Previous studies have demonstrated the pliability and adaptability of mammalian mandibles in response to different ecological demands such as food availability. The dwarf gerbil Gerbillus nanus has a wide distribution in Asia in which it encounters varied environments. These varied environments can house different food resources and it would be adaptively advantageous for the opportunistic rodents to have mandibles best suited for the most prevalent food resource. Geometric morphometric analysis was used to test this hypothesis by examining mandibular variation in 436 G. nanus specimens sampled from 44 localities. Based on this sample, mandibular morphology seems to be highly conserved in this species, with both size and shape being non-significantly different between pairs of geographic groups (i.e., locality clusters) and ecoregions. Mandibular size and shape are both not strongly predicted by 48 examined environmental variables. Despite this, the most variable aspect of mandibular shape was associated with its caudal regions, spanning from the coronoid process to the ventral mandibular border. These are regions of temporalis and masseter muscle attachments and thus mandibular variation could be associated with differential (potentially plastic) masticatory adaptations.

中文翻译：

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侏儒沙鼠Gerbillus nanus (Gerbillinae, Rodentia) 下颌地理变异的几何形态测量分析

先前的研究已经证明了哺乳动物下颌骨在应对不同生态需求（例如食物供应）时的柔韧性和适应性。侏儒沙鼠 Gerbillus nanus 在亚洲广泛分布，在其中遇到各种环境。这些不同的环境可以容纳不同的食物资源，对于机会主义啮齿动物来说，拥有最适合最普遍食物资源的下颌骨将是适应性有利的。通过检查从 44 个地点取样的 436 个 G. nanus 标本中的下颌变异，使用几何形态测量分析来检验这一假设。根据该样本，该物种的下颌形态似乎高度保守，地理组对（即地点集群）和生态区之间的大小和形状没有显着差异。下颌的大小和形状都没有被 48 项检查的环境变量强烈预测。尽管如此，下颌骨形状最可变的方面与其尾部区域相关，从冠突到下颌骨腹侧边界。这些是颞肌和咬肌附着区，因此下颌变异可能与不同的（可能是塑性的）咀嚼适应有关。