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4.  The Movement of Alleles  The Movement of Alleles Migration and Inter-breeding

5.  Random change in gene pool,  particularly powerful in small populations

8.  Small number of individuals from population migrate and form new population  May not carry all alleles in parent population  May carry alleles in different frequencies from parent population

9.  Catastrophic events (floods, diseases) leave a few survivors  Survivors may not carry all alleles in parent population  May carry alleles in different frequencies from parent population

11. Evolutionary Force Variation within population Variation between populations MutationIncreases Gene FlowIncreasesDecreases Genetic DriftDecreasesIncreases Natural SelectionDecreases or stabilizes Increases

12.  Time › Mutation and natural selection produce change over time › Enough time (and change) leads to appearance of new “kind”  Reproductive isolation › No gene flow to reduce differences between populations › Mutations, genetic drift, and natural selection increase differences