1
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Kissane RWP, Griffiths A, Sharp AC. Functional anatomy of the wing muscles of the Egyptian fruit bat (Rousettus aegyptiacus) using dissection and diceCT. J Anat 2024. [PMID: 39344777 DOI: 10.1111/joa.14145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 08/22/2024] [Accepted: 09/16/2024] [Indexed: 10/01/2024] Open
Abstract
Bats are unique among mammals for evolving powered flight. However, very little data are available on the muscle properties and architecture of bat flight muscles. Diffusible iodine contrast-enhanced computed tomography (diceCT) is an established tool for 3D visualisation of anatomy and is becoming a more readily accessible and widely used technique. Here, we combine this technique with gross dissection of the Egyptian fruit bat (Rousettus aegyptiacus) to compare muscle masses, fibre lengths and physiological cross-sectional areas (PCSA) of muscles with published forelimb data from an array of non-flying mammals and flying birds. The Egyptian fruit bat has a highly specialised pectoralis (pars posterior) architecturally optimised to generate power. The elbow flexion/extension muscles (biceps brachii and triceps brachii) have comparable PCSAs to the pectoralis, but shorter fibre lengths, which are optimised to generate large forces. Our data also show that the Egyptian fruit bat is more similar to flying birds than non-flying mammals with its highly disparate muscle architecture. Specifically, the Egyptian fruit bat have uniquely enlarged pectoralis muscles and elbow flexion and extension muscles (bicep brachii and triceps brachii) to aid powered flight. Finally, while the Egyptian fruit bat has a comparable heterogeneity in pectoralis (pars posterior) fibre length across the cranial-caudal axis to that seen in birds, the average normalised fibre length is larger than that seen in any of the surveyed birds. Our data here provide a greater understanding of the anatomy and functional specialisation of the forelimb musculature that powers flight.
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Affiliation(s)
- Roger W P Kissane
- Department of Musculoskeletal and Ageing Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
| | - Amy Griffiths
- School of Biosciences, University of Liverpool, Liverpool, UK
| | - Alana C Sharp
- Department of Musculoskeletal and Ageing Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
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2
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Herrel A, Theil JC, Faure L, Druelle F, Berillon G. Age- and size-related changes in hind limb muscles in two baboon species (Papio anubis and P. papio). J Anat 2024. [PMID: 39313987 DOI: 10.1111/joa.14140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 08/16/2024] [Accepted: 09/06/2024] [Indexed: 09/25/2024] Open
Abstract
Body size has an impact on all biological functions and analyzing how body size impacts functional traits such as locomotion is critical. Body size does not only vary across species but also during ontogeny. Indeed, juvenile animals are often at a competitive disadvantage due to their smaller absolute size. Consequently, understanding size- and age-related changes in the locomotor system is critical for our understanding of adult phenotypes. Here, we address this question by exploring growth of the hind limb muscles in two species of closely related baboons that differ in their ecology, the olive baboon, Papio Anubis, the Guinea baboon, and Papio papio. To do so, we dissected 40 P. anubis and 10 P. papio and measured the mass and physiological cross-sectional area (PCSA) of the hind limb muscles. Our results showed no sexual differences in size- or age-related growth patterns, but did show differences between species. Whereas the scaling of muscle mass and PCSA was largely isometric in P. anubis, allometric scaling was more common in P. papio. Despite these differences between species, the knee extensors and external rotators at the knee scaled with positive allometry in both species highlighting their important role during adult locomotion. Although life-history data for P. papio are scarce, we suggest that differences between species may be associated with differences in adult body size and age of locomotor independence between species.
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Affiliation(s)
- Anthony Herrel
- Mécanismes Adaptatifs et Evolution, UMR 7179, Muséum national d'Histoire naturelle CNRS, Paris, France
- Department of Biology, Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium
- Functional Morphology Laboratory, Department of Biology, University of Antwerp, Antwerp, Belgium
- Naturhistorisches Museum Bern, Bern, Switzerland
| | - Jean-Christophe Theil
- Mécanismes Adaptatifs et Evolution, UMR 7179, Muséum national d'Histoire naturelle CNRS, Paris, France
- Ecole Nationale Vétérinaire Alfort, Maisons-Alfort, France
| | - Léon Faure
- Mécanismes Adaptatifs et Evolution, UMR 7179, Muséum national d'Histoire naturelle CNRS, Paris, France
| | - François Druelle
- Functional Morphology Laboratory, Department of Biology, University of Antwerp, Antwerp, Belgium
- UMR 7194 (Histoire Naturelle de l'Homme Préhistorique), CNRS-Muséum National d'Histoire Naturelle-UPVD, Paris, France
- UAR 846, Primatology Station-Celphedia, CNRS, Rousset, France
| | - Gilles Berillon
- UMR 7194 (Histoire Naturelle de l'Homme Préhistorique), CNRS-Muséum National d'Histoire Naturelle-UPVD, Paris, France
- UAR 846, Primatology Station-Celphedia, CNRS, Rousset, France
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3
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Charles J, Kissane R, Hoehfurtner T, Bates KT. From fibre to function: are we accurately representing muscle architecture and performance? Biol Rev Camb Philos Soc 2022; 97:1640-1676. [PMID: 35388613 PMCID: PMC9540431 DOI: 10.1111/brv.12856] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 12/11/2022]
Abstract
