Shown is a table of the results of a study of grasshoppers showing frequencies of different size classes, along with the average number of offspring these individuals produce. Assuming that size is a heritable trait (and that the number of offspring is a good proxy for the fitness of the phenotype), which type of selection is operating in this population?
A) Stabilizing selection
B) Directional selection for larger individuals
C) Directional selection for smaller individuals
D) Disruptive
E) Intersexual

Question

Shown is a table of the results of a study of grasshoppers showing frequencies of different size classes, along with the average number of offspring these individuals produce.  Assuming that size is a heritable trait (and that the number of offspring is a good proxy for the fitness of the phenotype), which type of selection is operating in this population?
A) Stabilizing selection 
B) Directional selection for larger individuals 
C) Directional selection for smaller individuals 
D) Disruptive 
E) Intersexual

Quizplus · Accepted Answer

With directional selection for smaller individuals, it is likely that smaller individuals have an advantage in this population and are more fit. This is supported by the fact that smaller individuals have a higher average number of offspring than larger individuals. This suggests that the smaller size trait is being selected for and will likely become more common in the population over time.

Shown Is a Table of the Results of a Study