In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations?
A) selection for drab coloration of the algae-eaters
B) selection for nocturnal algae-eaters (active only at night)
C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young
D) selection for algae-eaters that become sexually mature at smaller overall body sizes
E) selection for algae-eaters that are faster swimmers

Question

Quizplus · Accepted Answer

Selection for larger female algae-eaters, bearing broods composed of more and larger young, is least likely to be observed in a pike-cichlid predation environment. This is because larger females and larger broods would be more easily seen by pike-cichlids, increasing the risk of predation. Therefore, selection is more likely to favor individuals that produce smaller broods with smaller offspring that are less visible to predators. Drab coloration (A) and nocturnal behavior (B) could both help algae-eaters avoid visual detection by pike-cichlids, making them more likely to be selected for. Selection for smaller overall body sizes (D) could also make algae-eaters less visible to predators, and faster swimming (E) could improve their ability to escape predation.

In a Hypothetical Environment, Fishes Called Pike-Cichlids Are Visual Predators