Do Now

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

Genetic Drift

Add in gene flow

Cheetahs

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

Example 1: Reproductive Chance

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

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

Selective Breeding Examples Farming Breeding of animals

Thoroughbred Horses

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

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

Another way of thinking about the bottleneck effect

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

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.