The size and arrangement of fibres play a determinate role in the kinetic and energetic performance of muscles. Extrapolations between fibre architecture and performance underpin our understanding of how muscles function and how they are adapted to power specific motions within and across species. Here we provide a synopsis of how this 'fibre to function' paradigm has been applied to understand muscle design, performance and adaptation in animals. Our review highlights the widespread application of the fibre to function paradigm across a diverse breadth of biological disciplines but also reveals a potential and highly prevalent limitation running through past studies. Specifically, we find that quantification of muscle architectural properties is almost universally based on an extremely small number of fibre measurements. Despite the volume of research into muscle properties, across a diverse breadth of research disciplines, the fundamental assumption that a small proportion of fibre measurements can accurately represent the architectural properties of a muscle has never been quantitatively tested. Subsequently, we use a combination of medical imaging, statistical analysis, and physics-based computer simulation to address this issue for the first time. By combining diffusion tensor imaging (DTI) and deterministic fibre tractography we generated a large number of fibre measurements (>3000) rapidly for individual human lower limb muscles. Through statistical subsampling simulations of these measurements, we demonstrate that analysing a small number of fibres (n < 25) typically used in previous studies may lead to extremely large errors in the characterisation of overall muscle architectural properties such as mean fibre length and physiological cross-sectional area. Through dynamic musculoskeletal simulations of human walking and jumping, we demonstrate that recovered errors in fibre architecture characterisation have significant implications for quantitative predictions of in-vivo dynamics and muscle fibre function within a species. Furthermore, by applying data-subsampling simulations to comparisons of muscle function in humans and chimpanzees, we demonstrate that error magnitudes significantly impact both qualitative and quantitative assessment of muscle specialisation, potentially generating highly erroneous conclusions about the absolute and relative adaption of muscles across species and evolutionary transitions. Our findings have profound implications for how a broad diversity of research fields quantify muscle architecture and interpret muscle function.
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Affiliation(s)
- James Charles
- Structure and Motion Lab, Comparative Biomedical SciencesRoyal Veterinary CollegeHawkshead LaneHatfieldHertfordshireAL9 7TAU.K.
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical SciencesUniversity of LiverpoolThe William Henry Duncan Building, 6 West Derby StreetLiverpoolL7 8TXU.K.
| | - Roger Kissane
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical SciencesUniversity of LiverpoolThe William Henry Duncan Building, 6 West Derby StreetLiverpoolL7 8TXU.K.
| | - Tatjana Hoehfurtner
- School of Life SciencesUniversity of Lincoln, Joseph Banks LaboratoriesGreen LaneLincolnLN6 7DLU.K.
| | - Karl T. Bates
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical SciencesUniversity of LiverpoolThe William Henry Duncan Building, 6 West Derby StreetLiverpoolL7 8TXU.K.
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4
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Wright MA, Sears KE, Pierce SE. Comparison of Hindlimb Muscle Architecture Properties in Small-Bodied, Generalist Mammals Suggests Similarity in Soft Tissue Anatomy. J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09608-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Cieri RL, Dick TJM, Morris JS, Clemente CJ. Scaling of fibre area and fibre glycogen concentration in the hindlimb musculature of monitor lizards: implications for locomotor performance with increasing body size. J Exp Biol 2022; 225:274383. [PMID: 35258618 DOI: 10.1242/jeb.243380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 12/22/2022]
Abstract
A considerable biomechanical challenge faces larger terrestrial animals as the demands of body support scale with body mass (Mb), while muscle force capacity is proportional to muscle cross-sectional area, which scales with Mb2/3. How muscles adjust to this challenge might be best understood by examining varanids, which vary by five orders of magnitude in size without substantial changes in posture or body proportions. Muscle mass, fascicle length and physiological cross-sectional area all scale with positive allometry, but it remains unclear, however, how muscles become larger in this clade. Do larger varanids have more muscle fibres, or does individual fibre cross-sectional area (fCSA) increase? It is also unknown if larger animals compensate by increasing the proportion of fast-twitch (higher glycogen concentration) fibres, which can produce higher force per unit area than slow-twitch fibres. We investigated muscle fibre area and glycogen concentration in hindlimb muscles from varanids ranging from 105 g to 40,000 g. We found that fCSA increased with modest positive scaling against body mass (Mb0.197) among all our samples, and ∝Mb0.278 among a subset of our data consisting of never-frozen samples only. The proportion of low-glycogen fibres decreased significantly in some muscles but not others. We compared our results with the scaling of fCSA in different groups. Considering species means, fCSA scaled more steeply in invertebrates (∝Mb0.575), fish (∝Mb0.347) and other reptiles (∝Mb0.308) compared with varanids (∝Mb0.267), which had a slightly higher scaling exponent than birds (∝Mb0.134) and mammals (∝Mb0.122). This suggests that, while fCSA generally increases with body size, the extent of this scaling is taxon specific, and may relate to broad differences in locomotor function, metabolism and habitat between different clades.
