We have evidence that the barren
island of Ascension aboriginally possessed less than half-a-dozen flowering
plants; yet many species have now become naturalised on it, as they have in
New Zealand and on every other oceanic island which can be named. In St.
Helena there is reason to believe that the naturalised plants and animals
have nearly or quite exterminated many native productions. He who admits
the doctrine of the creation of each separate species, will have to admit
that a sufficient number of the best adapted plants and animals were not
created for oceanic islands; for man has unintentionally stocked them far
more fully and perfectly than did nature.
Although in oceanic islands the species are few in number, the proportion
of endemic kinds (i.e. those found nowhere else in the world) is often
extremely large. If we compare, for instance, the number of endemic
land-shells in Madeira, or of endemic birds in the Galapagos Archipelago,
with the number found on any continent, and then compare the area of the
island with that of the continent, we shall see that this is true. This
fact might have been theoretically expected, for, as already explained,
species occasionally arriving, after long intervals of time in the new and
isolated district, and having to compete with new associates, would be
eminently liable to modification, and would often produce groups of
modified descendants.
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