Evoloution of Polar Bears (Lamarck vs Darwin) Essay

This relates back to the lab because in our lab we tested the ability of the finches beaks, small and large, to break small and large seeds. Darwin believed that based on the environment and food supply some finches, depending on their beak size and shape, were more likely to survive. For example, if finches lived on island that only consisted of large seeds, the finches with bigger beaks would be able to eat the bigger seeds. Where as the finches with smaller beaks would have more difficulty cracking the bigger seeds. This is exactly what our lab was testing.

The Grant’s are capable of studying Darwin’s theory of natural selection in action, after gathering data from their colleagues, Peter Boag and Laurene Ratcliffe, who would be their watch on Daphne Island. Peter and Laurene witnessed an important event in natural selection, during a life or death situation with the finches. Though the two scientists were anxious for rain, but they did not receive a single drop that season. Rain would mean reproduction and fertility for the finches; however, the birds were faced with e horrible drought. Food became scarce and the finch population declined. Easy seeds to obtain on the ground were nearly gone. The seeds with tougher defenses, such as the caltrop, were usually untouched, since they were hard to crack. The finches with inadequate beaks did not

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

Evolution: Charles Darwin's theory was that species change over time, or evolve, in response to their environment. A good example of this is the evolution of the Kangaroo. Approximately 55 MYA the kangaroos looked quite similar to a possum and it was a tree dweller with a prehensile tail, but as Gondwana split up, the rainforests disappeared, the climate became hotter and the land dry and arid, the kangaroo evolved along the way and have come to look like what they do now.

It was in Eurasia, within 500,000 years ago, that brown bears roamed the land. It was a time when Eurasia was found coated in ice and the Arctic ocean became it. A pack of brown bears were forced to separate for the hunt for food. It is believed that glaciers forced isolation upon the packs resulting in the deaths of many bears. Isolation was an important part of the evolution between the two bears as it forced those with an evolutionary advantage, such as the colour and thickness of their coats, to enhance these advantages and managed to survive and breed. Unlike those who were unable to cope with the environment. This generation then made new adaptations to further increase their likelihood of survival in the polar environment (PBS, 2015). For example, the bears required differently shaped teeth. As seen in the picture below, the back teeth of a polar bear are less in number and size. However, it is clear that the front teeth are larger and sharper. This is because of the change in environment forcing a change in diet for the bears; instead of eating berries the bears had to consume seals and needed sharper teeth to tear through skin. In order to camouflage themselves the bears, overtime, grew white fur to blend in with the snow. Another adaption made the these bears is the hunting technique used; at first only seal carcasses that had washed ashore were eaten by them however over time the bears

Charles Darwin believed in Evolution and natural selection. Evolution according to Charles Darwin was that all life is related in some way and has descended from a common ancestor. As random genetic mutations occur in an organism’s genetic code, the beneficial mutations aid in survival – this is called natural selection. Organisms that develop random mutations are better adapted to their environment and tend to survive and produce more offspring. Lamarck’s viewpoint on evolution was the law of use and disuse. He hypothesised that organisms react to changes in their environment by changing or strengthening a certain organ. Whilst an organ will stop working or disappear if it is stopped being used. The fault is this theory was that it could not explain how these strengthened or unused organs are passed on to other generations of the same organism. Charles Darwin’s theory of evolution is right, but Lamarck wasn’t far off the mark. A good example of Lamarck’s law of use and disuse in the Homo sapiens is that of the appendix. The appendix is an organ which is commonly believed to have ‘stopped working’, this organ was the remnant of large fermenting gut for plant life. This organ has ceased to work as Homo sapiens have stopped eating plant matter and started to eat organisms consisting of meat. This somewhat strengthens Lamarck’s

Darwin wanted to further his studies in plant and animal life, and he also became interested in the similarities of plant and animal species to those of the human species. He noticed that humans too also had to develop new characteristics that would help them adapt to their environments. This made him want to look further into where humans came from and also question the idea of creationism. He argued that men are animals because they have to adapt to their surroundings just as animals do. He suggested that the stronger animals have a better survival chance and they produce offspring that carry this trait. A whole new population of species can derive from these offspring and traits that have evolved from older generations and species. This became known as Darwin’s Theory of Evolution.