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Affiliation(s)
- Robert L Cieri
- School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia
| | - Taylor J M Dick
- School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.,School of Biomedical Sciences, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Jeremy S Morris
- Department of Biology, Wofford College, Spartanburg, SC 29303, USA
| | - Christofer J Clemente
- School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.,School of Biomedical Sciences, University of Queensland, St. Lucia, QLD 4072, Australia
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6
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Bishop PJ, Wright MA, Pierce SE. Whole-limb scaling of muscle mass and force-generating capacity in amniotes. PeerJ 2021; 9:e12574. [PMID: 34909284 PMCID: PMC8638577 DOI: 10.7717/peerj.12574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/09/2021] [Indexed: 11/20/2022] Open
Abstract
Skeletal muscle mass, architecture and force-generating capacity are well known to scale with body size in animals, both throughout ontogeny and across species. Investigations of limb muscle scaling in terrestrial amniotes typically focus on individual muscles within select clades, but here this question was examined at the level of the whole limb across amniotes generally. In particular, the present study explored how muscle mass, force-generating capacity (measured by physiological cross-sectional area) and internal architecture (fascicle length) scales in the fore- and hindlimbs of extant mammals, non-avian saurians (‘reptiles’) and bipeds (birds and humans). Sixty species spanning almost five orders of magnitude in body mass were investigated, comprising previously published architectural data and new data obtained via dissections of the opossum Didelphis virginiana and the tegu lizard Salvator merianae. Phylogenetic generalized least squares was used to determine allometric scaling slopes (exponents) and intercepts, to assess whether patterns previously reported for individual muscles or functional groups were retained at the level of the whole limb, and to test whether mammals, reptiles and bipeds followed different allometric trajectories. In general, patterns of scaling observed in individual muscles were also observed in the whole limb. Reptiles generally have proportionately lower muscle mass and force-generating capacity compared to mammals, especially at larger body size, and bipeds exhibit strong to extreme positive allometry in the distal hindlimb. Remarkably, when muscle mass was accounted for in analyses of muscle force-generating capacity, reptiles, mammals and bipeds almost ubiquitously followed a single common scaling pattern, implying that differences in whole-limb force-generating capacity are principally driven by differences in muscle mass, not internal architecture. In addition to providing a novel perspective on skeletal muscle allometry in animals, the new dataset assembled was used to generate pan-amniote statistical relationships that can be used to predict muscle mass or force-generating capacity in extinct amniotes, helping to inform future reconstructions of musculoskeletal function in the fossil record.
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Affiliation(s)
- Peter J Bishop
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology,Harvard University, Cambridge, Massachusetts, United States of America.,Geosciences Program, Queensland Museum, Brisbane, Queensland, Australia
| | - Mark A Wright
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology,Harvard University, Cambridge, Massachusetts, United States of America
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology,Harvard University, Cambridge, Massachusetts, United States of America
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7
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Iijima M, Munteanu VD, Elsey RM, Blob RW. Ontogenetic changes in limb posture, kinematics, forces and joint moments in American alligators (Alligator mississippiensis). J Exp Biol 2021; 224:273379. [PMID: 34746961 DOI: 10.1242/jeb.242990] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 11/03/2021] [Indexed: 12/31/2022]
Abstract
As animals increase in size, common patterns of morphological and physiological scaling may require them to perform behaviors such as locomotion while experiencing a reduced capacity to generate muscle force and an increased risk of tissue failure. Large mammals are known to manage increased mechanical demands by using more upright limb posture. However, the presence of such size-dependent changes in limb posture has rarely been tested in animals that use non-parasagittal limb kinematics. Here, we used juvenile to subadult American alligators (total length 0.46-1.27 m, body mass 0.3-5.6 kg) and examined their limb kinematics, forces, joint moments and center of mass (CoM) to test for ontogenetic shifts in posture and limb mechanics. Larger alligators typically walked with a more adducted humerus and femur and a more extended knee. Normalized peak joint moments reflected these postural patterns, with shoulder and hip moments imposed by the ground reaction force showing relatively greater magnitudes in the smallest individuals. Thus, as larger alligators use more upright posture, they incur relatively smaller joint moments than smaller alligators, which could reduce the forces that the shoulder and hip adductors of larger alligators must generate. The CoM shifted nonlinearly from juveniles through subadults. The more anteriorly positioned CoM in small alligators, together with their compliant hindlimbs, contributes to their higher forelimb and lower hindlimb normalized peak vertical forces in comparison to larger alligators. Future studies of alligators that approach maximal adult sizes could give further insight into how animals with non-parasagittal limb posture modulate locomotor patterns as they increase in mass and experience changes in the CoM.
