A Small Number of Birds Arrive on an Island from a Neighboring

A small number of birds arrive on an island from a neighboring larger island.This small population begins to adapt to the new food plants available on the island,and their beaks begin to change.About twice a year,one or two more birds from the neighboring island arrive.These new arrivals

A) speed up the process of speciation.
B) tend to promote adaptation to the new food plants.
C) tend to retard adaptation to the new food plants.
D) represent a colonizing event.
E) decrease gene flow.