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Today’s Objectives: 10/21/02

Today’s Objectives: 10/21/02. TSW be able to write the Hardy-Weinberg equation and explain it. TSW be able to list several evolutionary mechanisms. TSW be able to list several types of speciation and discuss the rates of evolution. Hardy-Weinberg Theorem. p 2 + 2pq + q 2 = 1

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Today’s Objectives: 10/21/02

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  1. Today’s Objectives: 10/21/02 • TSW be able to write the Hardy-Weinberg equation and explain it. • TSW be able to list several evolutionary mechanisms. • TSW be able to list several types of speciation and discuss the rates of evolution.

  2. Hardy-Weinberg Theorem p2 + 2pq + q2 = 1 Studies genetic (allelic frequencies)

  3. H-W Assumptions: • Large population size. • Random mating. • No migration. • No mutations or mutational equilibrium.

  4. Ways Evolution Can Occur

  5. Genetic Drift • Neutral selection – caused allelic frequencies to change based on chance • Founder effect • Bottleneck effect

  6. Gene Flow • Changes allelic frequencies because of migration of individuals.

  7. Mutation • Random events. • May be beneficial, harmful or insignificant.

  8. Natural Selection Definition Selection Pressure

  9. Types of Natural Selection • Directional selection • Industrial melanism in Biston betularia • Disruptive selection • Distinct subpopulations • Stabilizing selection • Keeps phenotypes stable for long periods of time.

  10. Speciation Reproductive isolation must be achieved!

  11. Types of Speciation • Allopatric • Geographic isolation – most common type • Adaptive radiation • Parapatric • In small, local subpopulations (demes) • Sympatric • Almost always in plants • In same population but do not interbreed

  12. Rates of Evolution Gradualism vs. Punctuated Equilibrium

  13. Mosaic Evolution Same structure is modified for multiple uses.

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