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Post by OldGreenGrolar on Sept 24, 2021 10:00:46 GMT -5
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Post by OldGreenGrolar on Sept 24, 2021 10:22:08 GMT -5
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Post by OldGreenGrolar on Oct 16, 2021 21:15:00 GMT -5
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Post by brobear on Feb 8, 2022 6:14:23 GMT -5
When Species Collide: Grizzly-Polar Bear Hybrids roaring.earth/when-species-collide-pizzlies-and-grolar-bears/?utm_source=bfb&utm_medium=pa&utm_campaign=4451&fbclid=IwAR0CyDjqroT3Ne6kmkFVH3khQIpeZhdTFeth0ixbMn5wsVgCGNKQJ0hAI04 As global temperatures rise, ecosystems and the species they harbor are adjusting in response. Many habitats are either shifting their boundaries polewards—or disappearing altogether—sending wildlife into new regions, where they interact with resident creatures in surprising and often unprecedented ways. When this geographic collision is between two closely related species, they sometimes cross-breed, leading to the emergence of an entirely new species. Perhaps one of the most fascinating examples of this is the grizzly-polar bear hybrid: the “pizzly” or “grolar” bear. Brown bears (Ursus arctos)—of which grizzlies are a subspecies—and polar bears (Ursus maritimus) are different species with different adaptations to their respective ecosystems, but they are closely related. Polar bears diverged from brown bears less than 500,000 years ago—not long at all on an evolutionary timescale—and the two animals retain enough genetic similarity that they can interbreed and produce fertile offspring. When the hybrid offspring come from a polar bear father and a grizzly bear mother, the hybrid is typically called a “pizzly” bear, a portmanteau of “polar” and “grizzly.” When the parentage is reversed? A “grolar” bear. Much of what we know about “pizzlies” and “grolar bears” comes from hybridization in captive conditions, specifically in zoos. In these situations, the hybrids are often the result of the two bear species cohabitating in the same enclosures. Around seventeen of these hybrid bears are known to exist, mostly in European zoos. The hybrids present as an amalgamation of the key characteristics of their parents. Their fur isn’t white or brown, but a dingy, creamy blond. They have long necks like polar bears, but hunched shoulders like grizzlies. Their feet are partly covered in fur, intermediate between the bare paws of grizzlies and the fuzzy feet of polar bears. Their heads blend together the sleek features of polar bear heads and the thick, rounded features of grizzly heads. In regards to behavior, though, the hybrids more resemble their polar bear parents, hurling large toys and stamping on objects in a similar fashion. They also lie down with their hind limbs splay-legged—a distinctive polar bear pose. Pizzlies and grolar bears are undoubtedly striking curiosities, but how regularly do they show up in the wild? Not that often. Many purported hybrids end up being purebreds of one of the two bear species. In 2016, a bear shot in Nunavut, Canada was thought to be a hybrid based on its cream-colored coat, but genetic testing later determined that it was just a grizzly with a rare, blond coat. However, true hybrids have definitely turned up in the wild in recent years. One of the most famous cases also comes from Nunavut, but a decade earlier. In 2006, an American hunter shot what was thought to be a polar bear (for which he had a hunting permit), albeit with strange features. After much drama and the possibility of incurring fines and jail time for targeting a species for which he had no permit, the hunter was let off the hook by genetic testing results, which confirmed that this was a special case: a wild grizzly-polar bear hybrid, thought to be the first ever recorded. In 2010, another bear—this time from the Northwest Territories—was confirmed by genetic testing as a three-quarters grizzly hybrid.
