What do these birds
have in common? Very little, judging from their specialized beaks, body types,
and behaviors.
Yet close examination and molecular analyses reveal otherwise.
Each is a member of a family of birds called honeycreepers, and they all share
the same common ancestor: a single finchlike species that scientists estimate
arrived on the Hawaiian Islands about 5 million years ago. At one time there were
as many as 57 species of honeycreepers.
This is certainly not the first time living creatures have
taken the dramatic evolutionary pathway known as adaptive radiation. The
Species Gallery highlights some of the most
extraordinary outcomes of this very common process.
How can one species evolve in so many different directions?
|
