Darwin's Rhea (Rhea darwinii); Darwin's
Finches (Geospiza)
The
ornithologist John Gould identified Darwin's South American "ostrich"
as a new species of rhea, and named it after its discoverer. Its
range is adjacent to that of the common rhea. In March 1837,
Darwin wrote in his notebook: "The same relation
that common ostrich bears to Petisse, extinct guanaco to recent:
in former case position, in latter time." That is, geographical relationships
mirror analogous relationships in time: there is
evidence of transmutation of species. Darwin's
biographer Janet Browne (1995) says "This moment more
than any other in Darwin's life deserves to be called a turning
point."
Darwin's
Finches (Geospiza) are similar to those on the South
American mainland, but show extensive variation in the forms of
their beaks even between adjacent islands. These specimens were
collected by Darwin himself and are kept in the British Museum.
Note the two specimens tagged in red:
this is a taxonomic convention to indicate type specimens
from which new species were first described.
