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Gerald F. Shields - One of the best experts on this subject based on the ideXlab platform.
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CytochromeBSequences Suggest Convergent Evolution of the Asian Takin and Arctic Muskox
Molecular Phylogenetics and Evolution, 1997Co-Authors: Pamela Groves, Gerald F. ShieldsAbstract:Abstract Relationships of the takin (Budorcas taxicolor) and Muskox (Ovibos moschatus) have been speculated upon for many years. Morphological and behavioral similarities between these species have led to suggestions that they are closely related. To test the hypothesis that characteristics shared by the takin and Muskox stem from a recent common ancestor, we compared sequences of their mitochondrial cytochromebgenes with those of three other species of Caprinae. We present data that may support rejection of the hypothesis of recent common ancestry and suggest that similarities in behavior and morphology in these two species might be attributed to convergent evolution rather than shared phylogeny.
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Cytochrome B sequences suggest convergent evolution of the Asian takin and Arctic Muskox.
Molecular phylogenetics and evolution, 1997Co-Authors: Pamela Groves, Gerald F. ShieldsAbstract:Relationships of the takin (Budorcas taxicolor) and Muskox (Ovibos moschatus) have been speculated upon for many years. Morphological and behavioral similarities between these species have led to suggestions that they are closely related. To test the hypothesis that characteristics shared by the takin and Muskox stem from a recent common ancestor, we compared sequences of their mitochondrial cytochrome b genes with those of three other species of Caprinae. We present data that may support rejection of the hypothesis of recent common ancestry and suggest that similarities in behavior and morphology in these two species might be attributed to convergent evolution rather than shared phylogeny.
Pamela Groves - One of the best experts on this subject based on the ideXlab platform.
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CytochromeBSequences Suggest Convergent Evolution of the Asian Takin and Arctic Muskox
Molecular Phylogenetics and Evolution, 1997Co-Authors: Pamela Groves, Gerald F. ShieldsAbstract:Abstract Relationships of the takin (Budorcas taxicolor) and Muskox (Ovibos moschatus) have been speculated upon for many years. Morphological and behavioral similarities between these species have led to suggestions that they are closely related. To test the hypothesis that characteristics shared by the takin and Muskox stem from a recent common ancestor, we compared sequences of their mitochondrial cytochromebgenes with those of three other species of Caprinae. We present data that may support rejection of the hypothesis of recent common ancestry and suggest that similarities in behavior and morphology in these two species might be attributed to convergent evolution rather than shared phylogeny.
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Cytochrome B sequences suggest convergent evolution of the Asian takin and Arctic Muskox.
Molecular phylogenetics and evolution, 1997Co-Authors: Pamela Groves, Gerald F. ShieldsAbstract:Relationships of the takin (Budorcas taxicolor) and Muskox (Ovibos moschatus) have been speculated upon for many years. Morphological and behavioral similarities between these species have led to suggestions that they are closely related. To test the hypothesis that characteristics shared by the takin and Muskox stem from a recent common ancestor, we compared sequences of their mitochondrial cytochrome b genes with those of three other species of Caprinae. We present data that may support rejection of the hypothesis of recent common ancestry and suggest that similarities in behavior and morphology in these two species might be attributed to convergent evolution rather than shared phylogeny.
Larry J. Hulbert - One of the best experts on this subject based on the ideXlab platform.
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rhenium osmium isotope and platinum group element constraints on the origin and evolution of the 1 27 ga Muskox layered intrusion
Journal of Petrology, 2008Co-Authors: Graham D Pearson, James M.d. Day, Larry J. HulbertAbstract:Platinum-group element (PGE: Os, Ir, Ru, Pt, Pd) and Re^Os isotope systematics determined for the entire preserved stratigraphy of the 1 27 Ga Muskox intrusion provide an exceptional view of magma chamber processes and mineralization in the main plutonic system of the Mackenzie large igneous province (LIP).We present new Re^Os isotope data for the intrusion, together with PGE and trace element abundances, and oxygen and Sm^Nd isotope data on samples that include local crustal materials, layered series peridotites, stratiform chromitites, marginal and roof zone rocks, and the Muskox Keel feeder dyke. Intrusive rocks span wide ranges in initial isotopic compositions (gOsi1⁄4þ1 0 to þ 87 6; eNdi1⁄4 0 4 to 6 6; dOOl1⁄4þ 5 5 to þ 6 9o) and highly siderophile element abundances (HSE: PGE and Re; Re1⁄4 0 02^105 ppb; Pt1⁄4 0 23^ 115 ppb; Os1⁄4 0 02 to4 200 ppb). HSE and fluid-immobile trace element abundance variations are consistent with relative compatibilities expected for cumulate rocks. The most radiogenic Os and unradiogenic Nd isotope compositions occur in the Muskox marginal and roof zones. Negative gOsi values in these rocks and their nonisochronous relations result from mobilization of Re in the intrusion through post-magmatic hydrothermal processes.The most significant process causing Os and Nd isotope variations in the layered series of the intrusion is crustal contamination of mantle-derived magma batches feeding individual cyclic units.This process may be directly responsible for formation of chromitite horizons within the intrusion. Accounting for crustal assimilation, the Muskox intrusion parental magma has gOsi1⁄4þ1 2 0 3, eNdi 4 ^1 0 0 4, dO þ5 5o and HSE abundances similar to those expected from 15% partial melting of the Mackenzie LIP mantle source. This composition is similar to that calculated for 1 27 Ga primitive upper mantle. Parental magmas were probably derived from a mantle source unaffected by long-term, large-scale melt depletion, with no appreciable input from recycled crust and lithosphere, or putative core contributions.
