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Mikkelsen D, McGowan AM, Gibson JS, Lanyon JM, Horsman S, Seddon JM. Faecal bacterial communities differ amongst discrete foraging populations of dugongs along the east Australian coast. FEMS Microbiol Ecol 2024; 100:fiae051. [PMID: 38658192 PMCID: PMC11141782 DOI: 10.1093/femsec/fiae051] [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] [Received: 09/09/2023] [Revised: 03/01/2024] [Accepted: 04/23/2024] [Indexed: 04/26/2024] Open
Abstract
Gut bacterial communities play a vital role in a host's digestion and fermentation of complex carbohydrates, absorption of nutrients, and energy harvest/storage. Dugongs are obligate seagrass grazers with an expanded hindgut and associated microbiome. Here, we characterised and compared the faecal bacterial communities of dugongs from genetically distinct populations along the east coast of Australia, between subtropical Moreton Bay and tropical Cleveland Bay. Amplicon sequencing of fresh dugong faecal samples (n=47) revealed Firmicutes (62%) dominating the faecal bacterial communities across all populations. Several bacterial genera (Bacteroides, Clostridium sensu stricto 1, Blautia and Polaribacter) were detected in samples from all locations, suggesting their importance in seagrass digestion. Principal coordinate analysis showed the three southern-most dugong populations having different faecal bacterial community compositions from northern populations. The relative abundances of the genera Clostridium sensu stricto 13 and dgA-11 gut group were higher, but Bacteroides was lower, in the southern dugong populations, compared to the northern populations, suggesting potential adaptive changes associated with location. This study contributes to our knowledge of the faecal bacterial communities of dugongs inhabiting Australian coastal waters. Future studies of diet selection in relation to seagrass availability throughout the dugong's range will help to advance our understanding of the roles that seagrass species may play in affecting the dugong's faecal bacterial community composition.
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Affiliation(s)
- Deirdre Mikkelsen
- School of Agriculture and Food Sustainability, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Alexandra M McGowan
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - Justine S Gibson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - Janet M Lanyon
- School of the Environment, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Sara Horsman
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - Jennifer M Seddon
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
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2
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Hautier L, Gomes Rodrigues H, Ferreira-Cardoso S, Emerling CA, Porcher ML, Asher RJ, Portela Miguez R, Delsuc F. From teeth to pad: tooth loss and development of keratinous structures in sirenians. Proc Biol Sci 2023; 290:20231932. [PMID: 38018114 PMCID: PMC10685118 DOI: 10.1098/rspb.2023.1932] [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] [Received: 08/29/2023] [Accepted: 11/03/2023] [Indexed: 11/30/2023] Open
Abstract
Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used μ-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.
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Affiliation(s)
- Lionel Hautier
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Helder Gomes Rodrigues
- Centre de Recherche en Paléontologie—Paris (CR2P), UMR CNRS 7207, Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France
| | - Sérgio Ferreira-Cardoso
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | | | - Marie-Lou Porcher
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | - Robert J. Asher
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Roberto Portela Miguez
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Frédéric Delsuc
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
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3
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Cherdsukjai P, Buddhachat K, Brown J, Kaewkool M, Poommouang A, Kaewmong P, Kittiwattanawong K, Nganvongpanit K. Age relationships with telomere length, body weight and body length in wild dugong ( Dugong dugon). PeerJ 2020; 8:e10319. [PMID: 33240643 PMCID: PMC7666544 DOI: 10.7717/peerj.10319] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/17/2020] [Indexed: 01/01/2023] Open
Abstract
The ability to estimate age and determine the growth status of free-ranging dugongs (Dugong dugon) is vital to providing insight into the basic biology of this endangered species. Currently, age estimation in dugong carcasses relies on counting dentin growth layer groups (GLGs) in tusks, but a disadvantage is they need to be intact. We explored whether measures of telomere length could be used as an alternative approach to age estimation in dugongs given that in other species, telomere length and age are inversely related. In this study, relative telomere length (rTL) was measured by qPCR in skin samples from 24 dugongs of varying ages determined by counts of GLGs. In addition, relationships between age by GLG counts and body weight and length and were examined. Our findings indicate that age estimated by GLGs was negatively correlated with telomere length using the logistic formula with a rate of telomere attrition of approximately 0.036 rTL/year between the ages of 5-20 years. By comparison, both body weight and length were positively correlated with GLG-based age, with growth rates of ~8.8 kg/year for weight and ~3.58 cm/year for length, respectively. After that, growth rates slowed substantially and then plateaued. The results suggest that physical maturity in dugongs occurs at 20 years of age and that measures of rTL might serve as a tool for age estimation in dugongs, living and deceased.
