The Theory Of Evolution By Natural Selection

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Part A: Evolution of Polar Bears
Introduction
The theory of evolution by natural selection (Darwinism), first formulated in Darwin 's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioural traits. Changes that allow an organism to better adapt to its environment will help it survive and that have more offspring. The first three ideas were already under discussion among earlier and contemporaneous naturalists working on the “species problem” as Darwin began his research. Darwin’s first contributions were the mechanism of natural selection and numerous amounts of evidence for evolutionary change from many sources. He also provided thoughtful explanations of the consequences of evolution for our understanding of the history of life and modern biological diversity.
 Species (populations of interbreeding organisms) change over time and space. The representatives of species living today differ from those that lived in the recent past, and populations in different geographic regions today differ slightly in form or behaviour
(Evolution Berkeley)
 All organisms share common ancestors with other organisms. Over time, populations may divide into different species, which share a common ancestral population. Far enough back in time, any pair of organisms shares a common ancestor. (Evolution Berkeley)
 Evolutionary change is gradual and slow in Darwin’s view. This claim was
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