An oil spill causes the middle of a bay to become uninhabitable, pushing the organisms living there to the perimeter.

A road bisecting a forest forces many organisms to retreat to the outlying trees, where they are more vulnerable to predators.

A housing development constructed in the middle of a field prevents organisms on one side of the field from crossing to the other side.

A law that makes it legal to hunt wolves in certain areas results in a dramatic increase in nearby elk populations.

An increase in the number of people moving to a lakeside community results in the lake being overfished.