The Experts below are selected from a list of 11808 Experts worldwide ranked by ideXlab platform
Yoko Satta - One of the best experts on this subject based on the ideXlab platform.
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mhc class ii dqb diversity in the japanese black bear Ursus thibetanus japonicus
BMC Evolutionary Biology, 2012Co-Authors: Yoshiki Yasukochi, Toshifumi Kurosaki, Masaaki Yoneda, Hiroko Koike, Yoko SattaAbstract:Background The major histocompatibility complex (MHC) genes are one of the most important genetic systems in the vertebrate immune response. The diversity of MHC genes may directly influence the survival of individuals against infectious disease. However, there has been no investigation of MHC diversity in the Asiatic black bear (Ursus thibetanus). Here, we analyzed 270-bp nucleotide sequences of the entire exon 2 region of the MHC DQB gene by using 188 samples from the Japanese black bear (Ursus thibetanus japonicus) from 12 local populations.
Andrew E Derocher - One of the best experts on this subject based on the ideXlab platform.
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two decades of mercury concentrations in barents sea polar bears Ursus maritimus in relation to dietary carbon sulfur and nitrogen
Environmental Science & Technology, 2020Co-Authors: Anna Lippold, Andrew E Derocher, Jon Aars, Rune Dietz, Christian Sonne, Magnus Andersen, Aurore Aubail, Igor Eulaers, Jeffrey M WelkerAbstract:Temporal trends of total mercury (THg) were examined in female polar bear (Ursus maritimus) hair (n = 199) from the Barents Sea in 1995–2016. In addition, hair values of stable isotopes (n = 190–19...
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the ecological and behavioral significance of short term food caching in polar bears Ursus maritimus
Arctic Science, 2020Co-Authors: Ian Stirling, Andrew E Derocher, Kristin L Laidre, Rinie Van MeursAbstract:The paucity of observations of wild polar bears (Ursus maritimus) caching of food (including hoarding, i.e., burying and remaining with a kill for up to a few days) has led to the conclusion that s...
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contrasting temporal patterns of mercury niche dynamics and body fat indices of polar bears and ringed seals in a melting icescape
Environmental Science & Technology, 2020Co-Authors: David J. Yurkowski, Derek C. G. Muir, Andrew E Derocher, Magali Houde, Evan Richardson, Nicholas J Lunn, Amy C Johnson, Ashley D Ehrman, Brent G. YoungAbstract:Polar bears (Ursus maritimus) and ringed seals (Pusa hispida) have a strong predator–prey relationship and are facing climate-associated Arctic habitat loss and harmful dietary exposure to total me...
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on the integration of ecological and physiological variables in polar bear toxicology research a systematic review
Environmental Reviews, 2018Co-Authors: Thea Bechshoft, Andrew E Derocher, Jon Aars, Heli Routti, Michelle Viengkone, Robert J Letcher, Rune Dietz, Christian Sonne, Bjorn Munro JenssenAbstract:Ecotoxicology evolved as a scientific field as awareness of the unintended effects of anthropogenic pollutants in biota increased. Polar bears (Ursus maritimus) are often the focus of Arctic contam...
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conservation and management of canada s polar bears Ursus maritimus in a changing arctic11this review is part of the virtual symposium flagship species flagship problems that deals with ecology biodiversity and management issues and climate impacts on species at risk and of canadian importance including the polar bear Ursus maritimus atlantic cod gadus morhua piping plover charadrius melodus and caribou rangifer tarandus
Canadian Journal of Zoology, 2011Co-Authors: E Peacock, Gregory W. Thiemann, Andrew E Derocher, Ian StirlingAbstract:Canada has an important responsibility for the research, conservation, and management of polar bears (Ursus maritimus Phipps, 1774) because the majority of polar bears in the world occur within the...
Michael Hofreiter - One of the best experts on this subject based on the ideXlab platform.