Their feet are made for the ice and snow; they have rough leather pads so they don’t slip on ice, fur between toes and sharp claws as a weapon. They are plantigrade and left handed. Their toes are webbed so they can swim in water. Their fur is a yellowish white; the top lay is long and hollow to absorb heat and can float in the water. The undercoat covers their black skin that has four inches of blubber, which is an extra layer of warmth. This kind of coat makes it uncomfortable for polar bears to be in the heat. A polar bears sense of smell is the best sense they have, they mostly rely on it. It can smell a dead whale 15 miles away, can smell where a seal is hiding in six inches of ice, and can smell a human before they could even see them. Their eyes are small to block out the sun reflecting off the snow and their ears are small, close to their heads to keep warm.

Evolution of the Polar Bear and their relationship to the Brown Grizzly: The Controversy Continues

Darwin and Lamarck also agreed that life evolved from less, simpler organisms to many, more complex organisms. The differences are that Lamarck believed in theory of inheritance of acquired characteristics, meaning if an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring. He said that change is made by what the organisms want or need. Lamarck also believed that evolution happens according to a predetermined plan and that the results have already been decided. Whereas Darwin’s theory was that diverse groups of animals evolve from one or a few common ancestors; the mechanism by which this takes place is natural selection. Natural selection is when random evolutionary changes are selected for by nature in a consistent, orderly and non-random way. Darwin believed that organisms have changed over time, and the ones living today are different from those that lived in the past. Darwin’s theory has been supported by a lot of evidence including the fact that over time, populations split into different species which are related because they are descended from a common ancestor. While Lamarck’s theory has been disproven; this has been done in two ways, by experiment and by the study of

There are not many creatures in the world that have the ability to not only survive thirty-two degrees below zero temperatures, but live in this climate as well. Among penguins and seals, polar bears are apart of the group of creatures that live everyday life in these freezing conditions. However, polar bears were not always able to do this. According to the Public Broadcast Service (PBS) website, polar bears evolved from brown bears through microevolution. Microevolution, by definition, is “small-scale evolution that occurs from one generation to the next” (Larsen p. A15). Due to the discovery of fossils, it is believed that brown bears evolved into polar bears between 70,000 to 100,000 years ago. This evolution can be seen by the change of fur color from brown to white to blend in while hunting for food and by the growth of a thicker, warmer coat to protect against the cold temperatures (PBS). This all occurred because of an event called the “ice age”. However, in the year 2316, an event called “global warming” will cause a much different evolution. Global warming is a phrase used to describe the ongoing, subtle rise in temperature of the earth and it’s oceans. Because of the small efforts being made to slow down global warming, nearly all of the ice caps in the ocean will most likely be melted by the year 2316. With polar bears only being able to survive by living on polar

The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7–8 ma.[11] The short-faced bears are thought to have been heavily carnivorous and the Florida spectacled bear more herbivorous,[12] while the American black bears remained arboreal omnivores, like their Asian ancestors. The black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why, of these three genera, it alone survived climate and vegetative changes through the last ice age while the other more specialized North American predators became extinct. However, both Arctodus and Tremarctos had survived several other ice ages. After these prehistoric ursids became extinct during

Lamarck believed that a population of individuals all of the same kind (identical characteristics in all members). Individuals capable of transformation. Whereas Darwin thought that a population of interbreeding individuals with similar characteristics, though variation is common among all of them at all times. Individuals fixed and unchanging. Population capable of transformation. For example Lamarck also thought that if a giraffe

As polar bears inhabit the Arctic regions of five separate nations, it is important to examine the different nation specific management plans in place for conservation of the species. By examining the various management plans in place, a comprehensive look into polar bear management of the species on a global level may be achieved. Of the five nations with polar bear populations, the three largest have some form of a national management plan in place. However, in all five nations, all have specific polar bear hunting regulations and restrictions that also assist in polar bear preservation.

In recent years, society has been extremely innovative with its technology, thereby generating a mass increase in the efficiency of the commodities we use in our daily lives, but also elevating the amount of pollution that’s being released into our ozone. This, sequentially, is worsening the effects of the polar bear’s prime enemy: global warming. It is indisputable that the longevity of any animal’s life should not be determined by the preference of a human being; it is unjust for us as people of the earth to decide which animal is more deserving of our help. However, we must start somewhere.