Body size is a heritable trait in the amphipod, and aquatic crustacean. fish preferentially consume large amphipods, leaving primarily small amphipods to breed. based on these observations, how would we expect evolution to affect ponds with and without fish?

Since fish feeds primarily on large amphipod, therefore what we expect to remain to evolve on ponds containing fish would be smaller amphipod or crustacean. Then correct answer to this question would be:

“Ponds with fish should have smaller amphipods.”

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.