Functional Subdivision of the Vertebral Column in Four South American Dolphins

Marchesi, María Constanza; Mora, Matías S.; Crespo, Enrique A.; Boy, Claudia Clementina; González‐José, Rolando; Goodall, Rae Natalie Prosser

doi:10.31687/saremmn.18.25.2.0.12

Cited by 6 publications

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“…Some of the wide range of behaviors and morphologies shown by cetaceans may be associated with variation along their vertebral columns, especially within Delphinidae (Buchholtz & Schur, ; Marchesi et al, , ; Viglino, Flores, Ercoli, & Alvarez, 2014). Description and functional interpretation of this variability is essential to recognize the structural units along the column (Buchholtz & Schur ; Marchesi et al, ).…”

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confidence: 99%

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Marchesi

Boy

Dans

et al. 2019

Marine Mammal Science

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In dolphins, centrum shape is one of the features that allows determination of stable and flexible regions in the vertebral column. The Commerson's (Cephalorhynchus commersonii; n = 37), Peale's (Lagenorhynchus australis; n = 24), dusky (Lagenorhynchus obscurus; n = 29), and hourglass dolphins (Lagenorhynchus cruciger; n = 10) are closely related species inhabiting the Southern Hemisphere that have diverse prey and habitat preferences. We applied 3D geometric morphometrics to describe differences in centrum shape along the vertebral columns of these species, and hypothesize how these differences may affect swimming. On each column, we chose a maximum of eight vertebrae and digitized 18 landmarks on each centrum with a Microscribe G2X. We explored shape differences amongst regions employing principal components analyses and computing Mahalanobis distances. We describe differences in centrum shape in relation to functional regions and among species; and analyze shape changes in relation to particular biomechanical requirements. The species studied here may be partially sympatric in the Southern Hemisphere, but they have important differences in foraging ecology and habitat preferences that could be related to differences in centrum shape along the vertebral column.

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Section: Introductionmentioning

confidence: 99%

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Marchesi

Boy

Dans

et al. 2019

Marine Mammal Science

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“…Regional morphological differences along the vertebral columns of different dolphins may indicate how swimming style may varies between species (Buchholtz, 2001;Buchholtz and Schur, 2004;Marchesi et al, 2018). Buchholtz and Schur (2004) suggested an approach to vertebral column functional analyses, specific to dolphins, that redefines regions of the column into functional subdivisions.…”

Section: Functional Subdivision Of the Vertebral Column And Vertebraementioning

confidence: 99%

“…Based on this functional approach, traditional lumbar and caudal regions are divided into three functional regions: torso, tailstock, and fluke (Figure 1). The torso includes all vertebrae between the thoracic region (last rib bearing vertebra) and the first vertebra that is taller than wide, which is thereby the anterior boundary of the tailstock (Figure 2; see also Marchesi et al, 2018). The torso is further divided into three sub-regions: anterior, mid-, and posterior torso.…”

Section: Functional Subdivision Of the Vertebral Column And Vertebraementioning

confidence: 99%

“…The torso is further divided into three sub-regions: anterior, mid-, and posterior torso. Vertebrae on which the neural spine inverts its inclination define the anterior and posterior boundaries of the mid-torso (see Buchholtz and Schur, 2004;Marchesi et al, 2017Marchesi et al, , 2018. Tailstock vertebrae are those that are taller than wide, and fluke vertebrae are much wider than tall, and have rectangular cross sections.…”

Section: Functional Subdivision Of the Vertebral Column And Vertebraementioning

confidence: 99%

“…Tailstock vertebrae are those that are taller than wide, and fluke vertebrae are much wider than tall, and have rectangular cross sections. For our four studied species, boundaries for the functional regions were determined following Marchesi et al (2017Marchesi et al ( , 2018.…”

Section: Functional Subdivision Of the Vertebral Column And Vertebraementioning

confidence: 99%

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Vertebral Morphology in Partially Sympatric Dolphins: A 3D Approach

et al. 2020

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Vertebral morphology in extant porpoises: Radiation and functional implications

Marchesi

Galatius

Zaffino

et al. 2022

Journal of Morphology

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Vertebral morphology has profound biomechanical implications and plays an important role in adaptation to different habitats and foraging strategies for cetaceans.Extant porpoise species (Phocoenidae) display analogous evolutionary patterns in both hemispheres associated with convergent evolution to coastal versus oceanic environments. We employed 3D geometric morphometrics to study vertebral morphology in five porpoise species with contrasting habitats: the coastal Indo-Pacific finless porpoise (Neophocaena phocaenoides); the mostly coastal harbor porpoise (Phocoena phocoena) and Burmeister's porpoise (Phocoena spinipinnis); and the oceanic spectacled porpoise (Phocoena dioptrica) and Dall's porpoise (Phocoenoides dalli).We evaluated the radiation of vertebral morphology, both in size and shape, using multivariate statistics. We supplemented data with samples of an early-radiating delphinoid species, the narwhal (Monodon monoceros); and an early-radiating delphinid species, the white-beaked dolphin (Lagenorhynchus albirostris). Principal component analyses were used to map shape variation onto phylogenies, and phylogenetic constraints were investigated through permutation tests. We established links between vertebral morphology and movement patterns through biomechanical inferences from morphological presentations. We evidenced divergence in size between species with contrasting habitats, with coastal species tending to decrease in size from their estimated ancestral state, and oceanic species tending to increase in size. Regarding vertebral shape, coastal species had longer centra and shorter neural processes, but longer transverse processes, while oceanic species tended to have disk-shaped vertebrae with longer neural processes. Within Phocoenidae, the absence of phylogenetic constraints in vertebral morphology suggests a high level of evolutionary lability. Overall, our results are in accordance with the hypothesis of speciation within the family from a coastal ancestor, through adaptation to particular habitats. Variation in vertebral morphology in this group of small odontocetes highlights the importance of environmental complexity and particular selective pressures for the speciation process through the development of adaptations that minimize energetic costs during locomotion and prey capture.

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Functional Subdivision of the Vertebral Column in Four South American Dolphins

Cited by 6 publications

References 0 publications

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

Vertebral Morphology in Partially Sympatric Dolphins: A 3D Approach

Vertebral morphology in extant porpoises: Radiation and functional implications

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