1
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Sanks J, Racicot R. Predicting ecology and hearing sensitivities in Parapontoporia-An extinct long-snouted dolphin. Anat Rec (Hoboken) 2024. [PMID: 39010732 DOI: 10.1002/ar.25538] [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: 04/08/2024] [Revised: 06/14/2024] [Accepted: 06/27/2024] [Indexed: 07/17/2024]
Abstract
Analyses of the cetacean (whale and dolphin) inner ear provide glimpses into the ecology and evolution of extinct and extant groups. The paleoecology of the long-snouted odontocete (toothed whale) group, Parapontoporia, is primarily marine with its depositional context also suggesting freshwater tolerance. As an extinct relative of the exclusively riverine Lipotes vexillifer, Parapontoporia provides insight into a transition from marine to freshwater environments. High-resolution X-ray CT scans (~3 microns or less) of three individual specimens from two species, P. sternbergi and P. pacifica, were acquired. Digital endocasts of the inner ear labyrinths were extracted non-destructively. Nine measurements of the inner ear were compared with an existing dataset covering 125 terrestrial and aquatic artiodactyls. These measurements were then subjected to a principal component analysis to interpret hearing sensitivities among other artiodactyls. Based on our analyses, Parapontoporia was likely to have been able to hear within narrow-band high frequency (NBHF) ranges. This finding indicates another convergence of NBHF-style hearing, or, more intriguingly, suggests that it may be an ancestral characteristic present among the longirostrine dolphins that dominated in the Miocene prior to the evolution of more modern lineages.
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Affiliation(s)
- Joyce Sanks
- Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Rachel Racicot
- Messel Research and Mammalogy Department, Senckenberg Forschungsinstitut und Naturkundemuseum (Senckenberg Research Institute and Natural History Museum), Frankfurt am Main, Germany
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2
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Hersh TA, Ravignani A, Whitehead H. Cetaceans are the next frontier for vocal rhythm research. Proc Natl Acad Sci U S A 2024; 121:e2313093121. [PMID: 38814875 PMCID: PMC11194516 DOI: 10.1073/pnas.2313093121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024] Open
Abstract
While rhythm can facilitate and enhance many aspects of behavior, its evolutionary trajectory in vocal communication systems remains enigmatic. We can trace evolutionary processes by investigating rhythmic abilities in different species, but research to date has largely focused on songbirds and primates. We present evidence that cetaceans-whales, dolphins, and porpoises-are a missing piece of the puzzle for understanding why rhythm evolved in vocal communication systems. Cetaceans not only produce rhythmic vocalizations but also exhibit behaviors known or thought to play a role in the evolution of different features of rhythm. These behaviors include vocal learning abilities, advanced breathing control, sexually selected vocal displays, prolonged mother-infant bonds, and behavioral synchronization. The untapped comparative potential of cetaceans is further enhanced by high interspecific diversity, which generates natural ranges of vocal and social complexity for investigating various evolutionary hypotheses. We show that rhythm (particularly isochronous rhythm, when sounds are equally spaced in time) is prevalent in cetacean vocalizations but is used in different contexts by baleen and toothed whales. We also highlight key questions and research areas that will enhance understanding of vocal rhythms across taxa. By coupling an infraorder-level taxonomic assessment of vocal rhythm production with comparisons to other species, we illustrate how broadly comparative research can contribute to a more nuanced understanding of the prevalence, evolution, and possible functions of rhythm in animal communication.
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Affiliation(s)
- Taylor A. Hersh
- Marine Mammal Institute, Oregon State University, Newport, OR97365
- Comparative Bioacoustics Group, Max Planck Institute for Psycholinguistics, Nijmegen6525 XD, The Netherlands
- Department of Biology, Dalhousie University, HalifaxNS B3H 4R2, Canada
| | - Andrea Ravignani
- Comparative Bioacoustics Group, Max Planck Institute for Psycholinguistics, Nijmegen6525 XD, The Netherlands
- Center for Music in the Brain, Department of Clinical Medicine, Aarhus University, Aarhus8000, Denmark
- Department of Human Neurosciences, Sapienza University of Rome, Rome00185, Italy
| | - Hal Whitehead
- Department of Biology, Dalhousie University, HalifaxNS B3H 4R2, Canada
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3
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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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4
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Laeta M, Oliveira JA, Siciliano S, Lambert O, Jensen FH, Galatius A. Cranial asymmetry in odontocetes: a facilitator of sonic exploration? ZOOLOGY 2023; 160:126108. [PMID: 37633185 DOI: 10.1016/j.zool.2023.126108] [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: 05/16/2023] [Revised: 07/31/2023] [Accepted: 08/04/2023] [Indexed: 08/28/2023]
Abstract
Directional cranial asymmetry is an intriguing condition that has evolved in all odontocetes which has mostly been associated with sound production for echolocation. In this study, we investigated how cranial asymmetry varies across odontocete species both in terms of quality (i.e., shape), and quantity (magnitude of deviation from symmetry). We investigated 72 species across all ten families of Odontoceti using two-dimensional geometric morphometrics. The average asymmetric shape was largely consistent across odontocetes - the rostral tip, maxillae, antorbital notches and braincase, as well as the suture crest between the frontal and interparietal bones were displaced to the right, whereas the nasal septum and premaxillae showed leftward shifts, in concert with an enlargement of the right premaxilla and maxilla. A clear phylogenetic signal related to asymmetric shape variation was identified across odontocetes using squared-change parsimony. The magnitude of asymmetry was widely variable across Odontoceti, with greatest asymmetry in Kogiidae, Monodontidae and Globicephalinae, followed by Physeteridae, Platanistidae and Lipotidae, while the asymmetry was lowest in Lissodelphininae, Phocoenidae, Iniidae and Pontoporiidae. Ziphiidae presented a wide spectrum of asymmetry. Generalized linear models explaining magnitude of asymmetry found associations with click source level while accounting for cranial size. Using phylogenetic generalized least squares, we reconfirm that source level and centroid size significantly predict the level of cranial asymmetry, with more asymmetric marine taxa generally consisting of bigger species emitting higher output sonar signal, i.e. louder sounds. Both characteristics theoretically support foraging at depth, the former by allowing extended diving and the latter being adaptive for prey detection at longer distances. Thus, cranial asymmetry seems to be an evolutionary pathway that allows odontocetes to devote more space for sound-generating structures associated with echolocation and thus increases biosonar search range and foraging efficiency beyond simple phylogenetic scaling predictions.
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Affiliation(s)
- Maíra Laeta
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, 20941-160 Rio de Janeiro, RJ, Brazil.
| | - João A Oliveira
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, 20941-160 Rio de Janeiro, RJ, Brazil
| | - Salvatore Siciliano
- Departamento de Ciências Biológicas, Escola Nacional de Saúde Pública Sergio Arouca/Fiocruz, 21040-360 Rio de Janeiro, RJ, Brazil; Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos (GEMM-Lagos), Rua São José, 1.260, Praia Seca, 28970-000 Araruama, RJ, Brazil
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, 1000 Brussels, Belgium
| | - Frants H Jensen
- Section for Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark; Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MA 02543, USA; Biology Department, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Anders Galatius
- Section for Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
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5
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Werth AJ, Crompton AW. Cetacean tongue mobility and function: A comparative review. J Anat 2023; 243:343-373. [PMID: 37042479 PMCID: PMC10439401 DOI: 10.1111/joa.13876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023] Open
Abstract
Cetaceans are atypical mammals whose tongues often depart from the typical (basal) mammalian condition in structure, mobility, and function. Their tongues are dynamic, innovative multipurpose tools that include the world's largest muscular structures. These changes reflect the evolutionary history of cetaceans' secondary adaptation to a fully aquatic environment. Cetacean tongues play no role in mastication and apparently a greatly reduced role in nursing (mainly channeling milk ingestion), two hallmarks of Mammalia. Cetacean tongues are not involved in drinking, breathing, vocalizing, and other non-feeding activities; they evidently play no or little role in taste reception. Although cetaceans do not masticate or otherwise process food, their tongues retain key roles in food ingestion, transport, securing/positioning, and swallowing, though by different means than most mammals. This is due to cetaceans' aquatic habitat, which in turn altered their anatomy (e.g., the intranarial larynx and consequent soft palate alteration). Odontocetes ingest prey via raptorial biting or tongue-generated suction. Odontocete tongues expel water and possibly uncover benthic prey via hydraulic jetting. Mysticete tongues play crucial roles driving ram, suction, or lunge ingestion for filter feeding. The uniquely flaccid rorqual tongue, not a constant volume hydrostat (as in all other mammalian tongues), invaginates into a balloon-like pouch to temporarily hold engulfed water. Mysticete tongues also create hydrodynamic flow regimes and hydraulic forces for baleen filtration, and possibly for cleaning baleen. Cetacean tongues lost or modified much of the mobility and function of generic mammal tongues, but took on noteworthy morphological changes by evolving to accomplish new tasks.
