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Grizzly bears, black bears, wolves, coyotes, cougars/ mountain lions,bobcats, wolverines, lynx, foxes, fishers and martens are the suite of carnivores that originally inhabited North America after the Pleistocene extinctions. This site invites research, commentary, point/counterpoint on that suite of native animals (predator and prey) that inhabited The Americas circa 1500-at the initial point of European exploration and subsequent colonization. Landscape ecology, journal accounts of explorers and frontiersmen, genetic evaluations of museum animals, peer reviewed 20th and 21st century research on various aspects of our "Wild America" as well as subjective commentary from expert and layman alike. All of the above being revealed and discussed with the underlying goal of one day seeing our Continent rewilded.....Where big enough swaths of open space exist with connective corridors to other large forest, meadow, mountain, valley, prairie, desert and chaparral wildlands.....Thereby enabling all of our historic fauna, including man, to live in a sustainable and healthy environment. - Blogger Rick

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Wednesday, March 26, 2014

U. of Calif Davis Professor Matthew Cronin has published a peer reviewed paper suggesting that polar bears and brown bears diverged as different species 1.2 million years ago and black bears diverged from the polar/brown bear lineage 2.3 million years ago.............Based on these findings, the polar bear was an independent species for about 1 million years...........It therefore survived previous cold and warm periods where sea ice was non-existent----------------The Professor theorizes that if Polar Bears previously survived without ice flows to hunt seals on, that perhaps they will survive into the future even if our polar caps completely melt out.......What variables if any, is Cronin not taking into account with this outlook?


Bear species' genetic relationships determined

Matthew Cronin, professor of animal genetics with the UAF School
 of Natural Resources and Extension and colleagues at the University
 of California Davis and Delta G Co. published a paper on bear
 genetics in the Journal of Heredity online in January. The paper,
 which will be printed in the next few months, describes the research
 involving genome sequence comparisons of the three bear species.
brown bear
Cronin also published papers on the relationships of the bears
 with different genetic analyses in 2012 with a collaborator at the 
U.S. Department of Agriculture in the Journal of Heredity, and in
 2013 with co-workers at Texas Tech University in the Canadian
 Journal of Zoology.

The 2014 paper replicates other research on bear genomes but 
includes analysis of genetic variation in more than 300 bears from
 Alaska and genetic elements not assessed previously in bears. 
These are known as ultra-conserved elements, and show the polar
 and brown bears to be more closely related than either is to black

The data was used in a “molecular clock” that uses the numbers
 of differences (mutations) in DNA sequences to estimate when
 the sequences, and hence the species, diverged. The data suggest
 that polar bears and brown bears diverged as different species 
1.2 million years ago, and black bears diverged from the
 polar/brown bear lineage 2.3 million years ago.  These estimates 
are within the ranges in other studies.

Utilizing labs at the University of California Davis, Cronin and
 technology experts pored over huge datasets. He also analyzed
 tissue samples from Montana and from Alaska’s Admiralty,
 Baranof and Chichagof islands, obtained from state and
 federal wildlife agencies. In recent years DNA science has 
improved so much that Cronin is able to study billions of 
nucleotides of DNA rather than the thousands he used to
 be limited to. “It’s very advanced because of the applications
 in medicine and agriculture,” Cronin said.

“The ramifications are that if the polar bear was an independent 
species for about 1 million years it survived previous cold and 
warm periods,” Cronin said. “This means the polar bear has 
been an independent lineage a long time through glacial and
 interglacial and warm periods.”

The last glacial period was at maximum extent about 22,000
 years ago, and was preceded by a warm interglacial period
 about 130,000 years ago. Other warm and cold periods
 preceded that. Cronin thinks that if polar bears survived
 previous warm periods in which there was little or no arctic 
summer sea ice, this should be used in  models predicting
 the species’ response to current climate change.

“It seems logical that if polar bears survived previous warm, 
ice-free periods, they could survive another. This is of course 
speculation, but so is predicting they will not survive, as the
 proponents of the endangered species act listing of polar 
bears have done.”

Cronin has been studying animal genetics for 25 years. 
He recently researched wood bison and plains bison. 
Comparing wolves in Southeast Alaska to species across
 the country is his next area of research.

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