Anatomy of the woodchuck (Marmota monax)

Bezuidenhout, Abraham J.; Evans, Howard E.

doi:10.5962/bhl.title.61270

Cited by 29 publications

(35 citation statements)

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“…Muscle names, origin and insertion for M. monax followed those of Bezuidenhout and Evans (Bezuidenhout and Evans, 2005) and muscles were grouped based on their main action (Table 1). The forelimbs were skinned and muscles (excluding those of the manus) were identified and systematically dissected.…”

Section: Muscle Architecture Measurementsmentioning

confidence: 99%

“…Although their forelimb osteology [i.e. mechanical advantage (Lagaria and Youlatos, 2006)] and myology (Bezuidenhout and Evans, 2005) have been described in detail, the architectural properties of their forelimb muscles have not been quantified and related to their digging habits. The aims of this study are: (1) to quantify muscle fiber architecture and MHC isoform composition in groundhogs; and (2) to estimate peak isometric force (F max ), joint torque and instantaneous power (W) of the forelimb musculature.…”

Section: Introductionmentioning

confidence: 99%

“…Groundhogs have morphological features more typical of a generalized burrower (Hildebrand, 1985;Kley and Kearney, 2007), including: a reduced nictitating membrane (covers only the medial corners of the cornea); relatively large, shovel-shaped hindfeet that lack webbing between the digits (Bezuidenhout and Evans, 2005); and muscular forelimbs with forefeet that have only four short (~1.5 cm) claws. Although their forelimb osteology [i.e.…”

Section: Introductionmentioning

confidence: 99%

“…It is one of 14 species of marmots (Steppan et al, 1999), all of which are herbivorous, and have the largest body sizes of any of the sciurids. Adult body mass ranges from 2.7 to 5.4 kg (Bezuidenhout and Evans, 2005), with an average dimorphic body mass of 3.8 kg for males and 3.5 kg for females (Snyder et al, 1961). Body mass varies with hibernation behavior, with the peak body mass occurring immediately prior to hibernation (~7 months per year).…”

Section: Introductionmentioning

confidence: 99%

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Forelimb muscle architecture and myosin isoform composition in the groundhog (Marmota monax)

Rupert

Rose

Organ

et al. 2014

Journal of Experimental Biology

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Scratch-digging mammals are commonly described as having large, powerful forelimb muscles for applying high force to excavate earth, yet studies quantifying the architectural properties of the musculature are largely unavailable. To further test hypotheses about traits that represent specializations for scratch-digging, we quantified muscle architectural properties and myosin expression in the forelimb of the groundhog (Marmota monax), a digger that constructs semi-complex burrows. Architectural properties measured were muscle moment arm, muscle mass (MM), belly length (ML), fascicle length (l F ), pennation angle and physiological cross-sectional area (PCSA), and these metrics were used to estimate maximum isometric force, joint torque and power. Myosin heavy chain (MHC) isoform composition was determined in selected forelimb muscles by SDS-PAGE and densitometry analysis. Groundhogs have large limb retractors and elbow extensors that are capable of applying moderately high torque at the shoulder and elbow joints, respectively. Most of these muscles (e.g. latissimus dorsi and pectoralis superficialis) have high l F /ML ratios, indicating substantial shortening ability and moderate power. The unipennate triceps brachii long head has the largest PCSA and is capable of the highest joint torque at both the shoulder and elbow joints. The carpal and digital flexors show greater pennation and shorter fascicle lengths than the limb retractors and elbow extensors, resulting in higher PCSA/MM ratios and force production capacity. Moreover, the digital flexors have the capacity for both appreciable fascicle shortening and force production, indicating high muscle work potential. Overall, the forelimb musculature of the groundhog is capable of relatively low sustained force and power, and these properties are consistent with the findings of a predominant expression of the MHC-2A isoform. Aside from the apparent modifications to the digital flexors, the collective muscle properties observed are consistent with its behavioral classification as a lessspecialized burrower and these may be more representative of traits common to numerous rodents with burrowing habits or mammals with some fossorial ability.

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Section: Muscle Architecture Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Forelimb muscle architecture and myosin isoform composition in the groundhog (Marmota monax)

Rupert

Rose

Organ

et al. 2014

Journal of Experimental Biology

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“…Las estructuras homólogas fueron establecidas en base a la literatura (evans, 1993;aRgot, 2001aRgot, , 2002aRgot, , 2003bezuidenHout & evans, 2005) y a través de la comparación morfológica de los ejemplares estudiados.…”

Section: Materials Y Métodosunclassified

Descripción del postcráneo de Rhipidomys austrinus y Graomys griseoflavus (Rodentia, Cricetidae, Sigmodontinae)

Carrizo

Díaz

2011

Iheringia, Sér. Zool.

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ABSTRACT. Postcranial description of Rhipidomys austrinus and Graomys griseoflavus (Rodentia, Cricetidae, Sigmodontinae). We described the postcranial skeleton of two species of sigmodontine rodents, Rhipidomys austrinus Thomas, 1921 and Graomys griseoflavus (Waterhouse, 1837). Each structure of the postcranial skeleton is here described in details of shape, size, surface, and orientation. The skeletal anatomy of these two species shows morphological characters associated with different patterns related to their type of locomotion. Rhipidomys austrinus exhibits characteristics consistent with its arboreal locomotion in several elements of the postcranium, while G. griseoflavus shows attributes related to terrestrial locomotion.

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Weighing homoplasy against alternative scenarios with the help of macroevolutionary modeling: A case study on limb bones of fossorial sciuromorph rodents

Wölfer

Nyakatura

2019

Ecology and Evolution

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Homoplasy is a strong indicator of a phenotypic trait's adaptive significance when it can be linked to a similar function. We assessed homoplasy in functionally relevant scapular and femoral traits of Marmotini and Xerini, two sciuromorph rodent clades that independently acquired a fossorial lifestyle from an arboreal ancestor. We studied 125 species in the scapular dataset and 123 species in the femoral dataset. Pairwise evolutionary model comparison was used to evaluate whether homoplasy of trait optima is more likely than other plausible scenarios. The most likely trend of trait evolution among all traits was assessed via likelihood scoring of all considered models. The homoplasy hypothesis could never be confirmed as the single most likely model. Regarding likelihood scoring, scapular traits most frequently did not differ among Marmotini, Xerini, and arboreal species. For the majority of femoral traits, results indicate that Marmotini, but not Xerini, evolved away from the ancestral arboreal condition. We conclude on the basis of the scapular results that the forelimbs of fossorial and arboreal sciuromorphs share mostly similar functional demands, whereas the results on the femur indicate that the hind limb morphology is less constrained, perhaps depending on the specific fossorial habitat.

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Anatomy of the woodchuck (Marmota monax)

Cited by 29 publications

References 0 publications

Forelimb muscle architecture and myosin isoform composition in the groundhog (Marmota monax)

Forelimb muscle architecture and myosin isoform composition in the groundhog (Marmota monax)

Descripción del postcráneo de Rhipidomys austrinus y Graomys griseoflavus (Rodentia, Cricetidae, Sigmodontinae)

Weighing homoplasy against alternative scenarios with the help of macroevolutionary modeling: A case study on limb bones of fossorial sciuromorph rodents

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