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Rhenium–Osmium Isotope and Platinum-Group Element Constraints on the Origin and Evolution of the 1·27 Ga Muskox Layered Intrusion
Journal of Petrology, 2008Co-Authors: James M.d. Day, D. Graham Pearson, Larry J. HulbertAbstract:Platinum-group element (PGE: Os, Ir, Ru, Pt, Pd) and Re^Os isotope systematics determined for the entire preserved stratigraphy of the 1 27 Ga Muskox intrusion provide an exceptional view of magma chamber processes and mineralization in the main plutonic system of the Mackenzie large igneous province (LIP).We present new Re^Os isotope data for the intrusion, together with PGE and trace element abundances, and oxygen and Sm^Nd isotope data on samples that include local crustal materials, layered series peridotites, stratiform chromitites, marginal and roof zone rocks, and the Muskox Keel feeder dyke. Intrusive rocks span wide ranges in initial isotopic compositions (gOsi1⁄4þ1 0 to þ 87 6; eNdi1⁄4 0 4 to 6 6; dOOl1⁄4þ 5 5 to þ 6 9o) and highly siderophile element abundances (HSE: PGE and Re; Re1⁄4 0 02^105 ppb; Pt1⁄4 0 23^ 115 ppb; Os1⁄4 0 02 to4 200 ppb). HSE and fluid-immobile trace element abundance variations are consistent with relative compatibilities expected for cumulate rocks. The most radiogenic Os and unradiogenic Nd isotope compositions occur in the Muskox marginal and roof zones. Negative gOsi values in these rocks and their nonisochronous relations result from mobilization of Re in the intrusion through post-magmatic hydrothermal processes.The most significant process causing Os and Nd isotope variations in the layered series of the intrusion is crustal contamination of mantle-derived magma batches feeding individual cyclic units.This process may be directly responsible for formation of chromitite horizons within the intrusion. Accounting for crustal assimilation, the Muskox intrusion parental magma has gOsi1⁄4þ1 2 0 3, eNdi 4 ^1 0 0 4, dO þ5 5o and HSE abundances similar to those expected from 15% partial melting of the Mackenzie LIP mantle source. This composition is similar to that calculated for 1 27 Ga primitive upper mantle. Parental magmas were probably derived from a mantle source unaffected by long-term, large-scale melt depletion, with no appreciable input from recycled crust and lithosphere, or putative core contributions.
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COMPOSITION OF CHROMITE IN THE UPPER CHROMITITE, Muskox LAYERED INTRUSION,NORTHWEST TERRITORIES
Canadian Mineralogist, 1998Co-Authors: Thomas S. Roach, Peter L. Roeder, Larry J. HulbertAbstract:The texture, mineralogy and composition of chromite in the upper chromitite of the Muskox intrusion, in the Northwest Territories, have been studied in two 0.5-meter sections of drill core. The principal rock-type is an orthopyroxenite that contains cumulus olivine, orthopyroxene and chromite, and the intercumulus minerals clinopyroxene and plagioclase. The minor minerals ilmenite and biotite are found, together with a number of accessory minerals, in pockets that are interpreted as sites of late intercumulus melt. The chromitite seam is up to 10 cm thick and contains chromite with a narrow range in composition: 0.64 2 ) = -9.1. The disseminated chromite in the orthopyroxenite shows a much greater range in composition, and increases in Fe (super 2+) /(Fe (super 2+) +Mg), Fe (super 3+) /(Fe (super 3+) +Al+Cr), Ti and Ni with stratigraphic height above the massive chromitite. The chromite in the Muskox chromitite is significantly higher in Fe (super 3+) , Ti and Fe (super 2+) /(Fe (super 2+) +Mg) than chromite in the Bushveld, Stillwater and Great Dyke chromitites; furthermore, the Muskox chromitites formed much higher in the stratigraphic section of the layered series than in these other intrusions. The Muskox chromitites are considered to have formed late in the magmatic history of the intrusion as a result of mixing of a fractionated magma with a more primitive magma and a component due to wall-rock assimilation.
