Ontogeny of Feeding Performance in Herbivorous Mammals: a case study using sheep (<i>Ovis aries</i>)

Feeding is among the most important behaviors in vertebrate animals, directly involving and affecting morphology, function, behaviour, and ecology. While ontogenetic trajectories of feeding performance have been investigated in carnivorous and omnivorous mammals, herbivorous mammals remain understudied. Here we assess the ontogeny of feeding performance in the domestic sheep (<i>Ovis aries</i>) to establish a baseline for understanding the ontogeny of feeding performance in mammalian herbivores. We reconstructed six major jaw adductor muscles in an ontogenetic series of eight sheep skulls (newborn to 6.5 years) and estimated their bite force, jaw gape, and occlusal pressure. Bite force was calculated using physiological cross-sectional area estimates, jaw gape was derived from muscle strain limits, and occlusal pressure was measured as bite force relative to postcanine occlusal area. Results show that both bite force and jaw gape scale with positive allometry relative to skull size and age, with bite force increasing from ~100 N in neonates to ~650 N in adults, and jaw gape increasing from around 25° to 32°. Muscle orientations shift dorsoventrally through growth, likely optimizing efficiency of vertical biting at the expense of mediolateral and rostrocaudal movements. In contrast, occlusal pressure–potentially a more germane measure of feeding performance in herbivores–remains relatively constant throughout ontogeny, suggesting that feeding efficiency is constant through growth despite changes in bite force, jaw gape, and muscle efficiency. Thus, although juvenile sheep exhibit lower relative and absolute bite forces and jaw gapes, they may not be at a relative feeding performance disadvantage compared to adults if occlusal pressure is considered. More broadly, constant occlusal pressure through ontogeny may partly explain the absence of pronounced ontogenetic dietary shifts in mammalian herbivores

取食行为是脊椎动物最重要的行为之一，直接关联并影响其形态、功能、行为与生态。尽管针对食肉与杂食哺乳动物的取食表现个体发育轨迹已有不少研究，但植食性哺乳动物的相关研究仍较为匮乏。本研究以家绵羊（*Ovis aries*）为研究对象，评估其取食表现的个体发育过程，以期为理解哺乳动物植食者的取食表现个体发育模式建立基准。我们对8个覆盖从新生到6.5岁不同发育阶段的绵羊头骨进行了6块主要下颌收肌的三维重建，并估算了它们的咬合力、下颌张口度与咬合压力。咬合力通过生理横截面积估算值计算得到，下颌张口度由肌肉应变极限推导而来，咬合压力则以咬合力与后犬齿咬合面积的比值进行测算。研究结果显示，相对于头骨尺寸与年龄，咬合力与下颌张口度均呈正异速生长：咬合力从新生个体的约100牛增长至成体的约650牛，下颌张口度则从约25°提升至32°。随着个体发育，肌肉的走行方向发生背腹向偏移，这可能以牺牲内外侧与吻尾向运动为代价，优化垂直咬合的效率。与之相对，咬合压力——这一指标可能更贴合植食动物的取食表现评估——在整个个体发育过程中始终保持相对稳定，这表明尽管咬合力、下颌张口度与肌肉效率均发生变化，但个体发育过程中的取食效率并未改变。因此，尽管幼年绵羊的绝对与相对咬合力及下颌张口度均低于成体，但如果以咬合压力为评估指标，幼年绵羊的相对取食表现并不处于劣势。从更广泛的角度来看，个体发育过程中咬合压力保持恒定，这或许可以部分解释哺乳动物植食者为何未出现显著的个体发育食性转变。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于草食哺乳动物（以绵羊为例）摄食性能的个体发育研究，通过重建8个绵羊头骨的颌骨肌肉并计算咬合力、颌骨开合度和咬合压力，发现咬合压力在个体发育中保持恒定，这可能解释草食哺乳动物缺乏显著食性转变的原因。数据集包含3D模型文件和分析代码，支持相关生物力学研究。