Genetic Drift and Natural Selection in Populations

The video tutorial covers events influencing allele frequencies, focusing on genetic drift and gene flow. Genetic drift includes the founder and bottleneck effects, where chance events alter allele frequencies. Gene flow involves the movement of alleles through immigration and emigration. The video also explains types of natural selection: directional, disruptive, and stabilizing, using examples to illustrate how these processes affect populations.

What is genetic drift primarily caused by?

• Mutations

• Chance events

• Gene flow

• Natural selection

In the founder effect, what happens to a small group of individuals?

• They become isolated from the larger population

• They undergo rapid evolution

• They migrate to a new continent

• They become extinct

What is the bottleneck effect compared to?

• A narrow bridge

• Shaking marbles out of a bottle

• A sieve

• A funnel

What is gene flow primarily associated with?

• Natural disasters

• Immigration and emigration

• Genetic mutations

• Selective breeding

Which type of natural selection results in a shift of the entire population's phenotype in one direction?

• Disruptive selection

• Stabilizing selection

• Random selection

• Directional selection

In disruptive selection, which phenotypes are favored?

• Recessive phenotypes

• Extreme phenotypes

• Dominant phenotypes

• Intermediate phenotypes

What happens to the population variation in stabilizing selection?

• It becomes wider

• It becomes narrower

• It remains the same

• It becomes random

Which type of natural selection is likely to occur if the environment has patches of very dark and very light areas?

• Directional selection

• Stabilizing selection

• Random selection

• Disruptive selection

What is the result of stabilizing selection on extreme phenotypes?

• They are favored

• They are selected against

• They become more common

• They remain unchanged

Which type of selection would likely occur if the environment changes to favor one extreme phenotype over others?

• Disruptive selection

• Stabilizing selection

• Directional selection

• Random selection