There is an island in the middle of a large river that houses a large population of ants. Damming of the river causes the island to flood and only the highest points of the island are now above water. The ants cannot swim, so are now in multiple isolated populations. Which of the following best describes this event?
A) This situation represents isolation by vicariance.
B) This situation represents isolation by dispersal.
C) This situation represents a form of s
D) Speciation will not occur in this case because of gene flow
E) Only a rare development of polyploidy could lead to speciation in this case.

Isolation by vicariance is known to occur when a large population of an organism is divided or broken up, because a barrier suddenly appeared. This situation usually affect the flow of the genes, that is characters , which will occur through natural selection.

In this case, the flood that occurred, through the damming of the water, is the barrier that occurred suddenly, which separated the population of the ants, and will or may automatically prevent transfer of characters.