1. LEARNING OBJECTIVE
3. Differentiate between different types of Natural Selection and how they impact Evolution

2. Three Types of Natural Selection
1. Directional Selection
2. Stabilizing selection
3. Disruptive selection

3. 1. Directional Selection
Individuals at one end of the curve
have higher fitness than individuals in
middle or at other end.
Graph shifts to left or right

4. 2. Stabilizing Selection
Individuals in center of the curve
have higher fitness than individuals at
either end
Graph stays in same place but narrows as more organisms in middle are produced.

5. 3. Disruptive Selection Individuals at edges of the curve
have higher fitness than individuals in middle.
Can cause graph to split into two.
Selection creates two distinct PHENOTYPES

6. LEARNING OBJECTIVE
4. Define Genetic Drift & how it can change a small populations gene frequency.

7. Genetic Drift
In a small population a change in allele frequency based on chance is called Genetic Drift
Genetic drift can occur when
a small group
of individuals
colonizes a
new habitat.

8. Immigration, emigration & migration can have an effect on Genetic Drift by changing the alleles in the Gene Pool of a population

9. LEARNING OBJECTIVE
5. Explain how Genetic Equilibrium can block evolution and the required factors to do this

10. Genetic Equilibrium
There are some conditions that can block evolution and create a balanced and stable Gene Pool
1. Must be random mating (sexual selection)
2. Population must be large
3. No immigration or emigration
4. No mutations