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

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

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

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.

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

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

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.

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

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

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