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Affiliation(s)
- Alexander J Werth
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia, USA
| | - A W Crompton
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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6
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Roston RA, Boessenecker RW, Geisler JH. Evolution and development of the cetacean skull roof: a case study in novelty and homology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220086. [PMID: 37183892 PMCID: PMC10184229 DOI: 10.1098/rstb.2022.0086] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 11/15/2022] [Indexed: 05/16/2023] Open
Abstract
Skulls of living whales and dolphins (cetaceans) are telescoped-bones of the skull roof are overlapped by expanded facial bones and/or anteriorly extended occipital bones. Evolution of the underlying skull roof (calvarium), which lies between the telescoped regions, is relatively unstudied. We explore the evolution and development of the calvarium of toothed whales (odontocetes) by integrating fetal data with Oligocene odontocete fossils from North America, including eight neonatal and juvenile skulls of Olympicetus†. We identified two potential synapomorphies of crown Cetacea: contact of interparietals with frontals, and a single anterior median interparietal (AMI) element. Within Odontoceti, loss of contact between the parietals diagnoses the clade including Delphinida, Ziphiidae and Platanistidae (=Synrhina). Delphinida is characterized by a greatly enlarged interparietal. New fetal series of delphinoids reveal a consistent developmental pattern with three elements: the AMI and bilateral posterior interparietals (PIs). The PIs most resemble the medial interparietal elements of terrestrial artiodactyls, suggesting that the AMI of cetaceans could be a unique ossification. More broadly, the paucity of conserved anatomical relationships of the interparietals, as well as the fact that the elements often do not coalesce into a single bone, demonstrates that assessing homology of the interparietals across mammals remains challenging. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
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Affiliation(s)
- R. A. Roston
- Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA 98195, USA
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - R. W. Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC 29424, USA
- University of California Museum of Paleontology, University of California, Berkeley, CA 94720, USA
| | - J. H. Geisler
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
- Department of Paleobiology, National Museum of Natural History, Washington, DC 20560, USA
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7
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Velez-Juarbe J. New heterodont odontocetes from the Oligocene Pysht Formation in Washington State, U.S.A., and a reevaluation of Simocetidae (Cetacea, Odontoceti). PeerJ 2023; 11:e15576. [PMID: 37377790 PMCID: PMC10292202 DOI: 10.7717/peerj.15576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
Odontocetes first appeared in the fossil record by the early Oligocene, and their early evolutionary history can provide clues as to how some of their unique adaptations, such as echolocation, evolved. Here, three new specimens from the early to late Oligocene Pysht Formation are described further increasing our understanding of the richness and diversity of early odontocetes, particularly for the North Pacific. Phylogenetic analysis shows that the new specimens are part of a more inclusive, redefined Simocetidae, which now includes Simocetus rayi, Olympicetus sp. 1, Olympicetus avitus, O. thalassodon sp. nov., and a large unnamed taxon (Simocetidae gen. et sp. A), all part of a North Pacific clade that represents one of the earliest diverging groups of odontocetes. Amongst these, Olympicetus thalassodon sp. nov. represents one of the best known simocetids, offering new information on the cranial and dental morphology of early odontocetes. Furthermore, the inclusion of CCNHM 1000, here considered to represent a neonate of Olympicetus sp., as part of the Simocetidae, suggests that members of this group may not have had the capability of ultrasonic hearing, at least during their early ontogenetic stages. Based on the new specimens, the dentition of simocetids is interpreted as being plesiomorphic, with a tooth count more akin to that of basilosaurids and early toothed mysticetes, while other features of the skull and hyoid suggest various forms of prey acquisition, including raptorial or combined feeding in Olympicetus spp., and suction feeding in Simocetus. Finally, body size estimates show that small to moderately large taxa are present in Simocetidae, with the largest taxon represented by Simocetidae gen. et sp. A with an estimated body length of 3 m, which places it as the largest known simocetid, and amongst the largest Oligocene odontocetes. The new specimens described here add to a growing list of Oligocene marine tetrapods from the North Pacific, further promoting faunistic comparisons across other contemporaneous and younger assemblages, that will allow for an improved understanding of the evolution of marine faunas in the region.
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Affiliation(s)
- Jorge Velez-Juarbe
- Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
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8
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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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9
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Goswami A, Noirault E, Coombs EJ, Clavel J, Fabre AC, Halliday TJD, Churchill M, Curtis A, Watanabe A, Simmons NB, Beatty BL, Geisler JH, Fox DL, Felice RN. Attenuated evolution of mammals through the Cenozoic. Science 2022; 378:377-383. [DOI: 10.1126/science.abm7525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Cenozoic diversification of placental mammals is the archetypal adaptive radiation. Yet, discrepancies between molecular divergence estimates and the fossil record fuel ongoing debate around the timing, tempo, and drivers of this radiation. Analysis of a three-dimensional skull dataset for living and extinct placental mammals demonstrates that evolutionary rates peak early and attenuate quickly. This long-term decline in tempo is punctuated by bursts of innovation that decreased in amplitude over the past 66 million years. Social, precocial, aquatic, and herbivorous species evolve fastest, especially whales, elephants, sirenians, and extinct ungulates. Slow rates in rodents and bats indicate dissociation of taxonomic and morphological diversification. Frustratingly, highly similar ancestral shape estimates for placental mammal superorders suggest that their earliest representatives may continue to elude unequivocal identification.
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Affiliation(s)
- Anjali Goswami
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
| | - Eve Noirault
- Department of Life Sciences, Natural History Museum, London, UK
| | - Ellen J. Coombs
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Julien Clavel
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
| | - Anne-Claire Fabre
- Department of Life Sciences, Natural History Museum, London, UK
- Naturhistorisches Museum Bern, Bern, Switzerland
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Thomas J. D. Halliday
- Department of Life Sciences, Natural History Museum, London, UK
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Morgan Churchill
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI, USA
| | - Abigail Curtis
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Akinobu Watanabe
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Nancy B. Simmons
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY, USA
| | - Brian L. Beatty
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Jonathan H. Geisler
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, NY, USA
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - David L. Fox
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Ryan N. Felice
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Genetics, Evolution, and Environment, University College London, London, UK
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK
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10
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The tempo of cetacean cranial evolution. Curr Biol 2022; 32:2233-2247.e4. [DOI: 10.1016/j.cub.2022.04.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/28/2022] [Accepted: 04/21/2022] [Indexed: 01/05/2023]
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11
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Liu Z, Chen P, Xu DM, Qi FY, Guo YT, Liu Q, Bai J, Zhou X, Shi P. Molecular convergence and transgenic evidence suggest a single origin of laryngeal echolocation in bats. iScience 2022; 25:104114. [PMID: 35391832 PMCID: PMC8980745 DOI: 10.1016/j.isci.2022.104114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 03/07/2022] [Accepted: 03/15/2022] [Indexed: 10/28/2022] Open
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12
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OUP accepted manuscript. Zool J Linn Soc 2022. [DOI: 10.1093/zoolinnean/zlac019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Sander PM, Griebeler EM, Klein N, Juarbe JV, Wintrich T, Revell LJ, Schmitz L. Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science 2021; 374:eabf5787. [PMID: 34941418 DOI: 10.1126/science.abf5787] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- P Martin Sander
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany.,The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA
| | - Eva Maria Griebeler
- Institut für Organismische und Molekulare Evolutionsbiologie, Evolutionäre Ökologie, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Nicole Klein
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany
| | - Jorge Velez Juarbe
- Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA
| | - Tanja Wintrich
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany.,Anatomisches Institut, Universität Bonn, 53115 Bonn, Germany
| | - Liam J Revell
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA.,Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Lars Schmitz
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA.,W.M. Keck Science Department of Claremont McKenna, Scripps, and Pitzer Colleges, Claremont, CA 91711, USA
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14
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Churchill M, Baltz C. Evolution of orbit size in toothed whales (Artiodactyla: Odontoceti). J Anat 2021; 239:1419-1437. [PMID: 34287886 PMCID: PMC8602015 DOI: 10.1111/joa.13522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 07/05/2021] [Accepted: 07/08/2021] [Indexed: 11/30/2022] Open
Abstract
For many marine tetrapods, vision is important for finding food and navigating underwater, and eye size has increased to improve the capture of light in dim ocean depths. Odontocete whales, in contrast, rely instead on echolocation for navigation and prey capture. We tested whether the evolution of echolocation has influenced the orbit size, a proxy for eye size, and examined how orbit size evolved over time. We also assessed variation in orbit size amongst whales and tested how body size, diving ability, sound production, foraging habitat, and prey capture strategy influenced the orbit size using phylogenetic independent contrasts and phylogenetic ANOVAs. Using measurements of orbit length and bizygomatic width, we calculated proportional orbit size for 70 extant and 29 extinct whale taxa, with an emphasis on Odontoceti. We then performed ancestral character state reconstruction on a time-calibrated composite phylogeny. Our analysis revealed that there was no shift in proportional orbit size from archaeocetes through stem odontocetes, indicating that the evolution of echolocation did not influence the orbit size. Proportional orbit size increased in Ziphiidae, Phocoenidae, and Cephalorhynchus. Proportional orbit size decreased in Balaenidae, Physeteridae, Platanistidae, and Lipotidae. Body size, diving ability, foraging environment, and prey capture strategy had a significant influence on orbit size, but only without phylogenetic correction. An increase in orbit size is associated with deep diving behavior in beaked whales, while progenesis and retention of juvenile features into adulthood explain the pattern observed in Phocoenidae and Cephalorhynchus. Decrease in proportional orbit size is associated with adaptation toward murky freshwater environments in odontocetes and skim feeding in balaenids. Our study reveals that the evolution of echolocation had little effect on orbit size, which is variable in whales, and that adaptation for different feeding modes and habitat explains some of this variance.
