| → species of the same genus, when 1859 1860 1861 1866 1869 |
| them, if 1872 |
|
| → climates! 1859 1860 1861 1866 |
| climates! In Russia the small Asiatic cockroach has everywhere driven before it its great congener. 1869 1872 |
|
| → has been known to 1866 1869 1872 |
| will 1859 1860 1861 |
|
|
|
| As
of the same genus
though by no means invariably,
similarity in habits and constitution, and always in structure, the struggle will generally be more severe between
→species of the same genus, when
they come into competition with each other, than between
of distinct genera. We see this in the recent extension over parts of the United States of one species of swallow having caused the decrease of another species. The recent increase of the missel-thrush in parts of Scotland has caused the decrease of the song-thrush. How frequently we hear of one species of rat taking the place of another species under the most different
→climates! In Russia the small Asiatic cockroach has everywhere driven before it its great congener. In Australia the imported hive-bee is rapidly exterminating the small, stingless native bee. One species of charlock
→has been known to
supplant
so in other cases. We can dimly see why the competition should be most severe between allied forms, which fill nearly the same place in the economy of nature; but probably in no one case could we precisely say why one species has been victorious over another in the great battle of life. |
|
| A corollary of the highest importance may be deduced from the foregoing remarks, namely, that the structure of every organic being is related, in the most essential yet often hidden manner, to that of all
organic beings, with which it comes into competition for food or residence, or from which it has to escape, or on which it preys. This is obvious in the structure of the teeth and talons of the tiger; and in that of the legs and claws of the parasite which clings to the hair on the
body.
|
