Muscle internal structure revealed by contrast-enhanced μCT and fibre recognition: The hindlimb extensors of an arboreal and a fossorial squirrel

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  • In individuals of similar body mass representing closely related species with different lifestyles, muscle architectural properties can be assumed to reflect adaptation to differing, lifestyle-related functional demands. We here employ a fiber recognition algorithm on contrast-enhanced micro-computed tomography (μCT) scans of one specimen each of an arboreal (Sciurus vulgaris) and a fossorial (Spermophilus citellus) sciuromorph rodent. The automated approach accounts for potential heterogeneity of architectural properties within a muscle by analyzing all fascicles that compose a muscle. Muscle architectural properties (volume, fascicle length, and orientation, and force-generating capacity) were quantified in 14 hindlimb (hip, knee, and ankle) extensor muscles and compared between specimens. We expected the arboreal squirrel to exhibit greater force-generating capacity and a greater capacity for length change allowing more powerful hindlimb extension. Generally and mostly matching our expectations, the S. vulgaris specimen had absolutely and relatively larger extensor muscles than the S. citellus specimen which were thus metabolically more expensive and demonstrate the relatively larger investment into powerful hindlimb extension necessary in the arboreal context. We conclude that detailed quantitative data on hindlimb muscle internal structure as was gathered here for a very limited sample further lends support to the notion that muscle architecture reflects adaptation to differential functional demands in closely related species with different locomotor behaviors and lifestyles.

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Metadaten
Author:John Nyakatura, Roxane Baumgarten, Daniel BaumORCiD, Heiko Stark, Dionisios Youlatos
Document Type:Article
Parent Title (English):Mammalian Biology
Year of first publication:2019
DOI:https://doi.org/10.1016/j.mambio.2019.10.007