Interspecific and intraspecific mitochondrial DNA variation in North American bears (Ursus)

1991 ◽  
Vol 69 (12) ◽  
pp. 2985-2992 ◽  
Author(s):  
Matthew A. Cronin ◽  
Steven C. Amstrup ◽  
Gerald W. Garner ◽  
Ernest R. Vyse
Keyword(s):  
Mitochondrial Dna ◽  
North American ◽  
Ursus Arctos ◽  
Phylogenetic Analyses ◽  
Sequence Divergence ◽  
Black Bears ◽  
Polar Bears ◽  
Brown Bears ◽  
Dna Variation ◽  
Base Substitutions

We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.

Phylogeography of Mitochondrial DNA Variation in Brown Bears and Polar Bears

2000 ◽  
Vol 15 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Gerald F. Shields ◽  
Deborah Adams ◽  
Gerald Garner ◽  
Martine Labelle ◽  
Jacy Pietsch ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Polar Bears ◽  
Brown Bears ◽  
Dna Variation

Mitochondrial DNA variation in water shrews (Sorex palustris, Sorex bendirii) from western North America: implications for taxonomy and phylogeography

2005 ◽  
Vol 83 (11) ◽  
pp. 1469-1475 ◽  
Author(s):  
M B O'Neill ◽  
D W Nagorsen ◽  
R J Baker
Keyword(s):  
Mitochondrial Dna ◽  
North America ◽  
Phylogenetic Analyses ◽  
Sequence Divergence ◽  
Vancouver Island ◽  
Western North America ◽  
Cytb Sequence ◽  
Dna Variation ◽  
Late Pliocene ◽  
Postglacial Colonization

Inter- and intra-specific variations in cytochrome b (Cytb) sequence were assessed in 22 specimens of Sorex palustris Richardson, 1828 and 6 specimens of Sorex bendirii (Merriam, 1884) from 20 locations in western North America. Phylogenetic analyses revealed three distinct clades: Boreal (S. p. palustris), Cordilleran (S. p. brooksi, S. p. navigator), and Coastal (S. b. palmeri, S. b. bendirii). Sequence divergence between the Boreal and the Coastal–Cordilleran lineages was 6.9%, while the divergence between the Coastal and the Cordilleran clades was 3.1%. Sorex palustris brooksi, a subspecies endemic to Vancouver Island, showed minor divergence from mainland samples of S. p. navigator. The results suggest that S. palustris may consist of two species: a boreal eastern form (S. palustris) and a Cordilleran form (S. navigator). The taxonomic validity of S. p. brooksi is unresolved. Distribution of the three clades are consistent with vicariance and isolation in coastal, Cordilleran, and eastern refugia in the Late Pliocene or Pleistocene. The Vancouver Island subspecies S. p. brooksi is probably derived from postglacial colonization in the Late Pleistocene.

Genetic relationships of North American bears (Ursus) inferred from amplified fragment length polymorphisms and mitochondrial DNA sequences

2013 ◽  
Vol 91 (9) ◽  
pp. 626-634 ◽  
Author(s):  
M.A. Cronin ◽  
M.M. McDonough ◽  
H.M. Huynh ◽  
R.J. Baker
Keyword(s):  
Mitochondrial Dna ◽  
Fragment Length ◽  
Genetic Relationships ◽  
Black Bears ◽  
Gene Pools ◽  
Polar Bears ◽  
Brown Bears ◽  
Southeast Alaska ◽  
Length Polymorphisms ◽  
Amplified Fragment Length Polymorphisms

The three species of bears in North America, polar bears (Ursus maritimus Phipps, 1774), brown bears (Ursus arctos L., 1758), and black bears (Ursus americanus Pallas, 1780), have differentiated morphologies and nuclear and mitochondrial genomes. An exception is a paraphyletic mitochondrial DNA relationship and some nuclear gene lineages common to polar bears and a population of brown bears from islands in southeast Alaska. In this study, we quantified the genetic relationships of extant brown bears and black bears from Alaska and Montana, and polar bears from Alaska, with amplified fragment length polymorphisms (AFLP) and mtDNA cytochrome-b sequences. Bayesian cluster analyses of the AFLP data show each species is distinct. All brown bears, including those from the islands in southeast Alaska, cluster separately from polar bears, and black bears cluster separately from brown bears and polar bears. The mtDNA of polar bears and southeast Alaska island brown bears is paraphyletic as reported previously, but the species have different haplotypes. These data indicate that extant populations of brown bears and polar bears have separate nuclear and mitochondrial gene pools and are supported as species under the genetic species concept.

scholarly journals Mitochondrial DNA Variation and Evolution of Japanese Black Cattle (Bos taurus)

Genetics ◽  
1998 ◽  
Vol 150 (3) ◽  
pp. 1169-1175
Author(s):  
H Mannen ◽  
S Tsuji ◽  
R T Loftus ◽  
D G Bradley
Keyword(s):  
Mitochondrial Dna ◽  
Bos Taurus ◽  
Phylogenetic Analyses ◽  
Sequence Divergence ◽  
Japanese Black Cattle ◽  
Dna Variation ◽  
North East ◽  
Domestication Process ◽  
Different Strains ◽  
Dense Tree

