Question

Given below are two statements:
Statement (I): Change of gene frequency in a population on immigration depends on immigration rate & difference of gene frequency between immigrants and natives.
Statement (II): The total genetic variance increases with increase in the inbreeding level in a population.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Inbreeding does not change the overall allele frequencies in a population.
However, it redistributes the alleles into homozygous genotypes, which increases the total genetic variance across the population.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The genetic structure of a population can be modified by evolutionary forces such as migration, mutation, selection, and systems of mating like inbreeding.
Understanding these dynamics is essential for managing genetic diversity in livestock herds.

Step 2: Detailed Explanation:
Let us evaluate both statements:
Statement (I) is correct.
Migration (immigration) introduces new alleles into a native population.
The change in gene frequency (\( \Delta p \)) due to migration is:
\[ \Delta p = m(p_m - p_0) \] where \( m \) is the rate of immigration, and \( (p_m - p_0) \) is the difference in gene frequency between the immigrants (\( p_m \)) and the natives (\( p_0 \)).
This shows the change depends directly on both factors.
Statement (II) is correct.
Inbreeding increases homozygosity by splitting a population into distinct homozygous lines.
While the genetic variance *within* inbred lines decreases, the genetic variance *between* these lines increases.
The total genetic variance of the entire population increases proportionally with the inbreeding coefficient (\( F \)):
\[ V_{Total} = V_G (1 + F) \] Therefore, both statements are correct.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.