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Affiliation(s)
- Masaya Iijima
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.,Nagoya University Museum, Furocho, Chikusa-Ku, Nagoya, Aichi 464-8601, Japan
| | - V David Munteanu
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, 5476 Grand Chenier Highway, Grand Chenier, LA 70643, USA
| | - Richard W Blob
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
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8
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Pallandre JP, Lavenne F, Pellé E, Breton G, Ribaud M, Bels V. Variation in the sacroiliac joint in Felidae. PeerJ 2021; 9:e11116. [PMID: 34026342 PMCID: PMC8121069 DOI: 10.7717/peerj.11116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 02/24/2021] [Indexed: 11/20/2022] Open
Abstract
Felidae species show a great diversity in their diet, foraging and hunting strategies, from small to large prey. Whether they belong to solitary or group hunters, the behavior of cats to subdue resisting small or large prey presents crucial differences. It is assumed that pack hunting reduces the per capita risk of each individual. We hypothesize that the sacroiliac articulation plays a key role in stabilizing the predator while subduing and killing prey. Using CT-scan from 59 felid coxal bones, we calculated the angle between both iliac articular surfaces. Correlation of this inter-iliac angle with body size was calculated and ecological stressors were evaluated on inter-iliac angle. Body size significantly influences inter-iliac angle with small cats having a wider angle than big cats. Arboreal species have a significantly larger angle compared to cursorial felids with the smallest value, and to scansorial and terrestrial species with intermediate angles. Felids hunting large prey have a smaller angle than felids hunting small and mixed prey. Within the Panthera lineage, pack hunters (lions) have a larger angle than all other species using solitary hunting strategy. According to the inter-iliac angle, two main groups of felids are determined: (i) predators with an angle of around 40° include small cats (i.e., Felis silvestris, Leopardus wiedii, Leptailurus serval, Lynx Canadensis, L. rufus; median = 43.45°), the only pack-hunting species (i.e., Panthera leo; median = 37.90°), and arboreal cats (i.e., L. wiedii, Neofelis nebulosa; median = 49.05°), (ii) predators with an angle of around 30° include solitary-hunting big cats (i.e., Acinonyx jubatus, P. onca, P. pardus, P. tigris, P. uncia; median = 31.80°). We suggest different pressures of selection to interpret these results. The tightening of the iliac wings around the sacrum probably enhances big cats’ ability for high speed and large prey control. In contrast, pack hunting in lions reduced the selective pressure for large prey.
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Affiliation(s)
- Jean-Pierre Pallandre
- Institut de Systématique Evolution Biodiversité (ISYEB-UMR7205, CNRS/MNHN/EPHE/UA), Sorbonne Université, Muséum national d'Histoire naturelle, Paris, France
| | - Franck Lavenne
- CNRS, INSB, Centre d'Etude et de Recherche Multimodale Et Pluridisciplinaire en imagerie du vivant, Bron, France
| | - Eric Pellé
- Direction Générale des collections, Sorbonne Université, Museum national d'Histoire naturelle, Paris, France
| | | | | | - Vincent Bels
- Institut de Systématique Evolution Biodiversité (ISYEB-UMR7205, CNRS/MNHN/EPHE/UA), Sorbonne Université, Muséum national d'Histoire naturelle, Paris, France
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9
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Viranta S, Holmala K, Laakkonen J. Unique hip and stifle extensor muscle patterns in the Eurasian lynx, Lynx lynx (Carnivora: Felidae). J Morphol 2021; 282:553-562. [PMID: 33491790 DOI: 10.1002/jmor.21328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 01/13/2021] [Accepted: 01/21/2021] [Indexed: 11/12/2022]
Abstract
The Eurasian lynx (Lynx lynx) is a medium-sized felid, with a tendency to hunt for prey larger than itself. We studied the lynx hindlimb musculoskeletal anatomy in order to determine possible anatomical adaptations to hunting large prey. In our previous work, we had found characters of both large and small felids in the lynx forelimb. The crouched limbs, typical of all felids, increase the energy demands for the antigravity muscles during locomotion. As a powerful pounce is required for the smaller felid to bring down large prey, strong hindquarters may be needed. We hypothesized that the muscle attachments are more mechanically advantageous and muscles heavier in the lynx as compared to other felids to compensate for the energy requirements. In support of this, we found unique patterns in the hindlimb musculature of the lynx. Insertion of the m. gluteus medius was large with a short moment arm around the hip joint, providing mechanical disadvantage, but rapid movement. The musculus vastus medialis was relatively heavier than in other felids emphasizing the role of the m. quadriceps femoris as a powerful stifle extensor. The extensor muscles support the crouched hind limbs, which is crucial when tackling large prey, and they are also responsible for the swift powerful pounce brought by extending the hindlimbs. However, we cannot rule out the possibility the characters are shared with other Lynx spp. or they are adaptations to other aspects of the locomotor strategy in the Eurasian lynx.
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Affiliation(s)
- Suvi Viranta
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Katja Holmala
- Natural Resources Institute Finland, Helsinki, Finland
| | - Juha Laakkonen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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10
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Cieri RL, Dick TJM, Clemente CJ. Monitoring muscle over three orders of magnitude: Widespread positive allometry among locomotor and body support musculature in the pectoral girdle of varanid lizards (Varanidae). J Anat 2020; 237:1114-1135. [PMID: 32710503 DOI: 10.1111/joa.13273] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 12/18/2022] Open
Abstract
There is a functional trade-off in the design of skeletal muscle. Muscle strength depends on the number of muscle fibers in parallel, while shortening velocity and operational distance depend on fascicle length, leading to a trade-off between the maximum force a muscle can produce and its ability to change length and contract rapidly. This trade-off becomes even more pronounced as animals increase in size because muscle strength scales with area (length2 ) while body mass scales with volume (length3 ). In order to understand this muscle trade-off and how animals deal with the biomechanical consequences of size, we investigated muscle properties in the pectoral girdle of varanid lizards. Varanids are an ideal group to study the scaling of muscle properties because they retain similar body proportions and posture across five orders of magnitude in body mass and are highly active, terrestrially adapted reptiles. We measured muscle mass, physiological cross-sectional area, fascicle length, proximal and distal tendon lengths, and proximal and distal moment arms for 27 pectoral girdle muscles in 13 individuals across 8 species ranging from 64 g to 40 kg. Standard and phylogenetically informed reduced major axis regression was used to investigate how muscle architecture properties scale with body size. Allometric growth was widespread for muscle mass (scaling exponent >1), physiological cross-sectional area (scaling exponent >0.66), but not tendon length (scaling exponent >0.33). Positive allometry for muscle mass was universal among muscles responsible for translating the trunk forward and flexing the elbow, and nearly universal among humeral protractors and wrist flexors. Positive allometry for PCSA was also common among trunk translators and humeral protractors, though less so than muscle mass. Positive scaling for fascicle length was not widespread, but common among humeral protractors. A higher proportion of pectoral girdle muscles scaled with positive allometry than our previous work showed for the pelvic girdle, suggesting that the center of mass may move cranially with body size in varanids, or that the pectoral girdle may assume a more dominant role in locomotion in larger species. Scaling exponents for physiological cross-sectional area among muscles primarily associated with propulsion or with a dual role were generally higher than those associated primarily with support against gravity, suggesting that locomotor demands have at least an equal influence on muscle architecture as body support. Overall, these results suggest that larger varanids compensate for the increased biomechanical demands of locomotion and body support at higher body sizes by developing larger pectoral muscles with higher physiological cross-sectional areas. The isometric scaling rates for fascicle length among locomotion-oriented pectoral girdle muscles suggest that larger varanids may be forced to use shorter stride lengths, but this problem may be circumvented by increases in limb excursion afforded by the sliding coracosternal joint.
