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Mechanisms for Evolution

Mechanisms for Evolution. What drives evolution?. Genes within a Population. White moth: bb. Black moth: BB. Genetic Equilibrium (Hardy-Weinberg Equilibrium). Allele frequency will not change if : 1. 2. 3. 4. 5. What if there is genetic change?. Microevolution –

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Mechanisms for Evolution

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  1. Mechanisms for Evolution What drives evolution?

  2. Genes within a Population White moth: bb Black moth: BB

  3. Genetic Equilibrium(Hardy-Weinberg Equilibrium) Allele frequency will not change if: 1. 2. 3. 4. 5.

  4. What if there is genetic change? Microevolution – Drivers of Microevolution: 1. 2. 3. 4. 5.

  5. 1. Small Population Genetic drift – Small populations can result from Example: 1 in 5 frogs is yellow and 60% of population is killed Population 1 Population 2

  6. Bottleneck Effect Severe event reduces Population size

  7. Bottleneck Effect - Today Northern Elephant Seal 1890s – 20 seals left due to overhunting

  8. Founder Effect

  9. 2. Gene flow (Migration) Gene flow – Population 2 Population 1

  10. 3. Sexual Selection • Examples: bright colouration, elaborate tail

  11. Physical Features Example: Two male hippos fighting over territory

  12. 4. Genetic Mutations What is a mutation? Beneficial mutation- Harmful mutation – Which would be selected for in a population? Which would be selected against?

  13. 5. Natural selection • “Survival of the Fittest”

  14. Stabilizing Selection

  15. Directional Selection • Example: Birds prefer to eat blue butterflies. Therefore, butterflies with a purple colouration are favoured in the environment

  16. Disruptive Selection • Example: Birds prefer to eat medium-blue coloured butterflies. Therefore, white and purple butterflies are favoured

  17. Sickle Cell Anemia in Africa Distribution of Malaria VS Distribution of Sickle Cell Anemia

  18. Sickle Cell Anemia • Which individuals are favoured in Africa?

  19. Summary

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