Types of Natural Selection

Label the natural selection graphs correctly...

• 1 Stabilizing, 2 Directional, 3 Disruptive

• 1 Disruptive, 2 Stabilizing, 3 Directional

• 1 Directional, 2 Stabilizing, 3 Disruptive

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NGSS.HS-LS4-3

NGSS.HS-LS4-4

A scientist measures the circumference of acorns in a population of oak trees and discovers that the most common circumference is 2 cm. There are very few acorns with circumferences of 3 cm or circumferences of 1 cm. Only the 2 cm circumference acorns survive.

• Stabilizing

• Directional

• Disruptive

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NGSS.HS-LS4-2

NGSS.HS-LS4-4

Starlings produce an average of five eggs. If there are more than five the parents cannot adequately feed the young. Fewer than five and predators may destroy them. As a result, five eggs becomes the most common number.

• Stabilizing

• Directional

• Disruptive

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NGSS.HS-LS4-2

NGSS.HS-LS4-4

Seed cracker birds have either large beaks or small beaks. They do not have medium sized beaks because medium sized beaks do not allow for adequate cracking of seeds.

• Stabilizing

• Directional

• Disruptive

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NGSS.HS-LS4-2

NGSS.HS-LS4-4

Explain how the beak size of finches on the Galápagos Islands is an example of natural selection.

• Finches with larger beaks were able to eat larger seeds and survived better during droughts.

• Finches with smaller beaks were more attractive to mates and reproduced more.

• Finches with colorful beaks were more likely to be seen by predators.

• Finches with medium-sized beaks were able to eat both small and large seeds equally well.

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DOK Level 2: Skill/Concept

Which of the following is an example of natural selection in action?

• A farmer breeding cows to produce more milk

• A population of moths becoming darker over generations due to industrial pollution

• A scientist genetically modifying bacteria to resist antibiotics

• A gardener cross-pollinating flowers to create new colors

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DOK Level 1: Recall

Describe a scenario where natural selection might lead to a change in a population of rabbits.

• Rabbits with thicker fur survive better in colder climates and reproduce more.

• Rabbits with longer ears are more likely to be caught by predators.

• Rabbits with shorter legs can run faster and escape predators.

• Rabbits with white fur are more visible in snowy environments.

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DOK Level 3: Strategic Thinking

A population of Madagascar hissing cockroaches lives in a woodpile. The cockroaches are eaten by lizards. Because the lizards have small heads, the lizards are unable to eat the very largest adult cockroaches, and instead prey upon small and medium sized adults. Over time, only the large headed lizards survive.

• Stabilizing

• Directional

• Disruptive

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NGSS.HS-LS4-2

NGSS.HS-LS4-4

Female birds that lay close to the optimum number of eggs have the most surviving offspring. Those that lay fewer or more eggs have lower relative fitness.

• Stabilizing

• Directional

• Disruptive

Tags

NGSS.HS-LS4-2

NGSS.HS-LS4-4

A population of birds with various size beaks eats seeds. Small seeds can be eaten by birds with small beaks. Larger, thicker seeds can only be eaten by birds with larger, thicker beaks. During a drought, only large thick seeds exist so only the large, thick-beaked birds survive.

• Stabilizing

• Directional

• Disruptive

Tags

NGSS.HS-LS4-2

NGSS.HS-LS4-4

NGSS.HS-LS4-5