Comparison of Hindlimb Muscle Architecture Properties in Small-Bodied, Generalist Mammals Suggests Similarity in Soft Tissue Anatomy
Comparison of Hindlimb Muscle Architecture Properties in Small-Bodied, Generalist Mammals Suggests Similarity in Soft Tissue Anatomy
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DOI：
10.1007/s10914-022-09608-6
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发表时间：
2022-04
影响因子：
1.9
通讯作者：
M. Wright;K. Sears;S. Pierce
中科院分区：
文献类型：
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作者：
M. Wright;K. Sears;S. Pierce
在它们进化史的前1亿多年中，大多数哺乳动物都非常小，许多动物表现出相对普遍的运动生态。在现存的哺乳动物中，体型小，多面手的物种有着相似的后肢骨形态和运动力学，但它们的肌肉系统的细节还没有被研究过。为了研究后肢肌肉结构特性是否也相似，我们解剖了灰色短尾负鼠（Monodelphis arctica）的后肢肌肉，并从文献中收集了其他三种小型哺乳动物（小家鼠，褐家鼠，豚鼠）的肌肉特性。然后，我们研究了后肢肌肉组织从整个肢体的角度来看，并通过分离成九个解剖区域的肢体。区域分析解释了数据中的显著更多的方差（r2：0.601 > 0.074），但仅检测到肌肉结构特性中的六个统计学显著的成对物种差异。这一发现表明，要么深保存兽后肢肌肉特性，或更有可能，生物力学的限制，由小的身体尺寸。此外，我们发现，无论是大生产力的专业化（即，PCSA）或更长的活动工作范围（即长肌束）在近端肢体区域，但既不专业化在更远端肢体区域。这种功能模式可能是小型哺乳动物穿越不平坦和移动基底的关键，无论环境如何。这些发现对于研究人员寻求重建和建模已灭绝哺乳动物在分支早期进化史中的软组织特性特别相关。
For the first 100+ million years of their evolutionary history, the majority of mammals were very small, and many exhibited relatively generalized locomotor ecologies. Among extant mammals, small-bodied, generalist species share similar hindlimb bone morphology and locomotor mechanics, but details of their musculature have not been investigated. To examine whether hindlimb muscle architecture properties are also similar, we dissected hindlimb muscles of the gray short-tailed opossum (Monodelphis domestica) and aggregated muscle properties from the literature for three other small-bodied mammals (Mus musculus,Rattus norvegicus,Cavia porcellus). We then studied hindlimb musculature from a whole-limb perspective and by separating the limb into nine anatomical regions. The region analysis explained substantially more variance in the data (r2: 0.601 > 0.074) but only detected six statistically significant pairwise species differences in muscle architecture properties. This finding suggests either deep conservation of therian hindlimb muscle properties or, more likely, a biomechanical constraint imposed by small body size. In addition, we find specialization for either large force production (i.e., PCSA) or longer active working ranges (i.e. long muscle fascicles) in proximal limb regions but neither specialization in more distal limb regions. This functional pattern may be key for small mammals to traverse across uneven and shifting substrates, regardless of environment. These findings are particularly relevant for researchers seeking to reconstruct and model soft tissue properties of extinct mammals during the early evolutionary history of the clade.