GRE Exam Dumps : GRE General Test

No act is done purely for the benefit of

Claim: others

All actions—even those that seem to be done

for other people—are based on self-interest.

Reason-

Write a response in which you discuss the extent to which you agree or disagree with the claim and the reason on which that claim is based.

As originally formulated, the selfish-herd theory of prey species aggregation assumed that predatory attacks were equally likely to be launched from any position within the environment. In some circumstances (e.g.. avian predators attacking prey from above), such an approach is appropriate. However, as James et at. argue, in many predator-prey associations, attacks are unlikely to occur from positions within the group. For example, it is likely that an ambushing predator waiting in the path of a group would be detected before the group moves over its position. Hence, in many ecological situations, predatory attacks on grouped prey will occur exclusively from outside the group. In such circumstances, there is a strong premium to a group member in being in the interior of the group.

The passage suggests that compared to members of the prey groups in "some circumstances." certain members of the prey groups in "many ecological situations" are likely to be less

In 1995 the United States National Park Service reintroduced wolves into Yellowstone National Park, from which they had been eliminated decades before by overhunting. Biologists hoped the reintroduction would return the park's mix of animals to a more natural state. After the wolves disappearance, the population of their onetime prey, the elk. had burgeoned. Subsequently, new tree growth declined as multiplying elk browsed young trees, denuding certain areas of the park. Following the wolves" return, the elk population declined and young trees rebounded. Most scientists attribute the vegetation changes to the wolves1 return. However. Ration observes that Yellowstone has not had a harsh winter since wolf numbers reached high levels and suggests that elk may not have needed to resort to trees for food.

It can be inferred from the passage that the scientists would he most likely to cite which of the following in support of their view?