Natural Selection

Natural selection was originally proposed by Charles by Charles Darwin to explain the variation in species of many living things that were found on the Galapagos Islands during his voyage with Captain Cook on the Beagle. The variation in the beaks of the Galapagos finch is an example.

The theory of natural selection can be stated as follows.

1. In any population of organisms there is a variation.

2. Organisms that have the best adaptive features for a particular environment survive ("survival of the fittest”).

3. Those organisms that survive pass on these adaptive features to their offspring.

While Darwin proposed the theory of natural selection he had no idea of how it worked. The science of genetics had not been developed.

The original wild finches contained a rich gene pool allowing variation. Natural selection selects those organisms with the adaptive features or genes that help the finch to survive in a particular environment. Those genes are passed onto the next generation. While some genes are selected others are not. Natural selection reduces the amount of genetic information in the gene pool.

This is similar to breeding a new variety of dog from a wild dog. As a new variety of dog is breed genetic information is lost. ie. a pure breed cannot breed another variety of dog. Scientists develop new varieties of wheat or rice by first searching for wild sources that are rich in genetic information.

Evolution is the theory that organisms become more complex overtime. New genetic information is provided to the gene pool of a organism by a series of mutations.

Footnote:

Critically analyse the scientific evidence for evolution: Points for and against evolution and then include a moral judgment statement.

It is sad that all of the exam questions are all about "what is the evidence for evolution". Students are not taught to critically think for themselves.

Or consider the question, Evaluate the Urey Miller experiment for chemical evolution. Include conditions and extrapolation of data. The question becomes "How does the Urey Miller experiment support evolution".

Politics and public opinion do influence science and education, especially when some scientists publicly crusade and belittle any opposing view. Students need to be taught to critically think for themselves about any science issue from evolution to global warming.