Question

Henry was studying two populations of the same species of lizards. One population lived on an island and the other lived on the mainland. Both populations were affected by a hurricane that hit the island and the mainland with equal force. A year later, Henry was testing the gene frequency and saw a decrease in genetic variation in the island species, but not in the mainland species. Which best describes a conclusion he might have reached? Gene flow greatly affects small populations, but large populations can recover. Genetic drift greatly affects small populations, but large populations can recover. Gene flow greatly affects large populations, but small populations can recover. Genetic drift greatly affects large populations, but small populations can recover.

Answer 1

Answer:

The correct option is Genetic drift greatly affects small populations, but large populations can recover.

Explanation:

Genetic drift is an evolutionary mechanism in which the allelic frequencies in a population change through many generations. Its effects are harder in a small-sized population.  

Genetic drift results in some alleles loss, even those that are beneficial for the population, and the fixation of some other alleles by an increase in their frequencies. The final consequence is to randomly attach one of the alleles.  

Genetic drift has important effects on a population when this last one reduces its size dramatically because of a disaster -bottleneck effect- or because of a population split -founder effect-.

In the exposed example, the hurricane caused a disaster in both populations, reducing the number of individuals on the island and in the mainland. Henry saw a decrease in genetic variation in the island species, but not in the mainland species. This could be because the island population was smaller than the mainland population, so it was more affected by the disaster. The loss of some alleles in the population caused a decrease in genetic variation in the island population.