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Post by brobear on Jun 10, 2022 0:07:11 GMT -5
How species form: What the tangled history of polar bear and brown bear relations tells us Date: June 6, 2022 www.sciencedaily.com/releases/2022/06/220606181204.htm Summary: A new study is providing an enhanced look at the intertwined evolutionary histories of polar bears and brown bears. Becoming separate species did not completely stop these animals from mating with each other. Scientists have known this for some time, but the new research draws on an expanded dataset -- including DNA from an ancient polar bear tooth -- to tease out more detail. A new study is providing an enhanced look at the intertwined evolutionary histories of polar bears and brown bears. Becoming separate species did not completely stop these animals from mating with each other. Scientists have known this for some time, but the new research draws on an expanded dataset -- including DNA from an ancient polar bear tooth -- to tease out more detail. The story that emerges reveals complexities similar to those that complicate human evolutionary history. "The formation and maintenance of species can be a messy process," says Charlotte Lindqvist, PhD, associate professor of biological sciences in the University at Buffalo College of Arts and Sciences, and an expert on bear genetics. "What's happened with polar bears and brown bears is a neat analog to what we're learning about human evolution: that the splitting of species can be incomplete. As more and more ancient genomes have been recovered from ancient human populations, including Neanderthals and Denisovans, we're seeing that there was multidirectional genetic mixing going on as different groups of archaic humans mated with ancestors of modern humans. Polar bears and brown bears are another system where you see this happening." "We find evidence for interbreeding between polar bears and brown bears that predates an ancient polar bear we studied," she says. "And, moreover, our results demonstrate a complicated, intertwined evolutionary history among brown and polar bears, with the main direction of gene flow going into polar bears from brown bears. This inverts a hypothesis suggested by other researchers that gene flow has been unidirectional and going into brown bears around the peak of the last ice age." The study will be published the week of June 6 in the Proceedings of the National Academy of Sciences. It was led by Lindqvist at UB in the U.S.; Luis Herrera-Estrella at the National Laboratory of Genomics for Biodiversity (LANGEBIO) in Mexico and Texas Tech University in the U.S.; and Kalle Leppälä at the University of Oulu in Finland. Tianying Lan, PhD, a former UB postdoctoral researcher now at Daicel Arbor Biosciences, was co-first author with Leppälä. The concept of Arctic-adapted polar bears capturing genetic material from brown bears, which are adapted to life in lower latitudes, is one of several findings of possible interest for scientists concerned with climate change impacts on threatened species. As the world warms and Arctic sea ice declines, polar bears and brown bears may run into each other more frequently in places where their ranges overlap. This makes their shared evolutionary history a particularly intriguing subject of study, Lindqvist says. Splitting of species can be a messy process As Lindqvist explains, scientists once thought modern humans and Neanderthals simply split into separate species after evolving from a common ancestor. Then, researchers found Neanderthal DNA in modern Eurasian people, implying that modern human populations received an influx of genes from Neanderthals at some point in their shared evolutionary history, she says. Only later did scientists realize that this genetic intermingling also supplemented Neanderthal populations with modern human genes, Lindqvist adds. In other words, interbreeding can be complex, not necessarily a one-way street, she says. The new study on bears reveals a remarkably similar story: The analysis finds evidence of hybridization in both polar bear and brown bear genomes, with polar bears in particular carrying a strong signature of an influx of DNA from brown bears, researchers say. Earlier research proposed the inverse pattern only, Lindqvist says. "It's exciting how DNA can help reveal ancient life history. Gene flow direction is harder to determine than merely its presence, but these patterns are vital to understanding how past adaptations have transferred among species to give modern animals their current features," says Leppälä, PhD, postdoctoral researcher in the research unit of mathematical sciences at the University of