Chapter 16, Problem 5STP

Summary Introduction

Introduction :

Natural selection plays a key role in the evolution process. Natural selection is referred to the selection or favoring of those organisms among the population which is reproductively and physically more fit than the other organisms of the population. This is the key force that helps in the evolution process.

Answer to Problem 5STP

Correct answer :

Option A) Average sized features are selected for in population X.

Explanation of Solution

Explanation/justification for the correct answer :

Natural selection is of three types based on the characters/phenotypes which it favors and its long-term effects:

Disruptive Selection, Stabilizing Selection, Directional Selection.

Here, in the given question, there is Stabilizing selection as it favors the intermediate phenotypes of characters. Stabilizing natural selection occurs when the population stabilizes on the particular trait, here the genetic variance of the population is decreased.

Explanation for incorrect answer :

Option (B) Large features are selected for in population X. Large features referred are to as the extreme phenotypes.When they are favored by natural selection, this leads to disruptive selection. In this case, usually, two peaks would be formed.

Option (C) Small features are selected for in population X. proteins. Small features are referred to as extreme phenotypes.When they are favored by natural selection, this leads to disruptive selection. In this case, usually, two peaks would be formed.

Option (D) Average sized features are against in population X. When the features or phenotypes are selected against any species, this doesn’t lead to any natural selection. This can reduce the population size drastically.