AKS 10b1 Types of Natural Selection - Scenarios

There are 2 types of worms: worms that eat at night (nocturnal) and worms that eat during the day (diurnal). The birds eat during the day and seem to be eating ONLY the diurnal worms. The nocturnal worms are in their burrows during this time. Each spring when the worms reproduce, they have about 500 babies but only 100 of these 500 ever become old enough to reproduce.

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones with medium coats. It is fall, soon to be winter. The temperatures are dropping rapidly and the bears must be kept warm, or they will freeze to death. Many of the bears have had ~2 cubs each but due to the extreme temperatures, many mothers only have one cub left.

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-5

Starlings produce an average of five eggs in each clutch. If there are more than five, the parents cannot adequately feed the young. If there are fewer than five, predators may destroy the entire clutch. This is an example of

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

The occurrence of large or small beak sizes among seed crackers in the absence of medium sized beaks is an example of

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

Panthers with teeth that are too short have difficulty capturing prey, while panthers with teeth that are too long have difficulty chewing their food

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

Spotted brown-and-white butterflies blend into lichen-covered tree bark, making it difficult for predators to see them, while solid brown and solid white butterflies are easier to see and get eaten.

• Stabilizing Selection

• Disruptive selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-3

Larger squirrels can carry larger acorns to their burrows, and they outcompete smaller squirrels when acorn supplies are limited

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

NGSS.HS-LS4-3

In a lake in South Africa, guppies are eaten by the pike fish, and the larger the guppy, the more difficulty it has escaping its pike fish predator.

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

NGSS.HS-LS4-3

The rocks at the bottom of a stream are either black or white. Snails that live on these rocks are a range of color from solid black to gray to solid white. A local freshwater fish loves to munch on these snails, but it cannot see the solid black or solid white snails when the snails are on matching rocks. Grey does not blend into either rock color and is much easier to see.

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4

NGSS.HS-LS4-2

Human babies usually do not survive if they are born under 4 pounds because their organs are too small to work properly; they cannot be born if they are too big because the mother would not be able to give birth without dying.

• Stabilizing Selection

• Disruptive Selection

• Directional Selection

Tags

NGSS.HS-LS4-4