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Affiliation(s)
| | - Kittisak Buddhachat
- Department of Biology, Faculty of Science, Naresuan University, Phitsanulok, Thailand
- Excellence Center in Veterinary Bioscience, Chiang Mai University, Chiang Mai, Thailand
| | - Janine Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, VA, USA
| | - Manthanee Kaewkool
- Department of Veterinary Biosciences and Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Anocha Poommouang
- Department of Veterinary Biosciences and Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | | | | | - Korakot Nganvongpanit
- Excellence Center in Veterinary Bioscience, Chiang Mai University, Chiang Mai, Thailand
- Department of Veterinary Biosciences and Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
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4
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Osmoregulation and electrolyte balance in a fully marine mammal, the dugong (Dugong dugon). J Comp Physiol B 2020; 190:139-148. [PMID: 31894351 DOI: 10.1007/s00360-019-01250-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 11/11/2019] [Accepted: 12/08/2019] [Indexed: 10/25/2022]
Abstract
Dugongs (Dugong dugon) are fully marine mammals that live independently of fresh water so must balance water and electrolytes in a hyperosmotic environment. To investigate osmoregulation, matched plasma and urine from 51 live wild dugongs were analysed for osmolality, major electrolytes (Na+, Cl-, K+), urea, creatinine, and glucose. Maximum urine osmolality (1468 mOsm kg -1) and Na+, K+, and Cl- concentrations (757, 131.3, 677 mmol L-1, respectively) indicate that dugongs are capable of concentrating urine above seawater and could potentially realise a net gain of free water from drinking seawater. However, mean urine osmolality of 925.4 (± 46.6) mOsm kg-1 suggests that mariposia is unlikely to be an important osmoregulatory mechanism. Dugongs may obtain enough preformed water from their seagrass diet and metabolic oxidation to maintain homeostasis. Mean plasma osmolality of 339.6 (± 1.8) mOsm kg-1 is higher than in the related manatees but within the range for fully marine cetaceans. Relatively high mean plasma Na+ (175.5 ± 1.7 mmol L-1) and K+ (6.9 ± 0.1 mmol L-1), as well as mean urinary Na+ (469.6 ± 22.5 mmol L-1) and K+ levels (32.5 ± 4.5 mmol L-1) may reflect a salt-rich seagrass diet. Pregnant females had higher mean plasma osmolality (355.3 ± 4.9 mmol L-1) than non-pregnant females and males (337.9 ± 1.7 mOsm kg-1), suggesting that fluid retention was not a feature of pregnancy. Further research on water intake and endocrinology will enhance our understanding of osmoregulation in dugongs.
