Types of Natural Selection

1. How can we tell if evolution is occuring?

1.1. Compare expected allele frequencies with observed frequencies.

1.2. Hardy-Weinberg theory of genetic equilibrium

1.2.1. Equal number of breeding males and fremales

1.2.2. Random mating

1.2.3. No mutation

1.2.4. No gene flow

1.2.5. No genetic drift (infinite size)

1.2.6. If conditions met- no change

1.2.7. Hardy-Weinberg equations may be used as mathematical models to test hypotheses

1.2.8. Why is it important?

1.2.8.1. Measures allele and genotype frequencies in populations

1.3. Suggests both allele and genotype frequencies will remain in equilibrium under specific conditions

2. Directional

2.1. Selection of one homozygote

3. Diversifying/disruptive

3.1. Selection for both homozygotes

4. Stabilizing/balancing

4.1. Selection for the heterozygote