Completed Q.
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. isolation by dispersal
B. isolation by vicariance
C. a form of sympatric speciation
D. only a rare development of polyploidy could lead to speciation in this case
E. speciation will not occur in this case because of gene flow
Answer
B. isolation by vicariance
Explanation:
The ant population was separated by an external factor which leads to habitat fragmentation. And the resulted disjoined distribution of ( ants) ended up in different isolated population. Since ants from their new habitats can not cross to other isolated habitats; and the ant population did not move out of the habitat on their own to from an isolated population but the new habitat was due to fragmentation by natural occurrence( flooding) and not by movements of the ants by themselves Then t is isolation by vicariance.
Therefore option B is the answer.
However if these ants can cross from one isolated habitat to another it will be isolated by dispersal. so B is the answer.
