Consider three populations of a plant species, each of which is isolated from other populations of the same species. Population X has had approximately 100 individuals in each generation for the past 200 generations. Population Y has had approximately 10 000 individuals in each generation for the past 200 generations. Population Z has had approximately 1 million individuals in each generation for the past 200 generations. If the environment changed and a new environmental condition exerted the exact same strength of directional selection on all three populations, which population would we expect to evolve most rapidly?

Question

Quizplus · Accepted Answer

Population size is inversely proportional to the rate of genetic drift. Genetic drift is a random change in allele frequencies that occurs in small populations and can lead to the loss of genetic variation. Directional selection is a type of natural selection that favors individuals with a particular trait. In this case, the new environmental condition exerts the exact same strength of directional selection on all three populations. Therefore, the population with the smallest population size (Population X) will experience the greatest amount of genetic drift and will evolve most slowly. The population with the largest population size (Population Z) will experience the least amount of genetic drift and will evolve most rapidly.

Consider Three Populations of a Plant Species, Each of Which