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Affiliation(s)
- Robert L Cieri
- School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia
| | - Taylor J M Dick
- School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia.,School of Biomedical Sciences, University of Queensland, St. Lucia, QLD, Australia
| | - Christofer J Clemente
- School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia.,School of Biomedical Sciences, University of Queensland, St. Lucia, QLD, Australia
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11
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Pallandre JP, Cornette R, Placide MA, Pelle E, Lavenne F, Abad V, Ribaud M, Bels VL. Iliac auricular surface morphofunctional study in felidae. ZOOLOGY 2019; 138:125714. [PMID: 31756647 DOI: 10.1016/j.zool.2019.125714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 11/19/2022]
Abstract
Felids show remarkable phenotypic similarities and are conservative in behavioral and ecological traits. In contrast, they display a large range in body mass from around 1kg to more than 300kg. Body size and locomotory specializations correlate to skull, limb and vertebral skeleton morphology. With an increase in body mass, felids prey selection switches from small to large, from using a rapid skull or spine lethal bite for small prey, to sustained suffocating bite for large prey. Dietary specialization correlates to skull and front limbs morphology but no correlation was found on the spine or on the hind limb. The morphology of the sacroiliac junction in relation to ecological factors remained to be described. We are presenting a study of the overall shape of the iliac auricular surface with qualitative and quantitative analyses of its morphology. Our results demonstrate that body mass, prey selection, and bite type, crucially influence the auricular surface, where no significant effect of locomotor specialization was found. The outline of the surface is significantly more elevated dorso-caudally and the joint surface shows an irregular W-shape topography in big cats whereas the surface in small cats is smoother with a C-shape topography and less of an elevated ridge. Biomechanically, we suggest that a complex auricular surface increases joint stiffness and provides more support in heavier cats, an advantage for subduing big prey successfully during a sustained bite.
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Affiliation(s)
- Jean-Pierre Pallandre
- Sorbonne Université, Muséum national d'Histoire naturelle, Institut de Systématique Evolution Biodiversité (UMR 7205 MNHN/CNRNS/UPMC/EPHE), 57 Rue Cuvier, 75005, Paris, France.
| | - Raphaël Cornette
- Sorbonne Université, Muséum national d'Histoire naturelle, Institut de Systématique Evolution Biodiversité (UMR 7205 MNHN/CNRNS/UPMC/EPHE), 57 Rue Cuvier, 75005, Paris, France
| | - Marie-Ange Placide
- Sorbonne Université, Muséum national d'Histoire naturelle, Institut de Systématique Evolution Biodiversité (UMR 7205 MNHN/CNRNS/UPMC/EPHE), 57 Rue Cuvier, 75005, Paris, France
| | - Eric Pelle
- Sorbonne Université, Muséum national d'Histoire naturelle, Direction Générale des collections, 57 Rue Cuvier, 75005, Paris, France
| | - Franck Lavenne
- Centre d'Etude et de Recherche Multimodale Et Pluridisciplinaire en imagerie du vivant (CNRS, INSB), 16-18 avenue Doyen Lépine, 69500, Bron, France
| | - Vincent Abad
- R & D, Manufacture des pneumatiques Michelin, 23 place des Carmes Dechaux, 63040, Clermont-Ferrand, France
| | - Mélina Ribaud
- Université Lyon, Ecole Centrale de Lyon, Institut Camille Jordan, 36 avenue Guy de Collonge, 69134, Ecully, France
| | - Vincent L Bels
- Sorbonne Université, Muséum national d'Histoire naturelle, Institut de Systématique Evolution Biodiversité (UMR 7205 MNHN/CNRNS/UPMC/EPHE), 57 Rue Cuvier, 75005, Paris, France
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12
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Butcher MT, Rose JA, Glenn ZD, Tatomirovich NM, Russo GA, Foster AD, Smith GA, Young JW. Ontogenetic allometry and architectural properties of the paravertebral and hindlimb musculature in Eastern cottontail rabbits (Sylvilagus floridanus): functional implications for developmental changes in locomotor performance. J Anat 2019; 235:106-123. [PMID: 31099418 PMCID: PMC6579946 DOI: 10.1111/joa.12991] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2019] [Indexed: 11/27/2022] Open
Abstract
