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Coombs EJ, Knapp A, Park T, Bennion RF, McCurry MR, Lanzetti A, Boessenecker RW, McGowen MR. Drivers of morphological evolution in the toothed whale jaw. Curr Biol 2024; 34:273-285.e3. [PMID: 38118449 DOI: 10.1016/j.cub.2023.11.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/22/2023]
Abstract
Toothed whales (odontocetes) emit high-frequency underwater sounds (echolocate)-an extreme and unique innovation allowing them to sense their prey and environment. Their highly specialized mandible (lower jaw) allows high-frequency sounds to be transmitted back to the inner ear. Echolocation is evident in the earliest toothed whales, but little research has focused on the evolution of mandibular form regarding this unique adaptation. Here, we use a high-density, three-dimensional geometric morphometric analysis of 100 living and extinct cetacean species spanning their ∼50-million-year evolutionary history. Our analyses demonstrate that most shape variation is found in the relative length of the jaw and the mandibular symphysis. The greatest morphological diversity was obtained during two periods of rapid evolution: the initial evolution of archaeocetes (stem whales) in the early to mid-Eocene as they adapted to an aquatic lifestyle, representing one of the most extreme adaptive transitions known, and later on in the mid-Oligocene odontocetes as they became increasingly specialized for a range of diets facilitated by increasingly refined echolocation. Low disparity in the posterior mandible suggests the shape of the acoustic window, which receives sound, has remained conservative since the advent of directional hearing in the aquatic archaeocetes, even as the earliest odontocetes began to receive sounds from echolocation. Diet, echolocation, feeding method, and dentition type strongly influence mandible shape. Unlike in the toothed whale cranium, we found no significant asymmetry in the mandible. We suggest that a combination of refined echolocation and associated dietary specializations have driven morphology and disparity in the toothed whale mandible.
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Affiliation(s)
- Ellen J Coombs
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, 10th St & Constitution Ave NW, Washington, DC 20560, USA; Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK.
| | - Andrew Knapp
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK; University College London, Gower Street, London WC1E 6BT, UK
| | - Travis Park
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK; School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Rebecca F Bennion
- Evolution & Diversity Dynamics Lab, Department of Geology, University of Liege, 4000 Liege, Belgium; O.D. Earth and History of Life, Royal Belgian Institute of Natural Sciences, 1000 Brussels, Belgium
| | - Matthew R McCurry
- Australian Museum Research Institute, 1 William Street, Sydney, NSW 2010, Australia; Earth & Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences (BEES), University of New South Wales, Kensington, NSW 2052, Australia; Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
| | - Agnese Lanzetti
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK; School of Geography, Earth, and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Robert W Boessenecker
- University of California Museum of Paleontology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Michael R McGowen
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, 10th St & Constitution Ave NW, Washington, DC 20560, USA
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Ecomorphology of toothed whales (Cetacea, Odontoceti) as revealed by 3D skull geometry. J MAMM EVOL 2023. [DOI: 10.1007/s10914-022-09642-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
AbstractExtant odontocetes (toothed whales) exhibit differences in body size and brain mass, biosonar mode, feeding strategies, and diving and habitat adaptations. Strong selective pressures associated with these factors have likely contributed to the morphological diversification of their skull. Here, we used 3D landmark geometric morphometric data from the skulls of 60 out of ~ 72 extant odontocete species and a well-supported phylogenetic tree to test whether size and shape variation are associated with ecological adaptations at an interspecific scale. Odontocete skull morphology exhibited a significant phylogenetic signal, with skull size showing stronger signal than shape. After accounting for phylogeny, significant associations were detected between skull size and biosonar mode, body length, brain and body mass, maximum and minimum prey size, and maximum peak frequency. Brain mass was also strongly correlated with skull shape together with surface temperature and average and minimum prey size. When asymmetric and symmetric components of shape were analysed separately, a significant correlation was detected between sea surface temperature and both symmetric and asymmetric components of skull shape, and between diving ecology and the asymmetric component. Skull shape variation of odontocetes was strongly influenced by evolutionary allometry but most of the associations with ecological variables were not supported after phylogenetic correction. This suggests that ecomorphological feeding adaptations vary more between, rather than within, odontocete families, and functional anatomical patterns across odontocete clades are canalised by size constraints.
