1. 3 Ways Evolution Happens
1. Artificial selection
2. Genetic Drift
3. Natural selection

2. 1. Artificial Selection
The process by which humans change a species by breeding it for certain traits.
neck feathers
crop
tail feathers
Pigeon breeding
Bred for tail feathers
Bred for crop
Bred for neck feathers

3. 2. Genetic Drift “Chance” causes a small population.
Dramatic event
Small group leaves or is separated
Result: less genetic variety

4. 3. Natural Selection Its all about Variation!
Mutations - Small changes / Lots of time
Genetic Recombination (crossing over, Independent assortment & Segregation)

5. Fitness determines survival
Variation leads to differential fitness.
Some organisms survive better than others
Fitness determines which individuals survive and reproduce.
Must have a selective advantage or trait (gene) will not increase within a population.

6. Selected for: Selected against:
Helpful traits which help survival are selected for in a population and increase in frequency.
Harmful traits or unsuccessful traits are selected against in a population and decrease in frequency.
A harmful trait that does not affect fitness is not selected against, ie: Alzheimer’s

7. Examples of Evolution Occurring
Extinction
Pesticide Resistance
Antibiotic Resistance

8. Extinction All members of a population die out.
Loss of genetic diversity.
Can be global or regional

9. Pesticide resistance:
Have to come up with new and more toxic chemicals to combat pests.
Weeds
Insects

10. Antibiotic resistance:
Need for new antibiotics
Evolutionary arms race*