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Unit 11 7F

Analyze and evaluate the effects of other evolutionary mechanisms, including genetic drift, gene flow, mutation, and recombination. Unit 11 7F. Let’s remember…. An allele is an alternative form of one gene B stands for black b stands for brown The allele would be…. Genetic Drift.

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Unit 11 7F

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  1. Analyze and evaluate the effects of other evolutionary mechanisms, including genetic drift, gene flow, mutation, and recombination. Unit 11 7F

  2. Let’s remember… • An allele is an alternative form of one gene B stands for black b stands for brown The allele would be…

  3. Genetic Drift • An evolutionary mechanism in which allele frequencies change in a population

  4. Allele frequency changes due to… • Natural disaster like flood, fire, or earthquake • A random change of the population (some are eliminated) • Different from natural selection b/c its by chance or randomly

  5. Original Pop Pop after change R = red star r = green heart 6R, 5r5r

  6. Bottleneck Effect • The change in allele frequency where only genes of the surviving population members can be passed to future generations

  7. Gene Pool • the sum of all the genes in an interbreeding population

  8. Gene Pool • 2 blue alleles • 1 red allele • 12 green alleles

  9. Founder Effect • The change in allele frequency in a gene pool that changes from a large population to a small population • Ex: small number of individuals get separated from a larger population… the change in the allele frequency is the founder effect

  10. Founder Effect

  11. Gene Flow • Occurs when the genes of 1 population flow into a different population • This change causes a shift in allele frequency

  12. Immigration • Alleles move INTO a population

  13. Emigration • Alleles move OUT OF a population

  14. Lots of gene flow… • Slows down evolution • Lots of new alleles coming into and out of a population • More genetic variation within a population • Makes 2 populations more similar

  15. Lack of gene flow… • Less variation within a population • Makes 2 populations more different and separates them

  16. Mutation • Any change in the genetic material of a cell • Can occur within individual genes OR • Can involve changes in piece of chromosomes

  17. If the mutation is beneficial to the organism, the mutation will be passed on to offspring • Slowly over time the mutation will become more common in a population

  18. Recombination • A source of heritable variation • Occurs for 2 reasons: • Independent assortment • Crossing over

  19. Independent Assortment

  20. Crossing Over

  21. Hardy-Weinberg Principle • States that allele frequencies in a population will remain constant unless one ore more factors cause those frequencies to change

  22. Hardy-Weinberg Equation P2 + 2pq + q2 = 1 Homozygous dominant Homozygous recessive Heterozygous p = dominant allele frequency q = recessive allele frequency

  23. Genetic Equilibrium • The situation in which allele frequencies remain constant (don’t change) • If frequencies don’t change, the population doesn't evolve

  24. Conditions required to maintain genetic equilibrium: • Random mating • Population must be large • No immigration or emigration • No mutations • No natural selection

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