Genetic Drift

Drawn to Scale High Chair Flat Tire

Genetic Drift Target: I will be able to define genetic drift, explain how founder and bottleneck effects result in genetic drift Genetic Drift: Chance events (not Natural Selection) that change the genetic composition of a population These random events change the allele frequencies over time. Pg. 73

They reduce the amount of genetic variation in the population Can cause fixation of one allele (One allele occurring over and over) Genetic Drift

Two types of Genetic Drift: 1. Founder Effect: The loss of genetic variation when a new colony is formed by a very small number of individuals (founders) from a larger population. Example: Polydactyly (extra fingers/toes) in the Old Order Amish of Pennsylvania

Gene Disorders Hit Amish Hard

2. Bottleneck Effect: The dramatic loss of genetic variation due to environmental effects or human activities.

Ex: Earthquakes, fires, droughts, over hunting, destroying habits Summary:

Two Types of Drift Founder Effect Bottleneck Effect Draw a real life example for each type of genetic drift, and the effects on the resulting populations *Use a minimum of 4 colors Pg. 72