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Affiliation(s)
- Morgan Churchill
- Department of BiologyUniversity of Wisconsin OshkoshOshkoshWIUSA
| | - Colin Baltz
- Department of BiologyUniversity of Wisconsin OshkoshOshkoshWIUSA
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15
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Lambert O, Goolaerts S. Late Miocene Survival of a Hyper-Longirostrine Dolphin and the Neogene to Recent Evolution of Rostrum Proportions Among Odontocetes. J MAMM EVOL 2021. [DOI: 10.1007/s10914-021-09573-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Racicot R. Evolution of whale sensory ecology: Frontiers in nondestructive anatomical investigations. Anat Rec (Hoboken) 2021; 305:736-752. [PMID: 34546007 DOI: 10.1002/ar.24761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/09/2021] [Accepted: 07/14/2021] [Indexed: 12/18/2022]
Abstract
Studies surrounding the evolution of sensory system anatomy in cetaceans over the last ~100 years have shed light on aspects of the early evolution of hearing sensitivities, the small relative size of the organ of balance (semicircular canals and vestibule), brain (endocast) shape and relative volume changes, and ontogenetic development of sensory-related structures. Here, I review advances in our knowledge of sensory system anatomy as informed by the use of nondestructive imaging techniques, with a focus on applied methods in computed tomography (CT and μCT), and identify the key questions that remain to be addressed. Of these, the most important are: Is lower frequency hearing sensitivity the ancestral condition for whales? Did echolocation evolve more than once in odontocetes; and if so, when and why? How has the structure of the cetacean brain changed, through the evolution of whales, and does this correspond to changes in hearing sensitivities? Finally, what are the general pathways of ontogenetic development of sensory systems in odontocetes and mysticetes? Answering these questions will allow us to understand important macroevolutionary patterns in a fully aquatic mammalian group and provides baseline data on species for which we have limited biological information because of logistical limitations.
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Affiliation(s)
- Rachel Racicot
- Abteilung Messelforschung und Mammalogie, Senckenberg Forschungsinstitut und Naturkundemuseum, Frankfurt am Main, Germany.,Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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17
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Mccurry MR, Marx FG, Evans AR, Park T, Pyenson ND, Kohno N, Castiglione S, Fitzgerald EMG. Brain size evolution in whales and dolphins: new data from fossil mysticetes. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Cetaceans (whales and dolphins) have some of the largest and most complex brains in the animal kingdom. When and why this trait evolved remains controversial, with proposed drivers ranging from echolocation to foraging complexity and high-level sociality. This uncertainty partially reflects a lack of data on extinct baleen whales (mysticetes), which has obscured deep-time patterns of brain size evolution in non-echolocating cetaceans. Building on new measurements from mysticete fossils, we show that the evolution of large brains preceded that of echolocation, and subsequently followed a complex trajectory involving several independent increases (e.g. in rorquals and oceanic dolphins) and decreases (e.g. in right whales and ‘river dolphins’). Echolocating whales show a greater tendency towards large brain size, thus reaffirming cognitive demands associated with sound processing as a plausible driver of cetacean encephalization. Nevertheless, our results suggest that other factors such as sociality were also important.
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Affiliation(s)
- Matthew R Mccurry
- Australian Museum Research Institute, 1 William Street, Sydney, New South Wales 2010, Australia
- Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
- Paleobiology, NMNH, Smithsonian Institution, Washington, DC, USA
| | - Felix G Marx
- Museum of New Zealand Te Papa Tongarewa, Wellington, 6011, New Zealand
- Department of Geology, University of Otago, Dunedin, 3054, New Zealand
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Geosciences, Museums Victoria, Melbourne, Victoria, Australia
| | - Travis Park
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, UK
| | - Nicholas D Pyenson
- Paleobiology, NMNH, Smithsonian Institution, Washington, DC, USA
- Department of Paleontology and Geology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Naoki Kohno
- Department of Geology and Palaeontology, National Museum of Nature and Science, Tsukuba, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Silvia Castiglione
- Department of Earth Sciences, Environment and Resources, University of Naples Federico II, 80138 Napoli,Italy
| | - Erich M G Fitzgerald
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Geosciences, Museums Victoria, Melbourne, Victoria, Australia
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, UK
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18
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Frainer G, Huggenberger S, Moreno IB, Plön S, Galatius A. Head adaptation for sound production and feeding strategy in dolphins (Odontoceti: Delphinida). J Anat 2021; 238:1070-1081. [PMID: 33319356 PMCID: PMC8053589 DOI: 10.1111/joa.13364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 01/01/2023] Open
Abstract
Head morphology in toothed whales evolved under selective pressures on feeding strategy and sound production. The postnatal development of the skull (n = 207) and mandible (n = 219) of six Delphinida species which differ in feeding strategy but exhibit similar sound emission patterns, including two narrow-band high-frequency species, were investigated through 3D morphometrics. Morphological changes throughout ontogeny were demonstrated based on the main source of variation (i.e., prediction lines) and the common allometric component. Multivariate trajectory analysis with pairwise comparisons between all species was performed to evaluate specific differences on the postnatal development of skulls and mandibles. Changes in the rostrum formation contributed to the variation (skull: 49%; mandible: 90%) of the entire data set and might not only reflect the feeding strategy adopted by each lineage but also represents an adaptation for sound production and reception. As an important structure for directionality of sound emissions, this may increase directionality in raptorial feeders. Phylogenetic generalized least squares analyses indicated that shape of the anterior portion of the skull is strongly dependent on phylogeny and might not only reflect feeding mode, but also morphological adaptations for sound production, particularly in raptorial species. Thus, postnatal development seems to represent a crucial stage for biosonar maturation in some raptorial species such as Pontoporia blainvillei and Sousa plumbea. The ontogeny of their main tool for navigation and hunting might reflect their natural history peculiarities and thus potentially define their main vulnerabilities to anthropogenic changes in the environment.
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Affiliation(s)
- Guilherme Frainer
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Ignacio B Moreno
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR/CLN/UFRGS), Universidade Federal do Rio Grande do Sul, Imbé, Brazil
| | - Stephanie Plön
- Bayworld Centre for Research and Education (BCRE), Port Elizabeth, South Africa
| | - Anders Galatius
- Marine Mammal Research, Department of Bioscience, Aarhus University, Roskilde, Denmark
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19
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Sadier A, Urban DJ, Anthwal N, Howenstine AO, Sinha I, Sears KE. Making a bat: The developmental basis of bat evolution. Genet Mol Biol 2021; 43:e20190146. [PMID: 33576369 PMCID: PMC7879332 DOI: 10.1590/1678-4685-gmb-2019-0146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 12/11/2020] [Indexed: 11/28/2022] Open
Abstract
Bats are incredibly diverse, both morphologically and taxonomically. Bats are the only mammalian group to have achieved powered flight, an adaptation that is hypothesized to have allowed them to colonize various and diverse ecological niches. However, the lack of fossils capturing the transition from terrestrial mammal to volant chiropteran has obscured much of our understanding of bat evolution. Over the last 20 years, the emergence of evo-devo in non-model species has started to fill this gap by uncovering some developmental mechanisms at the origin of bat diversification. In this review, we highlight key aspects of studies that have used bats as a model for morphological adaptations, diversification during adaptive radiations, and morphological novelty. To do so, we review current and ongoing studies on bat evolution. We first investigate morphological specialization by reviewing current knowledge about wing and face evolution. Then, we explore the mechanisms behind adaptive diversification in various ecological contexts using vision and dentition. Finally, we highlight the emerging work into morphological novelties using bat wing membranes.
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Affiliation(s)
- Alexa Sadier
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA
| | - Daniel J Urban
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA.,American Museum of Natural History, Department of Mammalogy, New York, USA
| | - Neal Anthwal
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA
| | - Aidan O Howenstine
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA
| | - Ishani Sinha
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA
| | - Karen E Sears
- University of California at Los Angeles, Department of Ecology and Evolutionary Biology, Los Angeles, USA
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20
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Laeta M, Ruenes GF, Siciliano S, Oliveira JA, Galatius A. Variation in cranial asymmetry among the Delphinoidea. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
The remarkable directional cranial asymmetry of odontocete skulls has been proposed to be related to sound production. We investigated the variation in quality and quantity of cranial asymmetry in the superfamily Delphinoidea using geometric morphometrics and then investigated the relationship between asymmetry and aspects of sound production. In the average asymmetric shape, the dorsal aspect of the skull outline and interparietal suture crest were displaced to the right, while the nasal septum, nasal bones and right premaxilla were displaced to the left. The nasal bone, premaxilla and maxilla were all larger on the right side. Three delphinoid families presented similar expressions of asymmetry; however, the magnitude of the asymmetry varied. The Monodontidae showed the greatest magnitude of asymmetry, whereas the Phocoenidae were much less asymmetric. The most speciose family, the Delphinidae, presented a wide spectrum of asymmetry, with globicephalines and lissodelphinines among the most and least asymmetric species, respectively. Generalized linear models explaining the magnitude of asymmetry with characteristics of echolocation clicks, habitat use and size revealed associations with source level, dive depth and centroid size. This supports a relationship between asymmetry and sound production, with more asymmetric species emitting louder sounds. For example, louder clicks would be beneficial for prey detection at longer ranges in deeper waters.
