Examples of Natural Selection - Biology

Topics: Dog, Biology, Genetics Pages: 2 (384 words) Published: November 17, 2010
Examples of natural selection

Emperor Penguins
An example of natural selection comes from animals in the Arctic. If the initial population has brown skin penguins and penguins with white skin, predators the penguins will see brown skin and therefore the penguins eat brown leather more often. Having fair skin and help to survive, and the gene for white skin will dominate the population. But if the population then migrates to a forested area, the penguins with dark skin have an advantage because they will be less easily seen by predators than those of white skin. Then the gene for dark skin will begin to spread through the population again.

Dogs / Wolves
The original class dog / wolf probably possessed the necessary information to produce a variety of coat lengths. The first specimens probably had a coat of medium length. In the simplified example of the illustration 4 , showing a single pair of genes in each dog. Each gene can occur in two ways. One form of the gene (L) contains instructions for long hair, the other (C) for short hair. In the first generation (row 1), we start from two individuals of half coat (LC) which generate descendants. Each of the descendants of the first generation of dogs can inherit a gene from each parent in order to have the two genes. In the second generation: (row 2) shows that the descendants can have short fur (CC), medium (LC) or long (LL). Now imagine a sudden cooling climate (e.g. glaciations). Only those individuals fitted long coat survive and give rise to third generation (row 3). So from now on, all dogs form and a new variety with long fur.  Note that:

1. Now they have adapted to their environment.
2. Now they are more specialized than their ancestors from generation 1. 3. This has occurred through natural selection.
4. No new genes are added.
5. In fact, there are genes that have disappeared from the population, that is, has been a loss of genetic information, the opposite of what evolution of the microbe to...
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