Oulu. "Population genomics is an increasingly powerful toolbox to study plant and animal evolution and the effects of human activity and climate change on endangered species," says Herrera-Estrella, PhD, President's Distinguished Professor of Plant Genomics and director of the Institute of Genomics for Crop Abiotic Stress Tolerance in the Texas Tech Department of Plant and Soil Science. He is also a professor emeritus at LANGEBIO. "Bears don't provide simple speciation stories any more than human evolution has. This new genomic research suggests that mammalian species groups can hide complicated evolutionary histories." Evidence from modern bear genomes -- and DNA from an ancient tooth The study analyzed the genomes of 64 modern polar and brown bears, including several new genomes from Alaska, a state where both species are found. The team also produced a new, more complete genome for a polar bear that lived 115,000 to 130,000 years ago in Norway's Svalbard archipelago. DNA for the ancient polar bear was extracted from a tooth attached to a subfossil jawbone, which is now housed at the Natural History Museum at the University of Oslo. Using this dataset, researchers estimate that polar bears and brown bears started to become distinct species about 1.3 to 1.6 million years ago, updating prior assessments made by some of the same scientists. The age of the split has been and remains a topic of scientific debate, with past interbreeding and limited fossil evidence for ancient polar bears among factors that make the timing hard to pinpoint, Lindqvist says. In any case: After becoming their own species, polar bears endured dramatic population decline and a prolonged genetic bottleneck, leaving these bears with much less genetic diversity than brown bears, the new study concludes. The findings confirm past research pointing to the same trends, and add evidence in support of this hypothesis. Together with the analysis of gene flow, these findings are providing new insights into the messy, intertwined evolutionary history of polar bears and brown bears. The international research team included scientists from UB, LANGEBIO, Texas Tech, the University of Oulu, the Far Northwestern Institute of Art and Science, the Alaska Department of Fish and Game, the Natural History Museum at the University of Oslo, Nanyang Technological University, University of Helsinki, and Aarhus University. The research was funded by the National Fish and Wildlife Foundation, U.S. National Science Foundation, Alaska Department of Fish and Game, and U.S. Geological Survey.
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Post by OldGreenGrolar on Jun 10, 2022 10:19:25 GMT -5
/\ That article shows that bringing back extinct bears like tyrant polar bears and steppe brown bears will make polar bears an indirect investment. Meaning the yellowish white bear will be sadly out breaded eventually.
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Post by brobear on Jun 11, 2022 1:12:29 GMT -5
/\ That article shows that bringing back extinct bears like tyrant polar bears and steppe brown bears will make polar bears an indirect investment. Meaning the yellowish white bear will be sadly out breaded eventually. The most likely extinct Pleistocene bear to be brought back is the cave bear. Scientists have their DNA complete. If it's really possible, I'd love to see my "other" favorite bear "in the flesh".
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Post by brobear on Sept 13, 2022 22:57:07 GMT -5
Meet the Polar Bear of Tomorrow Polar bears are interbreeding with grizzlies—and it may be their only hope www.sierraclub.org/sierra/meet-polar-bear-tomorrow-2?utm_source=facebook&utm_medium=cpc&utm_content=polarbear&utm_campaign=emacq&fbclid=IwAR1gwUi6Z73vYnIsDKpyKEdqn1hsBllExePIEyP1kI0c7eU7qKaBgcdVNVk By Sara Novak August 5, 2021 In 2006, Andrew Derocher was in the field with an Inuit hunter when a message crackled over the CB radio: A strange-looking bear had been shot a few miles away. The bear, found at the southern tip of Banks Island in Canada’s Northwest Territories, didn’t look like a typical polar bear. With a dingy white coat and scattered tufts of brown fur, it resembled a dirty version of the Arctic predator. It had dark rings encircling its eyes like sunglasses, and its claws were a few inches too long. Derocher, a professor of ecology at the University of Alberta, would later learn that the bear was the first known grizzly bear–polar bear hybrid found in the wild. Since then a handful of similar hybrids—nicknamed grolar bears or pizzly bears—have turned up. While the bears are still rare, says Larisa DeSantis, an associate professor of biological sciences at Vanderbilt