Question

identify which type of natural selection is described in each case below.
results in the evolution of the species: disruptive selection
results in new species:
favors traits at the two e
no increase in diversity: disruptive selection
one extreme trait is favo
diversity decreases:
diversity increases:
done

Explanation:

To solve this, we recall the types of natural selection:

• Disruptive selection: Favors extreme traits at both ends, increases diversity, can lead to new species (as populations diverge).
• Directional selection: Favors one extreme trait, shifts the population mean, no new species (just trait shift).
• Stabilizing selection: Favors intermediate traits, reduces diversity (no extreme traits), maintains species stability.

1. Results in new species:

Disruptive selection drives populations with extreme traits apart, potentially leading to speciation.

2. Favors traits at the two extremes:

By definition, disruptive selection favors traits at both ends of the spectrum.

3. No increase in diversity:

Stabilizing selection (or directional) reduces diversity. Stabilizing selects for the mean, so diversity decreases. Directional shifts to one extreme (also reduces diversity). But “no increase” matches stabilizing (or directional). However, if the option is stabilizing (from the dropdown), that’s correct.

4. One extreme trait is favored:

Directional selection favors one extreme trait (e.g., larger beaks in birds).

5. Diversity decreases:

Stabilizing selection (favors the middle, reduces extremes) or directional (shifts to one extreme, reduces the other). Stabilizing is a better fit here (maintains the status quo, reduces variation).

6. Diversity increases:

Disruptive selection (favors both extremes, increasing variation).

Answer:

• Results in new species: disruptive selection
• Favors traits at the two extremes: disruptive selection
• No increase in diversity: stabilizing selection (or directional, but from dropdown, stabilizing is an option)
• One extreme trait is favored: directional selection
• Diversity decreases: stabilizing selection (or directional)
• Diversity increases: disruptive selection

(Note: For dropdowns, select the matching option from the list provided. For example, “Results in new species” → disruptive selection; “Favors traits at the two extremes” → disruptive selection; “No increase in diversity” → stabilizing selection; “One extreme trait is favored” → directional selection; “Diversity decreases” → stabilizing selection; “Diversity increases” → disruptive selection.)