Question

Cheetah tends to be lighter body weight, that is exhibited in its evolution during the 4 million years period. The original population of cheetah had variable weights but lighter cheetahs reproduced more successfully and passed such alleles to their offsprings. Thus, the population of such light weight cheetahs increased in the population. Answer the following question.

The above example is based on

• A. Directional selection
• B. Stabilizing selection
• C. Disruptive selection
• D. None of these

Answer 1

The correct option is B Stabilizing selection

Stabilizing selection is a type of natural selection in which genetic diversity decreases and the population mean stabilizes on a particular trait value. This is thought to be the most common mechanism of action for natural selection because most traits do not appear to change drastically over time. Stabilizing selection commonly uses negative selection (purifying selection) to select against extreme values of the character. So, the above example is based on stabilizing selection. Thus, option B is correct.
Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups. So, the above example is not based on disruptive selection. Thus, option C is wrong.
In population genetics, directional selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. So, the above example is not based on directional selection. Thus, option A is wrong.