In a very large population, a quantitative trait has the following distribution pattern. If there is no gene flow, the curve shifts to the left or to the right, and the population size consequently increases over successive generations, which of the following is most likely occurring?
A) immigration or emigration
B) directional selection
C) disruptive selection
D) genetic drift

Question

In a very large population, a quantitative trait has the following distribution pattern. If there is no gene flow, the curve shifts to the left or to the right, and the population size consequently increases over successive generations, which of the following is most likely occurring?
A) immigration or emigration 
B) directional selection 
C) disruptive selection 
D) genetic drift

Quizplus · Accepted Answer

If the distribution pattern of a quantitative trait shifts to the left or the right over successive generations, it suggests that one extreme of the trait is being favored over the other. This is most likely due to directional selection, where natural selection acts to shift the frequency of a trait in one direction. Immigration or emigration would not cause a shift in distribution, and disruptive selection and genetic drift would not necessarily lead to a consistent shift in one direction.

In a Very Large Population, a Quantitative Trait Has the Following