Evoloution of Polar Bears (Lamarck vs Darwin) Essay

1102 Words May 29th, 2013 5 Pages
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 …show more content…
In 1977 a drought reduced the number of small seeds available for the birds, forcing them to rely on larger seeds and nuts, which were difficult for birds with smaller beaks to open. The number of birds unable to eat reduced as they died and gave way to harder beaked finches. Within a couple of generations they had evolved larger beaks. In 2003 another drought struck the Galapagos and as there were many large beaked finches, the food source of nuts dwindled, making the ability to eat smaller seeds an asset. The numbers of larger beaked birds dwindled as food became scarce, leaving the smaller birds to survive and reproduce. Darwin’s theory was not well received when first written in On the Origin of Species, though many scientists today use it as a basis for research in evolution.

Both theories suggest that a species changes over time to be able to better adapt to an environment. Though Lamarck thought that the entire population of that species would evolve as one, i.e. all offspring changes together with same adaptation. Darwin concluded that only the specimen with the mutation or an altered version of a feature to evolve a species as they would be able to adapt and survive easier than those without it, thus causing the “unevolved” to die off while the “evolved” lived. Over many many generations the species keeps evolving until it has perfected the new trait, also becoming a new
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