Q23-4TYU - Campbell Biology

Question

There are 25 individuals in population 1, all with genotype AA, and there are 40 individuals in population 2, all with genotype aa. Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation most likely resulted from

(A) genetic drift.

(B) gene flow.

(C) nonrandom mating.

(D) directional selection.

Step-by-Step Solution

Answer

1. The statement “genetic drift” is true.

2. The statement “gene flow” is false.

3. The statement “nonrandom mating” is false.

4. The statement “directional selection” is false.

Step 1: Environmental condition

Environmental conditions refer to those factors like temperature, mutagens, light, gender, and humidity affecting genes expression in an organism.

Step 2: Explanation of option ‘(A)’

The evolutionary mechanism in which allelic frequency goes up and down randomly in generations over time is called genetic drift. The genetic drift occurs repeatedly and gets influenced by a small population size until the allele is involved or lost within a population.

Thus, genetic variation (variation in gene sequence) that occurs in both small and large populations with different genotypes is due to the genetic drift.

Therefore, the given statement is true.

Step 3: Explanation of option ‘(B)’

Population genetics describes gene flow as a concept in which allelic movement changes the gene frequency of the population due to migration.

Thus, gene flow prevents genetic variation rather than introducing the change within the population; exchanging allelic frequency is associated with gene flow.

Therefore, the given statement is false.

Step 4: Explanation of option ‘(C)’

When individuals choose to select their mating partner and that chosen mate must have superior physical traits, it is called nonrandom mating.

Thus, nonrandom mating results in sexual dimorphism rather than acting on genetic variation.

Therefore, the given statement is false.

Step 5: Explanation of option ‘(D)’

The natural selection process in which a living organism with extreme phenotypic range is favored over other traits is called directional selection.

Thus, genetic drift results in genetic variation instead of directional selection for alteration in allele frequency.

Therefore, the given statement is false.