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Affiliation(s)
- Maíra Laeta
- Programa de Pós-graduação em Biodiversidade e Biologia Evolutiva, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos, Praia Seca, Araruama, RJ, Brazil
| | - Greicy F Ruenes
- Programa de Pós-graduação em Ecologia e Recursos Naturais, Universidade Estadual do Norte Fluminense “Darcy Ribeiro”, Campos dos Goytacazes, RJ, Brazil
- Laboratório de Ecologia de Mamíferos, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, Brazil
| | - Salvatore Siciliano
- Laboratório de Biodiversidade, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, Rio de Janeiro, Brazil
- Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos, Praia Seca, Araruama, RJ, Brazil
| | - João A Oliveira
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Anders Galatius
- Marine Mammal Research, Department of Bioscience, Aarhus University, Roskilde, Denmark
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21
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McGowen MR, Tsagkogeorga G, Álvarez-Carretero S, Dos Reis M, Struebig M, Deaville R, Jepson PD, Jarman S, Polanowski A, Morin PA, Rossiter SJ. Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture. Syst Biol 2020; 69:479-501. [PMID: 31633766 PMCID: PMC7164366 DOI: 10.1093/sysbio/syz068] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 10/02/2019] [Accepted: 10/06/2019] [Indexed: 12/20/2022] Open
Abstract
The evolution of cetaceans, from their early transition to an aquatic lifestyle to their subsequent diversification, has been the subject of numerous studies. However, although the higher-level relationships among cetacean families have been largely settled, several aspects of the systematics within these groups remain unresolved. Problematic clades include the oceanic dolphins (37 spp.), which have experienced a recent rapid radiation, and the beaked whales (22 spp.), which have not been investigated in detail using nuclear loci. The combined application of high-throughput sequencing with techniques that target specific genomic sequences provide a powerful means of rapidly generating large volumes of orthologous sequence data for use in phylogenomic studies. To elucidate the phylogenetic relationships within the Cetacea, we combined sequence capture with Illumina sequencing to generate data for \documentclass[12pt]{minimal}
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}{}$\sim $\end{document}3200 protein-coding genes for 68 cetacean species and their close relatives including the pygmy hippopotamus. By combining data from \documentclass[12pt]{minimal}
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}{}$>$\end{document}38,000 exons with existing sequences from 11 cetaceans and seven outgroup taxa, we produced the first comprehensive comparative genomic data set for cetaceans, spanning 6,527,596 aligned base pairs (bp) and 89 taxa. Phylogenetic trees reconstructed with maximum likelihood and Bayesian inference of concatenated loci, as well as with coalescence analyses of individual gene trees, produced mostly concordant and well-supported trees. Our results completely resolve the relationships among beaked whales as well as the contentious relationships among oceanic dolphins, especially the problematic subfamily Delphinidae. We carried out Bayesian estimation of species divergence times using MCMCTree and compared our complete data set to a subset of clocklike genes. Analyses using the complete data set consistently showed less variance in divergence times than the reduced data set. In addition, integration of new fossils (e.g., Mystacodon selenensis) indicates that the diversification of Crown Cetacea began before the Late Eocene and the divergence of Crown Delphinidae as early as the Middle Miocene. [Cetaceans; phylogenomics; Delphinidae; Ziphiidae; dolphins; whales.]
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Affiliation(s)
- Michael R McGowen
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.,Department of Vertebrate Zoology, Smithsonian Museum of Natural History, 10th & Constitution Ave. NW, Washington DC 20560, USA
| | - Georgia Tsagkogeorga
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Sandra Álvarez-Carretero
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Mario Dos Reis
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Monika Struebig
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Robert Deaville
- Institute of Zoology, Zoological Society of London, Outer Circle, London NW1 4RY, UK
| | - Paul D Jepson
- Institute of Zoology, Zoological Society of London, Outer Circle, London NW1 4RY, UK
| | - Simon Jarman
- School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Perth WA 6009, Australia
| | - Andrea Polanowski
- Australian Antarctic Division, 203 Channel Highway, Kingston TAS 7050, Australia
| | - Phillip A Morin
- Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 8901 La Jolla Shores Dr., La Jolla CA 92037 USA
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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22
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Bisconti M, Damarco P, Tartarelli G, Pavia M, Carnevale G. A natural endocast of an early Miocene odontocete and its implications in cetacean brain evolution. J Comp Neurol 2020; 529:1198-1227. [PMID: 32840887 DOI: 10.1002/cne.25015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/18/2022]
Abstract
The natural endocast Museo di Geologia e Paleontologia of the Università degli Studi di Torino (MGPT)-PU 13873 is described and analyzed in order to interpret its taxonomic affinities and its potential significance on our understanding of cetacean brain evolution. The endocast is from the early Miocene of Piedmont (between ca. 19 and 16 million years ago), Northwestern Italy, and shows a number of plesiomorphic characters. These include: scarcely rounded cerebral hemispheres, cerebellum exposed in dorsal view with little superimposition by the cerebral hemispheres, short temporal lobe, and long sylvian fissure. The distance between the hypophysis and the rostral pons is particularly high, as it was determined by the calculus of the hypothalamus quotient, suggesting that the development of a deep interpeduncular fossa was not as advanced as in living odontocetes. The encephalization quotient (EQ) of MGPT-PU 13873 is ~1.81; therefore, this specimen shows an EQ in line with other fossil whales of the same geological age (early Miocene). Comparative analysis shows that there is a critical lack of data from the late Miocene and Pliocene that prevents us to fully understand the recent evolution of the EQ diversity in whales. Moreover, the past diversity of brain size and shape in mysticetes is virtually unknown. All these observations point to the need of additional efforts to uncover evolutionary patterns and processes on cetacean brain evolution.
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Affiliation(s)
- Michelangelo Bisconti
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,San Diego Natural History Museum, San Diego, California, USA
| | - Piero Damarco
- Ente di Gestione del Parco Paleontologico Astigiano, Museo Paleontologico Territoriale dell'Astigiano, Asti, Italy
| | | | - Marco Pavia
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,Museo di Geologia e Paleontologia, Università degli Studi di Torino, Torino, Italy
| | - Giorgio Carnevale
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
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23
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Coombs EJ, Clavel J, Park T, Churchill M, Goswami A. Wonky whales: the evolution of cranial asymmetry in cetaceans. BMC Biol 2020; 18:86. [PMID: 32646447 PMCID: PMC7350770 DOI: 10.1186/s12915-020-00805-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/01/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unlike most mammals, toothed whale (Odontoceti) skulls lack symmetry in the nasal and facial (nasofacial) region. This asymmetry is hypothesised to relate to echolocation, which may have evolved in the earliest diverging odontocetes. Early cetaceans (whales, dolphins, and porpoises) such as archaeocetes, namely the protocetids and basilosaurids, have asymmetric rostra, but it is unclear when nasofacial asymmetry evolved during the transition from archaeocetes to modern whales. We used three-dimensional geometric morphometrics and phylogenetic comparative methods to reconstruct the evolution of asymmetry in the skulls of 162 living and extinct cetaceans over 50 million years. RESULTS In archaeocetes, we found asymmetry is prevalent in the rostrum and also in the squamosal, jugal, and orbit, possibly reflecting preservational deformation. Asymmetry in odontocetes is predominant in the nasofacial region. Mysticetes (baleen whales) show symmetry similar to terrestrial artiodactyls such as bovines. The first significant shift in asymmetry occurred in the stem odontocete family Xenorophidae during the Early Oligocene. Further increases in asymmetry occur in the physeteroids in the Late Oligocene, Squalodelphinidae and Platanistidae in the Late Oligocene/Early Miocene, and in the Monodontidae in the Late Miocene/Early Pliocene. Additional episodes of rapid change in odontocete skull asymmetry were found in the Mid-Late Oligocene, a period of rapid evolution and diversification. No high-probability increases or jumps in asymmetry were found in mysticetes or archaeocetes. Unexpectedly, no increases in asymmetry were recovered within the highly asymmetric ziphiids, which may result from the extreme, asymmetric shape of premaxillary crests in these taxa not being captured by landmarks alone. CONCLUSIONS Early ancestors of living whales had little cranial asymmetry and likely were not able to echolocate. Archaeocetes display high levels of asymmetry in the rostrum, potentially related to directional hearing, which is lost in early neocetes-the taxon including the most recent common ancestor of living cetaceans. Nasofacial asymmetry becomes a significant feature of Odontoceti skulls in the Early Oligocene, reaching its highest levels in extant taxa. Separate evolutionary regimes are reconstructed for odontocetes living in acoustically complex environments, suggesting that these niches impose strong selective pressure on echolocation ability and thus increased cranial asymmetry.
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Affiliation(s)
- Ellen J Coombs
- Genetics, Evolution, and Environment Department, University College London, Gower Street, London, WC1E 6BT, UK.
