| → structure of the animal to 1869 1872 |
| animal, by some modification of its structure, for 1859 1860 1861 1866 |
|
| → It is, however, 1869 1872 |
| But it is 1859 1860 1861 1866 |
|
| → into it like 1866 1869 1872 |
| like 1859 1860 1861 |
|
| ↑ 1 blocks not present in 1860 1861 1866 1869 1872; present in 1859 |
| Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.
|
|
| → of a species 1859 1860 1861 1866 1869 |
| OMIT 1872 |
|
| → of their own 1860 1861 1866 1869 |
| both of their own 1859 |
| proper to their 1872 |
|
| → OMIT 1869 1872 |
| on my theory, 1859 1860 1861 1866 |
|
|
species.
either case
it would be easy for natural selection to
the
→structure of the animal to
its changed habits, or exclusively
one of its several
habits.
→It is, however,
difficult to
and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often
almost simultaneously. Of cases of changed habits it will suffice merely to allude to that of the many British insects which now feed on exotic plants, or exclusively on artificial substances. Of diversified habits innumerable instances could be given: I have often watched a tyrant flycatcher (Saurophagus sulphuratus) in South America, hovering over one spot and then proceeding to another, like a kestrel, and at other times standing stationary on the margin of water, and then dashing
→into it like
a kingfisher at a fish. In our own country the larger titmouse (Parus major) may be seen climbing branches, almost like a creeper; it
like a shrike, kills small birds by blows on the head; and I have many times seen and heard it hammering the seeds of the yew on a branch, and thus breaking them like a nuthatch. In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching,
a whale, insects in the water. ↑
|
|
| As we sometimes see individuals
→of a species
following habits
different from those
→of their own
species and
the other species of the same genus, we might
→OMIT
that such individuals would occasionally
rise to new species, having anomalous habits, and with their structure either slightly or considerably modified from that of their
type. And such instances
occur in nature. Can a more striking instance of adaptation be given than that of a woodpecker for climbing trees and
seizing insects in the chinks of the
|
