Question

Male rhinoceros beetles have horns that they use to fight each other. Despite the competitive advantage of having large horns, horn length never exceeds two thirds of their body length. What form of selection explains why horn length is constrained?

• A. Directional selection
• B. Disruptive selection
• C. Artificial selection
• D. Stabilizing selection

Hint:

Stabilizing selection is often observed in traits where extreme values are disadvantageous for survival or reproduction.

Answer 1

The Correct Option is D

Step 1: Understanding Stabilizing selection.
Stabilizing selection occurs when extreme values of a trait are selected against, and intermediate values are favored. In this case, both very large and very small horn lengths are disadvantageous, and beetles with moderate horn lengths have a reproductive advantage. 
Step 2: Explanation of the other options.
Directional selection favors extreme traits in one direction.
Disruptive selection favors extreme traits at both ends.
Artificial selection is driven by human intervention.