Lecture 6 Natural Selection and Adaptationbb

Lecture 6 Natural Selection and Adaptationbb - Evolutionary...

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Unformatted text preview: Evolutionary Mechanisms (Microevolution) – Natural Selection – Mutation – Genetic Drift – Gene Flow – (Non-random Mating) Studying Natural Selection by Observation The Finches 3 Variation in Beak Size Distribution of beak depths 6 Weather Shifts • Year 1 = 137mm • Year 2 = 24 mm • Average = 130mm 7 Food Resource Change • Year 1 June: 1m 2 of soil, 10g seeds. • Year 2 June: 1m 2 of soil, 6g seeds • Year 2 December: 1m 2 of soil, 3g seeds 8 Seed Abundance vs. Time Seeds of Trilobus 10 11m beak Seed size and Time Another Year of Change • Year 3 - 50mm rain • Plants finally flowered/produced seeds. • Finch population decimated. 12 Finch Pop. Size vs. Time Distribution of beak depths 14 Differential reproduction Evolution is: A change in the frequency of an allele, such as an allele for beak depth, is the basic definition of evolution. 16 Evolution by natural selection in 3 years . . ....
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This note was uploaded on 10/22/2009 for the course BIO 124 taught by Professor Griscom during the Spring '07 term at James Madison University.

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Lecture 6 Natural Selection and Adaptationbb - Evolutionary...

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