University, the new hybrids may become more common as the Arctic ice melts, depriving polar bears of their customary hunting grounds on ice floes. This forces them to hunt on land, where they increasingly encounter northerly-ranging grizzlies. But DeSantis doesn’t think that hybridization is necessarily a bad thing. In fact, it gives her hope for the future. Her recent study, published in the journal Global Change Biology, shows how polar bears, having split from brown bears some 600,000 years ago, have evolved toward a hyper-carnivorous diet. With a narrow skull and enlarged canines, they’re meant for diving through small holes in the ice and grabbing blubber-rich ringed and bearded seals. DeSantis uses micro-wear on the teeth of both ancient and modern polar bears as well as those of modern grizzly bears to see what they had been eating. Her research shows that polar bears have traditionally consumed only soft foods such as blubber even during previous climate change events like the Medieval Warm Period a thousand years ago. But since the current warming period has been so rapid, DeSantis says, the bears are experiencing a dietary “tipping point” as they move onto land in search of terrestrial foods to fill their dietary needs. “Polar bears require ample fat and blubber to get enough calories, but now they’re turning elsewhere for food, eating carcasses and even trash,” says DeSantis. Grizzly bears, on the other hand, typically eat whatever they can get their paws on: fruit, salmon, seeds, shrubs, and tubers. Their wider jaw structure and stronger bite force make them better equipped to eat harder foods. Additionally, DNA evidence shows that during a previous warming period 100,000 years ago, polar and grizzly bears successfully mated in the Admiralty, Baranof, and Chichagof Islands. When grizzly and polar bears mate, they produce viable babies that can also mate and breed. DeSantis says the potential of it happening again and more widely can help polar bears survive. “The hybrids are more robust and could be better equipped to survive climate change,” she says. Chris Servheen, a retired grizzly bear expert for the US Fish and Wildlife Service, agrees with DeSantis that grizzly–polar bear hybrids could be more robust. “Grizzly bears are much more flexible. In fact, it’s easier to describe the few foods that they don’t eat rather than what they do,” says Servheen, now a professor of wildlife conservation at the University of Montana. He notes that only a handful of hybrid examples have been found in the wild, although more could be hiding in remote areas like Northern Russia and other icy outposts. (Polar bears are famously difficult to study because of their isolated habitats.) Servheen says that in recent years, polar and grizzly bears have been overlapping at bowhead whale carcass sites in places like Kaktovik, Alaska, a tiny village of 300 situated on the Beaufort Sea. The remains of traditional tribal whale hunts attract both grizzly and polar bears in search of easy nourishment. Derocher, a biologist who’s spent his career studying polar bears, thinks that hybridization isn’t necessarily a good thing for polar bears, as grizzlies could overwhelm the polar bears’ DNA. The gene pool of brown bears across the world is massive, while the gene pool of polar bears is tiny. “It’s like putting a drop of oil into a swimming pool,” says Derocher. “Polar bear features are genetically swamped by grizzly bears'.” If regular interbreeding occurred, polar bear features would almost immediately melt into the grizzlies'. Derocher says that the only way hybrids could maintain polar bear traits is if they continued to be geographically separate, maintaining some sort of segregation in the gene pools. But both Derocher and DeSantis agree that if drastic steps aren’t taken to shrink carbon emissions, polar bears in the lower Arctic will soon disappear, leaving only those found at the very highest reaches of Greenland and the Canadian archipelago where the ice is still solid. We’ll always have an Arctic that’s dark and cold in the winter, says Derocher, but if it doesn’t stay cold enough throughout the year, it will be difficult to maintain a viable population of polar bears through the end of the century. “Right now we’re not curbing greenhouse gas emissions in a way that would help polar bears,” says Derocher. And if we don’t reverse the trends soon, it won’t just be the bears that have trouble surviving. Sara Novak is an independent journalist who reports on travel, parenting, science, and health.
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Post by Deleted on Oct 19, 2022 5:03:24 GMT -5
Oh no, not this again. I'm not interested.
