Pdf bears are iconic mammals with a complex evolutionary history. Nevertheless, the mitochondrial genomes of brown bear are paraphyletic and extant polar bear sequences are recovered as a monophyletic sister clade to the brown bear population from alaskas abc islands, within the diversity of brown bear figure s2c. An analysis of newly sequenced polar bear genomes is providing important clues about the species evolution, suggesting that climate change and genetic exchange with. As shown in the diagram on the left, the polar bear is also related to the spectacled bear, the sloth bear, the sun bear, the american black bear, the asiatic black bear, and the brown bear. Encouraged by darwins response, lamont elaborated upon walrus and polar bear evolution in his 1861 travelogue, seasons with the seahorses. Jun 10, 2008 this is believed to be an important step in the evolution of a new subspecies of bear ursus maritimus or the polar bear. It has been known that polar bears evolved from brown bears, but. Polar bears evolved just 150,000 years ago live science. We propose that the dynamics of sea ice and the associated variability in access to food have played a major role in the evolution of the social structure and mating system of polar bears.
The taxonomic status of the sixth asian member, the giant panda ailuropoda melanoleuca, remains in question, although most evidence suggests that it belongs to ursidae. Mar 01, 2010 parsing the polar bear to arrive at the new portrait of polar bear evolution, the researchers used high throughput sequencing a speedy dna sequencing technique to compare the genetic information. The native biome of the species is the arctic tundra which is known for its extremely cold climate, low vegetation and cold desert like conditions. Polar bears ursus maritimus and brown bears ursus arctos have long fascinated naturalists and the public, and bear ecology and evolution. The polar bear is an excellent swimmer and often will swim for days. As the fuzzy and ferocious poster child for climate change issues, polar bears get plenty of press, whether its coverage of something as simple as the birth of a cub at a zoo or as political as a rejected ban on trading polar bear parts. Dna from a polar bear jawbone has revealed the arctic species first originated about 150,000 years ago, scientists announced today. Ancient hybridization and an irish origin for the modern polar bear. Jul 23, 2012 an analysis of newly sequenced polar bear genomes is providing important clues about the species evolution, suggesting that climate change and genetic exchange with brown bears helped create the. Polar bears and brown bears diverged much longer ago than previously thought, new research suggests. There are suggestions that before midcentury we could have a nearly icefree arctic in the summer. Polar bear evolution and adaptation even though the polar bear does fit into the category of being a bear, there is scientific evidence to show it has evolved into a definite species of its own. The origin and evolution of the polar bear matriline. The evolution of polar bears via fossils is very well documented.
Today, polar bears are adapted to their harsh northern environment. Dr susan crockford is an evolutionary biologist and an expert on polar bear evolution. In my opinion, the most important conclusion of this paper is that occasional but widespread hybridization among bears is why it has been so hard to say with confidence when polar bears arose which i addressed years ago, in my polar bear evolution series. It has no natural predators and knows no fear of humans, making it an extremely dangerous animal. If you liked this video please like, subscribe and check out desire souls channel which is linked bellow. Evolutionary history of polar and brown bears esa journals wiley. Polar bear evolution polar bear facts and information. It is very interesting to take a backwards look at polar bear. Brown bears were noted to have evolved 800,000 years ago.
For this reason, foods that polar bears consume during the ice. To date, global warming has been most pronounced in the arctic, and this trend is projected to continue. Polar bear ursus maritimus and brown bear ursus arctos are recently diverged species that inhabit vastly differing habitats. The consensus has been that this pattern reflects femalemediated gene flow from brown. An analysis of newly sequenced polar bear genomes is providing important clues about the species evolution, suggesting that climate change and genetic exchange with brown bears helped create the polar bear as we know it today. This may provide a better purchase on the slippery ice surface than naked pads. Darwin approved of lamonts hypothesis, and, because lamonts thinking on the subject predated the publication of on the origin of species, he later credited lamont as he did alfred russel wallace. Matt cronin, in case you didnt know, was the first to pick up the close genetic relationship between polar bears and grizzlies, as a result of research he and colleagues did back in the early 1990s cronin et al. My science assessment video on the evolutionary changes of the polar bear. Polar bears and brown bears diverged long ago evolution.
Apr 19, 2017 additionally, the brown bear mitochondrial mt genome was captured by polar bears during ancient hybridization 8 and polar bear alleles are distributed across brown bear populations all over the. Pdf the evolutionary history of bears is characterized by gene. There is a new polar bear genetics paper out in the journal of heredity, by university of alaska fairbanks genetics professor matt cronin and colleagues. The usgs alaska science center leads longterm research on polar bears to inform local, state, national and international policy makers regarding conservation of the species and its habitat. Darwin, wallace and the other 19th century naturalists who traveled widely were fascinated by the distribution of animals and plants in their habitats. One small fossil, one giant step for polar bear evolution. Its hearing is about as acute as that of a human, and its vision is also good at long distances. Just as changes in the genes have led to changes in the fur colour from brown to white, a natural selection has led to changes in the genes that regulate the. Population genomics reveal recent speciation and rapid. Climate change likely caused polar bear to evolve quickly. Polar bear evolution is marked by rapid changes in gene copy number in response to dietary shift.