James M.d. Day - One of the best experts on this subject based on the ideXlab platform.
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rhenium osmium isotope and platinum group element constraints on the origin and evolution of the 1 27 ga Muskox layered intrusion
Journal of Petrology, 2008Co-Authors: Graham D Pearson, James M.d. Day, Larry J. HulbertAbstract:Platinum-group element (PGE: Os, Ir, Ru, Pt, Pd) and Re^Os isotope systematics determined for the entire preserved stratigraphy of the 1 27 Ga Muskox intrusion provide an exceptional view of magma chamber processes and mineralization in the main plutonic system of the Mackenzie large igneous province (LIP).We present new Re^Os isotope data for the intrusion, together with PGE and trace element abundances, and oxygen and Sm^Nd isotope data on samples that include local crustal materials, layered series peridotites, stratiform chromitites, marginal and roof zone rocks, and the Muskox Keel feeder dyke. Intrusive rocks span wide ranges in initial isotopic compositions (gOsi1⁄4þ1 0 to þ 87 6; eNdi1⁄4 0 4 to 6 6; dOOl1⁄4þ 5 5 to þ 6 9o) and highly siderophile element abundances (HSE: PGE and Re; Re1⁄4 0 02^105 ppb; Pt1⁄4 0 23^ 115 ppb; Os1⁄4 0 02 to4 200 ppb). HSE and fluid-immobile trace element abundance variations are consistent with relative compatibilities expected for cumulate rocks. The most radiogenic Os and unradiogenic Nd isotope compositions occur in the Muskox marginal and roof zones. Negative gOsi values in these rocks and their nonisochronous relations result from mobilization of Re in the intrusion through post-magmatic hydrothermal processes.The most significant process causing Os and Nd isotope variations in the layered series of the intrusion is crustal contamination of mantle-derived magma batches feeding individual cyclic units.This process may be directly responsible for formation of chromitite horizons within the intrusion. Accounting for crustal assimilation, the Muskox intrusion parental magma has gOsi1⁄4þ1 2 0 3, eNdi 4 ^1 0 0 4, dO þ5 5o and HSE abundances similar to those expected from 15% partial melting of the Mackenzie LIP mantle source. This composition is similar to that calculated for 1 27 Ga primitive upper mantle. Parental magmas were probably derived from a mantle source unaffected by long-term, large-scale melt depletion, with no appreciable input from recycled crust and lithosphere, or putative core contributions.
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Rhenium–Osmium Isotope and Platinum-Group Element Constraints on the Origin and Evolution of the 1·27 Ga Muskox Layered Intrusion
Journal of Petrology, 2008Co-Authors: James M.d. Day, D. Graham Pearson, Larry J. HulbertAbstract:Platinum-group element (PGE: Os, Ir, Ru, Pt, Pd) and Re^Os isotope systematics determined for the entire preserved stratigraphy of the 1 27 Ga Muskox intrusion provide an exceptional view of magma chamber processes and mineralization in the main plutonic system of the Mackenzie large igneous province (LIP).We present new Re^Os isotope data for the intrusion, together with PGE and trace element abundances, and oxygen and Sm^Nd isotope data on samples that include local crustal materials, layered series peridotites, stratiform chromitites, marginal and roof zone rocks, and the Muskox Keel feeder dyke. Intrusive rocks span wide ranges in initial isotopic compositions (gOsi1⁄4þ1 0 to þ 87 6; eNdi1⁄4 0 4 to 6 6; dOOl1⁄4þ 5 5 to þ 6 9o) and highly siderophile element abundances (HSE: PGE and Re; Re1⁄4 0 02^105 ppb; Pt1⁄4 0 23^ 115 ppb; Os1⁄4 0 02 to4 200 ppb). HSE and fluid-immobile trace element abundance variations are consistent with relative compatibilities expected for cumulate rocks. The most radiogenic Os and unradiogenic Nd isotope compositions occur in the Muskox marginal and roof zones. Negative gOsi values in these rocks and their nonisochronous relations result from mobilization of Re in the intrusion through post-magmatic hydrothermal processes.The most significant process causing Os and Nd isotope variations in the layered series of the intrusion is crustal contamination of mantle-derived magma batches feeding individual cyclic units.This process may be directly responsible for formation of chromitite horizons within the intrusion. Accounting for crustal assimilation, the Muskox intrusion parental magma has gOsi1⁄4þ1 2 0 3, eNdi 4 ^1 0 0 4, dO þ5 5o and HSE abundances similar to those expected from 15% partial melting of the Mackenzie LIP mantle source. This composition is similar to that calculated for 1 27 Ga primitive upper mantle. Parental magmas were probably derived from a mantle source unaffected by long-term, large-scale melt depletion, with no appreciable input from recycled crust and lithosphere, or putative core contributions.