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK.
| | - Julien Clavel
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Travis Park
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
| | - Morgan Churchill
- Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, WI, 54901, USA
| | - Anjali Goswami
- Genetics, Evolution, and Environment Department, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK
- Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK
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24
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Bianucci G, de Muizon C, Urbina M, Lambert O. Extensive Diversity and Disparity of the Early Miocene Platanistoids (Cetacea, Odontoceti) in the Southeastern Pacific (Chilcatay Formation, Peru). Life (Basel) 2020; 10:life10030027. [PMID: 32197480 PMCID: PMC7151620 DOI: 10.3390/life10030027] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 11/27/2022] Open
Abstract
Several aspects of the fascinating evolutionary history of toothed and baleen whales (Cetacea) are still to be clarified due to the fragmentation and discontinuity (in space and time) of the fossil record. Here we open a window on the past, describing a part of the extraordinary cetacean fossil assemblage deposited in a restricted interval of time (19–18 Ma) in the Chilcatay Formation (Peru). All the fossils here examined belong to the Platanistoidea clade as here redefined, a toothed whale group nowadays represented only by the Asian river dolphin Platanista gangetica. Two new genera and species, the hyper-longirostrine Ensidelphis riveroi and the squalodelphinid Furcacetus flexirostrum, are described together with new material referred to the squalodelphinid Notocetus vanbenedeni and fragmentary remains showing affinities with the platanistid Araeodelphis. Our cladistic analysis defines the new clade Platanidelphidi, sister-group to Allodelphinidae and including E. riveroi and the clade Squalodelphinidae + Platanistidae. The fossils here examined further confirm the high diversity and disparity of platanistoids during the early Miocene. Finally, morphofunctional considerations on the entire platanistoid assemblage of the Chilcatay Formation suggest a high trophic partitioning of this peculiar cetacean paleocommunity.
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Affiliation(s)
- Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, 56126 Pisa, Italy
- Correspondence:
| | - Christian de Muizon
- CR2P (CNRS, MNHN, SU), Muséum National d’Histoire Naturelle, Département Origines et Évolution, 75005 Paris, France;
| | - Mario Urbina
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima 15072, Peru;
| | - Olivier Lambert
- Institut Royal des Sciences Naturelles de Belgique, D.O. Terre et Histoire de la Vie, 1000 Brussels, Belgium
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Racicot RA, Boessenecker RW, Darroch SAF, Geisler JH. Evidence for convergent evolution of ultrasonic hearing in toothed whales (Cetacea: Odontoceti). Biol Lett 2019; 15:20190083. [PMID: 31088283 DOI: 10.1098/rsbl.2019.0083] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Toothed whales (Cetacea: Odontoceti) are the most diverse group of modern cetaceans, originating during the Eocene/Oligocene transition approximately 38 Ma. All extant odontocetes echolocate; a single origin for this behaviour is supported by a unique facial source for ultrasonic vocalizations and a cochlea adapted for hearing the corresponding echoes. The craniofacial and inner ear morphology of Oligocene odontocetes support a rapid (less than 5 Myr) early evolution of echolocation. Although some cranial features in the stem odontocetes Simocetus and Olympicetus suggest an ability to generate ultrasonic sound, until now, the bony labyrinths of taxa of this grade have not been investigated. Here, we use µCT to examine a petrosal of a taxon with clear similarities to Olympicetus avitus. Measurements of the bony labyrinth, when added to an extensive dataset of cetartiodactyls, resulted in this specimen sharing a morphospace with stem whales, suggesting a transitional inner ear. This discovery implies that either the lineage leading to this Olympicetus--like taxon lost the ability to hear ultrasonic sound, or adaptations for ultrasonic hearing evolved twice, once in xenorophids and again on the stem of the odontocete crown group. We favour the latter interpretation as it matches a well-documented convergence of craniofacial morphology between xenorophids and extant odontocetes.
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Affiliation(s)
- Rachel A Racicot
- 1 W.M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges , Claremont, CA 91711 , USA.,2 Vertebrate Paleontology Department and The Dinosaur Institute, Natural History Museum of Los Angeles County , Los Angeles, CA 90007 , USA.,3 Department of Earth and Environmental Sciences, Vanderbilt University , Nashville, TN 37340 , USA
| | - Robert W Boessenecker
- 4 Department of Geology and Environmental Geosciences, College of Charleston , Charleston, SC 29414 , USA
| | - Simon A F Darroch
- 3 Department of Earth and Environmental Sciences, Vanderbilt University , Nashville, TN 37340 , USA
| | - Jonathan H Geisler
- 5 Department of Anatomy, New York Institute of Technology, College of Osteopathic Medicine , Old Westbury, NY 11568 , USA
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26
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Park T, Mennecart B, Costeur L, Grohé C, Cooper N. Convergent evolution in toothed whale cochleae. BMC Evol Biol 2019; 19:195. [PMID: 31651234 PMCID: PMC6813997 DOI: 10.1186/s12862-019-1525-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 10/01/2019] [Indexed: 11/10/2022] Open
Abstract
Background Odontocetes (toothed whales) are the most species-rich marine mammal lineage. The catalyst for their evolutionary success is echolocation - a form of biological sonar that uses high-frequency sound, produced in the forehead and ultimately detected by the cochlea. The ubiquity of echolocation in odontocetes across a wide range of physical and acoustic environments suggests that convergent evolution of cochlear shape is likely to have occurred. To test this, we used SURFACE; a method that fits Ornstein-Uhlenbeck (OU) models with stepwise AIC (Akaike Information Criterion) to identify convergent regimes on the odontocete phylogeny, and then tested whether convergence in these regimes was significantly greater than expected by chance. Results We identified three convergent regimes: (1) True’s (Mesoplodon mirus) and Cuvier’s (Ziphius cavirostris) beaked whales; (2) sperm whales (Physeter macrocephalus) and all other beaked whales sampled; and (3) pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales and Dall’s porpoise (Phocoenoides dalli). Interestingly the ‘river dolphins’, a group notorious for their convergent morphologies and riverine ecologies, do not have convergent cochlear shapes. The first two regimes were significantly convergent, with habitat type and dive type significantly correlated with membership of the sperm whale + beaked whale regime. Conclusions The extreme acoustic environment of the deep ocean likely constrains cochlear shape, causing the cochlear morphology of sperm and beaked whales to converge. This study adds support for cochlear morphology being used to predict the ecology of extinct cetaceans.
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Affiliation(s)
- Travis Park
- Department of Life Sciences, Natural History Museum, Cromwell Road, SW7 5BD, London, UK.
| | - Bastien Mennecart
- Naturhistorisches Museum Basel, Augustinergasse 2, 4001, Basel, Switzerland.,Naturhistorisches Museum Wien, Burgring 7, 1010, Vienna, Austria
| | - Loïc Costeur
- Naturhistorisches Museum Basel, Augustinergasse 2, 4001, Basel, Switzerland
| | - Camille Grohé
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA.,Laboratory Paleontology Evolution Paleoecosystems Paleoprimatology (PALEVOPRIM) - UMR 7262, CNRS-INEE/University of Poitiers, 86073, Poitiers Cedex 9, France
| | - Natalie Cooper
- Department of Life Sciences, Natural History Museum, Cromwell Road, SW7 5BD, London, UK
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27
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Serio C, Castiglione S, Tesone G, Piccolo M, Melchionna M, Mondanaro A, Di Febbraro M, Raia P. Macroevolution of Toothed Whales Exceptional Relative Brain Size. Evol Biol 2019. [DOI: 10.1007/s11692-019-09485-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Frainer G, Moreno IB, Serpa N, Galatius A, Wiedermann D, Huggenberger S. Ontogeny and evolution of the sound-generating structures in the infraorder Delphinida (Odontoceti: Delphinida). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz118] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractThe ontogeny of the structures involved in sound generation and modulation in dolphins was investigated through a comparison of the soft nasal structures of foetal, perinatal, neonatal and adult specimens of Pontoporiidae, Phocoenidae and Delphinidae. Foetal samples were sectioned at 10 µm in the saggital and coronal planes, and stained for histological examination. Computed tomography and magentic resonance imaging scan series were combined with new data to represent the ontogenetic stages of the three groups. The images were analysed in 3D-Slicer to characterize the general head topography. The origins of the melon and the vestibular air sac were detected between Carnegie stages C16 and F22. The three groups analysed showed distinct formation of the nasal plug and nasal plug muscles, mainly with regard to the loss of fat pathways (or their maintenance in Pontoporiidae) and the development of the nasal plug muscles on both sides (during perinatal development of Phocoenidae) or just on the left side (during postnatal development in Delphinidae). Broadband vocalizing delphinidans might have evolved under heterochronic events acting on the formation of sound-generating structures such as the rostrum and vestibular air sacs, and on the transformation of the branches of the melon, probably leading to a reduced directionality of the sonar beam.
