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Unformatted text preview: s exist for each gene. The collection of these alleles is called the gene pool.
• Alleles naturally occur in certain frequencies in a gene pool.
• These frequencies can be changed ... over time.
• Three patterns of natural selection: 1. Directional selection - one extreme phenotype is fittest, phenotype moves toward that extreme over time
2. Stabilizing selection - extreme phenotypes are less fit than the optimal intermediate phenotype - most common in
stable, unchanging environments 3. Disruptive selection - 2 or more extreme phenotypes are fitter than the intermediate phenotype \ s Directional selection ' e( 1l Occurs when an extreme phe...
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This document was uploaded on 03/27/2014 for the course BIOLOGY Bio 2 at Timber Creek High.
- Fall '09