Due to small body size, an immature musculoskeletal system, and other growth-related limits on performance, juvenile mammals frequently experience a greater risk of predation than their adult counterparts. As a result, behaviorally precocious juveniles are hypothesized to exhibit musculoskeletal advantages that permit them to accelerate rapidly and evade predation. This hypothesis was tested through detailed quantitative evaluation of muscle growth in wild Eastern cottontail rabbits (Sylvilagus floridanus). Cottontail rabbits experience high rates of mortality during the first year of life, suggesting that selection might act to improve performance in growing juveniles. Therefore, it was predicted that muscle properties associated with force and power capacity should be enhanced in juvenile rabbits to facilitate enhanced locomotor performance. We quantified muscle architecture from 24 paravertebral and hindlimb muscles across ontogeny in a sample of n = 29 rabbits and evaluated the body mass scaling of muscle mass (MM), physiological cross-sectional area (PCSA), isometric force (Fmax ), and instantaneous power (Pinst ), along with several dimensionless architectural indices. In contrast to our hypothesis, MM and PCSA for most muscles change with positive allometry during growth by scaling at M b 1.3 and M b 1.1 , respectively, whereas Fmax and Pinst generally scale indistinguishably from isometry, as do the architectural indices tested. However, scaling patterns indicate that the digital flexors and ankle extensors of juvenile S. floridanus have greater capacities for force and power, respectively, than those in adults, suggesting these muscle properties may be a part of several compensatory features that promote enhanced acceleration performance in young rabbits. Overall, our study implies that body size constraints place larger, more mature rabbits at a disadvantage during acceleration, and that adults must develop hypertrophied muscles in order to maintain mechanical similarity in force and power capacities across development. These findings challenge the accepted understanding that juvenile animals are at a performance detriment relative to adults. Instead, for prey-predator interactions necessitating short intervals of high force and power generation relative to body mass, as demonstrated by rapid acceleration of cottontail rabbits fleeing predators, it may be the adults that struggle to keep pace with juveniles.
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Affiliation(s)
- M. T. Butcher
- Department of Biological SciencesYoungstown State UniversityYoungstownOHUSA
| | - J. A. Rose
- Department of Biological SciencesYoungstown State UniversityYoungstownOHUSA
| | - Z. D. Glenn
- Department of Biological SciencesYoungstown State UniversityYoungstownOHUSA
| | - N. M. Tatomirovich
- Department of Biological SciencesYoungstown State UniversityYoungstownOHUSA
| | - G. A. Russo
- Department of AnthropologyStony Brook UniversityStony BrookNYUSA
| | - A. D. Foster
- Department of AnatomyCampbell UniversityBuies CreekNCUSA
| | - G. A. Smith
- Department of Biological SciencesKent State University at StarkCantonOHUSA
| | - J. W. Young
- Department of Anatomy and NeurobiologyNortheast Ohio Medical UniversityRootstownOHUSA
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13
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Jones KE, Benitez L, Angielczyk KD, Pierce SE. Adaptation and constraint in the evolution of the mammalian backbone. BMC Evol Biol 2018; 18:172. [PMID: 30445907 PMCID: PMC6240174 DOI: 10.1186/s12862-018-1282-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/30/2018] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The axial skeleton consists of repeating units (vertebrae) that are integrated through their development and evolution. Unlike most tetrapods, vertebrae in the mammalian trunk are subdivided into distinct thoracic and lumbar modules, resulting in a system that is constrained in terms of count but highly variable in morphology. This study asks how thoracolumbar regionalization has impacted adaptation and evolvability across mammals. Using geometric morphometrics, we examine evolutionary patterns in five vertebral positions from diverse mammal species encompassing a broad range of locomotor ecologies. We quantitatively compare the effects of phylogenetic and allometric constraints, and ecological adaptation between regions, and examine their impact on evolvability (disparity and evolutionary rate) of serially-homologous vertebrae. RESULTS Although phylogenetic signal and allometry are evident throughout the trunk, the effect of locomotor ecology is partitioned between vertebral positions. Lumbar vertebral shape correlates most strongly with ecology, differentiating taxa based on their use of asymmetric gaits. Similarly, disparity and evolutionary rates are also elevated posteriorly, indicating a link between the lumbar region, locomotor adaptation, and evolvability. CONCLUSION Vertebral regionalization in mammals has facilitated rapid evolution of the posterior trunk in response to selection for locomotion and static body support.