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Post by brobear on Oct 19, 2022 5:54:48 GMT -5
Oh no, not this again. I'm not interested. Yes; this topic is old news. I agree. You have been a member for just about three months now and this is your first post. But, that's ok. Lots of people join and never post. So, you are (understandably) uninterested in grolar bears. Where are your interests in bears? "Inquiring minds want to know"
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Post by Deleted on Nov 6, 2022 12:26:24 GMT -5
Oh no, not this again. I'm not interested. Yes; this topic is old news. I agree. You have been a member for just about three months now and this is your first post. But, that's ok. Lots of people join and never post. So, you are (understandably) uninterested in grolar bears. Where are your interests in bears? "Inquiring minds want to know" No ; i am interested in Grolar Bears, but i'm not interested in Grizzly VS Polar Bear because i know who'd likely win. Grizzly, end of the story. Polar Bears may be a little bit bigger, but Grizzlies are more aggressive and have more muscles.
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Post by brobear on Nov 6, 2022 13:43:45 GMT -5
Yes; this topic is old news. I agree. You have been a member for just about three months now and this is your first post. But, that's ok. Lots of people join and never post. So, you are (understandably) uninterested in grolar bears. Where are your interests in bears? "Inquiring minds want to know" No ; i am interested in Grolar Bears, but i'm not interested in Grizzly VS Polar Bear because i know who'd likely win. Grizzly, end of the story. Polar Bears may be a little bit bigger, but Grizzlies are more aggressive and have more muscles. Love your enthusiasm. In every confrontation caught on video that I've seen, the grizzly dominated the polar bear. But, I suspect that those results came more from wolverine-like bluff. Polar bears are not used to seeing other large quadruped animals in their turf. The aggressive behavior of the grizzlies was frightening to them. However, I would estimate the average full-grown boar polar bear to weigh roughly double the weight of the average barren ground grizzly. I would, however, wager on an Alaskan peninsula brown bear or a Kodiak bear against a polar bear. Even that would not be a sure-win though. By the way, kaijufan - Welcome to the Domain.
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Post by Deleted on Nov 13, 2022 2:41:39 GMT -5
Polar Bear would kill very small a Grizzly but not a similarly sized one.
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Post by brobear on Nov 13, 2022 5:29:46 GMT -5
Polar Bear would kill very small a Grizzly but not a similarly sized one. I agree.
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Post by Deleted on Nov 13, 2022 8:34:07 GMT -5
Thanks. Polar Bear will lose to a similarly sized Grizzly more often than not.
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Post by OldGreenGrolar on Nov 15, 2022 6:38:25 GMT -5
One thing to say: despite the fact the grizzly is more aggressive, the polar bear is still known as king of the arctic (including the areas where grizzlies enter, black bears enter the arctic circle in Churchill).
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Post by OldGreenGrolar on Nov 15, 2022 19:29:14 GMT -5
Notice that there is nowhere it is said: ‘grizzlies are king of the arctic in areas they share territory with polar bears.’ It seems purely carnivorous are generally considered king in their domain. Yet just because an animal is considered king doesn’t mean it is the strongest.
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Post by brobear on Nov 15, 2022 23:23:57 GMT -5
Notice that there is nowhere it is said: ‘grizzlies are king of the arctic in areas they share territory with polar bears.’ It seems purely carnivorous are generally considered king in their domain. Yet just because an animal is considered king doesn’t mean it is the strongest. The grizzly visits the arctic. He is a tourist. The polar bear lives there. He is a native. As the polar bears start becoming more familiar with the grizzlies, the tide of dominance might change and the grizzlies might learn to avoid the big boar polars.
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Post by OldGreenGrolar on Nov 16, 2022 1:44:57 GMT -5
/\ They actually avoid the older male boars. It is the younger ones that flew. Already posted an article somewhere on this forum. Originally from Shaggybear andAVA.
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Post by brobear on Nov 16, 2022 1:57:28 GMT -5
In this video, the huge male polar bears retreat from the smaller grizzlies.
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