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5
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Melo TP, Ribeiro AM, Martinelli AG, Soares MB. Early evidence of molariform hypsodonty in a Triassic stem-mammal. Nat Commun 2019; 10:2841. [PMID: 31253810 PMCID: PMC6598982 DOI: 10.1038/s41467-019-10719-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/22/2019] [Indexed: 11/29/2022] Open
Abstract
Hypsodonty, the occurrence of high-crowned teeth, is widespread among mammals with diets rich in abrasive material, such as plants or soil, because it increases the durability of dentitions against wear. Hypsodont postcanine teeth evolved independently in multiple mammalian lineages and in the closely related mammaliaforms since the Jurassic period. Here, we report the oldest record, to our knowledge, of hypsodont postcanines in the non-mammaliaform stem-mammal, Menadon besairiei, from the early Late Triassic. The postcanines are long and columnar, with open roots. They were not replaced in older individuals and remained functional after the total wear of the crown enamel. Dental histology suggests that, convergently to hypsodont mammals, wear was compensated by the prolonged growth of each postcanine, resulting in dentine hypsodont teeth most similar to extant xenarthran mammals. These findings highlight the constraints imposed by limited tooth replacement and tooth wear in the evolutionary trajectories of herbivorous mammals and stem-mammals. Hypsodonty is a durable pattern of dentition seen in mammals with abrasive diets. Here, Melo and colleagues describe new fossils of the stem-mammal Menadon besairiei from the Late Triassic, which show the convergent evolution of hypsodonty before mammals.
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Affiliation(s)
- Tomaz P Melo
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91501-970, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, Brazil.
| | - Ana Maria Ribeiro
- Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul, Rua Dr Salvador França, 1427, 90690-000, Porto Alegre, Rio Grande do Sul, Brazil
| | - Agustín G Martinelli
- CONICET- Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Ave. Ángel Gallardo 470, C1405DJR CABA, Buenos Aires, Argentina
| | - Marina Bento Soares
- Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91501-970, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, Brazil
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6
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Wang S, Stiegler J, Wu P, Chuong CM, Hu D, Balanoff A, Zhou Y, Xu X. Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks. Proc Natl Acad Sci U S A 2017; 114:10930-10935. [PMID: 28973883 PMCID: PMC5642708 DOI: 10.1073/pnas.1708023114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Beaks are innovative structures characterizing numerous tetrapod lineages, including birds, but little is known about how developmental processes influenced the macroevolution of these important structures. Here we provide evidence of ontogenetic vestigialization of alveoli in two lineages of theropod dinosaurs and show that these are transitional phenotypes in the evolution of beaks. One of the smallest known caenagnathid oviraptorosaurs and a small specimen of the Early Cretaceous bird Sapeornis both possess shallow, empty vestiges of dentary alveoli. In both individuals, the system of vestiges connects via foramina with a dorsally closed canal homologous to alveoli. Similar morphologies are present in Limusaurus, a beaked theropod that becomes edentulous during ontogeny; and an analysis of neontological and paleontological evidence shows that ontogenetic reduction of the dentition is a relatively common phenomenon in vertebrate evolution. Based on these lines of evidence, we propose that progressively earlier postnatal and embryonic truncation of odontogenesis corresponds with expansion of rostral keratin associated with the caruncle, and these progenesis and peramorphosis heterochronies combine to drive the evolution of edentulous beaks in nonavian theropods and birds. Following initial apomorphic expansion of rostral keratinized epithelia in perinatal toothed theropods, beaks appear to inhibit odontogenesis as they grow postnatally, resulting in a sequence of common morphologies. This sequence is shifted earlier in development through phylogeny until dentition is absent at hatching, and odontogenesis is inhibited by beak formation in ovo.
