Evolution and Natural Selection - Essay Example

However in the mid-nineteenth century, scientist like Charles Darwin and Alfred Wallace sought to explain this process of adaptation and change as a natural one without attributing it to the influence of higher beings and spiritual powers. Fossil records are perhaps the best natural evidence of evolution. While the fossils of simpler organism are found among older rocks, the newer ones have fossils of more complex organisms.. (GCSE, BBC) Evolution is of 2 main types: Microevolution and macroevolution.

Microevolution emphasises on genetic change from one generation to another while macroevolution deals with the process of gradual change in the physical form of living creatures. (The Process of Speciation, Global Change Program, University of Michigan) This paper will focus on the theory of evolution put forth by Charles Darwin. Key aspects of evolution like the process of Natural Selection and Variation will be discussed. Also, with reference to reference to 'Darwin's finches', the paper will describe how geographical isolation has caused new species to evolve from a common ancestor Darwin was influenced by observations made during his voyage as naturalist on the survey ship Beagle.

After studying several plant and animal species, Charles Darwin published some of his key observations and ideas in his book, "The Origin of Species." His theory of evolution comprises 4 parts:1. As fossils records shows the world is constantly changing. Several organisms have become extinct and others have changed over time are are rather different from their previously existing forms. 2. All organisms share a common ancestor and hence certain common features.3. The process of change is a gradual one4.

The mechanism of evolutionary change is natural selection.(Evolution and Natural Selection, Global Change, University of Michigan)Natural Selection:The concept of Natural Selection according to Darwin is the mechanism for evolutionary change. He discussed Natural Selection in the context of an organism 'struggle for existence'. Every organism Darwin believed tended to produce far more offspring than can actually survive. Limited resources often caused several of these to perish. As a result, there was intense competition between these organisms and only some survive to live and reproduce further.

Darwin also believed that the population within a species remained more or less constant over time. However these species do show a wide variation in features and these variations are passed on from one generation to another. (Ridley, 2003). The following chart describes the process of Natural selection.Source: Evolution and Natural Selection, Global Change, University of MichiganFor natural selection to occur, reproduction is a very important aspect. Offspring's inherit certain important features from their parents, which help them in the struggle for existence.

Besides there are 2 essential requirement, namelya. heritable variation of some trait like the beak or skin colour The differences in these traits could b a result of environmental factors and could often be significant for survival in that environment.differential survival and reproduction of that trait is essential to ensure that (Evolution and Na