1. Mechanisms for Evolution
What drives evolution?

2. Genes within a Population
White moth: bb
Black moth: BB

3. Genetic Equilibrium (Hardy-Weinberg Equilibrium)
Allele frequency will not change if: 1. 2. 3. 4. 5.

4. What if there is genetic change?
Microevolution –
Drivers of Microevolution: 1. 2. 3. 4. 5.
Are these definitions really 1?Yes b/c genes influence phenotype and therefore change in organism

5. 1. Small Population Genetic drift – Small populations can result from
Example: 1 in 5 frogs is yellow and 60% of population is killed
Population 1
Population 2

7. Bottleneck Effect
Severe event reduces
Population size

8. Bottleneck Effect - Today
Northern Elephant Seal
1890s – 20 seals left due to overhunting

9. Founder Effect

10. 2. Gene flow (Migration)
Gene flow –
Population 2
Population 1

11. 3. Sexual Selection
Examples: bright colouration, elaborate tail

12. Physical Features
Example: Two male hippos fighting over territory

13. 4. Genetic Mutations What is a mutation? Beneficial mutation -
Harmful mutation –
Which would be selected for in a population? Which would be selected against?
Mutation – source of additional/change in genetic info

14. 5. Natural selection
“Survival of the Fittest”

15. Stabilizing Selection

16. Directional Selection
Example: Birds prefer to eat blue butterflies. Therefore, butterflies with a purple colouration are favoured in the environment

17. Disruptive Selection
Example: Birds prefer to eat medium-blue coloured butterflies. Therefore, white and purple butterflies are favoured

18. Sickle Cell Anemia in Africa
Distribution of Malaria VS
Distribution of Sickle Cell Anemia

19. Sickle Cell Anemia
Which individuals are favoured in Africa?

20. Summary