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Darwin’s Finches

Darwin and his journey
Darwin travelled to the
Galapagos Islands on the HMS
Beagle
...
He stayed there for 5
weeks, in which Darwin only
collected a small number of
finch samples, forgetting to
record where he found them
...
According to Grant
(1986) Darwin stated that, "the
most curious fact is the perfect
gradation in the size of the
beaks of the different species of
Geospiza—Seeing this gradation
and diversity of structure in one
small, intimately related group
of birds, one might really fancy
that, from an original paucity of
birds in this archipelago, one
species had been taken and
modified for different ends
...
He found 14 different
types of finches
...

The theory suggested that these
individual isolated populations
would diverge to such an extent
that they would be unable to
produce viable offspring if they
bred, the main definition for
becoming a new species
...


By: Colette & Omar

History of the finches
The Galapagos Islands’ isolation long
ago ensured that none of the species
found in South America were found
here
...

South American ancestors of the
Darwin's Finches were likely blown
off course by strong winds
...
Here they began to
spread out across all of the individual
islands and breed
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Populations of birds on different
islands became isolated from each
other and a gradual accumulation of
small adaptations to the particular
environment led to the population's
characteristics drifting apart
...


Their beaks have evolved over
time to be best suited to their
function
...
Finches that eat buds
and fruit would be less
successful at doing this, while
their claw like beaks can grind
down their food and thus give
them a selective advantage in
circumstances where buds are
the only real food source for
finches
...




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