The average survival rates of individuals of different sizes in a mouse population were assayed and are presented in the table. Assume that body size is at least partially heritable.Assuming that all other aspects are independent of size, this population is most likely experiencing _______ selection, and the variation in the population should _______ over many generations.
A) directional; increase
B) directional; decrease
C) stabilizing; increase
D) stabilizing; decrease
E) diversifying; increase

Question

The average survival rates of individuals of different sizes in a mouse population were assayed and are presented in the table.  Assume that body size is at least partially heritable.Assuming that all other aspects are independent of size, this population is most likely experiencing _______ selection, and the variation in the population should _______ over many generations.
A) directional; increase 
B) directional; decrease 
C) stabilizing; increase 
D) stabilizing; decrease 
E) diversifying; increase

Quizplus · Accepted Answer

Stabilizing selection favors individuals with intermediate traits, in this case, an intermediate body size. This indicates that there is already some degree of phenotypic convergence towards the average body size, which means that the variation in the population should decrease over many generations.

The Average Survival Rates of Individuals of Different Sizes in a Mouse