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Galapagos Islands
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Biological Evolution of the Galapagos
Whether in the sea staring into
the violet straight pupil of an octopus, observing a marine
iguana washed by waves gnawing at algae, or facing a serene
wisened tortoise-- any visitor to the Galapagos Islands can
not help but ponder, "how did such creature come into
existence?" And they would not be the first.
Considering the small size of these
islands, we feel the more astonished at the number of their
aboriginal beings, and at their confined range... Hence, both
in space and time, we seem to be brought somewhere near to
that great fact, that mystery of mysteries --the appearance
of the new beings on this earth.
Charles Darwin, 1845

In such a harsh and
unforgiving environment, it is difficult to believe that the
flora and fauna arriving by chance at these islands had any
hope to establish a dynasty of descendents. However the fact
remains, bringing more wonder during you tour, that life does
exist with such diversity in an environment that seems to
offer so little.
Certainly, many of the initial arrivals
to the islands did not come at an opportune time: at a time
without a mate to greet them, without a plant to feed on,
without a bit of soil to put down roots. Often, over the millions
of years that chance brought birds in a storm, sea lions and
penguins in currents, seeds across from the continent, the
first life to remain would have been "pioneer" species.
These species are those that can exist out of seemly nothing,
such as plants growing out of lava. They survive to die and
leave their organic material for the next wave of immigrants
--feeding the next flora, the next vegetarian creature.
Darwin's observations, specifically on
what are now called "Darwin's Finches," regarding
the adapted species that existed on the islands eventually
provided the basis for his Theory of Natural Selection. At
the time, it was a dynamic departure from the commonly held
belief that species were static. Explained briefly, the concept
of the evolution of species is based on a number of characteristics
of survival and reproduction. In most populations, the number
of species is larger than the available resources and competition
is inevitable. Within the normal variation that occurs in
species, occasionally a mutation or difference will occur
that will be somehow advantagous to survival or breeding,
and those with the positive change will have a greater number
of offspring. As the offspring are likely to receive these
same genetic advantages, they also will be more likely to
survive and pass on their genes. Those best adapted to their
environment, best specified and best adaptive will survive.
After years of isolation on the Galapagos,
where small populations of a species must have existed, adaptations
within that species would be more drastic as there was no
large mainstream population to act as a buffer for variations.
Often, variations of an ancestor are
apparent. The land iguanas of Santa Fe, distinct in their
yellow color, like their cousins on other islands have adapted
to eat cactus, spines and all. Their second cousins, the marine
iguanas, perhaps adapted to eat from the sea, avoiding the
competition on land. The most famous example are the 13 species
of Darwin's finches, all stemming from a single ancestor,
and adapting to such varying diets as cactus, parasites and
even blood. The process of adaptation is well documented in
Jonathan Weiner's "The Beak of the Finch," published
by Vintage Books.
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