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Skull ecomorphological variation of narwhals (Monodon monoceros, Linnaeus 1758) and belugas (Delphinapterus leucas, Pallas 1776) reveals phenotype of their hybrids. PLoS One 2022; 17:e0273122. [PMID: 35960760 PMCID: PMC9374245 DOI: 10.1371/journal.pone.0273122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 08/03/2022] [Indexed: 11/19/2022] Open
Abstract
Narwhals and belugas are toothed whales belonging to the Monodontidae. Belugas have a circumpolar Arctic and sub-Artic distribution while narwhals are restricted to the Atlantic Arctic. Their geographical ranges overlap during winter migrations in the Baffin Bay area (Canada/West Greenland) and successful interbreeding may occur. Here, we employed geometric morphometrics on museum specimens to explore the cranium and mandible morphology of a known hybrid (NHMD MCE 1356) and the cranium morphology of a putative hybrid (NHMD 1963.44.1.4) relative to skull morphological variation in the parental species. Specifically, we used 3D models of skulls from 69 belugas, 86 narwhals, and the two known/putative hybrids and 2D left hemi-mandibles from 20 belugas, 64 narwhals and the known hybrid. Skull shape analyses allowed clear discrimination between species. Narwhals are characterised by a relatively short rostrum and wide neurocranium while belugas show a more elongated and narrower cranium. Sexual size dimorphism was detected in narwhals, with males larger than females, but no sexual shape dimorphism was detected in either species (excluding presence/absence of tusks in narwhals). Morphological skull variation was also dependent on different allometric slopes between species and sexes in narwhals. Our analyses showed that the cranium of the known hybrid was phenotypically close to belugas but its 2D hemi-mandible had a narwhal shape and size morphology. Both cranium and mandible were strongly correlated, with the pattern of covariation being similar to belugas. The putative hybrid was a pure male narwhal with extruded teeth. Comparison of genomic DNA supported this result, and stable carbon and nitrogen isotope values suggested that the putative hybrid had a more benthic foraging strategy compared to narwhals. This work demonstrates that although the known hybrid could be discriminated from narwhals and belugas, detection of its affinities with these parental species was dependent on the part of the skull analysed.
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Extensive Interspecific Gene Flow Shaped Complex Evolutionary History and Underestimated Species Diversity in Rapidly Radiated Dolphins. J MAMM EVOL 2021. [DOI: 10.1007/s10914-021-09581-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractRecently diverged taxa are often characterized by high rates of hybridization, which can complicate phylogenetic reconstruction. For this reason, the phylogenetic relationships and evolutionary history of dolphins are still not very well resolved; the question of whether the genera Tursiops and Stenella are monophyletic is especially controversial. Here, we performed re-sequencing of six dolphin genomes and combined them with eight previously published dolphin SRA datasets and six whole-genome datasets to investigate the phylogenetic relationships of dolphins and test the monophyly hypothesis of Tursiops and Stenella. Phylogenetic reconstruction with the maximum likelihood and Bayesian methods of concatenated loci, as well as with coalescence analyses of sliding window trees, produced a concordant and well-supported tree. Our studies support the non-monophyletic status of Tursiops and Stenella because the species referred these genera do not form exclusive monophyletic clades. This suggests that the current taxonomy of both genera might not reflect their evolutionary history and may underestimate their diversity. A four-taxon D-statistic (ABBA-BABA) test, five-taxon DFOIL test, and tree-based PhyloNet analyses all showed extensive gene flow across dolphin species, which could explain the instability in resolving phylogenetic relationship of oceanic dolphins with different and limited markers. This study could be a good case to demonstrate how genomic data can reveal complex speciation and phylogeny in rapidly radiating animal groups.
