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, shifting the population's trait distribution.
• Disruptive selection: Favors two opposite extremes.
• Stabilizing selection: Favors intermediate phenotypes.

1. Analyze the scenario: Initially, most mice ate berries (one trait), after drought, more ate insects (a new extreme) and by year 10, most ate insects + berries (shifting toward the "eating insects" extreme). This is directional selection (favoring one extreme: insect-eating behavior over berry-only).
2. Evaluate options:

• First option: Disruptive (two extremes) – incorrect.
• Second option: Directional (favors one extreme) – matches.
• Third option: Stabilizing – incorrect (no intermediate favored).
• Fourth option: Disruptive – incorrect.

Answer:

Her title is accurate because one extreme is favored.