Tord Bretten - One of the best experts on this subject based on the ideXlab platform.
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Mycoplasma conjunctivae-Associated Keratoconjunctivitis in Norwegian Muskox (Ovibos moschatus).
Journal of wildlife diseases, 2019Co-Authors: Kjell Handeland, Tord Bretten, Knut Madslien, Ingolf Røtvei, Jørn Våge, Torstein TengsAbstract:In late summer 2014, an outbreak of ocular disease occurred in the Norwegian Muskox (Ovibos moschatus) population. Animals showed rings of pus around their eyes and one euthanized animal was diagnosed with acute keratoconjunctivitis. The DNA sequence analysis of eye-swab samples from this animal revealed a high abundance of Mycoplasma conjunctivae.
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Mycoplasma ovipneumoniae--a primary cause of severe pneumonia epizootics in the Norwegian Muskox (Ovibos moschatus) population.
PloS one, 2014Co-Authors: Kjell Handeland, Torstein Tengs, Branko Kokotovic, Turid Vikøren, Roger D. Ayling, Bjarne Bergsjø, Ólöf G. Sigurðardóttir, Tord BrettenAbstract:The Norwegian Muskox (Ovibos moschatus) population lives on the high mountain plateau of Dovre and originates from animals introduced from Greenland. In the late summers of 2006 and 2012, severe outbreaks of pneumonia with mortality rates of 25-30% occurred. During the 2012 epidemic high quality samples from culled sick animals were obtained for microbiological and pathological examinations. High throughput sequencing (pyrosequencing) of pneumonic lung tissue revealed high concentrations of Mycoplasma ovipneumoniae in all six animals examined by this method and Pasteurella multocida subsp. multocida in four animals, whereas no virus sequences could be identified. Mycoplasma ovipneumoniae and P. multocida multocida were also isolated by culture. Using real time PCR on lung swabs, M. ovipneumoniae was detected in all of the 19 pneumonic lungs examined. Gross pathological examination revealed heavy consolidations primarily in the cranial parts of the lungs and it also identified one case of otitis media. Histologically, lung lesions were characterized as acute to subacute mixed exudative and moderately proliferative bronchoalveolar pneumonia. Immunohistochemical (IHC) examination revealed high load of M. ovipneumoniae antigens within lung lesions, with particularly intensive staining in the neutrophils. Similar IHC finding were observed in archived lung tissue blocks from animals examined during the 2006 epidemic. An M. ovipneumoniae specific ELISA was applied on bio-banked Muskox sera from stray Muskoxen killed in the period 2004–2013 and sick Muskoxen culled, as well as sera from wild reindeer (Rangifer tarandus tarandus) on Dovre and Muskoxen from Greenland. Serology and mycoplasma culturing was also carried out on sheep that had been on pasture in the Muskox area during the outbreak in 2012. Our findings indicated separate introductions of M. ovipneumoniae infection in 2006 and 2012 from infected co-grazing sheep. Salt licks shared by the two species were a possible route of transmitting infection.
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Sick pneumonic Muskox.
2014Co-Authors: Kjell Handeland, Torstein Tengs, Branko Kokotovic, Turid Vikøren, Roger D. Ayling, Bjarne Bergsjø, Ólöf G. Sigurðardóttir, Tord BrettenAbstract:A young sick (pneumonic) Muskox. Note the protruding tongue.
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Phylogenetic tree.
2014Co-Authors: Kjell Handeland, Torstein Tengs, Branko Kokotovic, Turid Vikøren, Roger D. Ayling, Bjarne Bergsjø, Ólöf G. Sigurðardóttir, Tord BrettenAbstract:Neighbor-joining analysis of Muskox mycoplasma isolates using Kimura 2-parameter distances and near full-length 16S rRNA sequences. Bootstrap values above 85% have been indicated (100 pseudo-replicates).
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Sheep serology and Mycoplasma culturing.
2014Co-Authors: Kjell Handeland, Torstein Tengs, Branko Kokotovic, Turid Vikøren, Roger D. Ayling, Bjarne Bergsjø, Ólöf G. Sigurðardóttir, Tord BrettenAbstract:Number of sheep found positive/examined for Mycoplasma ovipneumoniae by culture and serology in four sheep flocks that had been on pasture in southern part of the Muskox range during summer 2012.Sheep serology and Mycoplasma culturing.