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Affiliation(s)
- Katrina E. Jones
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138 USA
| | - Lorena Benitez
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138 USA
| | - Kenneth D. Angielczyk
- Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605-2496 USA
| | - Stephanie E. Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138 USA
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14
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Harper CM, Sylvester AD. Effective Mechanical Advantage Allometry of Felid Elbow and Knee Extensors. Anat Rec (Hoboken) 2018; 302:775-784. [PMID: 30312539 DOI: 10.1002/ar.23973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 03/30/2018] [Accepted: 04/09/2018] [Indexed: 11/06/2022]
Abstract
Larger terrestrial mammals have generally been found to use more extended limb postures, a mechanism which maintains muscular requirements at larger sizes by improving the effective mechanical advantage (EMA) of limb musculature. Felids, however, have been documented to maintain joint angles across body sizes. If felid morphology scales isometrically, it would mean larger felids have relatively weaker muscles, compromising locomotor activities. Here, we examine the allometric relationships between the EMA of the elbow and knee extensors and body mass, finding that the EMA of the triceps brachii and quadriceps muscles scale with positive allometry. When species-specific joint angles were used rather than felid-average joint angles, EMA scales to body mass with more positive allometry. When the scaling of the muscle and ground reaction force (GRF) lever arms were investigated individually the allometric signal was lost; however, the muscle lever arms generally have allometric slope coefficients that are consistent with positive allometry, while the GRF lever arms demonstrate negative allometric slope coefficients. This suggests there are subtle alterations to limb morphology allowing different felid species to achieve an increased EMA via distinctive mechanisms. The quadriceps EMA was found to scale with sufficient positive allometry to compensate for increases in size without alteration in muscular anatomy; however, this is not the case for the triceps brachii EMA. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:775-784, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Christine M Harper
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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15
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Carrizo LV, Tulli MJ, Abdala V. Postnatal growth of forelimb musculo-tendinous systems in sigmodontine rats (Rodentia: Cricetidae). J Mammal 2018. [DOI: 10.1093/jmammal/gyy084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Luz Valeria Carrizo
- Instituto de Biología Subtropical (IBS)-nodo Posadas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional de Misiones (UNaM), Laboratorio de Genética Evolutiva, Félix de Azara, Posadas, Argentina
| | - María José Tulli
- Unidad Ejecutora Lillo-CONICET, Instituto de Herpetología-Fundación Miguel Lillo, Miguel Lillo, Tucumán, Argentina
| | - Virginia Abdala
- Instituto de Biodiversidad Neotropical (IBN), UNT-CONICET, Cátedra de Biología General, Facultad de Ciencias Naturales, UNT, Horco Mole, Yerba Buena, Tucumán, Argentina
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16
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Iijima M, Kubo T, Kobayashi Y. Comparative limb proportions reveal differential locomotor morphofunctions of alligatoroids and crocodyloids. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171774. [PMID: 29657781 PMCID: PMC5882705 DOI: 10.1098/rsos.171774] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 02/02/2018] [Indexed: 05/13/2023]
Abstract
Although two major clades of crocodylians (Alligatoroidea and Crocodyloidea) were split during the Cretaceous period, relatively few morphological and functional differences between them have been known. In addition, interaction of multiple morphofunctional systems that differentiated their ecology has barely been assessed. In this study, we examined the limb proportions of crocodylians to infer the differences of locomotor functions between alligatoroids and crocodyloids, and tested the correlation of locomotor and feeding morphofunctions. Our analyses revealed crocodyloids including Gavialis have longer stylopodia (humerus and femur) than alligatoroids, indicating that two groups may differ in locomotor functions. Fossil evidence suggested that alligatoroids have retained short stylopodia since the early stage of their evolution. Furthermore, rostral shape, an indicator of trophic function, is correlated with limb proportions, where slender-snouted piscivorous taxa have relatively long stylopodia and short overall limbs. In combination, trophic and locomotor functions might differently delimit the ecological opportunity of alligatoroids and crocodyloids in the evolution of crocodylians.
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Affiliation(s)
- Masaya Iijima
- Department of Natural History Sciences, Hokkaido University, N10W8 Kita-ku, Sapporo, Hokkaido, Japan
- Author for correspondence: Masaya Iijima e-mail:
| | - Tai Kubo
- The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yoshitsugu Kobayashi
- Hokkaido University Museum, Hokkaido University, N10W8 Kita-ku, Sapporo, Hokkaido, Japan
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17
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McHorse BK, Biewener AA, Pierce SE. Mechanics of evolutionary digit reduction in fossil horses (Equidae). Proc Biol Sci 2018; 284:rspb.2017.1174. [PMID: 28835559 DOI: 10.1098/rspb.2017.1174] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/12/2017] [Indexed: 01/15/2023] Open
Abstract
Digit reduction is a major trend that characterizes horse evolution, but its causes and consequences have rarely been quantitatively tested. Using beam analysis on fossilized centre metapodials, we tested how locomotor bone stresses changed with digit reduction and increasing body size across the horse lineage. Internal bone geometry was captured from 13 fossil horse genera that covered the breadth of the equid phylogeny and the spectrum of digit reduction and body sizes, from Hyracotherium to Equus To account for the load-bearing role of side digits, a novel, continuous measure of digit reduction was also established-toe reduction index (TRI). Our results show that without accounting for side digits, three-toed horses as late as Parahippus would have experienced physiologically untenable bone stresses. Conversely, when side digits are modelled as load-bearing, species at the base of the horse radiation through Equus probably maintained a similar safety factor to fracture stress. We conclude that the centre metapodial compensated for evolutionary digit reduction and body mass increases by becoming more resistant to bending through substantial positive allometry in internal geometry. These results lend support to two historical hypotheses: that increasing body mass selected for a single, robust metapodial rather than several smaller ones; and that, as horse limbs became elongated, the cost of inertia from the side toes outweighed their utility for stabilization or load-bearing.
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Affiliation(s)
- Brianna K McHorse
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA .,Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA 01730, USA
| | - Andrew A Biewener
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA 01730, USA
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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18
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Biomechanics of predator-prey arms race in lion, zebra, cheetah and impala. Nature 2018; 554:183-188. [PMID: 29364874 DOI: 10.1038/nature25479] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 01/02/2018] [Indexed: 11/08/2022]
Abstract
The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator-prey pairs, lion-zebra and cheetah-impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator-prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate.
