Darwin's finches show only microevolution. In a long-term study, the
changes were small and oscillated back and forth. They show no evidence
for macroevolution.
The extensive work on Darwin's finches done by the Grants shows in some
detail how microevolution works, including details of transmutation
and the power of natural selection (Weiner 1994). In the years that
the Grants have been studying the finches, we would not expect to see
macroevolution.
Darwin's finches show a pattern of morphological differences that
indicate that they all derived from a common ancestor. The difference
between the woodpecker finch and the large ground finch are about as
great as those within the whole finch family. Darwin's finches do not
show macroevolution occurring, but they are evidence that it has
occurred.
References:
Weiner, J., 1994. (See below.)
Further Reading:
Weiner, Jonathan, 1994. The Beak of the Finch: A story of evolution in
our time. New York: Knopf.
Grant, B. Rosemary and Peter R. Grant, 2003. What Darwin's finches can
teach us about the evolutionary origin and regulation of biodiversity.
BioScience 53(10): 965-975.
