Answer:
a. Modes of selection exerted by wasps: <u>directional (positive) and stabilizing</u>
If the galls are small in size, wasps are able to penetrate through and easily feed off of it. Hence, an average or large gall size of Eurosta is more likely to survive.
b. Modes of selection exerted by birds: <u>directional (negative) and stabilizing</u>
Birds will get attracted to large sized galls. Hence, the average and smaller sized galls of Eurosta are more likely to survive
c. Mode of selection exerted by beetles: <u>disruptive</u>
Beetles favor feeding on the average sized galls of Eurosta. Hence, the two extreme sizes - small and large galls of Eurosta - are more likely to survive. This will give two peaks if allele frequencies are plotted on a graph.