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Affiliation(s)
- Guilherme Frainer
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul, Imbé, Brazil
- Department II of Anatomy, University of Cologne, Cologne, Germany
| | - Ignacio B Moreno
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul, Imbé, Brazil
| | - Nathalia Serpa
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul, Imbé, Brazil
| | - Anders Galatius
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Dirk Wiedermann
- Max Planck Institute for Metabolism Research, Cologne, Germany
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29
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Roston RA, Roth VL. Cetacean Skull Telescoping Brings Evolution of Cranial Sutures into Focus. Anat Rec (Hoboken) 2019; 302:1055-1073. [DOI: 10.1002/ar.24079] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 10/12/2018] [Accepted: 10/21/2018] [Indexed: 01/09/2023]
Affiliation(s)
| | - V. Louise Roth
- Department of Biology; Duke University; Durham North Carolina
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30
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Galatius A, Olsen MT, Steeman ME, Racicot RA, Bradshaw CD, Kyhn LA, Miller LA. Raising your voice: evolution of narrow-band high-frequency signals in toothed whales (Odontoceti). Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly194] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Anders Galatius
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Morten Tange Olsen
- Evolutionary Genomics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen O, Denmark
| | | | - Rachel A Racicot
- W. M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, CA, USA
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
- Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN, USA
| | - Catherine D Bradshaw
- School of Geographical Sciences, University of Bristol, Bristol, UK
- Met Office Hadley Centre, Exeter, UK
| | - Line A Kyhn
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Lee A Miller
- Department of Biology, University of Southern Denmark, Odense, Denmark
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31
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Churchill M, Miguel J, Beatty BL, Goswami A, Geisler JH. Asymmetry drives modularity of the skull in the common dolphin (Delphinus delphis). Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly190] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Morgan Churchill
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI, USA
| | - Jacob Miguel
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
| | - Brian L Beatty
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
| | - Anjali Goswami
- Life Sciences Department, Natural History Museum, London, UK
| | - Jonathan H Geisler
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
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32
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Jensen FH, Johnson M, Ladegaard M, Wisniewska DM, Madsen PT. Narrow Acoustic Field of View Drives Frequency Scaling in Toothed Whale Biosonar. Curr Biol 2018; 28:3878-3885.e3. [DOI: 10.1016/j.cub.2018.10.037] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/12/2018] [Accepted: 10/12/2018] [Indexed: 11/27/2022]
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33
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Cominelli S, Devillers R, Yurk H, MacGillivray A, McWhinnie L, Canessa R. Noise exposure from commercial shipping for the southern resident killer whale population. MARINE POLLUTION BULLETIN 2018; 136:177-200. [PMID: 30509799 DOI: 10.1016/j.marpolbul.2018.08.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 06/24/2018] [Accepted: 08/22/2018] [Indexed: 06/09/2023]
Abstract
This study assesses vessel-noise exposure levels for Southern Resident Killer Whales (SRKW) in the Salish Sea. Kernel Density Estimation (KDE) was used to delineate SRKW summer core areas. Those areas were combined with the output of a regional cumulative noise model describing sound level variations generated by commercial vessels (1/3-octave-bands from 10 Hz to 63.1 kHz). Cumulative distribution functions were used to evaluate SRKW's noise exposure from 15 vessel categories over three zones located within the KDE. Median cumulative noise values were used to group categories based on the associated exposure levels. Ferries, Tugboats, Vehicle Carriers, Recreational Vessels, Containers, and Bulkers showed high levels of exposure (Leq-50th > 90 dB re 1 μPa) within SRKW core areas. Management actions aiming at reducing SRKW noise exposure during the summer should target the abovementioned categories and take into consideration the spatial distribution of their levels of exposure, their mechanical and their operational characteristics.
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Affiliation(s)
- Simone Cominelli
- Department of Geography, Memorial University of Newfoundland, Newfoundland and Labrador, St. John's, NL A1B 3X9, Canada.
| | - Rodolphe Devillers
- Department of Geography, Memorial University of Newfoundland, Newfoundland and Labrador, St. John's, NL A1B 3X9, Canada
| | - Harald Yurk
- Fisheries and Oceans Canada, Aquatic Ecosystems Marine Mammal Science, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
| | | | - Lauren McWhinnie
- Department of Geography, University of Victoria, Victoria, BC V8W 3R4, Canada
| | - Rosaline Canessa
- Department of Geography, University of Victoria, Victoria, BC V8W 3R4, Canada
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34
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Boessenecker RW, Geisler JH. New records of the archaic dolphin Agorophius (Mammalia: Cetacea) from the upper Oligocene Chandler Bridge Formation of South Carolina, USA. PeerJ 2018; 6:e5290. [PMID: 30280011 PMCID: PMC6166619 DOI: 10.7717/peerj.5290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/02/2018] [Indexed: 12/05/2022] Open
Abstract
The stem odontocete Agorophius pygmaeus (Ashley Formation, lower Oligocene, South Carolina; 29.0–26.57 Ma) has been a critical point of comparison for studies of early neocete evolution owing to its early discovery as well as its transitional anatomy relative to archaeocete whales and modern odontocetes. Some time during the late nineteenth century the holotype skull went missing and has never been relocated; supplementary reference specimens have since been recently referred to the species from the Ashley Formation and the overlying Chandler Bridge Formation (upper Oligocene; 24.7–23.5). New crania referable to Agorophius sp. are identifiable to the genus based on several features of the intertemporal region. Furthermore, all published specimens from the Chandler Bridge Formation consistently share larger absolute size and a proportionally shorter exposure of the parietal in the skull roof than specimens from the Ashley Formation (including the holotype). Furthermore, these specimens include well-preserved ethmoid labyrinths and cribriform plates, indicating that Agorophius primitively retained a strong olfactory sense. These new crania suggest that at least two species of Agorophius are present in the Oligocene of South Carolina, revealing a somewhat more complicated taxonomic perspective.
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Affiliation(s)
- Robert W Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC, United States of America.,Museum of Paleontology, University of California, Berkeley, Berkeley, CA, United States of America
| | - Jonathan H Geisler
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, United States of America
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35
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Liu Z, Qi FY, Xu DM, Zhou X, Shi P. Genomic and functional evidence reveals molecular insights into the origin of echolocation in whales. SCIENCE ADVANCES 2018; 4:eaat8821. [PMID: 30306134 PMCID: PMC6170035 DOI: 10.1126/sciadv.aat8821] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 08/27/2018] [Indexed: 05/15/2023]
Abstract
Echolocation allows toothed whales to adapt to underwater habitats where vision is ineffective. Because echolocation requires the ability to detect exceptional high-frequency sounds, fossils related to the auditory system can help to pinpoint the origin of echolocation in whales. However, because of conflicting interpretations of archaeocete fossils, when and how whales evolved the high-frequency hearing correlated with echolocation remain unclear. We address these questions at the molecular level by systematically investigating the convergent evolution of 7206 orthologs across 16 mammals and find that convergent genes between the last common ancestor of all whales (LCAW) and echolocating bats are not significantly enriched in functional categories related to hearing, and that convergence in hearing-related proteins between them is not stronger than that between nonecholocating mammalian lineages and echolocating bats. However, these results contrast with those of parallel analyses between the LCA of toothed whales (LCATW) and echolocating bats. Furthermore, we reconstruct the ancestral genes for the hearing protein prestin for the LCAW and LCATW; we show that the LCAW prestin exhibits the same function as that of nonecholocating mammals, but the LCATW prestin shows functional convergence with that of extant echolocating mammals. Mutagenesis shows that functional convergence of prestin is driven by convergent changes in the prestins S392A and L497M in the LCATW and echolocating bats. Our results provide genomic and functional evidence supporting the origin of high-frequency hearing in the LCAW, not the LCATW, and reveal molecular insights into the origin and evolutionary trajectories of echolocation in whales.
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Affiliation(s)
- Zhen Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Fei-Yan Qi
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650223, China
| | - Dong-Ming Xu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Xin Zhou
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Peng Shi
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
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36
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Goldbogen JA, Madsen PT. The evolution of foraging capacity and gigantism in cetaceans. ACTA ACUST UNITED AC 2018; 221:221/11/jeb166033. [PMID: 29895582 DOI: 10.1242/jeb.166033] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The extant diversity and rich fossil record of cetaceans provides an extraordinary evolutionary context for investigating the relationship between form, function and ecology. The transition from terrestrial to marine ecosystems is associated with a complex suite of morphological and physiological adaptations that were required for a fully aquatic mammalian life history. Two specific functional innovations that characterize the two great clades of cetaceans, echolocation in toothed whales (Odontoceti) and filter feeding in baleen whales (Mysticeti), provide a powerful comparative framework for integrative studies. Both clades exhibit gigantism in multiple species, but we posit that large body size may have evolved for different reasons and in response to different ecosystem conditions. Although these foraging adaptations have been studied using a combination of experimental and tagging studies, the precise functional drivers and consequences of morphological change within and among these lineages remain less understood. Future studies that focus at the interface of physiology, ecology and paleontology will help elucidate how cetaceans became the largest predators in aquatic ecosystems worldwide.
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Affiliation(s)
- J A Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, 120 Ocean View Boulevard, Pacific Grove, CA 93950, USA
| | - P T Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, C.F. Møllers Allé 3, 8000 Aarhus C, Denmark.,Aarhus Institute of Advanced Studies, Høegh-Guldbergs Gade 6B, DK-8000 Aarhus C, Denmark
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37
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The bony labyrinth of toothed whales reflects both phylogeny and habitat preferences. Sci Rep 2018; 8:7841. [PMID: 29777194 PMCID: PMC5959912 DOI: 10.1038/s41598-018-26094-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 04/20/2018] [Indexed: 11/08/2022] Open
Abstract
The inner ear of toothed whales (odontocetes) is known to have evolved particular shapes related to their abilities to echolocate and move under water. While the origin of these capacities is now more and more examined, thanks to new imaging techniques, little is still known about how informative inner ear shape could be to tackle phylogenetic issues or questions pertaining to the habitat preferences of extinct species. Here we show that the shape of the bony labyrinth of toothed whales provides key information both about phylogeny and habitat preferences (freshwater versus coastal and fully marine habitats). Our investigation of more than 20 species of extinct and modern odontocetes shows that the semi-circular canals are not very informative, in contrast to baleen whales, while the cochlea alone bears a strong signal. Inner ear shape thus provides a novel source of information to distinguish between morphologically convergent lineages (e.g. river dolphins).
