Question

a scientist wrote a paper titled \directional selection in action\ after observing a population of mice for 15 years. the mice typically preferred to eat berries, although a few would also eat insects. after a drought in year 3, the scientist observed that more mice were eating insects. by year 10, most of the mice in the population ate insects in addition to berries. which best describes her article?
her title is accurate because two opposite extremes are favored.
her title is accurate because one extreme is favored.
she should change her title because she is observing stabilizing selection.
she should change her title because she is observing disruptive selection.

Explanation:

1. Recall types of natural selection:

• Directional selection: favors one extreme phenotype over others, shifting the population's trait distribution in one direction.
• Disruptive selection: favors two opposite extremes.
• Stabilizing selection: favors the intermediate phenotype, reducing variation.

1. Analyze the scenario: Initially, most mice ate berries (one extreme), a few ate insects (the other extreme). After drought, more ate insects, and by year 10, most ate insects (shifting toward the insect - eating extreme). This matches directional selection (favoring one extreme: insect - eating).

• Option 1: Wrong, two extremes favored is disruptive selection.
• Option 2: Correct, directional selection favors one extreme (insect - eating here).
• Option 3: Wrong, stabilizing selection favors the middle, not observed here.
• Option 4: Wrong, disruptive selection favors two extremes, not observed here.

Answer:

Her title is accurate because one extreme is favored.