Unit 7 Topics 1-4

Who is the "Father of Evolution?

• Jean- Baptiste Lamarck

• Charles Darwin

• Aristotle

• Gregor Mendel

Which of the following evolves?

• Individuals

• Populations

Answer explanation

Individuals are selected for or against based on their phenotypic characters. That selection causes certain phenotypes to be more likely to survive and thus the frequency of the trait in the population will change. This means that the population has evolved not the individuals.

Which of the following is NOT a mode of natural selection?

• Directional

• Deconstructive

• Stabilizing

• Disruptive

Peppered moths became darker during the industrial revolution due to the trees becoming darker. What type of selection describes the peppered moth population?

• Directional

• Stabilizing

• Disruptive

Answer explanation

Before the industrial revolution, the moths were light. After the industrial revolution, the moths were dark. The frequency of the dark phenotype has increased; thus, it is DIRECTIONAL selection as phenotype has shifted towards ONE phenotype.

Birth weight averages between 6 to 8 pounds. Which type of selection describes birth weight of humans?

• Directional

• Stabilizing

• Disruptive

Answer explanation

The frequency of birth weights have maintained between 6 to 8 pounds. Since the weight has stabilized to the intermediate phenotype, this is STABILIZING selection.

Drought causes an absence of food for medium beaked birds. Which type of selection describes the bird population?

• Directional

• Stabilizing

• Disruptive

Answer explanation

As the food for the medium (intermediate) beaked birds decreased, these birds are less likely to survive. There is a decrease in the intermediate phenotype and an increase in the TWO extreme phenotypes, so this is DISRUPTIVE selection.

What is natural selection"

• Organism with less favorable traits are more likely to live

• Nature selects for the less favorable traits

• Organism with more favorable traits are more likely to live

• Nature selects against the most favorable traits.

Answer explanation

Individuals with more favorable traits will be more likely to survive. Since they are more likely to survive, they are more likely to leave offspring (and those offspring are more likely to survive). So, nature selects for the more favorable traits and against less favorable traits.

Evolution produces perfect organisms

• True

• False

Answer explanation

The environment is constantly changing thus the favorable traits are constantly changing. In addition, natural selection can only select from available phenotypes. If the mutation does not exist, it cannot be selected for.

How is artificial selection different than natural selection

• Artificial picks best traits for past events

• Artificial picks best traits for future events

• Artificial picks traits based on human’s interests

• Artificial picks traits based on predator/prey interests

Answer explanation

Artificial selection is human selecting for traits they find favorable.

For example:

Corn has two varieties: thin/small seeds vs fat/plump seeds. Farmers have utilized artificial selection to produce majority plump kernels by constantly planting plump seeds so over time majority of the population has plump seeds.

Peppered moths are an example of artificial selection.

• True

• False

Answer explanation

During the industrial revolution, humans caused the increase of smog and soot in the air which darkened the trees of the peppered moths’ habitat. Over many generations, it was observed that the moths underwent directional selection to a darker moth phenotype.

Although humans caused the selective pressure which led to the directional selection, nature still determined reproductive fitness of the phenotypes.