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Do Now.

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Presentation on theme: "Do Now."— Presentation transcript:

1 Do Now

2 Unit 4 Retakes! SIGN UP/ RETAKE Due by Thursday, March 27

3 Genetic Drift

4 Add in gene flow

5 Cheetahs

6 What is genetic drift? Genetic drift: any event that randomly changes the gene pool and often decreases genetic variation

7 Example 1: Reproductive Chance

8 Example 2: Disasters! Fire, Lightning, Earthquake, Tsunami, etc

9 Selective Breeding Selective Breeding is the process of breeding plants and animals together to get the most desired traits Selective breeding = artificial selection (It’s not a natural process) Scientists will typically take two organisms, each with helpful mutations and cross them

10 Selective Breeding Examples
Farming Breeding of animals

11 Thoroughbred Horses

12 When does genetic drift have a big impact?
Genetic drift has the biggest impact when the population is small.

13 What are two types of genetic drift that have a big impact?
Bottleneck effect: the result of a disaster event which greatly reduces population size, including decreased genetic variation With teddy grahams

14 Another way of thinking about the bottleneck effect

15 What are two types of genetic drift that have a big impact?
2. Founder effect: the result of starting a new population with a small number of individuals, including changes in the gene pool and decreased genetic variation

16 Compare genetic drift to natural selection
Both Natural Selection In genetic drift, the survivors are just lucky because genetic drift is completely random. Genetic drift and natural selection are both ways that populations change/ evolve. In natural selection, the survivors are those with advantageous traits.

17


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