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Affiliation(s)
- Shuo Wang
- Laboratory of Vertebrate Evolution, College of Life Science, Capital Normal University, Beijing 100048, China;
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Josef Stiegler
- Department of Biological Sciences, The George Washington University, Washington, DC 20052
| | - Ping Wu
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Cheng-Ming Chuong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Dongyu Hu
- Paleontological Institute of Shenyang Normal University, Paleontological Museum of Liaoning, Key Laboratory for Evolution of Past Life in Northeast Asia, Ministry of Land and Resources, Shenyang 110034, China
| | - Amy Balanoff
- Center for Functional Anatomy and Evolution, Johns Hopkins University, Baltimore, MD 21205
| | - Yachun Zhou
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
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7
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Convergent Traits in Mammals Associated with Divergent Behaviors: the Case of the Continuous Dental Replacement in Rock-Wallabies and African Mole-Rats. J MAMM EVOL 2016. [DOI: 10.1007/s10914-016-9348-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Springer MS, Signore AV, Paijmans JLA, Vélez-Juarbe J, Domning DP, Bauer CE, He K, Crerar L, Campos PF, Murphy WJ, Meredith RW, Gatesy J, Willerslev E, MacPhee RDE, Hofreiter M, Campbell KL. Interordinal gene capture, the phylogenetic position of Steller's sea cow based on molecular and morphological data, and the macroevolutionary history of Sirenia. Mol Phylogenet Evol 2015; 91:178-93. [PMID: 26050523 DOI: 10.1016/j.ympev.2015.05.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 05/22/2015] [Accepted: 05/28/2015] [Indexed: 01/02/2023]
Abstract
The recently extinct (ca. 1768) Steller's sea cow (Hydrodamalis gigas) was a large, edentulous North Pacific sirenian. The phylogenetic affinities of this taxon to other members of this clade, living and extinct, are uncertain based on previous morphological and molecular studies. We employed hybridization capture methods and second generation sequencing technology to obtain >30kb of exon sequences from 26 nuclear genes for both H. gigas and Dugong dugon. We also obtained complete coding sequences for the tooth-related enamelin (ENAM) gene. Hybridization probes designed using dugong and manatee sequences were both highly effective in retrieving sequences from H. gigas (mean=98.8% coverage), as were more divergent probes for regions of ENAM (99.0% coverage) that were designed exclusively from a proboscidean (African elephant) and a hyracoid (Cape hyrax). New sequences were combined with available sequences for representatives of all other afrotherian orders. We also expanded a previously published morphological matrix for living and fossil Sirenia by adding both new taxa and nine new postcranial characters. Maximum likelihood and parsimony analyses of the molecular data provide robust support for an association of H. gigas and D. dugon to the exclusion of living trichechids (manatees). Parsimony analyses of the morphological data also support the inclusion of H. gigas in Dugongidae with D. dugon and fossil dugongids. Timetree analyses based on calibration density approaches with hard- and soft-bounded constraints suggest that H. gigas and D. dugon diverged in the Oligocene and that crown sirenians last shared a common ancestor in the Eocene. The coding sequence for the ENAM gene in H. gigas does not contain frameshift mutations or stop codons, but there is a transversion mutation (AG to CG) in the acceptor splice site of intron 2. This disruption in the edentulous Steller's sea cow is consistent with previous studies that have documented inactivating mutations in tooth-specific loci of a variety of edentulous and enamelless vertebrates including birds, turtles, aardvarks, pangolins, xenarthrans, and baleen whales. Further, branch-site dN/dS analyses provide evidence for positive selection in ENAM on the stem dugongid branch where extensive tooth reduction occurred, followed by neutral evolution on the Hydrodamalis branch. Finally, we present a synthetic evolutionary tree for living and fossil sirenians showing several key innovations in the history of this clade including character state changes that parallel those that occurred in the evolutionary history of cetaceans.
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Affiliation(s)
- Mark S Springer
- Department of Biology, University of California, Riverside, CA 92521, USA.
