Isolation due to habitat fragmentation can lead to morphological and functional variation between populations, with the effect being well documented in rodents. Here, we investigated whether such morphological variation could be identified between British populations of the Eurasian red squirrel (Sciurus vulgaris). This species was once widespread across Great Britain, but suffered a severe population decline across the 20th century, leaving a highly fragmented distribution. The aim was to test for morphological and biomechanical variation of the mandible between the remaining British red squirrel populations, and between British and continental European red squirrels. Linear and geometric morphometric methods were used to analyse shape in a sample of over 250 red squirrel hemi‐mandibles from across Britain plus a sample from Germany representing the central European subspecies. Procrustes ANOVA identified significant shape variation between populations, with particularly distinct differences being noted between red squirrels from Germany and several British red squirrel populations, which may reflect their evolutionary history. Linear biomechanical measurements showed that the red squirrels from Formby and Jersey had a significantly lower mechanical advantage of the temporalis muscle than other British populations, suggesting they were less efficient at gnawing. This functional difference may be related to many factors, such as founder effect, potential inbreeding and/or past supplemental feeding with less mechanically resistant food items.

中文翻译：

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孤立的英国红松鼠（Sciurus vulgaris）种群之间的形态和功能变异

由于生境破碎化而造成的隔离可能导致种群之间的形态和功能变异，啮齿动物已充分证明了这种作用。在这里，我们调查了这种形态变化是否可以在欧亚红松鼠（Scuulus vulgaris）的英国种群之间找到。）。该物种曾经在英国广泛分布，但在整个20世纪遭受了严重的人口减少，分布高度分散。目的是测试剩余的英国红松鼠种群之间以及英国和欧洲大陆红松鼠之间的下颌骨的形态和生物力学变化。线性和几何形态计量学方法用于分析来自英国各地的250多个红松鼠半下颌骨以及代表中欧亚种的德国样本中的形状。Procrusts ANOVA识别出种群之间的显着形状差异，其中德国红松鼠和一些英国红松鼠种群之间的差异尤为明显，这可能反映了它们的进化历史。线性生物力学测量结果显示，来自Formby和Jersey的红松鼠对颞肌的机械优势明显低于其他英国人群，表明它们的咬效率较低。这种功能上的差异可能与许多因素有关，例如创建者的影响，潜在的近亲繁殖和/或过去对机械抵抗力较低的食品的补充喂养。