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The Process of Evolution

The Process of Evolution. How it Works and How we See It. Topic Outline. Evolution in a Genetic Context - Microevolution Hardy-Weinberg Causes of Microevolution Natural Selection Types of Selection Maintenance of Variations Speciation Modes of Speciation. Background Vocabulary. Gene

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The Process of Evolution

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  1. The Process of Evolution How it Works and How we See It

  2. Topic Outline • Evolution in a Genetic Context - Microevolution • Hardy-Weinberg • Causes of Microevolution • Natural Selection • Types of Selection • Maintenance of Variations • Speciation • Modes of Speciation

  3. Background Vocabulary • Gene • Allele • Phenotype vs Genotype • Homozygous • Heterozygous • Gene pool • Microevolution • Polygenic (Quantitative) vs Monogenic Traits

  4. The Hardy-Weinberg Model p2 + 2pq + q2 And p+q=1

  5. What Does it Mean? • p=Frequency of Dominant allele • q=Frequency of recessive allele • p2=frequency of Homozygous dominant individuals • q2=frequency of homozygous recessive indviduals • 2pq=frequency of heterozygotes

  6. So What? • The Hardy-Weinberg principle states an equilibrium of allele frequencies in a gene pool of a sexually reproducing population, p2 + 2pq + q2, won’t change as long as certain conditions are met. What are these conditions?

  7. Example: Industrial Melanism

  8. Causes of Microevolution • Genetic Mutations • Gene Flow • Nonrandom Mating • Genetic Drift • Natural Selection

  9. MUTATIONS • Gene mutations -- -- the only source of new alleles • Chromosomal mutations -- -- alterations in the number, composition, or the arrangement of gene’s on a chromosome

  10. Chromosomal mutations

  11. Deletion

  12. Translocation

  13. Duplication

  14. Inversion

  15. Gene Flow Physical Movement of Alleles

  16. Nonrandom Mating Assortative mating Sexual selection

  17. Genetic Drift • Bottleneck Effect • Founder Effect

  18. Bottleneck Effect

  19. Founder Effect

  20. Founder Effect 2

  21. Natural Selection

  22. Types of Selection • Directional Selection • Stabilizing Selection • Disruptive Selection

  23. Directional Selection

  24. Stabilizing Selection

  25. Disruptive Selection

  26. Maintenance of Variations Are there any advantages to variation in a population?

  27. Sickle Cell Distribution

  28. Speciation • Species Definition • Morphological • Biological • Reproductive Isolation • Phylogenetic

  29. Species • A group of interbreeding populations that share a gene pool and are reproductively isolated from other species. • Subpopulations can exchange genes. Different species can’t.

  30. Reproductive Isolating Mechanisms Prezygotic Isolating Mechanisms Postzygotic Isolating Mechanisms

  31. Modes of Speciation • Allopatric Speciation-spatial separation • Sympatric Speciation- no spatial separation

  32. SYMPATRIC SPECIATION --EX SPECIES A: 2N=14, N = 7 DUPLICATION SPECIES A’: 2N=28 N = 14 SPECIES A X SPECIES B 2N=21 N=?

  33. Adaptive Radiation

  34. Review • Evolution in a Genetic Context - Microevolution • Hardy-Weinberg • Causes of Microevolution • Natural Selection • Types of Selection • Maintenance of Variations • Speciation • Modes of Speciation

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