| | - Anthony V Signore
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Johanna L A Paijmans
- Department of Biology, The University of York, Wentworth Way, Heslington, York YO10 5DD, UK
| | - Jorge Vélez-Juarbe
- Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA
| | - Daryl P Domning
- Laboratory of Evolutionary Biology, Department of Anatomy, Howard University, Washington, DC 20059, USA; Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
| | - Cameron E Bauer
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Kai He
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Lorelei Crerar
- Department of Biology, George Mason University, Fairfax, VA 22030, USA
| | - Paula F Campos
- Center for GeoGenetics, Natural History Museum, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark; CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
| | - Robert W Meredith
- Department of Biology and Molecular Biology, Montclair State University, Montclair, NJ 07043, USA
| | - John Gatesy
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Eske Willerslev
- Center for GeoGenetics, Natural History Museum, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark
| | - Ross D E MacPhee
- Department of Mammalogy, American Museum of Natural History, New York, NY 10024, USA
| | - Michael Hofreiter
- Department of Biology, The University of York, Wentworth Way, Heslington, York YO10 5DD, UK; Adaptive and Evolutionary Genomics, Institute for Biochemistry and Biology, Faculty of Mathematics and Natural Sciences, University of Potsdam, Karl-Liebknecht-Strasse 24-24, 14476 Potsdam, Germany
| | - Kevin L Campbell
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
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Dental wear in dolphins (Cetacea: Delphinidae) from southern Brazil. Arch Oral Biol 2013; 58:134-41. [DOI: 10.1016/j.archoralbio.2012.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 08/03/2012] [Accepted: 08/05/2012] [Indexed: 11/22/2022]
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10
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Gomes Rodrigues H, Solé F, Charles C, Tafforeau P, Vianey-Liaud M, Viriot L. Evolutionary and biological implications of dental mesial drift in rodents: the case of the Ctenodactylidae (Rodentia, Mammalia). PLoS One 2012. [PMID: 23185576 PMCID: PMC3503976 DOI: 10.1371/journal.pone.0050197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dental characters are importantly used for reconstructing the evolutionary history of mammals, because teeth represent the most abundant material available for the fossil species. However, the characteristics of dental renewal are presently poorly used, probably because dental formulae are frequently not properly established, whereas they could be of high interest for evolutionary and developmental issues. One of the oldest rodent families, the Ctenodactylidae, is intriguing in having longstanding disputed dental formulae. Here, we investigated 70 skulls among all extant ctenodactylid genera (Ctenodactylus, Felovia, Massoutiera and Pectinator) by using X-ray conventional and synchrotron microtomography in order to solve and discuss these dental issues. Our study clearly indicates that Massoutiera, Felovia and Ctenodactylus differ from Pectinator not only by a more derived dentition, but also by a more derived eruptive sequence. In addition to molars, their dentition only includes the fourth deciduous premolars, and no longer bears permanent premolars, conversely to Pectinator. Moreover, we found that these premolars are lost during adulthood, because of mesial drift of molars. Mesial drift is a striking mechanism involving migration of teeth allowed by both bone remodeling and dental resorption. This dental innovation is to date poorly known in rodents, since it is only the second report described. Interestingly, we noted that dental drift in rodents is always associated with high-crowned teeth favoring molar size enlargement. It can thus represent another adaptation to withstand high wear, inasmuch as these rodents inhabit desert environments where dust is abundant. A more accurate study of mesial drift in rodents would be very promising from evolutionary, biological and orthodontic points of view.
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Affiliation(s)
- Helder Gomes Rodrigues
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail: (HGR); (LV)
| | - Floréal Solé
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Cyril Charles
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Paul Tafforeau
- European Synchrotron Radiation Facility, Grenoble, France
| | - Monique Vianey-Liaud
- Laboratoire de Paléontologie, Institut des Sciences de l’Évolution de Montpellier, Unité Mixte de Recherche 5554 Centre National de la Recherche Scientifique, Université Montpellier 2, Montpellier, France
| | - Laurent Viriot
- Team “Evo-Devo of Vertebrate Dentition”, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail: (HGR); (LV)
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11
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Beatty BL, Vitkovski T, Lambert O, Macrini TE. Osteological Associations With Unique Tooth Development in Manatees (Trichechidae, Sirenia): A Detailed Look at Modern Trichechus and a Review of the Fossil Record. Anat Rec (Hoboken) 2012; 295:1504-12. [PMID: 22777871 DOI: 10.1002/ar.22525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/18/2012] [Indexed: 11/10/2022]
Affiliation(s)
- Brian Lee Beatty
- New York College of Osteopathic Medicine, Old Westbury, New York, USA.
