Natural Selection and Evolution Concepts

The lecture covers natural selection as a key driver of evolution, alongside genetic drift and gene flow. It explains Darwin's theory and the criteria for natural selection, including gene transmission, selection pressure, and evolutionary fitness. The lecture uses a graph to illustrate phenotype distribution and discusses three types of natural selection: directional, disruptive, and stabilizing. Each type affects genetic variation differently, with directional selection favoring one extreme, disruptive selection favoring both extremes, and stabilizing selection favoring intermediate phenotypes. Overall, natural selection reduces genetic variation by favoring certain genes.

Which of the following is NOT a cause of evolution discussed in the lecture?

• Natural selection

• Gene flow

• Genetic drift

• Artificial selection

In the context of natural selection, what does evolutionary fitness refer to?

• The ability to find food

• The ability to migrate to new areas

• The ability to adapt to the environment and reproduce

• The ability to survive without reproducing

What is represented on the x-axis of the graph used in the lecture?

• Evolutionary fitness

• Phenotypes

• Types of natural selection

• Frequency of individuals

In directional selection, what happens to the population graph?

• It shifts to favor one extreme phenotype

• It shifts to favor intermediate phenotypes

• It splits into two peaks

• It remains unchanged

Which type of natural selection is illustrated when a population graph shows a bell curve shifting to one side?

• Disruptive selection

• Directional selection

• Balancing selection

• Stabilizing selection

Which type of natural selection favors both extreme phenotypes?

• Balancing selection

• Directional selection

• Disruptive selection

• Stabilizing selection

What is the result of disruptive selection on a population's phenotype distribution?

• A single peak at the intermediate phenotype

• Two peaks at the extreme phenotypes

• A flat distribution

• A single peak at one extreme phenotype

What is the main effect of stabilizing selection on a population?

• It has no effect on genetic variation

• It favors extreme phenotypes

• It increases genetic variation

• It favors intermediate phenotypes

Which type of natural selection decreases genetic variation by removing extreme phenotypes?

• Directional selection

• Disruptive selection

• Balancing selection

• Stabilizing selection

What happens to genetic variation in a population under any type of natural selection?

• It fluctuates randomly

• It decreases

• It remains the same

• It increases