natural selection）作用。 本研究结果显示，头部形态、饮食与咬合力之间确实存在相关性，但其关联方向与幅度……