Institut des Sciences de l'Évolution de Montpellier (UMR5554), 34095 Montpellier Cedex 5, France
Institut de Génomique Fonctionnelle de Lyon (UMR5242), 69007 Lyon, France.
J Exp Biol. 2019 Jun 17;222(Pt 12):jeb204867. doi: 10.1242/jeb.204867.
Morphological traits are frequently used as proxies for functional outputs such as bite force performance. This allows researchers to infer and interpret the impacts of functional variation, notably in adaptive terms. Despite their mechanical bases, the predictive power of these proxies for performance is not always tested. In particular, their accuracy at the intraspecific level is rarely assessed, and they have sometimes been shown to be unreliable. Here, we compared the performance of several morphological proxies in estimating bite force, across five species of murine rodents, at the interspecific and intraspecific levels. Proxies used included the size and shape of the mandible, as well as individual and combined muscular mechanical advantage (temporalis, superficial masseter and deep masseter). Maximum voluntary bite force was measured in all individuals included. To test the accuracy of predictions allowed by the proxies, we combined linear regressions with a leave-one-out approach, estimating an individual's bite force based on the rest of the dataset. The correlations between estimated values and the measurements were tested. At the interspecific and intraspecific levels, size and shape were better estimators than mechanical advantage. Mechanical advantage showed some predictive power at the interspecific level, but generally not within species, except for the deep masseter in In a few species, size and shape did not allow us to predict bite force. Extrapolations of performance based on mechanical advantage should therefore be used with care, and are mostly unjustified within species. In the latter case, size and shape are preferable.
形态特征通常被用作功能输出的代理，例如咬合力性能。这使得研究人员能够推断和解释功能变异的影响，特别是在适应方面。尽管它们具有机械基础，但这些代理在性能方面的预测能力并不总是经过测试。特别是，它们在种内水平上的准确性很少被评估，并且有时被证明是不可靠的。在这里，我们比较了几种形态学代理在估计五种鼠科啮齿动物的咬合力方面的性能，包括下颌骨的大小和形状，以及个体和组合肌肉机械优势（颞肌、浅层咬肌和深层咬肌）。在所有纳入的个体中都测量了最大自愿咬合力。为了测试代理预测的准确性，我们结合了线性回归和留一法，根据数据集的其余部分估计个体的咬合力。测试了估计值与测量值之间的相关性。在种间和种内水平上，大小和形状比机械优势更好的估计器。机械优势在种间水平上具有一定的预测能力，但在种内水平上通常没有，除了深层咬肌在少数物种中，大小和形状不允许我们预测咬合力。基于机械优势的性能外推应该谨慎使用，并且在种内情况下大多是不合理的。在后一种情况下，大小和形状是首选。