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38
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Fordyce RE, Marx FG. Gigantism Precedes Filter Feeding in Baleen Whale Evolution. Curr Biol 2018; 28:1670-1676.e2. [PMID: 29754903 DOI: 10.1016/j.cub.2018.04.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/19/2018] [Accepted: 04/06/2018] [Indexed: 10/16/2022]
Abstract
Baleen whales (Mysticeti) are the largest animals on Earth, thanks to their ability to filter huge volumes of small prey from seawater. Mysticetes appeared during the Late Eocene, but evidence of their early evolution remains both sparse and controversial [1, 2], with several models competing to explain the origin of baleen-based bulk feeding [3-6]. Here, we describe a virtually complete skull of Llanocetus denticrenatus, the second-oldest (ca. 34 Ma) mysticete known. The new material represents the same individual as the type and only specimen, a fragmentary mandible. Phylogenetic analysis groups Llanocetus with the oldest mysticete, Mystacodon selenensis [2], into the basal family Llanocetidae. Llanocetus is gigantic (body length ∼8 m) compared to other early mysticetes [7-9]. The broad rostrum has sharp, widely spaced teeth with marked dental abrasion and attrition, suggesting biting and occlusal shearing. As in extant mysticetes, the palate bears many sulci, commonly interpreted as osteological correlates of baleen [3]. Unexpectedly, these sulci converge on the upper alveoli, suggesting a peri-dental blood supply to well-developed gums, rather than to inter-alveolar racks of baleen. We interpret Llanocetus as a raptorial or suction feeder, revealing that whales evolved gigantism well before the emergence of filter feeding. Rather than driving the origin of mysticetes, baleen and filtering most likely only arose after an initial phase of suction-assisted raptorial feeding [2, 4, 5]. This scenario differs strikingly from that proposed for odontocetes, whose defining adaptation-echolocation-was present even in their earliest representatives [10].
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Affiliation(s)
- R Ewan Fordyce
- Department of Geology, University of Otago, Dunedin, New Zealand; Departments of Vertebrate Zoology and Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Felix G Marx
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium; School of Biological Sciences, Monash University, Clayton, VIC, Australia; Geosciences, Museum Victoria, Melbourne, VIC, Australia.
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39
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Churchill M, Geisler JH, Beatty BL, Goswami A. Evolution of cranial telescoping in echolocating whales (Cetacea: Odontoceti). Evolution 2018; 72:1092-1108. [DOI: 10.1111/evo.13480] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/23/2018] [Indexed: 12/01/2022]
Affiliation(s)
- Morgan Churchill
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
- Department of Anatomy, College of Osteopathic Medicine New York Institute of Technology Old Westbury New York 11568
| | - Jonathan H. Geisler
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
| | - Brian L. Beatty
- Department of Biology University of Wisconsin Oshkosh Oshkosh Wisconsin 54901
| | - Anjali Goswami
- Life Sciences Department The Natural History Museum London SW7 5BD United Kingdom
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40
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Bianucci G, Bosio G, Malinverno E, de Muizon C, Villa IM, Urbina M, Lambert O. A new large squalodelphinid (Cetacea, Odontoceti) from Peru sheds light on the Early Miocene platanistoid disparity and ecology. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172302. [PMID: 29765678 PMCID: PMC5936943 DOI: 10.1098/rsos.172302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
The South Asian river dolphin (Platanista gangetica) is the only extant survivor of the large clade Platanistoidea, having a well-diversified fossil record from the Late Oligocene to the Middle Miocene. Based on a partial skeleton collected from the Chilcatay Formation (Chilcatay Fm; southern coast of Peru), we report here a new squalodelphinid genus and species, Macrosqualodelphis ukupachai. A volcanic ash layer, sampled near the fossil, yielded the 40Ar/39Ar age of 18.78 ± 0.08 Ma (Burdigalian, Early Miocene). The phylogenetic analysis places Macrosqualodelphis as the earliest branching squalodelphinid. Combined with several cranial and dental features, the large body size (estimated body length of 3.5 m) of this odontocete suggests that it consumed larger prey than the other members of its family. Together with Huaridelphis raimondii and Notocetus vanbenedeni, both also found in the Chilcatay Fm, this new squalodelphinid further demonstrates the peculiar local diversity of the family along the southeastern Pacific coast, possibly related to their partition into different dietary niches. At a wider geographical scale, the morphological and ecological diversity of squalodelphinids confirms the major role played by platanistoids during the Early Miocene radiation of crown odontocetes.
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Affiliation(s)
- Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Giulia Bosio
- Dipartimento di Scienze dell'Ambiente e del Territorio e di Scienze della Terra, Università di Milano-Bicocca, Milan, Italy
| | - Elisa Malinverno
- Dipartimento di Scienze dell'Ambiente e del Territorio e di Scienze della Terra, Università di Milano-Bicocca, Milan, Italy
| | - Christian de Muizon
- Département Origines et Évolution, CR2P (CNRS, MNHN, UPMC), Muséum National d'Histoire Naturelle, Paris, France
| | - Igor M. Villa
- Dipartimento di Scienze dell'Ambiente e del Territorio e di Scienze della Terra, Università di Milano-Bicocca, Milan, Italy
| | - Mario Urbina
- Departamento de Paleontologia de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Olivier Lambert
- DO Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
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Abstract
ABSTRACT
The Odontocetes (toothed whales) possess two types of specialized fat and, therefore, represent an interesting group when considering the evolution and function of adipose tissue. All whales have a layer of superficial blubber, which insulates and streamlines, provides buoyancy and acts as an energy reserve. Some toothed whales deposit large amounts of wax esters, rather than triacylglycerols, in blubber, which is unusual. Waxes have very different physical and physiological properties, which may impact blubber function. The cranial acoustic fat depots serve to focus sound during echolocation and hearing. The acoustic fats have unique morphologies; however, they are even more specialized biochemically because they are composed of a mix of endogenous waxes and triacylglycerols with unusual branched elements (derived from amino acids) that are not present in other mammals. Both waxes and branched elements alter how sound travels through a fat body; they are arranged in a 3D topographical pattern to focus sound. Furthermore, the specific branched-chain acid/alcohol synthesis mechanisms and products vary phylogenetically (e.g. dolphins synthesize lipids from leucine whereas beaked whales use valine). I propose that these specialized lipids evolved first in the head: wax synthesis first emerged to serve an acoustic function in toothed whales, with branched-chain synthesis adding additional acoustic focusing power, and some species secondarily retained wax synthesis pathways for blubber. Further research is necessary to elucidate specific molecular mechanisms controlling the synthesis and deposition of wax esters and branched-chain fatty acids, as well as their spatial deposition within tissues and within adipocytes.
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Affiliation(s)
- Heather N. Koopman
- Biology & Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28401, USA
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42
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Boessenecker RW, Fraser D, Churchill M, Geisler JH. A toothless dwarf dolphin (Odontoceti: Xenorophidae) points to explosive feeding diversification of modern whales (Neoceti). Proc Biol Sci 2018; 284:rspb.2017.0531. [PMID: 28835549 DOI: 10.1098/rspb.2017.0531] [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: 03/12/2017] [Accepted: 07/17/2017] [Indexed: 11/12/2022] Open
Abstract
Toothed whales (Odontoceti) are adapted for catching prey underwater and possess some of the most derived feeding specializations of all mammals, including the loss of milk teeth (monophyodonty), high tooth count (polydonty), and the loss of discrete tooth classes (homodonty). Many extant odontocetes possess some combination of short, broad rostra, reduced tooth counts, fleshy lips, and enlarged hyoid bones-all adaptations for suction feeding upon fishes and squid. We report a new fossil odontocete from the Oligocene (approx. 30 Ma) of South Carolina (Inermorostrum xenops, gen. et sp. nov.) that possesses adaptations for suction feeding: toothlessness and a shortened rostrum (brevirostry). Enlarged foramina on the rostrum suggest the presence of enlarged lips or perhaps vibrissae. Phylogenetic analysis firmly places Inermorostrum within the Xenorophidae, an early diverging odontocete clade typified by long-snouted, heterodont dolphins. Inermorostrum is the earliest obligate suction feeder within the Odontoceti, a feeding mode that independently evolved several times within the clade. Analysis of macroevolutionary trends in rostral shape indicate stabilizing selection around an optimum rostral shape over the course of odontocete evolution, and a post-Eocene explosion in feeding morphology, heralding the diversity of feeding behaviour among modern Odontoceti.
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Affiliation(s)
- Robert W Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC 29424, USA .,University of California Museum of Paleontology, University of California, Berkeley, CA 94720, USA
| | - Danielle Fraser
- Palaeobiology, Canadian Museum of Nature, PO Box 3443 Stn 'D', Ottawa, Ontario, Canada K1P 6P4
| | - Morgan Churchill
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA.,Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI 54901, USA
| | - Jonathan H Geisler
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA
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43
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Park T, Evans AR, Gallagher SJ, Fitzgerald EMG. Low-frequency hearing preceded the evolution of giant body size and filter feeding in baleen whales. Proc Biol Sci 2018; 284:rspb.2016.2528. [PMID: 28179519 DOI: 10.1098/rspb.2016.2528] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/11/2017] [Indexed: 11/12/2022] Open
Abstract
Living baleen whales (mysticetes) produce and hear the lowest-frequency (infrasonic) sounds among mammals. There is currently debate over whether the ancestor of crown cetaceans (Neoceti) was able to detect low frequencies. However, the lack of information on the most archaic fossil mysticetes has prevented us from determining the earliest evolution of their extreme acoustic biology. Here, we report the first anatomical analyses and frequency range estimation of the inner ear in Oligocene (34-23 Ma) fossils of archaic toothed mysticetes from Australia and the USA. The cochlear anatomy of these small fossil mysticetes resembles basilosaurid archaeocetes, but is also similar to that of today's baleen whales, indicating that even the earliest mysticetes detected low-frequency sounds, and lacked ultrasonic hearing and echolocation. This suggests that, in contrast to recent research, the plesiomorphic hearing condition for Neoceti was low frequency, which was retained by toothed mysticetes, and the high-frequency hearing of odontocetes is derived. Therefore, the low-frequency hearing of baleen whales has remained relatively unchanged over the last approximately 34 Myr, being present before the evolution of other signature mysticete traits, including filter feeding, baleen and giant body size.
