| ←Subtitle not present 1859 1860 1861 The
Probable
Effects of
the Action of Natural
Selection through
Divergence
of
Character
and
Extinction
,
on
the
Descendants
of
a
Common
Ancestor.
1866 1869 1872 |
| → ought to have 1859 1860 1861 1866 |
| has 1869 1872 |
|
|
individual body— a subject so well elucidated by Milne Edwards. No physiologist doubts that a stomach
adapted to digest vegetable matter alone, or flesh alone, draws most nutriment from these substances. So in the general economy of any land, the more widely and perfectly the animals and plants are diversified for different habits of life, so will a greater number of individuals be capable of there supporting themselves. A set of animals, with their organisation but little diversified, could hardly compete with a set more perfectly diversified in structure. It may be doubted, for instance, whether the Australian marsupials, which are divided into groups differing but little from each other, and feebly representing, as Mr. Waterhouse and others have remarked, our carnivorous, ruminant, and rodent mammals, could successfully compete with these
orders. In the Australian mammals, we see the process of diversification in an early and incomplete stage of development. →
|
| After the foregoing discussion, which
→ought to have
been much
we
assume that the modified descendants of any one species will succeed
so much the better as they become more diversified in structure, and are thus enabled to encroach on places occupied by other beings. Now let us see how this principle of
benefit being derived from divergence of character, combined with the principles of natural selection and of extinction,
to act. |
|
| The accompanying diagram will aid us in understanding this rather perplexing subject. Let A to L represent the species of a genus large in its own country; these species are supposed to resemble each other in unequal
as is so generally the case in nature, and as is represented in the diagram by the letters standing at unequal distances. I have said a large
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