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12
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Continuous dental replacement in a hyper-chisel tooth digging rodent. Proc Natl Acad Sci U S A 2011; 108:17355-9. [PMID: 21987823 DOI: 10.1073/pnas.1109615108] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Contrary to their reptilian ancestors, which had numerous dental generations, mammals are known to usually develop only two generations of teeth. However, a few mammal species have acquired the ability to continuously replace their dentition by the constant addition of supernumerary teeth moving secondarily toward the front of the jaw. The resulting treadmill-like replacement is thus horizontal, and differs completely from the vertical dental succession of other mammals and their extinct relatives. Despite the developmental implications and prospects regarding the origin of supernumerary teeth, this striking innovation remains poorly documented. Here we report another case of continuous dental replacement in an African rodent, Heliophobius argenteocinereus, which combines this dental system with the progressive eruption of high-crowned teeth. The escalator-like mechanism of Heliophobius constitutes an original adaptation to hyper-chisel tooth digging involving high dental wear. Comparisons between Heliophobius and the few mammals that convergently acquired continuous dental replacement reveal that shared inherited traits, including dental mesial drift, delayed eruption, and supernumerary molars, comprise essential prerequisites to setting up this dental mechanism. Interestingly, these dental traits are present to a lesser extent in humans but are absent in mouse, the usual biological model. Consequently, Heliophobius represents a suitable model to investigate the molecular processes leading to the development of supernumerary teeth in mammals, and the accurate description of these processes could be a significant advance for further applications in humans, such as the regeneration of dental tissues.
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Miller EH, Mahoney SP, Kennedy ML, Kennedy PK. Variation, Sexual Dimorphism, and Allometry in Molar Size of the Black Bear. J Mammal 2009. [DOI: 10.1644/08-mamm-a-055.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Miller EH, Sung HC, Moulton VD, Miller GW, Finley JK, Stenson GB. Variation and Integration of the Simple Mandibular Postcanine Dentition in Two Species of Phocid Seal. J Mammal 2007. [DOI: 10.1644/06-mamm-a-243r.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Domning DP, Beatty BL. Use of tusks in feeding by dugongid sirenians: Observations and tests of hypotheses. Anat Rec (Hoboken) 2007; 290:523-38. [PMID: 17516442 DOI: 10.1002/ar.20540] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most living and fossil sea cows of the subfamily Dugonginae (Dugongidae, Sirenia, Mammalia) are characterized by large upper incisor tusks, which are thought to play an important role (at least primitively) in feeding on seagrass rhizomes. Testing this hypothesis is difficult, because the only extant tusked sirenian (Dugong dugon) is morphologically and perhaps behaviorally aberrant. The tests attempted here involve examination of stomach contents of wild Recent dugongs, experiments using plastic replicas of diverse tusks to harvest seagrasses, gross anatomical observations on tusks and skulls, measurements of tusk tip geometry, and observations of microwear on tusks. We conclude that (a) male D. dugon (with erupted tusks) do not consume more rhizomes than females (without erupted tusks); (b) the tusks do not play a significant role in feeding in the modern dugong; (c) larger, more bladelike tusks are more effective at harvesting rhizomes, but the effect of shape was not experimentally separated from the effect of exposed tusk length; (d) some fossil dugongines show apparent cranial adaptations for downward and backward cutting motions of their large, bladelike tusks; (e) geometry of wear surfaces is consistent with use of at least the more bladelike tusks as cutting instruments; (f) preliminary observations of microwear in D. dugon do not indicate more than occasional use of the tusks in purposeful harvesting of rhizomes, and then only opportunistically by large adult males. The hypothesis of such tusk use by extinct dugongines (in contrast to the living species) is so far corroborated, but available data and tests do not suffice to establish this conclusively.
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Affiliation(s)
- Daryl P Domning
- Laboratory of Evolutionary Biology, Department of Anatomy, Howard University, Washington, DC 20059, USA.
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