Phylogeography of Brown Bears (Ursus arctos) of Alaska and Paraphyly within the Ursidae

Talbot, Sandra L.; Shields, Gerald F.

doi:10.1006/mpev.1996.0044

Cited by 190 publications

(193 citation statements)

References 6 publications

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“…4, the cave bear clusters with the brown and polar bears with maximal bootstrap and posterior probability values. Besides, the sequencing of a western brown bear mitochondrial genome confirms Ursus arctos as a paraphyletic taxon with respect to U. maritimus (23). However, the brown and polar bears group is not paraphyletic toward the cave bear, showing that the cave bear lineage appeared before the diversification within the brown bears.…”

Section: Resultsmentioning

confidence: 86%

Deciphering the complete mitochondrial genome and phylogeny of the extinct cave bear in the Paleolithic painted cave of Chauvet

Bon

Caudy

Dieuleveult

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Retrieving a large amount of genetic information from extinct species was demonstrated feasible, but complete mitochondrial genome sequences have only been deciphered for the moa, a bird that became extinct a few hundred years ago, and for Pleistocene species, such as the woolly mammoth and the mastodon, both of which could be studied from animals embedded in permafrost. To enlarge the diversity of mitochondrial genomes available for Pleistocene species, we turned to the cave bear (Ursus spelaeus), whose only remains consist of skeletal elements. We collected bone samples from the Paleolithic painted cave of Chauvet-Pont d'Arc (France), which displays the earliest known human drawings, and contains thousands of bear remains. We selected a cave bear sternebra, radiocarbon dated to 32,000 years before present, from which we generated overlapping DNA fragments assembling into a 16,810-base pair mitochondrial genome. Together with the first mitochondrial genome for the brown bear western lineage, this study provides a statistically secured molecular phylogeny assessing the cave bear as a sister taxon to the brown bear and polar bear clade, with a divergence inferred to 1.6 million years ago. With the first mitochondrial genome for a Pleistocene carnivore to be delivered, our study establishes the Chauvet-Pont d'Arc Cave as a new reservoir for Paleogenetic studies. These molecular data enable establishing the chronology of bear speciation, and provide a helpful resource to rescue for genetic analysis archeological samples initially diagnosed as devoid of amplifiable DNA.ancient DNA ͉ pleistocene ͉ Ursus spelaeus

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Section: Resultsmentioning

confidence: 86%

Deciphering the complete mitochondrial genome and phylogeny of the extinct cave bear in the Paleolithic painted cave of Chauvet

Bon

Caudy

Dieuleveult

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…We radiometrically dated the permafrost specimens to determine whether a succession of populations belonging to the different clades could explain the distribution of sequences (9,10). Total amino acids from samples P1-P6 were extracted (20) and then converted to graphitic carbon at the University of California, Riverside Radiocarbon Laboratory (21).…”

Section: Methodsmentioning

confidence: 99%

“…2a). Sequences from the western Alaskan clade (IIIa) also were found in Asia and northern and eastern Europe, suggesting a recent connection across the Bering Land Bridge (9,10).…”

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confidence: 98%

“…The recent appearance of brown bears in North America and their division into four genetically distinct populations with highly divergent mitochondrial control region sequences implied separate invasions of North America from long-isolated Old World populations (9,10). Clade II was postulated to represent the earliest invasion, followed by clades IV and IIIa͞IIIb.…”

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confidence: 99%

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Population genetics of Ice Age brown bears

Leonard

Wayne

Cooper

2000

Proc. Natl. Acad. Sci. U.S.A.

291

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The Pleistocene was a dynamic period for Holarctic mammal species, complicated by episodes of glaciation, local extinctions, and intercontinental migration. The genetic consequences of these events are difficult to resolve from the study of present-day populations. To provide a direct view of population genetics in the late Pleistocene, we measured mitochondrial DNA sequence variation in seven permafrost-preserved brown bear (Ursus arctos) specimens, dated from 14,000 to 42,000 years ago. Approximately 36,000 years ago, the Beringian brown bear population had a higher genetic diversity than any extant North American population, but by 15,000 years ago genetic diversity appears similar to the modern day. The older, genetically diverse, Beringian population contained sequences from three clades now restricted to local regions within North America, indicating that current phylogeographic patterns may provide misleading data for evolutionary studies and conservation management. The late Pleistocene phylogeographic data also indicate possible colonization routes to areas south of the Cordilleran ice sheet.

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“…Polar bears apparently branched off of brown bear stocks less than 300,000 years ago (Cronin et al 1991, Talbot andShields 1996). If that is true, then polar bears have persisted through two periods that were warmer than the present.…”

Section: Alleged Political Influence On Usgs Researchmentioning

confidence: 99%

Rebuttal of “Polar Bear Population Forecasts: A Public-Policy Forecasting Audit”

et al. 2009

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Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears (Ursus maritimus). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38(5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were “unscientific and inconsequential to decision makers.” We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations. In summary, we show that the AGS audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public-policy debate.

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Phylogeography of Brown Bears (Ursus arctos) of Alaska and Paraphyly within the Ursidae

Cited by 190 publications

References 6 publications

Deciphering the complete mitochondrial genome and phylogeny of the extinct cave bear in the Paleolithic painted cave of Chauvet

Deciphering the complete mitochondrial genome and phylogeny of the extinct cave bear in the Paleolithic painted cave of Chauvet

Population genetics of Ice Age brown bears

Rebuttal of “Polar Bear Population Forecasts: A Public-Policy Forecasting Audit”

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