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I. Mechanism of Evolution Populations evolve Gene pool : all the alleles from a populations Allelic frequency : % of al

I. Mechanism of Evolution Populations evolve Gene pool : all the alleles from a populations Allelic frequency : % of allele frequency Genetic equilibrium : frequency of alleles remain the same over time. B. Changes in genetic equilibrium 1. mutations 2. environmental factors

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I. Mechanism of Evolution Populations evolve Gene pool : all the alleles from a populations Allelic frequency : % of al

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  1. I. Mechanism of Evolution • Populations evolve • Gene pool: all the alleles from a populations • Allelic frequency: % of allele frequency • Genetic equilibrium: frequency of alleles remain the same over time

  2. B. Changes in genetic equilibrium 1. mutations 2. environmental factors 3. Genetic drift: alteration of alleles frequency by chance events. a. small populations = worst b. isolation, emigration, immigration

  3. C. Natural Selection 1. Traits have variations & these variations5or6chance of survival 2. Stabilizing: favors average individuals

  4. 3. Directional: favors one extreme 4. Disruptive: favors either extreme of a variation.

  5. 5. NS can alter genetic equilibrium of gene pool over time. D. Evolution of species 1. speciation: members of similar populations no longer interbreed to produce fertile offspring.

  6. 2. Barriers to prevent interbreeding a. geographic isolation (p.417) b. reproductive (temporal) isolation c. behavioral isolation

  7. E. Rate of speciation 1. gradualism: gradual change of adaptation 2. punctuated equilibrium: rapidly with long periods of genetic equilibrium between. (p.419)

  8. F. Patterns of Evolution 1. Adaptive radiation: species evolves to fit a # of diverse habitats. 2. Divergent evolution: species that were once similar to become more diverse and possibly a new species. (p.420)

  9. 3. Coevolution: 2 species evolve in response to each other b/c of similar environmental pressures.

  10. 4. Convergent Evolution: two species from different taxonomic groups evolve to become one

  11. G. Hardy- Weinberg equation 1. used to predict genotype frequencies in a pop that is not evolving 2. p2 + 2pq + q2 = 1

  12. 3. shows that frequencies can be predicted if the pop meets certain conditions: a. very large pop b. no emigration or immigration c. no mutations d. random mating e. no natural selection 4. Real pops rarely meet

  13. F. The millions of species alive today arose from a single original life form through a branching process called specialization

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