Biological Evolution - Research Article from Macmillan Science Library: Animal Sciences

This encyclopedia article consists of approximately 6 pages of information about Biological Evolution.
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Causes of Biological Evolution

There are five forces that cause evolution: natural selection, mutation, gene flow, nonrandom mating, and genetic drift. All five depend on the existence of genetic variation, which is necessary for any evolutionary change. Natural selection is the differences in the survival and reproduction rates of individuals with different phenotypes. When phenotypes can be genetically inherited, natural selection produces adaptations as the population evolves. Natural selection can remove variation from a population if it is stabilizing selection. Diversifying selection can increase the amount of variation in a population. Directional selection changes the average trait in the population.

Genetic mutations occur when errors are made in replicating (copying) and dividing DNA. Mutation is the ultimate source of genetic variation. Most of the time, mutations either have no effect on the phenotype, and therefore are neutral, or have a harmful effect. Rarely, a mutation will create a...

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This section contains 1,732 words
(approx. 6 pages at 300 words per page)
Buy the Biological Evolution Encyclopedia Article
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Macmillan Science Library: Animal Sciences
Biological Evolution from Macmillan Science Library: Animal Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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