Abstract：
Skeletal muscle fibre architecture provides important insights into performance of vertebrate locomotor and feeding behaviours. Chemical digestion and in situ sectioning of muscle bellies along their lengths to expose fibres, fibre orientation and intramuscular tendon, are two classical methods for estimating architectural variables such as fibre length (Lf) and physiological cross-sectional area (PCSA). It has recently been proposed that Lf estimates are systematically shorter and hence less accurate using in situ sectioning. Here we addressed this hypothesis by comparing Lf estimates between the two methods for the superficial masseter and temporalis muscles in a sample of strepsirrhine and platyrrhine primates. Means or single-specimen Lf estimates using chemical digestion were greater in 17/32 comparisons (53.13%), indicating the probability of achieving longer fibres using chemical digestion is no greater than chance in these taxonomic samples. We further explored the impact of sampling on scaling of Lf and PCSA in platyrrhines applying a bootstrapping approach. We found that sampling-both numbers of individuals within species and representation of species across the clade significantly influence scaling results of Lf and PCSA in platyrrhines. We show that intraspecific and clade sampling strategies can account for differences between previously published platyrrhine scaling studies. We suggest that differences in these two methodological approaches to assessing muscle architecture are relatively less consequential when estimating Lf and PCSA for comparative studies, whereas achieving more reliable estimates within species through larger samples and representation of the full clade space are important considerations in comparative studies of fibre architecture and scaling.
摘要：
骨骼肌纤维结构为脊椎动物运动和进食行为的表现提供了重要的见解。化学消化和肌肉腹部沿其长度的原位切片以暴露纤维，纤维取向和肌内肌腱，是估计诸如纤维长度(Lf)和生理横截面积(PCSA)的结构变量的两种经典方法。最近有人提出，使用原位切片，Lf估计值系统地较短，因此准确性较低。在这里，我们通过比较链霉菌和platyrrhine灵长类动物样本中浅表咬肌和颞肌的两种方法之间的Lf估计值来解决这一假设。使用化学消化的平均值或单样本Lf估计值在17/32比较中更大(53.13%)，表明使用化学消化获得较长纤维的可能性并不比这些分类学样品中的机会大。我们进一步探讨了应用自举方法采样对latyrhines中Lf和PCSA缩放比例的影响。我们发现，物种内的个体数量和整个进化枝的物种代表性都会显着影响lf和PCSA在platyrhine中的缩放结果。我们表明，种内和进化枝采样策略可以解释先前发表的Platyrrhine缩放研究之间的差异。WesuggestthatdifferencesinthesetwomethodologyapproachestoassessingmusclearchitecturearerelativelylessconsequentialwhenestimatingLfandPCSAforcomparativestudies,而通过更大的样本和完整进化枝空间的表示在物种内实现更可靠的估计是纤维结构和缩放比较研究中的重要考虑因素。