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19
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Shape Covariation (or the Lack Thereof) Between Vertebrae and Other Skeletal Traits in Felids: The Whole is Not Always Greater than the Sum of Parts. Evol Biol 2018; 45:196-210. [PMID: 29755151 PMCID: PMC5938317 DOI: 10.1007/s11692-017-9443-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/18/2017] [Indexed: 12/25/2022]
Abstract
Within carnivorans, cats show comparatively little disparity in overall morphology, with species differing mainly in body size. However, detailed shape analyses of individual osteological structures, such as limbs or skulls, have shown that felids display significant morphological differences that correlate with their observed ecological and behavioural ranges. Recently, these shape analyses have been extended to the felid axial skeleton. Results demonstrate a functionally-partitioned vertebral column, with regions varying greatly in level of correlation between shape and ecology. Moreover, a clear distinction is evident between a phylogenetically-constrained neck region and a selection-responsive posterior spine. Here, we test whether this regionalisation of function reflected in vertebral column shape is also translated into varying levels of phenotypic integration between this structure and most other skeletal elements. We accomplish this comparison by performing pairwise tests of integration between vertebral and other osteological units, quantified with 3D geometric morphometric data and analysed both with and without phylogenetic correction. To our knowledge, this is the first study to test for integration across a comprehensive sample of whole-skeleton elements. Our results show that, prior to corrections, strong covariation is present between vertebrae across the vertebral column and all other elements, with the exception of the femur. However, most of these significant correlations disappear after correcting for phylogeny, which is a significant influence on cranial and limb morphology of felids and other carnivorans. Our results thus suggest that the vertebral column of cats displays relative independence from other skeletal elements and may represent several distinct evolutionary morphological modules.
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20
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Abstract
The survival of both the hunter and the hunted often comes down to speed. Yet how fast an animal can run is intricately linked to its size, such that the fastest animals are not the biggest nor the smallest. The ability to maintain high speeds is dependent on the body's capacity to withstand the high stresses involved with locomotion. Yet even when standing still, scaling principles would suggest that the mechanical stress an animal feels will increase in greater demand than its body can support. So if big animals want to be fast, they must find solutions to overcome these high stresses. This article explores the ways in which extant animals mitigate size-related increases in musculoskeletal stress in an effort to help understand where all the giants have gone.
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Affiliation(s)
- Taylor J. M. Dick
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christofer J. Clemente
- School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- * E-mail:
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21
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Regional differentiation of felid vertebral column evolution: a study of 3D shape trajectories. ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0304-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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22
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Cuff AR, Sparkes EL, Randau M, Pierce SE, Kitchener AC, Goswami A, Hutchinson JR. The scaling of postcranial muscles in cats (Felidae) I: forelimb, cervical, and thoracic muscles. J Anat 2016; 229:128-41. [PMID: 27074986 DOI: 10.1111/joa.12477] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/04/2016] [Indexed: 11/26/2022] Open
Abstract
The body masses of cats (Mammalia, Carnivora, Felidae) span a ~300-fold range from the smallest to largest species. Despite this range, felid musculoskeletal anatomy remains remarkably conservative, including the maintenance of a crouched limb posture at unusually large sizes. The forelimbs in felids are important for body support and other aspects of locomotion, as well as climbing and prey capture, with the assistance of the vertebral (and hindlimb) muscles. Here, we examine the scaling of the anterior postcranial musculature across felids to assess scaling patterns between different species spanning the range of felid body sizes. The muscle architecture (lengths and masses of the muscle-tendon unit components) for the forelimb, cervical and thoracic muscles was quantified to analyse how the muscles scale with body mass. Our results demonstrate that physiological cross-sectional areas of the forelimb muscles scale positively with increasing body mass (i.e. becoming relatively larger). Many significantly allometric variables pertain to shoulder support, whereas the rest of the limb muscles become relatively weaker in larger felid species. However, when phylogenetic relationships were corrected for, most of these significant relationships disappeared, leaving no significantly allometric muscle metrics. The majority of cervical and thoracic muscle metrics are not significantly allometric, despite there being many allometric skeletal elements in these regions. When forelimb muscle data were considered in isolation or in combination with those of the vertebral muscles in principal components analyses and MANOVAs, there was no significant discrimination among species by either size or locomotory mode. Our results support the inference that larger felid species have relatively weaker anterior postcranial musculature compared with smaller species, due to an absence of significant positive allometry of forelimb or vertebral muscle architecture. This difference in strength is consistent with behavioural changes in larger felids, such as a reduction of maximal speed and other aspects of locomotor abilities.
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Affiliation(s)
- Andrew R Cuff
- Department of Genetics, Evolution and Environment, University College London, London, UK.,Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, Herts, UK
| | - Emily L Sparkes
- Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, Herts, UK
| | - Marcela Randau
- Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Stephanie E Pierce
- Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, Herts, UK.,Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Andrew C Kitchener
- National Museums Scotland, Edinburgh, UK.,Institute of Geography, University of Edinburgh, Edinburgh, UK
| | - Anjali Goswami
- Department of Genetics, Evolution and Environment, University College London, London, UK
| | - John R Hutchinson
- Department of Genetics, Evolution and Environment, University College London, London, UK.,Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, Herts, UK
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