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Affiliation(s)
- Travis Park
- School of Biological Sciences, Monash University, Melbourne, Australia .,Geosciences, Museums Victoria, Melbourne, Australia
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Melbourne, Australia.,Geosciences, Museums Victoria, Melbourne, Australia
| | | | - Erich M G Fitzgerald
- Geosciences, Museums Victoria, Melbourne, Australia.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Department of Life Sciences, Natural History Museum, London, UK
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44
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Bankoff RJ, Jerjos M, Hohman B, Lauterbur ME, Kistler L, Perry GH. Testing Convergent Evolution in Auditory Processing Genes between Echolocating Mammals and the Aye-Aye, a Percussive-Foraging Primate. Genome Biol Evol 2017; 9:1978-1989. [PMID: 28810710 PMCID: PMC5553384 DOI: 10.1093/gbe/evx140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2017] [Indexed: 01/04/2023] Open
Abstract
Several taxonomically distinct mammalian groups-certain microbats and cetaceans (e.g., dolphins)-share both morphological adaptations related to echolocation behavior and strong signatures of convergent evolution at the amino acid level across seven genes related to auditory processing. Aye-ayes (Daubentonia madagascariensis) are nocturnal lemurs with a specialized auditory processing system. Aye-ayes tap rapidly along the surfaces of trees, listening to reverberations to identify the mines of wood-boring insect larvae; this behavior has been hypothesized to functionally mimic echolocation. Here we investigated whether there are signals of convergence in auditory processing genes between aye-ayes and known mammalian echolocators. We developed a computational pipeline (Basic Exon Assembly Tool) that produces consensus sequences for regions of interest from shotgun genomic sequencing data for nonmodel organisms without requiring de novo genome assembly. We reconstructed complete coding region sequences for the seven convergent echolocating bat-dolphin genes for aye-ayes and another lemur. We compared sequences from these two lemurs in a phylogenetic framework with those of bat and dolphin echolocators and appropriate nonecholocating outgroups. Our analysis reaffirms the existence of amino acid convergence at these loci among echolocating bats and dolphins; some methods also detected signals of convergence between echolocating bats and both mice and elephants. However, we observed no significant signal of amino acid convergence between aye-ayes and echolocating bats and dolphins, suggesting that aye-aye tap-foraging auditory adaptations represent distinct evolutionary innovations. These results are also consistent with a developing consensus that convergent behavioral ecology does not reliably predict convergent molecular evolution.
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Affiliation(s)
- Richard J Bankoff
- Department of Anthropology, Pennsylvania State University, University Park, PA.,Intercollege Program in Bioethics, Pennsylvania State University, University Park, PA
| | - Michael Jerjos
- Department of Anthropology, Pennsylvania State University, University Park, PA
| | - Baily Hohman
- Department of Anthropology, Pennsylvania State University, University Park, PA
| | - M Elise Lauterbur
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY
| | - Logan Kistler
- Department of Anthropology, Pennsylvania State University, University Park, PA.,Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington DC
| | - George H Perry
- Department of Anthropology, Pennsylvania State University, University Park, PA.,Department of Biology, Pennsylvania State University, University Park, PA
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45
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Tanaka Y, Abella J, Aguirre-Fernández G, Gregori M, Fordyce RE. A new tropical Oligocene dolphin from Montañita/Olón, Santa Elena, Ecuador. PLoS One 2017; 12:e0188380. [PMID: 29261688 PMCID: PMC5737981 DOI: 10.1371/journal.pone.0188380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 10/31/2017] [Indexed: 11/18/2022] Open
Abstract
A new small probable Oligocene dolphin from Ecuador represents a new genus and species, Urkudelphis chawpipacha. The new taxon is known from a single juvenile skull and earbones; it differs from other archaic dolphins in features including widely exposed frontals at the vertex, a dorsally wide open vomer at the mesorostral groove, and a strongly projected and pointed lateral tuberosity of the periotic. Phylogenetic analysis places it toward the base of the largely-extinct clade Platanistoidea. The fossil is one of a few records of tropical fossil dolphins.
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Affiliation(s)
- Yoshihiro Tanaka
- Osaka Museum of Natural History, Osaka, Japan
- Numata Fossil Museum, Hokkaido, Japan
- Division of Academic Resources and Specimens, Hokkaido University Museum, Sapporo, Hokkaido, Japan
| | - Juan Abella
- Facultad de Ciencias del Mar, Universidad Estatal Península de Santa Elena, Santa Elena, Ecuador
- Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici ICP, Campus de la UAB, Cerdanyola del Vallès, Barcelona, Spain
| | | | - Maria Gregori
- Facultad de Ciencias del Mar, Universidad Estatal Península de Santa Elena, Santa Elena, Ecuador
| | - R. Ewan Fordyce
- Department of Geology, University of Otago, Dunedin, New Zealand
- Departments of Paleobiology and Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States of America
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46
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Boessenecker RW, Ahmed E, Geisler JH. New records of the dolphin Albertocetus meffordorum (Odontoceti: Xenorophidae) from the lower Oligocene of South Carolina: Encephalization, sensory anatomy, postcranial morphology, and ontogeny of early odontocetes. PLoS One 2017; 12:e0186476. [PMID: 29117197 PMCID: PMC5695589 DOI: 10.1371/journal.pone.0186476] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 10/02/2017] [Indexed: 11/18/2022] Open
Abstract
We report five new specimens of xenorophid dolphins from North and South Carolina. Four of the specimens represent the xenorophid Albertocetus meffordorum, previously only known from the holotype skull. The other is a fragmentary petrosal from the upper Oligocene Belgrade Formation that we refer to Echovenator sp, indicating at least two xenorophids from that unit. Two of the Albertocetus meffordorum specimens are from the lower Oligocene Ashley Formation: 1) a partial skeleton with neurocranium, fragmentary mandible, ribs, vertebrae, and chevrons, and 2) an isolated braincase. The partial vertebral column indicates that Albertocetus retained the ancestral morphology and locomotory capabilities of basilosaurid archaeocetes, toothed mysticetes, and physeteroids, and caudal vertebrae that are as wide as tall suggest that the caudal peduncle, which occurs in all extant Cetacea, was either wide or lacking. CT data from the isolated braincase were used to generate a digital endocast of the cranial cavity. The estimated EQ of this specimen is relatively high for an Oligocene odontocete, and other aspects of the brain, such as its anteroposterior length and relative size of the temporal lobe, are intermediate in morphology between those of extant cetaceans and terrestrial artiodactyls. Ethmoturbinals are also preserved, and are similar in morphology and number to those described for the Miocene odontocete Squalodon. These fossils extend the temporal range of Albertocetus meffordorum into the early Oligocene, its geographic range into South Carolina, and expand our paleobiological understanding of the Xenorophidae.
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Affiliation(s)
- Robert W. Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, South Carolina, United States of America
- University of California Museum of Paleontology, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Erum Ahmed
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States of America
| | - Jonathan H. Geisler
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York, United States of America
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47
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How the Land Became the Locus of Major Evolutionary Innovations. Curr Biol 2017; 27:3178-3182.e1. [DOI: 10.1016/j.cub.2017.08.076] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 11/23/2022]
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49
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50
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Park T, Fitzgerald EMG, Evans AR. Ultrasonic hearing and echolocation in the earliest toothed whales. Biol Lett 2017; 12:rsbl.2016.0060. [PMID: 27072406 DOI: 10.1098/rsbl.2016.0060] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/18/2016] [Indexed: 11/12/2022] Open
Abstract
The evolution of biosonar (production of high-frequency sound and reception of its echo) was a key innovation of toothed whales and dolphins (Odontoceti) that facilitated phylogenetic diversification and rise to ecological predominance. Yet exactly when high-frequency hearing first evolved in odontocete history remains a fundamental question in cetacean biology. Here, we show that archaic odontocetes had a cochlea specialized for sensing high-frequency sound, as exemplified by an Oligocene xenorophid, one of the earliest diverging stem groups. This specialization is not as extreme as that seen in the crown clade. Paired with anatomical correlates for high-frequency signal production in Xenorophidae, this is strong evidence that the most archaic toothed whales possessed a functional biosonar system, and that this signature adaptation of odontocetes was acquired at or soon after their origin.
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Affiliation(s)
- Travis Park
- School of Biological Sciences, Monash University, Melbourne, Australia Geosciences, Museum Victoria, Melbourne, Australia
| | - Erich M G Fitzgerald
- Geosciences, Museum Victoria, Melbourne, Australia National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Melbourne, Australia Geosciences, Museum Victoria, Melbourne, Australia
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