Polar bears ursus maritimus are the poster child for the impacts of climate change on species, and justifiably so. This is because there are so many differences from them and other forms of bears. Made this for a science assignment about evolution duh. In the case of polar bears, anatomical and physiological adaption suggests that this species co evolved with the ringed seals who are primarily predated by the polar bears spicer, 20. Ten good reasons not to worry about polar bears gwpf. Pdf the role of pleistocene glaciations in shaping the evolution of. Our analyses of cnv shed light on the genomic underpinnings of ecological adaptation during polar bear evolution. Genome scale studies in brown and polar bears nd that 8. Recent findings suggest that polar bears evolved from a common ancestor of the brown bear between 350,0006 million years ago. On the mating system of polar bears canadian journal of zoology. The polar bear ursus maritimus introduction polar bears. Future conservation strategies would significantly benefit from an understanding of basic evolutionary information. Polar bears split from the brown bear, their closest relative, less than 500,000 years agofar more. Polar bear, great white northern bear found throughout the arctic region.
While we may be in awe of what we see with these magnificent creatures today, there is evidence that points to evolution for them over time. Polar bear evolution polar bears incredible evolution. Polar bear evolution the polar bear is a member of the ursidae family and shares a common ancestor with the black and brown bear. Nature once exerted such extreme pressure on the brown bear that it. The ancestors probably had lived in the southeastern alaska during pleistocene period and separated from brown bears. Brown bear to polar bear evolution in 1996 scientists concluded that the brown bears of alexander archipelago were derived from ancestors which gave birth to modern day polar bears. Adaptation is the key to survival, and adaptations of the polar bear, which help it survive the harsh environment of arctic tundra, are undoubtedly the best when it comes to kingdom animalia. Thus, analysis of the polar bear and brown bear genomes represents a unique opportunity to investigate the evolutionary mechanisms and genetic underpinnings of rapid ecological adaptation in mammals.
The species in which it is most closely related to is the brown bear. Mar 28, 2015 made this for a science assignment about evolution duh. The work helps us understand what makes a polar bear a polar bear and how fast this evolution occurred, comments charlotte lindqvist, an evolutionary biologist at the university at buffalo in new york. Polar bears evolved from brown bears 100,000 to 250,000 years ago.
Stratigraphy and dating of a rare polar bear fossil jaw bone, found on the svalbard archipelago in norway, suggest that it is,000 to 110,000 years old and reveal that polar bears were a distinct species at this time. One small fossil, one giant step for polar bear evolution april 2010. We characterized the current terrestrial diet of polar bears in western hudson bay by. Except for one subspecies of grizzly bear, the polar bear is the largest and most powerful carnivore on land. Adaptation is the key to survival, and adaptations of the polar bear, which help it survive the harsh environment of arctic tundra, are undoubtedly. Pregnant polar bears will spend time on coastlines in maternity dens where they stay a few months after they give birth. This is believed to be an important step in the evolution of a new subspecies of bear ursus maritimus or the polar bear.
Mar 23, 2014 my science assessment video on the evolutionary changes of the polar bear. Polar bear evolution where do polar bears come from. Estimates of when polar bears started splitting from brown bears continue to change as geneticists learn more about the polar bear s genome. During winter polar bears will migrate along the southern edge of an ice pack. Adult females and males move to areas of the sea ice where the greatest success in hunting is realized. One of the furthest related ancestors of the polar bear is the giant panda.
Polar bears ursus maritimus are among those species most. Jun 20, 2012 polar bear evolution facts and information. Polar bear evolution tracked climate change, new dna study. She has been working for 35 years in archaeozoology, paleozoology and. Hecht in chaline, 1983 describes polar bear evolution. The evolutionary changes of the polar bear youtube.
As a family, bears are thought to have evolved some 4. Polar bear evolution is marked by rapid changes in gene copy. Parsing the polar bear to arrive at the new portrait of polar bear evolution, the researchers used high throughput sequencing a speedy dna sequencing. Coevolution occurs when two or species reciprocally affect the evolution of one another. Over the next 20,000 years, body size reduced and the skull elongated. Polar bears ursus maritimus are one of 4 marine mammal species managed by the u.
Polar bear evolution is marked by rapid changes in gene. Polar bear name and evolution polar bears international. Brown bears and polar bears are found in europe and these 2 species plus the american black bear ursus americanus inhabit. The polar bear has many adaptations for its life on the polar ice pack. The polar bear has an extremely well developed sense of smell, being able to detect seals nearly 1. This is a good thing as there are no trees or rocks to hide behind in their habitat. Mar 19, 2010 time estimates for the brown bearpolar bear divergence vary considerably. Strong ancestral gene flow between the asiatic black bear and the ancestor to polar, brown and american black bear explains uncertainties in. The evolution of the polar bear from brown bear to arctic wonder. In winter, polar bear foot pads may be densely furred. One that stood out was a gene called apob, which helps transfer fat from blood into cells.
311 787 1596 626 825 1341 811 393 1519 920 569 616 900 699 314 597 533 369 1556 597 1575 305 45 1268 1095 89 1335 70 325 987 1166 1356 1151 9 162 695