powerpoint 6 --Genetic Variation and Natural Selection

powerpoint 6 --Genetic Variation and Natural Selection -...

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: How does a population evolve? Outline: 1. Natural Selection 2. How is genetic variation measured? 3. Directional selection 4. Stabilizing selection 5. Disruptive selection 6. Sexual selection 7. Key terms 8. Conclusions Natural Selection Natural selection is the primary mechanism of adaptive evolution Accumulates and maintains favorable genotypes in a population Increases the frequencies of certain genotypes, fitting organisms to their environment over generations How is genetic variation measured? Population geneticists measure genetic variation both at the level of whole genes and at the molecular level of DNA Gene diversity measure the average percent of gene loci that are heterozygous Humans genetic variation: o Gene diversity is about 14% in humans. o Nucleotide diversity is only 0.1% You and your neighbor have the same nucleotide at 999 out of every 1000 nucleotide sites in your DNA. Directional Change in the Range of Variation
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powerpoint 6 --Genetic Variation and Natural Selection -...

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