Question

Following is the diagrammatic representation of the operation of natural selection of different traits. Which of the following options correctly identifies all three graphs A, B, and C. 

A.

A	B	C
Directional	Stabilising	Disruptive

 B.

Stabilising

Directional

Disruptive

 C.

Disruptive

Stabilising

Directional

 D.

Directional

Disruptive

Stabilising

Answer 1

Hint:  Natural selection is the process by which populations of living organisms change and adapt. Individuals in the general population are inherently variable, which means they are all different in certain ways. This variation means that certain individuals have characteristics more suited to the environment than others.

Complete step-by-step answer:
Graph A, B, and C show stabilising, directional and disruptive traits of natural selection.
In stabilizing selection, the median phenotype is chosen at the time of natural selection and does not tilt the bell curve in any manner. Instead, this makes the peak of the bell curve even greater than what would be considered normal.
Directional selection of natural selection is named after the shape of an approximate bell curve that is formed when all individual traits are plotted. Rather than the bell curve falling directly in the middle of the axes on which they are drawn, it tilts either to the right or the left by different degrees. Consequently, it has moved in one direction or another.
In disruptive selection rather than the bell curve that has one peak in the middle, it has two peaks with one valley in the middle of them.

Therefore the correct answer is Option B.

Note: Stabilizing selection leads to a reduction of a population‘s genetic variance when natural selection favours an average phenotype and chooses as opposed to extreme variations. In directional selection, a population’s genetic variance moves toward a new phenotype when subjected to changes in the environment. Diversifying or disruptive selection raises genetic variance when natural selection chooses two or more extreme phenotypes that everyone has particular advantages.