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niche partitioning between two sympatric genetically distinct cave bears Ursus spelaeus and Ursus ingressus and brown bear Ursus arctos from austria isotopic evidence from fossil bones
Quaternary International, 2011Co-Authors: Herve Bocherens, Gernot Rabeder, Thomas Tutken, Mathias Stiller, Keith A Hobson, Martina Pacher, James A Burns, Michael HofreiterAbstract:Abstract In the Austrian caves of Gamssulzen and Ramesch, two genetically distinct cave bears, Ursus ingressus and Ursus spelaeus eremus, apparently lived side by side for 15,000 years, together with brown bears Ursus arctos. The possible ecological partitioning of these three types of bears was investigated using multi-isotopic tracking of organic (δ13Ccoll, δ15Ncoll) and inorganic (δ13Ccarb, δ18Ocarb, δ18OPO4) fractions of bone. The cave bears from Ramesch, Ursus spelaeus eremus, were ecologically distinct from the cave bears from Gamssulzen, Ursus ingressus, both being ecologically distinct from brown bears from Ramesch, Ursus arctos. Both cave bear types were purely herbivorous but likely consumed different plant types and/or plants from different habitats, while brown bears included some animal proteins in their diet. Bone apatite δ18O values strongly suggest that both types of cave bears used isotopically distinct water sources, indicating that they may not have occupied the same landscape, either separated in space or in time due to climatic shifts. Therefore, the influence of environmental conditions strongly constrained the genetic structure of these bears.
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New Taxa of Alpine Cave Bears (Ursidae, Carnivora)
2004Co-Authors: Gernot Rabeder, Michael Hofreiter, Doris Nagel, Gerhard WithalmAbstract:Les differences morphologiques et metriques entre plusieurs populations d'ours des cavernes alpins de meme âge sont suffisamment importantes pour qu'on puisse supposer l'existence de plusieurs lignees evolutives distinctes. Les datations par le radiocarbone confirment la coexistence de formes morphologiquement differentes. De plus les analyses sur l'ADN fossile montrent qu'existent au moins trois lignees d'ours des cavernes. Pour deux de ces groupes, les donnees morphologiques comme les donnees genetiques prouvent des isolats de reproduction. Aussi nous suggerons qu' Ursus spelaeus correspond au moins a deux especes differentes. Ursus ingressus n. sp. est repandu dans les Alpes orientales et dans les Alpes Dinariques de Slovenie et Croatie . Pour les deux autres formes morphologiques, nous proposons la distinction de deux sous-especes, Ursus spelaeus ladinicus n. ssp. dans les Dolomites et Ursus spelaeus eremus n. ssp. dans le Massif des Totes Gebirge : elles sont en effet relativement proches genetiquement mais il n'existe pour l'instant aucune donnee sur leur croisement eventuel.
Bjorn Munro Jenssen - One of the best experts on this subject based on the ideXlab platform.
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on the integration of ecological and physiological variables in polar bear toxicology research a systematic review
Environmental Reviews, 2018Co-Authors: Thea Bechshoft, Andrew E Derocher, Jon Aars, Heli Routti, Michelle Viengkone, Robert J Letcher, Rune Dietz, Christian Sonne, Bjorn Munro JenssenAbstract:Ecotoxicology evolved as a scientific field as awareness of the unintended effects of anthropogenic pollutants in biota increased. Polar bears (Ursus maritimus) are often the focus of Arctic contam...
C. Hanni - One of the best experts on this subject based on the ideXlab platform.
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Ancient DNA analysis reveals divergence of the cave bear, Ursus spelaeus, and brown bear, Ursus arctos, lineages
Current Biology - CB, 2001Co-Authors: O. Loreille, L. Orlando, M. Patou-mathis, M. Philippe, P. Taberlet, C. HanniAbstract:The cave bear, Ursus spelaeus, represents one of the most frequently found paleontological remains from the Pleistocene in Europe. The species has always been confined to Europe and was contemporary with the brown bear, Ursus arctos. Relationships between the cave bear and the two lineages of brown bears defined in Europe, as well as the origins of the two species, remain controversial, mainly due to the wide morphological diversity of the fossil remains, which makes interpretation difficult [1, 2]. Sequence analysis of ancient DNA is a useful tool for resolving such problems because it provides an independent source of data [3]. We previously amplified a short DNA fragment of the mitochondrial DNA control region (mt control region) of a 40,000-year-old Ursus spelaeus sample [4]. In this paper, we describe the DNA analysis of two mtDNA regions, the control region and the cytochrome b gene. Control region sequences were obtained from ten samples of cave bears ranging from 130,000 to 20,000 years BP, and one particularly well-conserved sample gave a complete cyt b sequence. Our data demonstrate that cave bears split largely before the lineages of brown bears around 1.2 million years ago, Given its abundance, its wide distribution in space and time, and its large morphological diversity, the cave bear is a promising model for direct observation of the evolution of sequences throughout time, extinction periods, and the differentiation of populations shaped by climatic fluctuations during the Pleistocene.
