Selective Pressures
The polar bear, as all modern species, came to have its current genome and characteristics through adaptation due to selective pressures. The polar bears environment is very physically demanding. As an endothermic animal, the polar bear produces its own heat and requires high amounts of energy and insulation to keep its body at a functioning temperature. One adaptation due to evolution that aids the bear in heat conservation includes its black colored nose. This adaptation causes sunlight to be attracted to the dark coloring of the nose, warming the air it inhales through its nostrils, and stopping harsh arctic air from directly entering the lungs.The bears' environment also requires it to be well adapted to long periods of time without food. The bears are instinctively programmed to hibernate in the coldest times of the year, leaving them in a sleeping state without any new nutrients for months at a time.The requirement to survive without constant food ingestion also stems from the severe seasons in the arctic territory. The bears are only able to hunt seals, their main food source, during the winter months when they are able to travel over the sea ice and hunt the seals and pups surfacing and hiding among holes in the ice.
Polar bears are also becoming increasingly scarce due to global warming. With the rising temperatures on our planet, the ice caps are melting and the sea levels are rising. Since the polar bears rely on the ice caps so heavily for hunting, the melting of the northern ice has had an immense effect of them. With less ice available for the polar bears, it is harder for the polar bears to get their food (seals), leading to an increase in death due to starvation, a major drop in body condition, and a lower percentage of survival in cubs. There is also a rise in the percentage of cannibalism among polar bears since there are not many other food sources. Drowning is another common effect of global warming since the sea levels are rising. Polar bears drift out far from the mainland after a chunk of ice breaks off of an ice cap due to its partial melting. The bears are not able to swim all the way back to the land, and end up drowning. There is a large selective pressure on the polar bear population, and only the ones who are most suited to getting food are surviving in the difficult environment.
Polar bears are also becoming increasingly scarce due to global warming. With the rising temperatures on our planet, the ice caps are melting and the sea levels are rising. Since the polar bears rely on the ice caps so heavily for hunting, the melting of the northern ice has had an immense effect of them. With less ice available for the polar bears, it is harder for the polar bears to get their food (seals), leading to an increase in death due to starvation, a major drop in body condition, and a lower percentage of survival in cubs. There is also a rise in the percentage of cannibalism among polar bears since there are not many other food sources. Drowning is another common effect of global warming since the sea levels are rising. Polar bears drift out far from the mainland after a chunk of ice breaks off of an ice cap due to its partial melting. The bears are not able to swim all the way back to the land, and end up drowning. There is a large selective pressure on the polar bear population, and only the ones who are most suited to getting food are surviving in the difficult environment.
Click to set custom HTML