Polar Bear Evolution

The Polar bear lives in the artic and uses the area’s costal waters and ice sheets. They are well equipped to live in this environment because they have a thick coat which serves as an insulator. They mainly prey on seals but have also been known to consume dead whales. They can grow to be 7.25 to 8 feet tall and can weigh around 900 to 1,600 pounds. Polar bears are a keystone species, if their numbers decrease there is a possibility that the seal populations will increase which could be devastating for crustaceans and fish. They help keep populations in balance.

It is believed the Polar bears that walk the earth today, had descended from brown bears. This occurred through geographical isolation due to glacial drift in an area close to Siberia. They had undergone a rapid evolution, with changes that enabled them to adapt and survive in an Arctic habitat.

The bear have evolved along time ago and now there is only eight species existing. They evolved from early canids during the late Oligocene and early Miocene, about 25 million years ago. The earliest ancestors where the Dormaalocyon Latouri. An intermediate ancestor was the short faced bear, very similar to the modern day bear. It lived through the pleistocene period. It grew to thirteen feet long and was a herbivore. The ancestors to the modern day bears lived in the same climate and ate the same things. The modern bear contrast from the ancestor because the ancestor was more skinny and was smaller, and it was more cat like. The eight species of bear that still exist. They are the Polar bear, Brown bear, American black bear, Asian

The white phased black bear was said to have traversed barriers of the sea during the last ice age when glaciers covered most of northwest British Columbia. When temperatures started to rise, and glaciers started to retreat it is believed that the white bear was then isolated on the islands off the coast of BC. The white coats would suggest an adaptation to the white snow for hunting, however if that was the case, the evolutionary trail should have left the recessive gene behind when it was no longer useful to them in the temperate forests. Most research that is done on the Spirit bear is to try and understand the polymorphism of this species and how it has come to last among a low frequency in a minute area. Evidence now suggest that the reason for the white fur is actually a very important adaptation for the bear and is still very useful even in the array of

The Polar Bear (Ursus maritimus) is a bear native largely within the Arctic Circle encircling the Arctic Ocean, its surrounding seas and land masses. Although it is closely related to the Brown Bear, it has evolved to occupy a narrower ecological forte, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet. Though there are many theories surrounding evolution, the two stand outstanding hypotheses applying to the modification from Brown Bear to Polar Bear are Lamarck’s theory of Use and Disuse, and Darwin’s theory of Natural Selection. The intention of this paper is to compare these thesis and determine the most appropriate in

This subspecies is arguable better and more adaptive than brown bears after enduring such extreme environmental pressure. Evidence of this evolution includes fossil records and the analysis of DNA and the bear’s evolutionary path (PBS, 2015). Scientists used the technique of 'identity by state tact', which is the analysis of the length of DNA and the segments

Grizzly bears have had to adapt when the weather is off like having a warm winter it sets their internal clock off to where when they should be hibernating they are still out or cold weather comes late they are already awake from hibernation or cold weather comes to to early and they aren’t hibernating. They also have to deal with man made disasters like oil spills or fires, both can kill bears and kill what they eat like fish which could then kill the bears if they can not eat enough food because their immune system will deteriorate and kill them. Grizzly Bears are divergent because recent studies have shown that some grizzly bear’s mothers are polar bears and fathers are grizzly bears. This means that the fathers travel long distances to mate with mother polar bears. The most recent studies have suggested that they have been divergent from about 150,000 years ago. (Tia Ghose) Past research revealed that brown bears on ABC Islands, off the southeastern coast of Alaska, had mitochondrial DNA that look just like polar bear DNA.(Mitochondrial DNA comes only from the mother and is carried in the cytoplasm in the cell’s energy-making structures called mitochondria.) (Tia

In the scientific article, “Love in the Time of Climate Change: Grizzlies and Polar Bears Now Mating,” by Adam Popescu, believes that climate change is helping to cause grizzlies and polar bears to mate. He points out that glacier sheets are retreating, this forces the polar bears to move into grizzly’s territory. Moreover, that the permafrost is also starting to melt, which is causing grizzlies to wander into the polar bears territory. Consequently, he goes on to put that because of this mating, the grizzlies are eating up the polar bears genetically. He concludes that if this trend keeps up, in a few decades any kind of the bear population in this area will be no more. Lastly, the author’s purpose is to make readers aware of the hidden effects

The American black bear (Ursus americanus) is native to North America, more specifically Canada and northern and southeastern United States. Ursus americanus once ranged from Mexico and all throughout United States and into Canada, but as human population increased and climatic conditions have changed, Ursus americanus moved to locations with lower populations and cooler climates, which are northern North America as well as southeastern United States. Ursus americanus are found with the highest populations in Canada and northwestern United states where there are lower human populations, larger forests, and cooler climates.

The polar bear, the largest land carnivore in North America, one of the largest animals in the world and a favorite at zoos worldwide, has, over the years, adapted to its harsh Arctic environment. The appropriately named ‘ursus maritimum’ or sea bear usually lives between 15 and 18 years in the wild and spends most of its life on ice. It is the most recent of the eight bear species. The first polar bear was a brown bear subspecies, with brown bear dimensions and brown bear teeth. The polar bear evolution was rapid due to the small population and extreme pressure to survive. Even today, the polar bear continues to evolve to better adapt to the harsh realities of Arctic life.

For the past few weeks, we have been reading the informational text, Where Do Polar Bears Live? Today, you are going to take an assessment where you will have the opportunity to show what you have learned. There are two parts to the assessment. The first part is a 1 short response question, and the second part is 5 multiple choice questions.

The water bears live all over the world from the deepest sea to the Himalayas. Most of the water bears live in fresh water, often in wet or moist habitats that are subject to frequent periods of drying and then rewetting such as the moss on a roof or algae in the gutters. Other areas include hot springs, glaciers, lichens, leaf-litters. Their ability to form a “tun” allows them to be blown around the world by the wind. The water bears enter a cryptobiotic phase in environments with intermittent moisture that allows them to survive conditions such as drought, low oxygen, salinity changes, or extreme temperatures.

The polar bear lives up in the Arctic region where global warming and climate change are melting the ice caps that the bears thrive on. They use the ice as a platform from hunting and rest. The random pocket holes in the ice, where the seals pop up at, is where the polar bear catches its prey. With this reduction of ice, “the abundance of seals, and increases the amount of energy and time needed for hunting, leaving less energy for reproduction” (Endangered Species and Habitats).

The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatly resemble the Asiatic species,[9] though later specimens grew to sizes comparable to grizzlies.[10] From the Holocene to present, American black bears seem to have shrunk in size,[2] but this has been disputed because of problems with dating these fossil specimens.[7]

 The polar bear has to be able to stay warm in the harsh winter cold. In fact sometimes because they have such thick fur they have to lay down on the snow to cool off so the harsh cold isnt even enough to keep them up to tempreture.