Question

In a population, stabilizing selection is the result of
                  (A) Founder effect
                  (B) Heterozygous advantage
                  (C) Population bottleneck
                  (D) Random mating
                  (E) Reproductive isolation

Answer 1

Hint:-A group of individuals belonging to the same species constitute a population. Genetic diversity is achieved when a particular trait has various alleles in a population. Genetic diversity within a population helps certain individuals adapt more readily to the changing environment. The study of this diversity is known as population genetics. Individuals may have certain traits that get selected over a period of time and help the individual survive in that particular environment.

Complete step-by-step solution:-
 When a small group of individuals with a common trait separate from a larger population, it is known as the founder effect. This greatly reduces the genetic variation in the population.
Heterozygous advantage is an advantage that the individuals with heterozygous genotype have. They are more likely to be selected over individuals that have homozygous recessive or dominant genotype.
Population bottleneck occurs when an unexpected event such as famine, reduces the size of a population. This could lead to loss of certain genotypes.
Random mating is a term used to describe the situation where an individual is equally likely to mate with all individuals of the opposite sex. They do not look for any particular characteristic in their mate that sets them apart from others.
Reproductive isolation is the process by which specific genotypes are contained. There is not much diversity within the isolated population after a point. All this leads to the formation of distinct species. Two distinct species may cohabitate the same area or a geographical barrier could have been the cause of speciation. Reproductive isolation can be achieved by a certain geographical barrier or physiological changes in the individuals. It could occur before or after the fertilization process occurs.
Stabilizing selection in a population refers to the selection of traits or genotypes that are not extreme (come somewhere in between two distinct genotypes).
The correct option is (B) heterozygous advantage.

Note:-
The other forms of selection include directional selection, disruptive selection and frequency-dependent selection.
When a particular trait is favored over the others, the population has more of that trait. This is known as directional selection. Disruptive selection is the type of selection wherein individuals with extremely distinct traits are favored. Frequency-dependent selection favors traits that are either rare or common depending upon the frequency with which it appears in a given population. All the selection processes are a part of natural selection and they influence evolution and survival of an organism.