Question

In a population of plants, some were extremely tall and the remaining were extremely dwarf. No plants of the population showed intermediate height. The type of operation of natural selection in the above case is

• A. Balancing
• B. Directional
• C. Stabilizing
• D. Disruptive

Answer 1

The Correct Option is D

Disruptive Selection favors extreme phenotypes (very tall and very dwarf plants) over intermediate traits, splitting the population into two distinct groups.

Other Types of Selection:

• (A) Balancing: Maintains genetic diversity (e.g., heterozygote advantage).
• (B) Directional: Favors one extreme phenotype (e.g., taller plants only).
• (C) Stabilizing: Favors intermediate phenotypes (eliminates extremes).

Since, Both extremes coexisting without intermediates, the correct answer is disruptive selection (D).

Answer 2

Disruptive selection is a type of natural selection that favors individuals at both extremes of a trait distribution, rather than those with intermediate traits. This leads to a bimodal distribution, where the population diverges into two distinct groups. For example, in a population of birds with a range of beak sizes, birds with either very small or very large beaks may be favored over those with medium-sized beaks, which may not be as efficient at obtaining food. Over time, this can result in two distinct phenotypic groups within the population, potentially leading to speciation.

Other types:

• (B) Directional: Favors one extreme (e.g., only tall plants).
• (C) Stabilizing: Favors intermediates (e.g., medium height).
• (A) Balancing: Maintains genetic diversity (e.g., heterozygote advantage).

Correct Answer: (D) Disruptive selection