Abstract This article describes complete mitochondrial DNA displacement loop sequences from 32 Japanese Black cattle and the analysis of these data in conjunction with previously published sequences from African, European, and Indian subjects. The origins of North East Asian domesticated cattle are unclear. The earliest domestic cattle in the region were Bos taurus and may have been domesticated from local wild cattle (aurochsen; B. primigenius), or perhaps had an origin in migrants from the early domestic center of the Near East. In phylogenetic analyses, taurine sequences form a dense tree with a center consisting of intermingled European and Japanese sequences with one group of Japanese and another of all African sequences, each forming distinct clusters at extremes of the phylogeny. This topology and calibrated levels of sequence divergence suggest that the clusters may represent three different strains of ancestral aurochs, adopted at geographically and temporally separate stages of the domestication process. Unlike Africa, half of Japanese cattle sequences are topologically intermingled with the European variants. This suggests an interchange of variants that may be ancient, perhaps a legacy of the first introduction of domesticates to East Asia.

scholarly journals Heart rate during hyperphagia differs between two bear species

2019 ◽  
Vol 15 (1) ◽  
pp. 20180681 ◽  
Author(s):  
Boris Fuchs ◽  
Koji Yamazaki ◽  
Alina L. Evans ◽  
Toshio Tsubota ◽  
Shinsuke Koike ◽  
...  
Keyword(s):  
Heart Rate ◽  
Ursus Arctos ◽  
Brown Bear ◽  
Black Bear ◽  
Black Bears ◽  
Brown Bears ◽  
Fat Reserves ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Increased Activity

Hyperphagia is a critical part of the yearly cycle of bears when they gain fat reserves before entering hibernation. We used heart rate as a proxy to compare the metabolic rate between the Asian black bear ( Ursus thibetanus ) in Japan and the Eurasian brown bear ( Ursus arctos ) in Sweden from summer into hibernation. In the hyperphagic period, black bears feed on fat- and carbohydrate-rich hard masts whereas brown bears feed on sugar-rich berries. Availability of hard masts has quantitative and spatial annual fluctuations, which might require increased activity and result in intraspecific stress. Using generalized additive mixed models we analysed the differences in heart rate between the two species. Black bears had decreased heart rates during summer but had doubled heart rate values throughout the hyperphagic period compared to brown bears. This letter illustrates the different physiological consequences of seasonal differences in food availability in two species of the same genus dealing with the same phenological challenge.

scholarly journals Do Wild Polar Bears (Ursus maritimus) Use Tools When Hunting Walruses (Odobenus rosmarus)?

ARCTIC ◽  
2021 ◽  
Vol 74 (2) ◽  
pp. 175-187
Author(s):  
Ian Stirling ◽  
Kristin L. Laidre ◽  
Erik W. Born
Keyword(s):  
Food Source ◽  
Ursus Arctos ◽  
Ursus Maritimus ◽  
Ecological Knowledge ◽  
Polar Bears ◽  
Brown Bears ◽  
Direct Observations ◽  
Odobenus Rosmarus ◽  
In Captivity ◽  
In The Wild

Since the late 1700s, reports of polar bears (Ursus maritimus) using tools (i.e., pieces of ice or stones) to kill walruses (Odobenus rosmarus) have been passed on verbally to explorers and naturalists by their Inuit guides, based on local traditional ecological knowledge (TEK) as well as accounts of direct observations or interpretations of tracks in the snow made by the Inuit hunters who reported them. To assess the possibility that polar bears may occasionally use tools to hunt walruses in the wild, we summarize 1) observations described to early explorers and naturalists by Inuit hunters about polar bears using tools, 2) more recent documentation in the literature from Inuit hunters and scientists, and 3) recent observations of a polar bear in a zoo spontaneously using tools to access a novel food source. These observations and previously published experiments on brown bears (Ursus arctos) confirm that, in captivity, polar and brown bears are both capable of conceptualizing the use of a tool to obtain a food source that would otherwise not be accessible. Based on the information from all our sources, this may occasionally also have been the case in the wild. We suggest that possible tool use by polar bears in the wild is infrequent and mainly limited to hunting walruses because of their large size, difficulty to kill, and their possession of potentially lethal weapons for both their own defense and the direct attack of a predator. 

Hematology of the brown bear (Ursus arctos) from southwestern Yukon Territory, Canada

1972 ◽  
Vol 50 (3) ◽  
pp. 279-286 ◽  
Author(s):  
A. M. Pearson ◽  
D. W. Halloran
Keyword(s):  
Ursus Arctos ◽  
Binding Capacity ◽  
Total Iron ◽  
Erythrocyte Count ◽  
Black Bears ◽  
Iron Binding ◽  
Total Iron Binding Capacity ◽  
Brown Bears ◽  
Erythrocyte Indices ◽  
Iron Binding Capacity

Blood samples from 22 brown bears (Ursus arctos) and 5 black bears (Ursus americanus) were examined for erythrocyte count, erythrocyte morphology, erythrocyte diameter, hematocrit, hemoglobin, erythrocyte indices, serum iron, total iron-binding capacity, leucocyte count, and leucocyte differential count.A statistically significant decrease in erythrocyte count and hematocrit and increase in erythrocyte indices was found in brown bears from spring to summer. Limited evidence suggests that the spring to summer change may be reversed in the fall.No differences were apparent between sexes at any season but it was indicated that young bears had lower red blood cell concentration, lower hematocrit, and lower hemoglobin concentration than other animals.Leucocyte differential counts in the study were similar to those reported for other bears. Anisocytosis with numerous spherocytes and burr cells characterized the erythrocytes.Serum iron and total iron-binding capacity varied but did not suggest iron-deficiency anemia.Hematology results for the black bears were similar to those of brown bears but our small sample did not allow an investigation of seasonal changes in the species.

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