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Guidarelli G, Colangelo P, de Francesco MC, Nicolosi P, Meloro C, Loy A. Phenotypic Changes Across a Geographic Gradient: The Case of Three Sympatric Dolphin Species. Evol Biol 2017. [DOI: 10.1007/s11692-017-9435-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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del Castillo DL, Viglino M, Flores DA, Cappozzo HL. Skull ontogeny and modularity in two species ofLagenorhynchus: Morphological and ecological implications. J Morphol 2016; 278:203-214. [DOI: 10.1002/jmor.20629] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/28/2016] [Accepted: 10/21/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Daniela L. del Castillo
- Laboratorio de Ecología, Comportamiento y Mamíferos Marinos, División Mastozoología; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Av. Ángel Gallardo 470 (C1405DJR) Buenos Aires Argentina
- CONICET. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
| | - Mariana Viglino
- CONICET. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
- Instituto Patagónico de Geología y Paleontología, CCT CONICET-CENPAT; Boulevard Brown 2915 (U9120ACD) Puerto Madryn Chubut Argentina
| | - David A. Flores
- CONICET. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
- Unidad Ejecutora Lillo, CONICET-Fundación Miguel Lillo; Miguel Lillo 251 Tucumán 4000 Argentina
- Instituto de Vertebrados, Fundación Miguel Lillo; Miguel Lillo 251 (CP4000) Tucumán Argentina
| | - Humberto L. Cappozzo
- Laboratorio de Ecología, Comportamiento y Mamíferos Marinos, División Mastozoología; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Av. Ángel Gallardo 470 (C1405DJR) Buenos Aires Argentina
- CONICET. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico, Departamento de Ciencias Naturales y Antropología; Fundación Azara, Universidad Maimonides; Hidalgo 775 7mo (C1405BDB) Buenos Aires Argentina
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de Francesco MC, Loy A. Intra- and Interspecific Interactions as Proximate Determinants of Sexual Dimorphism and Allometric Trajectories in the Bottlenose Dolphin Tursiops truncatus (Cetacea, Odontoceti, Delphinidae). PLoS One 2016; 11:e0164287. [PMID: 27764133 PMCID: PMC5072710 DOI: 10.1371/journal.pone.0164287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 09/22/2016] [Indexed: 11/18/2022] Open
Abstract
Feeding adaptation, social behaviour, and interspecific interactions related to sexual dimorphism and allometric growth are particularly challenging to be investigated in the high sexual monomorphic Delphinidae. We used geometric morphometrics to extensively explore sexual dimorphism and ontogenetic allometry of different projections of the skull and the mandible of the bottlenose dolphin Tursiops truncatus. Two-dimensional landmarks were recorded on the dorsal, ventral, lateral, and occipital views of the skull, and on the lateral view of the left and the right mandible of 104 specimens from the Mediterranean and the North Seas, differing environmental condition and degree of interspecific associations. Landmark configurations were transformed, standardized and superimposed through a Generalized Procrustes Analysis. Size and shape differences between adult males and females were respectively evaluated through ANOVA on centroid size, Procrustes ANOVA on Procrustes distances, and MANOVA on Procrustes coordinates. Ontogenetic allometry was investigated by multivariate regression of shape coordinates on centroid size in the largest homogenous sample from the North Sea. Results evidenced sexual dimorphic asymmetric traits only detected in the adults of the North Sea bottlenose dolphins living in monospecific associations, with females bearing a marked incision of the cavity hosting the left tympanic bulla. These differences were related to a more refined echolocalization system that likely enhances the exploitation of local resources by philopatric females. Distinct shape in immature versus mature stages and asymmetric changes in postnatal allometry of dorsal and occipital traits, suggest that differences between males and females are established early during growth. Allometric growth trajectories differed between males and females for the ventral view of the skull. Allometric trajectories differed among projections of skull and mandible, and were related to dietary shifts experienced by subadults and adults.
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Affiliation(s)
- Maria Carla de Francesco
- Department of Biosciences and Territory, University of Molise, Fonte Lappone locality, Pesche, (IS) I-86090, Italy
| | - Anna Loy
- Department of Biosciences and Territory, University of Molise, Fonte Lappone locality, Pesche, (IS) I-86090, Italy
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Esteve-Altava B. In search of morphological modules: a systematic review. Biol Rev Camb Philos Soc 2016; 92:1332-1347. [DOI: 10.1111/brv.12284] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 12/25/2022]
Affiliation(s)
- Borja Esteve-Altava
- Department of Comparative Biomedical Sciences; Royal Veterinary College; Hawkshead Lane, North Mymms Hatfield Hertfordshire AL9 7TA UK
- Department of Anatomy; College of Medicine, Howard University; 520 W Street, NW, Numa Adams Building Washington DC 20059 USA
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